Toyotec's how to make your MK3 16v breathe on a budget. Part 2 added 14-12-09

Discussion in '16-valve' started by Toyotec, Sep 13, 2009.

  1. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    So you have bought a MK3 16v in stdish form and you are eager to experience "the fury". Before going out on that loud pedal you start to read the threads on ClubGTi. Then the question comes...What filter is the best?
    Well yours truly decided to find out and to do that, it was essential to team up with the good guys at Streamline Garage, in London, to use their newly installed 2400BHP AWD Dyno Dynamics rollers [​IMG]
    to validate the typical air induction combination you would find on a MK3 today.

    These methods can be applied to most airboxes found on other engine types.

    First of all I would like to thank eatonMK2, VWsingh and cs98sss4 for the use of the specimen/victims in this study and of course Theo@Streamline for letting me loose on his dyno to perform the 25 tests back to back

    Now let the testing begin!
    [​IMG]

    The vehicle used in in this test is a 95 plate MK3 16v called N7NDO. It has a STD ABF engine with 113K miles. The only small mods are, ported throttle and matched inlet system.
    [​IMG]

    The filter configurations that where tested were;
    Open throttle-body ( thanks to the factory speed density digi 3.x system)
    Std VW airbox w/OE filter
    Std VW airbox w/K&N panel
    Piper pod filter
    Modified VW airbox top half, STD bottom half
    Modified VW airbox complete.
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]

    Each configuration was tested at least 2 times.
    The ambient air temp was 19 deg C.
    25 tests were run.

    After safely strapping down the vehicle on the rolls, the air ducting and and filter box were removed and the first power run was conducted.
    [​IMG]

    The throttle duct and the STD top half of the air box were installed and placed in line of the dyno fan.
    [​IMG]

    With the STD top half already in place, the standard panel filter was then compared to a K&N filter in the STD bottom half. A genuine VAG filter was used.

    This was later removed and a Piper cross pod filter was installed and then tested.
    [​IMG]

    Lastly a modified airbox, which had the OE tapered velocity stack modified and in its place a larger diameter and more bell mouthed unit, was tested with the standard bottom half and then a modified bottom half.
    [​IMG]

    Not one to focus on just peak power points we shall study what happened to the torque as ultimately this would affect peak bhp points if one follows the mathematical formula BHP=TQ*RPM/5252. I will state the peak power developed in concluding.

    Looking at the plots for 4 conditions,
    Open throttle - FlyBHP/TQ, AFR 1
    STD airbox - FlyBHP/TQ, AFR 6
    Pipercross Pod - FlyBHP/TQ, AFR 12
    Complete modified airbox - FlyBHP/TQ, AFR 25

    [​IMG]

    We can see that;
    • The torque deltas between tests is clearly evident post 4500rpm

    • The engine's PCM fuel calibration remains into closed loop control up to 4000rpm

    • Latter part of engine speed range the fuel mixture seems to be between open loop lambda and component protection lambda, this difference in AFR is correlated to torque development in tests

    • There are torque improvements when running the pod filter over the std airbox, but this may not be real world as the pod filter was inline of the dyno fan. In real service the engine bay heat would be conducted by the alloy silver surface of the filter, heat up the air-charge thus reducing torque. This combination also resulted in torque hanging on for longer in the engine speed range. The shorter induction length may have contributed to this effect.

    • The engine performed poorly when the throttle was open with any ducting. This may have been influenced by the hot air generated by the exhaust manifold just under the throttle.

    • There was no improvement when the VAG panel filter was swapped with the K&N unit, but airflow through the OE item would deteriorate after 10000miles. There was no improvement without a filter in the box.
    • The torque generation of the Pod filter was matched when the modified top half was attached to the STD bottom half

    • The best torque spread occurred when the complete modified airbox was installed


    Test 1, open throttle body, resulted in the in the worse torque curve and had peak bhp measurement of 142bhp@6200rpm

    Test 6, STD airbox, had improved torque range and resulted in 145bhp@6100rpm

    Test 12, Pipercross Pod filter, improved the torque range further and resulted in a peak of 148.5bhp@6500rpm

    My choice, Test 25, Modified air box and OE filter, improved torque even further than any of the other combinations and resulted in a peak power measurement of 151.2BHP@6200rpm
    [​IMG]

    I have always been a believer of this type of modification and this is evident of what you will find on The WOLF R, the 3A 8v MK2 on MS and my 98 VR6. Goes to show that you do not have to spend loads of money on a shiny new induction kit if you apply some thought and modify the existing factory unit. The above modification only about 10 pounds was spent, vs 60-70 pounds on an induction kit. It makes a similar but refined sound as an open pod filter.
    Hope this 10 pound modification inspires some to think next time you are about to shell out that hard earned.

    Next steps,
    • With the best air induction system now fