K&N Air Intakes, 9.4 more horsepower!! WOW!- Mtbr.com
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  1. #1
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    K&N Air Intakes, 9.4 more horsepower!! WOW!

    Dumb..not to mention that you usually have to at least reset the ECU, not to mention an upgraded ECU is usually best to fully utilize such things and a restrictive exhaust still limits you and means on most cars there'll be virutally no gain unless you open up the exhaust too. But damn it sounds good!
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  2. #2
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    You can reset the ECU on most vehicles in about 15 seconds. Depending on the vehicle you can actually get reasonable gains, but it is still money better spent on suspension.

  3. #3
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    A new K&N filter gives you gains of a few HP that you may or may not feel. The problem is that it does not trap all of the dirt particles that will flow to it so your engine gets a lot more dirt than it would normally get until the oil on the media catches enough dirt to actually start to filter the air well enough to compare to a standard paper filter that you would otherwise be using. Here's the surprise: when the filter is trapping the dirt like a standard filter it flows like one, too. The downside is that you had to allow a bunch of dirt into your engine before this stage, thereby cutting the life of your engine shorter than it should be. Do this test: put the filter up to a light and see just how much light you can see through it.

    I once watched as a mechanic pulled a K&N cone filter off a car. The filter was maintained by the owner according to the instructions from K&N. He then pulled the intake tract down to the inlet of the turbo and there was fine dirt lining the inside of the intake, not to mention the layer of oil that contaminated his expensive MAF. The turbo compressor was getting sandblasted for however many miles it took for the filter to clog up enough to actually filter the dirt. The owner of that car put his airbox back on and went back to a standard air filter and swore off K&N filters.

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    You have echoed what I was thinking, but didn't say in the interest of not being rude.

    The aftermarket is full of stuff that looks cool, sounds cool, but isn't really cool

    The same can be said for many exhaust and intake setups out there, an engine is designed to flow a certain amount of cfm from the factory, and no manner of aftermarket stuff can change that unless, and until you do Internal modifications to the engine that increases the engines cfm of flow. Granted, there used to be some very restrictive exhausts done for the sake of emissions, but today's engines are largely past that point. There is a reason they put a pipe of a particular size on there, leave it be until/unless it's justified. Otherwise, your just blowing money needlessly, making a lot of noise and actually going SLOWER for the most part

  5. #5
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    I was gonna say...

    Quote Originally Posted by pcguy
    You have echoed what I was thinking, but didn't say in the interest of not being rude.

    The aftermarket is full of stuff that looks cool, sounds cool, but isn't really cool

    The same can be said for many exhaust and intake setups out there, an engine is designed to flow a certain amount of cfm from the factory, and no manner of aftermarket stuff can change that unless, and until you do Internal modifications to the engine that increases the engines cfm of flow. Granted, there used to be some very restrictive exhausts done for the sake of emissions, but today's engines are largely past that point. There is a reason they put a pipe of a particular size on there, leave it be until/unless it's justified. Otherwise, your just blowing money needlessly, making a lot of noise and actually going SLOWER for the most part
    I'm always intersted in a few more horsies, especically if they are cheap. I hear the most restrictive part of the intake is those long mainfold runners, not the airflow meter, throttle body, intake box or anything else that is easily upgraded. The thing is, those long intake runners are exactly why the VW engines make so much low end torque. They do so at the expense of top end horsepower, which you don't really use anyway.

    I'll probably do better by chipping the ECU.

  6. #6
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    I've got a K&N stuffed into the factory air box on my Ru, with the sides of the box cut out for the big vroom, and a gutted y-pipe straight back to a Cherry Bomb. That's gotta bump me up to 94, maybe 95 HP.

  7. #7
    PCC
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    Quote Originally Posted by pcguy
    You have echoed what I was thinking, but didn't say in the interest of not being rude.

    The aftermarket is full of stuff that looks cool, sounds cool, but isn't really cool

    The same can be said for many exhaust and intake setups out there, an engine is designed to flow a certain amount of cfm from the factory, and no manner of aftermarket stuff can change that unless, and until you do Internal modifications to the engine that increases the engines cfm of flow. Granted, there used to be some very restrictive exhausts done for the sake of emissions, but today's engines are largely past that point. There is a reason they put a pipe of a particular size on there, leave it be until/unless it's justified. Otherwise, your just blowing money needlessly, making a lot of noise and actually going SLOWER for the most part
    That doesn't apply to turbo engines because the turbo can be made to push more air into the engine until you reach the efficiency limits of the turbo itself. More air + more fuel = more horsepower. In the case of my '06 GLI, a downtube plus a chip can equal 40+ HP and over 100 ft/lbs of torque. A larger exhaust just makes more noise.

    Pimpbot, look at what the folks are doing to their cars on the forums at VWVortex. I have to admit that I haven't looked at performance mods to the 1.8T much.

  8. #8
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    horsepower is stupid.

    adding marginally effective parts for minimal gain doubly so.




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    With turbos the sky is the limit, just keep cranking up the boost, but eventually something goes BANG

  10. #10
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    The best is how people always think the HP increase they state can be added onto the peak HP, when it can be in a different range than where Peak HP is reached.

    The sludge in the intercooler is a great part of K&N's package, too.

  11. #11
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    They did a article in motor trend a while back, That tested stock intake & k&n intake on the same car & the k&n actually ran .1 slower than stock.
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  12. #12
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    Quote Originally Posted by PCC
    That doesn't apply to turbo engines because the turbo can be made to push more air into the engine until you reach the efficiency limits of the turbo itself. More air + more fuel = more horsepower. In the case of my '06 GLI, a downtube plus a chip can equal 40+ HP and over 100 ft/lbs of torque. A larger exhaust just makes more noise.

    Pimpbot, look at what the folks are doing to their cars on the forums at VWVortex. I have to admit that I haven't looked at performance mods to the 1.8T much.
    Not exactly, turbo engines still have limitations. That downtube and cat-back exhaust has to be opened up to really take advantage of ramming more air through the intake, so yes, you have to open up "both ends" to really take advantage of that "upgrade". I know, because I've done it. You already have a "larger exhaust" by going with that downpipe, because you're reducing the backpressure and allowing the exhaust gases to turn that turbo faster and quicker. Maybe it's not the exact same process with a non-turbo engine, but again, you still just can't put on an intake and get "gains".
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  13. #13
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    Quote Originally Posted by SUPASTAR2
    They did a article in motor trend a while back, That tested stock intake & k&n intake on the same car & the k&n actually ran .1 slower than stock.
    Sometimes due to increased heat, sometimes due to inaccurate MAF due to the different intake, and so on. There's lots of variables, those are some of the ones that affect the car I drive.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

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  14. #14
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    Quote Originally Posted by Jayem
    Sometimes due to increased heat, sometimes due to inaccurate MAF due to the different intake, and so on. There's lots of variables, those are some of the ones that affect the car I drive.
    my car is unaffected by variables. I have a special variable proof coating i had the dealership put on. Maybe you should look in to it.



    This thread is really funny.
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    I don't worry about peak HP, and I got gobs of torque.

    Don't need to win the race, when you can just run em over


  16. #16
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    Poor man mods..

    I find it amazing what cheap mods you can find by poking around the web for manufacturer forums. In one day i found that a amsoil filter, mod'd air box, and poor mans cat back could yield additional HP for my 4runner. Took me one weekend to do everything. Reset the ECU and it was great for the time i sold it.

  17. #17
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    alot of new cars dont require resetting the ECU as they have learning ECU's. You need to run the new part for a few weeks before it leanrs how to make the most of it.
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    Quote Originally Posted by dragonhead08
    alot of new cars dont require resetting the ECU as they have learning ECU's. You need to run the new part for a few weeks before it leanrs how to make the most of it.
    If by new you mean nearly everything thats fuel injected. OBD1 dates back to the 80s .... most every ECM switches back and forth between open and closed loop to adjust for changing conditions.

    You don't need to reset your ECM after an air filter change anymore than you need to after a change in outside temp or after driving to a different altitude.

    I personally prefer AEM dryflow filters. I noticed a nice MPG bump after install on my 5.3L chevrolet. Although I do still run a K&N on my turbo honda.

  19. #19
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    Quote Originally Posted by JFoster
    I personally prefer AEM dryflow filters. I noticed a nice MPG bump after install on my 5.3L chevrolet. Although I do still run a K&N on my turbo honda.
    The AEM filters did quite well for filtration ability too in a magazine shootout (I can't remember which one right now).

    I have a Fram Boost intake on my Jeep (won it). Exact same as the AEM intake. In fact, the instruction sheet had an AEM intake in the picture! Power feels the same, although it sounds different. MPG jumped a whopping 0.3 mpg, but it was the same time as we went from winter to summer blend gas, so that probably attributed more to the change than the intake. In all I view it as a big expensive accessory that did nothing for me, but then again, I paid nothing for it.


    As for K&N, I've seen testing results and first hand have seen dust passing the filter, so I won't use them anymore. I like how you can take a dry one and see bits of light thru the spaces in the fibers.

  20. #20
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    i like foam filters, they are reusable, they filter they best, and if you get one thats extremely large, it will flow very well
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  21. #21
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    I personally prefer to spend my extra cash on bike partz than car mods. I can get plenty of speeding tickets running stock, thank you.

    Make that stock, with the bike atop the car . . . .
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  22. #22
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    Putting a K&N filter or intake on a forced induction motor is kinda useless.

    Your engine is not struggling to suck air since the turbo is force feeding it. And the turbo is not going to be bothered by restriction. The end result is still going to be the amount of pressure your turbo supplies... regardless of what type of filter or intake you have installed.

    Spend your money on a new downpipe. Install a manual boost controller. Sure, the K&N sounds nice, but you just threw away some cash and chances are you are letting through more dirt. Its proven the K&N doesnt filter as efficiently as some other manufacturers out there.

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    plus if you aren't gonna replace your exhaust system and maybe even put some headers on ... you don't see the full benefits of a k&n.

  24. #24
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    In the Subaru world, headers are pointless unless you are going for big power (400hp plus)

    A good downpipe is all you really need, not to mention the rest of the exhaust. But its not cheap.

  25. #25
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    Quote Originally Posted by TheSubaruJunkie
    Install a manual boost controller.
    No, don't do that to an 04/05 due to the closed-loop ECU, you'll fry your engine as it will be ultra-lean and build up to full boost at partial throttle. In fact with a stock turbo and stage two flash, there really isn't much point because you easily overpower the injectors if you above 17 or so lbs of boost, and the turbo also goes out of it's efficiency range fairly quickly if you try to build up more. The solution is a bigger turbo of course, but in general MBCs aren't a good upgrade unless you have a bunch of other supporting mods (like a turbo) which need to then be controlled by the MBC. Other year wrxs though don't have as big a problem with this, 06 and on have bigger injectors, 03 and 02 don't have the screwy closed-loop ecu problem.
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  26. #26
    Uphill isn't a sport!!
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    Ahhh...

    My Subaru makes 8psi stock. After I installed my intercooler it dropped to 5. I installed a MBC to bring it back up and am now running 10. at 14 the ECU shuts off the fuel.

    Ive never owned a WRX, so thats news to me.

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    Quote Originally Posted by TheSubaruJunkie
    Ahhh...

    My Subaru makes 8psi stock. After I installed my intercooler it dropped to 5. I installed a MBC to bring it back up and am now running 10. at 14 the ECU shuts off the fuel.

    Ive never owned a WRX, so thats news to me.
    Dude, I don't think anybody here has your EA82T in mind.

  28. #28
    Uphill isn't a sport!!
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    Naw man, i sold that RX over a year ago and replaced it with a Turbo Legacy.

    EJ22T FTW!!!!

  29. #29
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    Subarus....

    Quote Originally Posted by TheSubaruJunkie
    Ahhh...

    My Subaru makes 8psi stock. After I installed my intercooler it dropped to 5. I installed a MBC to bring it back up and am now running 10. at 14 the ECU shuts off the fuel.

    Ive never owned a WRX, so thats news to me.
    ... don't come stock with an intercooler? What is this, 1980? I thought all turbos or supercharged engines were intercooled these days.

  30. #30
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    Nope,

    In Japan, Australia, New Zealand they came with Air to Water intercoolers. And of course all the WRX's had air to air. However, in 1993 (well, 1991 when the US Turbo Legacy was introduced) they did not have intercoolers. Nor did the 1986 to 1990 GL10/Loyale's.

    Good thing they are easy to install.

  31. #31
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    Quote Originally Posted by TheSubaruJunkie
    Putting a K&N filter or intake on a forced induction motor is kinda useless.

    Your engine is not struggling to suck air since the turbo is force feeding it. And the turbo is not going to be bothered by restriction. The end result is still going to be the amount of pressure your turbo supplies... regardless of what type of filter or intake you have installed.


    -Brian
    Not true.Intake upgrades have a greater effect on an FI car. Feeding a turbo cooler air translates to cooler IATs. And restricting the intake decreases efficientcy . Just because it will still build full boost doesn't mean its moving as many CFMs. The less efficient a turbo system is the more heat it generates, which translates into higher EGTs and higher risk of detonation.

  32. #32
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    Quote Originally Posted by JFoster
    Not true.Intake upgrades have a greater effect on an FI car. Feeding a turbo cooler air translates to cooler IATs. And restricting the intake decreases efficientcy . Just because it will still build full boost doesn't mean its moving as many CFMs. The less efficient a turbo system is the more heat it generates, which translates into higher EGTs and higher risk of detonation.
    Which is perhaps why the MKV GTI has an intercooler . . . .

    I'm with Jayem, I would not put money into intake upgrades till I put a larger/better exhaust on the car and chipped it. Besides, suspension is the better mod anyway. Or perhaps a driving class to up your skillz.

  33. #33
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    Quote Originally Posted by Random Drivel
    Which is perhaps why the MKV GTI has an intercooler . . . .

    I'm with Jayem, I would not put money into intake upgrades till I put a larger/better exhaust on the car and chipped it. Besides, suspension is the better mod anyway. Or perhaps a driving class to up your skillz.
    It depends on the car. VW put a catalytic converter on the downpipe right at the exit of the turbo. While this is great for cold engine emissions it does kill some HP and causes some turbo lag. Aftermarket downpipes put a single catalytic converter downstream of the turbo like most other manufacturers do so there are horsepower gains to be made even if the diameter of the downpipe has not been changed.

    I don't buy that a turbo car cannot benefit from a less restrictive intake system. A car engine, whether turbocharged or supercharged or naturally aspirated, is still an air pump. The easier you make the flow of air going into or out of an engine the more power it will make. On a superaspirated engine this does not manifest itself as increased HP so much as a decrease in turbo lag. There are some gains to be made with a freer flowing intake but not all that much. To me it's not worth the negatives associated with an aftermarket intake system (increased dirt in the engine, increased noise, lighter wallet, not enough gains to be excited about, potential to be ticketed for a "modified car" - looks stock under the hood = better for me). Bigger gains can be made with a chip on a turbocharged car.

  34. #34
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    Quote Originally Posted by PCC
    I don't buy that a turbo car cannot benefit from a less restrictive intake system. A car engine, whether turbocharged or supercharged or naturally aspirated, is still an air pump. The easier you make the flow of air going into or out of an engine the more power it will make. .
    Not quite, you have to open both ends or it's simply not going to be able to breath. What comes in must go out, and you can't just "bolt on" an intake and get "gains". It doesn't work that way, and dynos prove this every day. There's a lot more to this in terms of cats, headers, the turbo size, design of the downpipe and how it affects the function of the wastegate, and so on. That's why most people see no gains with an "intake". If it were so simple the manufacturers would do it from the beginning.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

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  35. #35
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    Quote Originally Posted by Random Drivel
    Which is perhaps why the MKV GTI has an intercooler . . . .

    I'm with Jayem, I would not put money into intake upgrades till I put a larger/better exhaust on the car and chipped it. Besides, suspension is the better mod anyway. Or perhaps a driving class to up your skillz.
    An intercooler does provide a much cooler Intake Air Temp than a non intercooler set up, but no intercooler is 100% efficient ... infact most are far from it. So while the IAT will be much less than a non intercooled version it will never be as cool as the ambient air outside. Depending on the efficientcy of the set up the IAT will be a set percentage hotter than the ambient air temp ... lowering the temp of the air pulled in will reduce the temp of the air discharged.


    Quote Originally Posted by Jayem
    Not quite, you have to open both ends or it's simply not going to be able to breath. What comes in must go out, and you can't just "bolt on" an intake and get "gains". It doesn't work that way, and dynos prove this every day. There's a lot more to this in terms of cats, headers, the turbo size, design of the downpipe and how it affects the function of the wastegate, and so on. That's why most people see no gains with an "intake". If it were so simple the manufacturers would do it from the beginning.
    You can bolt on an intake only and see "gains" . As I pointed out earlier the AEM intake on my 1/2 ton with 5.3 made a noticeable difference, while most likely not the advertised 16hp there is a noticeable difference when passing or towing, and approx. 2-3mpg.

    As PCC said it depends alot on the design of the engine, and though exhaust and intakes mods do compliment each other that doesn't mean you won't see a gain unless you do both.

    Do to the emissions restrictions today OEM exhausts are typically the most restrictive part and most vehicles will see a more significant gain from a more free flowing exhaust. Like wise the AEM intake I put on my '01 Integra GSR made little difference, I would guess 0-2hp and ~1mpg.

    On my turbo car ('95 integra) the difference between 2.5" and 3" exhaust can be 20+ hp. And I have seen similar dyno gains posted by people switching from small foam filters to large K&Ns ... as the smaller filters just don't have the surface area required to pass the CFM a turbo can move.

    I tune with UberData and write my own fuel and timing maps and use a wideband 02 to monitor my adjustments... so I haven't had any experiences with plug and play chips. I'd like to try out a chip on the truck though, it could use any MPG gains I can get

  36. #36
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    Quote Originally Posted by JFoster

    You can bolt on an intake only and see "gains" . As I pointed out earlier the AEM intake on my 1/2 ton with 5.3 made a noticeable difference, while most likely not the advertised 16hp there is a noticeable difference when passing or towing, and approx. 2-3mpg.
    2-3mpg? Wouldn't you think if that was real manufacturers would do that right away? 2-3mpg is huge, and if it was that easy I'm sure they would be all over it. Besides, you don't gain mpg by having more power available.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

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    Quote Originally Posted by Jayem
    2-3mpg? Wouldn't you think if that was real manufacturers would do that right away? 2-3mpg is huge, and if it was that easy I'm sure they would be all over it. Besides, you don't gain mpg by having more power available.
    the problem is that some aftermarket intakes will create more sound. and that might be something everyone wants.

    sometimes the more power you have the better milage you get. for example the GTI posted above with a chip tuning program installed will give the car 2-3 more mpg due to the fact that the new programming makes the car run more air. stock HP is 200/200tq. with chip the engine now produces ~230hp/260tq. added power allows the driver to shift at lower rpms which saves you some gas.

  38. #38
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    Quote Originally Posted by Jayem
    2-3mpg? Wouldn't you think if that was real manufacturers would do that right away? 2-3mpg is huge, and if it was that easy I'm sure they would be all over it. Besides, you don't gain mpg by having more power available.
    Well I didn't make it up. I figure my average mpg after most every highway trip . Before the intake it was consistently around 15 mpg and after it has been between 17-18 mpg depending on average speed.

    And yes, when you increase efficientcy there is usually a gain in both hp and mpg.

    Quote Originally Posted by tpliquid
    the problem is that some aftermarket intakes will create more sound. and that might be something everyone wants.

    sometimes the more power you have the better milage you get. for example the GTI posted above with a chip tuning program installed will give the car 2-3 more mpg due to the fact that the new programming makes the car run more air. stock HP is 200/200tq. with chip the engine now produces ~230hp/260tq. added power allows the driver to shift at lower rpms which saves you some gas.
    You're right, with both my intake only vehicles there is a noticeable difference in tone upon acceleration but it is minimal and I liked it. I am hesitant to replace my truck exhaust as I don't want it to be loud at all.

    I run my honda a little bit leaner than usual (about 15:1 vs 14.7:1) in the cruising / vacuum portion of the map and average 34-36mpg on the hwy vs ~28mpg when stock with ~100 less horse power.

  39. #39
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    Quote Originally Posted by tpliquid
    sometimes the more power you have the better milage you get. for example the GTI posted above with a chip tuning program installed will give the car 2-3 more mpg due to the fact that the new programming makes the car run more air. stock HP is 200/200tq. with chip the engine now produces ~230hp/260tq. added power allows the driver to shift at lower rpms which saves you some gas.
    +1 on making more power and getting a bump in mileage. The trick is to not abuse the extra power all the time.

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    Quote Originally Posted by PCC
    +1 on making more power and getting a bump in mileage. The trick is to not abuse the extra power all the time.
    +2 I have a GIAC flashed/chipped VW GLI - it gained around 40 HP if I remember but my mileage went up 2 MPG on my trip computers average MPG which i reset after getting the GIAC mod. I drive the same way to work and back every day.

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    Quote Originally Posted by Jayem
    2-3mpg? Wouldn't you think if that was real manufacturers would do that right away? 2-3mpg is huge, and if it was that easy I'm sure they would be all over it. Besides, you don't gain mpg by having more power available.
    OEM manufacturers have to make compromises, Jayem. Just because it's a gain in mpg doesn't mean it doesn't have it's pitfall(s) elsewhere.

    Come on, Jayem, you know better than this.


    But i'll give you a big pat on the back on your 'power does not equal better economy' retort. I love hearing kids these days ..... "yeah, and it makes more power so it get's better mileage". I like to screw around with their heads and ask them "so why don't we see Civics with Mustang engines in them then? Or Mustangs with a Nascar engine?!?!". The look on their faces is priceless as they all look at each other wondering why not.

    Lord love the marketing team!


    Anyway, back to bikes. Cars are for kids .....
    I ..... need ..... DIRT!!!!!

    ... and cookies. :D

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    What many people are ignoring, or unaware of, is that even a 2-3 mpg gain is HUGE for a manufacturer. Google CAFE standards to gain some insight.

    The problem with HP gains via intake/exhaust/remapping the ecu is that you are often affecting the emissions (something else that a manufacturer is constrained by) as well as noise (especially on cars sold in the EU, their noise standards are pretty strict) and theoretically the longevity of the engine.

    My car has been massaged to be more fun when I stomp on the throttle. It makes aabout 100 more hp/160+ more ft/lbs of torque but my average mpg has fallen. It might, fingers crossed, pass the smog sniff test. It's too loud to pass EU sound standards, CA DMV sound standards, etc.

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    Urinal mint, good points, but, there's much more to it than that. Engine longevity plays a part in all this. If, for example, VW had released their 2.0T engine, that is currently in the Audi A3, A4, VW GTI, GLI, Jetta, and Passat models, with 225 HP instead of 200 HP then the potential for engine component failures goes up exponentially. 25 HP may not seem like a lot but it does stress components, like the connecting rods, crankshaft, turbo, clutch, transaxle, halfshafts, etc, etc, etc, more over a long period of time. Also, gasoline quality varies from state to state, heck, even from station to station, not to mention the occasional driver who puts regular unleaded in their tank to save a few dollars when the manufacturer specifies premium unleaded. Also consider that they have to worry about the cost of the drivetrain and hitting price points so that a fickle customer would buy their product instead of another manufacturer's product.

    Another thing to consider is that manufacturers design their cars and engines (unlike what Ford had done back in the 70's and 80's) to last at least 100K, if not more. A slightly tweaked power output could potentially reduce the ability of the engine and other components to go the distance.

    As yet another thing to consider: we're talking about highly tuned engines here. Back in the Hot Rod era people were all amazed when an engine produced the magic 1 HP per cubic inch landmark. These days, we're talking about 1 HP per cubic centimeter, which equates to somewhere around 1.6 HP per cubic inch (this figure I pulled out of my butt so don't quote me on it - based on a 2 liter engine being about 122 cubic inches), whether naturally aspirated or superaspirated. These are very highly tuned engines and the higher you tune an engine the shorter its potential lifespan is. Back in the day it was acceptable to rebuild a tuned engine every 100K miles or so, nowadays, this is unacceptable because lesser tuned engines have gone over a quarter million miles.

    When VW/Audi put together the RS4 engine, which is basically the same engine that is in the GTI/GLI/et al, they beefed up almost the entire engine for that extra 40 HP. A lot of folks who chip tune these engines will tell you that the stock internals of the 200 HP engine can take the punishment of even 275 HP and more but what they don't tell you is that your engine's lifespan will be reduced as a result. VW/Audi didn't really need to beef up that engine for the extra power but they did it to increase the engine's longevity. I believe that Subaru did this as well with their STI engines compared to their non-STI counterparts but I don't know jack about Subarus other than that their exhaust note sounds out of tune to me.

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    Quote Originally Posted by PCC
    As yet another thing to consider: we're talking about highly tuned engines here. Back in the Hot Rod era people were all amazed when an engine produced the magic 1 HP per cubic inch landmark. These days, we're talking about 0.1 HP per cubic centimeter, which equates to somewhere around 1.6 HP per cubic inch (this figure I pulled out of my butt so don't quote me on it - based on a 2 liter engine being about 122 cubic inches)
    Agree with it all, fixed this part. 1 in^3 is roughly 16.4 c^3.

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    Quote Originally Posted by PCC
    Urinal mint, good points, but, there's much more to it than that. Engine longevity plays a part in all this.
    Sorry, that's so obvious that I didn't think it worth mentioning.

    Quote Originally Posted by PCC
    Also, gasoline quality varies from state to state, heck, even from station to station, not to mention the occasional driver who puts regular unleaded in their tank to save a few dollars when the manufacturer specifies premium unleaded.
    Running regular in a modern car that "requires" premium will not reduce the longevity of the engine or adversely affect it.

    You car will make less hp/torque (because the timing is retarded to prevent pre-detonation aka "knocking") but your wallet won't be quite as light.

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    Quote Originally Posted by urinal mint
    Sorry, that's so obvious that I didn't think it worth mentioning.



    Running regular in a modern car that "requires" premium will not reduce the longevity of the engine or adversely affect it.

    You car will make less hp/torque (because the timing is retarded to prevent pre-detonation aka "knocking") but your wallet won't be quite as light.
    I haven't actually done the math for the difference in wallet impact, but my GTi with a regular high compression non-turbo 4-banger loses 2-3 MPG consistently when I run regular grade gas. I usually run plus. I have found no difference when I run premium vs plus.

    My car doesn't require premium, BTW. In fact, the manual doesn't say it requires 89 grade either. 87 is regular grade around here. 89 is probably just enough to get it up the ignition advance curve to get out of the cruddy zone.. or something like that.

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    Quote Originally Posted by adam728
    Agree with it all, fixed this part. 1 in^3 is roughly 16.4 c^3.
    Thanks, adam, I was thinking of 100 HP per liter then messed up the calculation.

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    Quote Originally Posted by AndrewTO
    OEM manufacturers have to make compromises, Jayem. Just because it's a gain in mpg doesn't mean it doesn't have it's pitfall(s) elsewhere.

    Come on, Jayem, you know better than this.
    Well, the thing is that a bigger intake or an intake that somehow flows more air allows the injectors to then supply more fuel and more fuel and more air=more power. That's where you're extra HP comes from if any, because you can cram more fuel and air in there. Sounds good, but how does that equate to better milege with an "intake"? It's using more fuel to make that extra horsepower.
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    Basically more power allows you to run the same speed at a lower rpm. Fewer turns of the motor = fewer injector pulses = less fuel. To an extent. Its not all in the raw HP, the key is efficientcy.

    To comment on what AndrewTO was saying, mustang engines while powerful are far from efficient. While large displacement has the edge on raw power the japs have efficientcy (power per liter) dialed.

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    Quote Originally Posted by JFoster
    Basically more power allows you to run the same speed at a lower rpm. Fewer turns of the motor = fewer injector pulses = less fuel. To an extent. Its not all in the raw HP, the key is efficientcy.

    To comment on what AndrewTO was saying, mustang engines while powerful are far from efficient. While large displacement has the edge on raw power the japs have efficientcy (power per liter) dialed.
    Yeah, but your jamming as much or more gas in there as before, it's not "more power" that allows you to run "less power" at the same speed, you're running the same power at the same speed, because it takes a certain amount of power to maintain a certain speed.

    Think of it in terms of injector duty cycle or flow;

    If they can flow a certain amount of fuel per second, that is what allows you to maintain a certain speeds. If they can now flow more fuel per second, it will still take that SAME original amount of fuel to maintain that original speed, the difference is now you're capable of producing more power, reaching a higher speed, or getting to a speed faster, all of which will cause you to use more fuel, not less. Increasing the amount of fuel and air will not cause you to burn less fuel at a given speed. It also won't change the requirements to maintain that speed.

    Things that would cause you to burn less fuel would be things like lighter flywheels, lighter pulleys, less overall weight in the car, better aerodynamics, lighter wheels, better fuel atomization, etc. Increasing the amount of fuel and air will give you the ability to make more power, but it won't do the things like above, and it won't decrease the amount of fuel that you'll use. It goes back to what the poster said before, if "more power" is more fuel efficient, then why wouldn't they just put V8s and V12s in every car, and why aren't these V12 cars more fuel efficient? It's because mods like an intake (if sucessfull in terms of not messing up the MAF and other aspects) allow more fuel and air to go into an engine, and in the end that is where the power comes from, you can cram a whole lot more fuel and air in to a 6L V8 running at 5K rpm, and that in no way makes it "more efficient", it just gives it more power. Your efficiency goes down because you end up with more cylinders to move, more accessories or bigger ones needed (like bigger water pumps/fuel pumps), and the efficiency goes down.

    I guess it stems from the lack of understanding why you get more power and the requirements for a certain speed. The computer is going to put enough fuel and air in there to make you go a certain speed, that requirement isn't going to change by putting on an intake, because the requirement to go x speed takes y amount of fuel and z amount of air. So that's what the computer will do. If your intake allows you to make 5hp more, then you still be using y and z to go x speed, the difference is that now you can push the accelerator and go faster (and burn more fuel of course) or accelerate to that speed faster (and burn more fuel of course). When you make more power, it's y+ some figure that is now possible, and z+ some figure that is now possible, both due to the increase in airflow up to the limit of that airflow or injector. If two cars weigh the same with the same aerodynamics and other features and one has a 4cyl and one has a V12, they will both need the same power to maintain the same speed. The V12 will have to use more fuel to do so due to bigger required accessories. friction, and other factors, but they will both be making the same power at the wheels. The difference is that you may reach a point where the 4cyl engine can no longer meet that power requirement. But at the same speed, all things except the engine being equal, both will make the same power at the wheels. By upping the horsepower you have the potential to now drive faster, but the requirement to maintain a certain speed that you could maintain before is going to use the same amount of power as it did before.

    So putting an engine in any car with "more power" doesn't make it use less power at a given speed, that's just not the way it works.
    Last edited by Jayem; 04-16-2008 at 11:56 AM.
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    When you make changes to an intake or exhaust you potentially change the torque curve of the engine as well as it's volumetric efficiency at all different rpms/throttle positions. It is possible for a mod to increase power at wide open throttle and also increase efficiency durning normal driving.

    Look back to cars in the late 70's early 80's when emissions equipment was a massive burden on cars. I recall reading a fairly recent test in a Hot Rod mag where they took a Buick 455 and rebuilt it all to stock specs. Power was anemic, under 200 hp if I remember correctly. Wth just a cam swap they grabbed 40-50 hp and commented on the better fuel economy because the engine ran more effiecently. Ported stock heads and a better intake manifold had them near 100 hp gains, and after that an aftermarket carb swap bumped things up again. I think they ended up in the 340 hp range. (kind of sad now that you can do that with half the displacement now days, not even counting forced induction).

    As for stuffing a bigger engine in a car for better mileage, it does seem to work that way with the Jeep Wrangler guys. Dropping an older Dodge 360 or the new Hemi in a brick shaped TJ usually leads to better gas mileage than with the stock inline 6 trying to push it down the highway. I even read one article where a Viper V-10 swap yeilded as high as 24 mpg when driven right. Most 4 cylinder Jeeps won't see the high side of 20 mpg, and 18 mpg with the 6 cylinder is doing very well.

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    Quote Originally Posted by Jayem
    Yeah, but your jamming as much or more gas in there as before, it's not "more power" that allows you to run "less power" at the same speed, you're running the same power at the same speed, because it takes a certain amount of power to maintain a certain speed.

    Think of it in terms of injector duty cycle or flow;

    If they can flow a certain amount of fuel per second, that is what allows you to maintain a certain speeds. If they can now flow more fuel per second, it will still take that SAME original amount of fuel to maintain that original speed, the difference is now you're capable of producing more power, reaching a higher speed, or getting to a speed faster, all of which will cause you to use more fuel, not less. Increasing the amount of fuel and air will not cause you to burn less fuel at a given speed. It also won't change the requirements to maintain that speed.

    Things that would cause you to burn less fuel would be things like lighter flywheels, lighter pulleys, less overall weight in the car, better aerodynamics, lighter wheels, better fuel atomization, etc. Increasing the amount of fuel and air will give you the ability to make more power, but it won't do the things like above, and it won't decrease the amount of fuel that you'll use. It goes back to what the poster said before, if "more power" is more fuel efficient, then why wouldn't they just put V8s and V12s in every car, and why aren't these V12 cars more fuel efficient? It's because mods like an intake (if sucessfull in terms of not messing up the MAF and other aspects) allow more fuel and air to go into an engine, and in the end that is where the power comes from, you can cram a whole lot more fuel and air in to a 6L V8 running at 5K rpm, and that in no way makes it "more efficient", it just gives it more power. Your efficiency goes down because you end up with more cylinders to move, more accessories or bigger ones needed (like bigger water pumps/fuel pumps), and the efficiency goes down.

    I guess it stems from the lack of understanding why you get more power and the requirements for a certain speed. The computer is going to put enough fuel and air in there to make you go a certain speed, that requirement isn't going to change by putting on an intake, because the requirement to go x speed takes y amount of fuel and z amount of air. So that's what the computer will do. If your intake allows you to make 5hp more, then you still be using y and z to go x speed, the difference is that now you can push the accelerator and go faster (and burn more fuel of course) or accelerate to that speed faster (and burn more fuel of course). When you make more power, it's y+ some figure that is now possible, and z+ some figure that is now possible, both due to the increase in airflow up to the limit of that airflow or injector. If two cars weigh the same with the same aerodynamics and other features and one has a 4cyl and one has a V12, they will both need the same power to maintain the same speed. The V12 will have to use more fuel to do so due to bigger required accessories. friction, and other factors, but they will both be making the same power at the wheels. The difference is that you may reach a point where the 4cyl engine can no longer meet that power requirement. But at the same speed, all things except the engine being equal, both will make the same power at the wheels. By upping the horsepower you have the potential to now drive faster, but the requirement to maintain a certain speed that you could maintain before is going to use the same amount of power as it did before.

    So putting an engine in any car with "more power" doesn't make it use less power at a given speed, that's just not the way it works.
    But increasing the power of the existing engine does make it more efficient. You're looking at this in terms of adding displacement via larger engine, when the issue is more power from the same engine/displacement.

    In relation to how an air intake "can on some vehicles" increase mpg is related directly to Air Fuel Ratio. Cars do not tune in real time via wideband 02. They make computer generated guesses based off the reading of a narrow band 02 sensor. Narrow band is a very vague reading, and manufacture settings for the fuel map are fairly rich (safe). You can move in more air with modifications such as an intake without changing the reading of a narrow band 02(actually just decreasing the temp makes the charge denser and therefore moves in more oxygen in the same amount of air or CFM), resulting in leaner more powerful AFR thats actually closer to optimum 14.7:1 . As I have found you can actually go fairly lean (~15.5:1) in low labor portions of the fuel map such as cruising (Vacuum) with no issues like detonation. This becomes a more sensitive issue with chips or programs that advance ignition timing. This is the only reason my integra gets increased mileage, not from any power gain from the turbo ... the turbo isn't even spooled when cruising (Precision SC61 57/.63 AR ) I am in vacuum.

    Anyway, you have more air and the same fuel which actually makes more power everywhere. so just as you said :

    it's not "more power" that allows you to run "less power" at the same speed
    You're right, its more power that allows you to run fewer RPMs at the same speed.

    you're running the same power at the same speed, because it takes a certain amount of power to maintain a certain speed.

    Correct, so when you gain say 8hp throughout the cruising RPM range where you previously made ... lets say [email protected] and [email protected] , and you needed 228hp to run 60mph .... now you gain 8 hp and run [email protected] and the same 60mph. This results in fewer revolutions of the motor to do the same work as before, fewer revolutions means fewer intake cycles, and so fewer (or actually shorter) injector pulses .

    So in short, your car stock is probably a fair amount richer than the optimum 14.7:1 AFR and you MIGHT be able to lean it out a little with either freer flowing intake or exhaust and move closer to 14.7:1 and run more efficiently (better mpg).

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    Quote Originally Posted by JFoster
    Correct, so when you gain say 8hp throughout the cruising RPM range where you previously made ... lets say [email protected] and [email protected] , and you needed 228hp to run 60mph .... now you gain 8 hp and run [email protected] and the same 60mph. This results in fewer revolutions of the motor to do the same work as before, fewer revolutions means fewer intake cycles, and so fewer (or actually shorter) injector pulses .
    I am on your side in terms of mods can add power and help fuel effiecency. But I disagree with this part quotes above, as you would have to regear your car to see those gains (unless you have a CVT, and even then I am not sure the clutches are setup to relearn power curve changes). If your car spins 2000 rpm at 60 mph it will do so regardless of intake/exhaust/turbo/cam changes, unless you change the final gearing, tire height, or shift into a different gear.

    That and your power estimates are way high. Heck, my buddies completely un-aerodynamic Suzuki Samurai can cough along at 60 mph with only 55 hp under the hood. I recall reading sometime ago that an "average" sedan uses 30-35 hp to hold 55 mph.

    Engines are funny things, with TONS of variables involved. A mod might boost WOT power at say, 3000 rpm, but lower power at that same rpm when running the throttle only 10% open. Or it might help power at all throttle positions and rpm. Just need to test test test....

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    Quote Originally Posted by JFoster
    This results in fewer revolutions of the motor to do the same work as before, fewer revolutions means fewer intake cycles, and so fewer (or actually shorter) injector pulses .
    .
    Sure, but it also means more fuel per ingnition cycle, the intake allows more air, the injectors compensate with more fuel, this is where the increased power comes from, so despite that you may be able to have less intake cycles or injector pulses, you're putting more fuel in there for each cycle than you did before. How is that saving you fuel or getting you better milege?

    That just goes back to the thing before that it's going to take a fairly fixed amount of fuel and air to generate a certain amount of horsepower, and that amount of horsepower that is needed to go a certain speed is also fixed. You're not burning less fuel with less cycles when you're dumping more fuel in there with each cycle.
    Last edited by Jayem; 04-18-2008 at 10:10 AM.
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    Quote Originally Posted by adam728
    I am on your side in terms of mods can add power and help fuel effiecency.....
    Some can, but my big argument here is just an intake or a mod that just forces more fuel and air to be burned. It adds power, but doesn't increase efficiency. Better fuel atomization/dispersion might help with milege, lighter pulleys and flywheel might help, changing drive ratios might help, different size wheels might help, changing the mixture might help, and so on. Heck, putting a bigger turbo on my car can help because it takes longer to spool and if you drive it correctly, it actually increases milege if you're staying out of the crazy-boost range, but that's also difficult to do. Hot air intakes help with efficiency by limiting the amount of power (similer to the turbo before it hits it's boost range) and causing you to accelerate slower and burn less fuel. There are plenty of mods that can help increase efficiency, but few that make a huge difference by themselves, and 2-3mpg with an "intake" designed to make more power just doesn't make sense, unless it's screwed up the MAF and caused the engine to run way leaner (causing long term damage to the engine and components). One other problem is equating engine "efficiency" to milege, because it's not the same thing, although it has some effect, but there are other variables that can easily swing things in both directions.
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    I don't spend my money on car or bike crap. I save my money so I can invest it in stocks, bonds and 401K's and go from semi retired to fully retired. BTW, I drive a VW TDI, no biodiesel, no quality control in place,




    I want people to be able to eat cheap and have grain for beer from farmers at reasonable prices.

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    Quote Originally Posted by RandyBoy
    I don't spend my money on car or bike crap. I save my money so I can invest it in stocks, bonds and 401K's and go from semi retired to fully retired. BTW, I drive a VW TDI, no biodiesel, no quality control in place.
    Good for you. What does that have to do with this thread?
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    Quote Originally Posted by RandyBoy
    I want people to be able to eat cheap and have grain for beer from farmers at reasonable prices.
    then quit eating meat. for every 16 lbs. of grain fed to cattle the return is about 1 pound of meat. talk about a waste...

    on topic: high performance injectors increase mileage when driven "normally" because they atomize fuel more thoroughly due to the increased hole count on the nozzles. yes, they have the ABILITY to flow more fuel, but are not always doing so. the more atomized the fuel is, the less is required to achieve the same power.
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  59. #59
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    Quote Originally Posted by RandyBoy
    I don't spend my money on car or bike crap. I save my money so I can invest it in stocks, bonds and 401K's and go from semi retired to fully retired. BTW, I drive a VW TDI, no biodiesel, no quality control in place.
    What do you plan to do after you retire?

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    Quote Originally Posted by JFoster
    If by new you mean nearly everything thats fuel injected. OBD1 dates back to the 80s .... most every ECM switches back and forth between open and closed loop to adjust for changing conditions.

    You don't need to reset your ECM after an air filter change anymore than you need to after a change in outside temp or after driving to a different altitude.

    I personally prefer AEM dryflow filters. I noticed a nice MPG bump after install on my 5.3L chevrolet. Although I do still run a K&N on my turbo honda.
    nope, at least OBD 2 and not all are learning. It really depends on what car you have as not asll have them. Not all new cars have learning ECU's. I'm talking more along the line of the last 5 years. I wouldnt recommend an ECU reset as everything your ECU has learned as far as your driving habits would be lost. AEM dryflows are great filters but they lack a velocity stack that some of the tuned systems have, ie: S&B/Injen. AEM is great option for GM's as my father in law has seen a whole mess of transmissions get toasted from their AFM's clogged with filter oil.
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    Quote Originally Posted by adam728
    I am on your side in terms of mods can add power and help fuel effiecency. But I disagree with this part quotes above, as you would have to regear your car to see those gains ....
    you're right about the regearing, you wouldn't actually be able to run lower rpms and achieve the same speed ... you would run the same speed with less throttle input, as it would make the original power requirement sooner.


    Quote Originally Posted by Jayem
    Sure, but it also means more fuel per ingnition cycle, the intake allows more air, the injectors compensate with more fuel, this is where the increased power comes from, .
    No man, they don't see changes in air that accurately. Especially a MAP system, but even with a MAS system they measure in CFM . So just by using cooler denser air there is more oxygen in the same CFM so it runs slightly leaner as there is no change in CFM and so no additional fuel. Now at WOT there would be an increase in CFM and therefore fuel ... resulting in the peak power gain and probably less fuel mileage than originally under WOT. So I would agree with you in regards to the max power gain comes from both more air and fuel ... but the power increase during part throttle is primarily from a slightly leaner burn, which equates to slightly better MPG.

    Just to be clear I am not argueing just to argue ... just trying to share what I have found first hand.

    To elaborate on just how much of a large of a change can go unseen by a MAP/Narrow band 02 set up, I converted my 1980 IH ScoutII rock crawler from carb to GM fuel injection.

    So I pulled the throttle body fuel injection off an '88 suburban with a 350 and modified it to fit on my IH 345. Since the motors are fairly close in displacement it will run the 345 pretty well, but the 345 does not breathe as well as a 350 so it runs quite rich.

    Now as you and most people might think it would "see" the rich condition or the decrease in intake air volume and compensate, but its just not that sensitive. So while the difference is drastic enough to make the 345 run really rich and probably get super shitty mpg, its not drastic enough for the ECM to compensate or throw a rich code.

    In much the same way some mods can change the AFR to a leaner mix, and while it is lean enough to see a slight bump in MPG it is not lean enough for the ECM to respond with more fuel, or to be dangerous.

  62. #62
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    Quote Originally Posted by JFoster

    No man, they don't see changes in air that accurately. Especially a MAP system, but even with a MAS system they measure in CFM . So just by using cooler denser air there is more oxygen in the same CFM so it runs slightly leaner as there is no change in CFM and so no additional fuel. Now at WOT there would be an increase in CFM and therefore fuel ... resulting in the peak power gain and probably less fuel mileage than originally under WOT. So I would agree with you in regards to the max power gain comes from both more air and fuel ... but the power increase during part throttle is primarily from a slightly leaner burn, which equates to slightly better MPG.
    There is no gaurentee of "cooler and denser" air, "cold air intakes" might give this to you, but there's no gaurentee, but the O2 sensors (on various parts of the exhaust and so forth) also play into it and will adjust the parameters as necessary, so not everything is based on MAF. Otherwise, you might be sucking in hotter air, especially with a short-ram type intake. In any case, leaning out the mixture is not going to give you more power, the right amount of mixture for best power is different for best efficiency, and there's a certain amount of cylinder cooling that contributes to producing "best power", so things still are not adding up here, not to mention you aren't going to get more power unless you are burning more fuel (combusting with air), so either you're making more power or your not, or you are leaning out the mixture to a point where it's putting the engine components through more stress with more heat, but again, that isn't going to necessarily make any more power even.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

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  63. #63
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    Quote Originally Posted by Nat
    What do you plan to do after you retire?
    Ride my bike more, fly fish more, spend more time actively investing, and spending less time on MTBR!!!!.

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    Quote Originally Posted by Jayem
    Good for you. What does that have to do with this thread?
    Biodiesel and K & N = same deal, misrepresentation and being sold a bill of goods. Neither is better than The Original they try to replace. Both are inferior goods, compared to a factory air filter and D2 diesel fuel.

    Dont' get caught up in all the hype, the dirt doesn't. Just buy a K & N air filter sticker to stick on your air box if you want to look cool. Only a poseur actually installs the junk air filter K &N sells.

  65. #65
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    Quote Originally Posted by Jayem
    There is no gaurentee of "cooler and denser" air, "cold air intakes" might give this to you, but there's no gaurentee, .
    Right, just like the HP and MPG claims advertised are not garunteed ... some vehicles do see cooler intake temps and power/mpg gains, some don't ... thats true.

    Quote Originally Posted by Jayem
    , but the O2 sensors (on various parts of the exhaust and so forth) also play into it and will adjust the parameters as necessary, so not everything is based on MAF.
    No, a narrow band 02 sensor will not see a change as minor as an intake would make. They read RICH - GOOD - LEAN .... vague. Whereas my PLXM300 Wide band will read from full rich (10:1) to full lean (20:1) and be accurate to the 0.01 a narrow band has 3 ranges; rich (probably 10:1 - 13:1) good (probably 13:1- 17:1) lean (17-20) ... you can see the same vague signal the narrow band sends your ECM with a cheap guage


    As compared to the accurate numerical readout of a wideband


    So what I am saying is the motor can be running substantially lean or rich with out the ecm even knowing . Plenty of varience to affect mpg.


    Quote Originally Posted by Jayem
    In any case, leaning out the mixture is not going to give you more power, ..... not to mention you aren't going to get more power unless you are burning more fuel (combusting with air), so either you're making more power or your not,
    No, leaner is always more powerful up until the point it causes detonation.


    Quote Originally Posted by Jayem
    the right amount of mixture for best power is different for best efficiency,
    Right, NA cars usually achieve max power with around 13.5:1 AFR and turbo cars are usually around 12:1 . But this is only at WOT and would make for horrible mpg at part throttle. And 14.7:1 is commonly accepted as the magic number for part throttle for max efficiency.


    Quote Originally Posted by Jayem
    there's a certain amount of cylinder cooling that contributes to producing "best power",... you are leaning out the mixture to a point where it's putting the engine components through more stress with more heat, but again, that isn't going to necessarily make any more power even.
    No, there is a difference between leaner and a lean condition. By which I mean you can go from a 14:1 AFR to 14.7:1 which is leaner but actually closer to optimal, makes more power, gets better mpg, but does not cause heat or stress issues like a lean condition which would be more like 16:1.

    As I said earlier I have played with the cruise portion of my map to achieve max mpg and actually went as lean as 15.5:1 with no change in exhaust gas temp reading.

  66. #66
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    Quote Originally Posted by JFoster

    No, leaner is always more powerful up until the point it causes detonation.




    Right, NA cars usually achieve max power with around 13.5:1 AFR and turbo cars are usually around 12:1 . But this is only at WOT and would make for horrible mpg at part throttle. And 14.7:1 is commonly accepted as the magic number for part throttle for max efficiency.
    .
    No, not quite, the ratio remains the same regardless of turbo or not, the thing is that the heat generated by a turbo engine is immense so that's why it's 12:1 at WOT. At 12:1 it won't kill and cook every component. Stoiometric (sp) is what it is, it doesn't change with the engine or any other parameters really, it's a constant for all intents and purposes. My turbo engine does 14.7 at partial throttle and only 12:1ish at WOT, just as it should, but that 12:1 is to keep the temps and stress down on the engine.

    But please look this up, best efficiency is the leanest mixture you can maintain, maximum amount of heat generated, best power is rich of that point because the extra fuel helps to cool the cylinders and engine and produce more power. if you don't believe me, look it up.
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  67. #67
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    Quote Originally Posted by Jayem
    No, not quite, the ratio remains the same regardless of turbo or not, the thing is that the heat generated by a turbo engine is immense so that's why it's 12:1 at WOT. At 12:1 it won't kill and cook every component. Stoiometric (sp) is what it is, it doesn't change with the engine or any other parameters really, it's a constant for all intents and purposes. My turbo engine does 14.7 at partial throttle and only 12:1ish at WOT, just as it should, but that 12:1 is to keep the temps and stress down on the engine.

    But please look this up, best efficiency is the leanest mixture you can maintain, maximum amount of heat generated, best power is rich of that point because the extra fuel helps to cool the cylinders and engine and produce more power. if you don't believe me, look it up.
    best efficiency is the leanest mixture you can maintain - this is what I have been saying all along in regards to how an intake might increase MPG . A slightly leaner mix under part throttle can be more efficient, and achieve better mpg.

    best power is rich of that point because the extra fuel helps to cool the cylinders and engine and produce more power - Right, I also already agreed that peak power would only be seen at WOT due to more air AND fuel.

    What I am saying about leaner being more powerful is in regards to a rich condition, where in the vehicle is running somewhat rich of optimal... so leaning it out increases power.

    For instance if you played with the fuel maps for your car and changed it from where its at now (optimal 12:1 @ WOT) to a richer 10:1 @ WOT it would run like ass, pig rich. And so when you leaned it back out to 12:1 it would increase power, as leaner is more powerful up until the point it causes issues ie heat/knock/etc

    No, not quite, the ratio remains the same regardless of turbo or not - I am not sure what you mean here ... the ratio of 14.7:1 for part throttle is the same....but the FI car definately needs a richer ratio under WOT/full boost ... which I agree is due to the heat, the additional fuel helps dissapate the heat.

    Anyway, all that I am trying to put into this thread is that an air filter or intake or any other modification to the way an engine breathes can in some instances increase fuel mileage at part throttle (cruise) as the small amount of air increase is not substantial enough to merrit fuel increase from the ECM and therefore the vehicle which was running on the rich side of optimal is now slightly leaner and closer to optimal.

    I am not saying its garunteed. It will vary depending on vehicle. And engines that are relatively efficient in design to begin with will see less if any gain. But some vehicles can see an increase in MPG from an intake. Again from personal experience:

    '01 Acura Integra GSR 1.8L Vtec - Stock + AEM Short ram = 0mpg and no noticeable HP

    '00 Chevrolet 1500 4x4 5.3 Vortec - Stock + AEM Brute Force = 2-3mpg hwy and a felt power increase when towing or passing.

    I also wanted to point out to someone that mentioned velocity stacks. The AEM for my Acura did not include a velo stack but the AEM for my truck does utilize a stack at the filter.

  68. #68
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    The thing with mileage improving with tune goes something like this:

    More power means that you can shift earlier to maintain the same level of acceleration than you would if the car was not modified. Shifting earlier means that you are revving less per mile travelled and that means less fuel burned.

  69. #69
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    An ECU reset can help sometimes. Of course if its learning ECU then its going to learn it eventually anyway. Plus if you took some parts off while you tested out, you might get some trouble codes you want to clear out. But resetting the ECU can speed up the learning. It can just as easily slow it down if your net setup is very close to your old setup.

    cant hurt.

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    haha. Car talk on MTBR is almost as bad as it is on IRC.

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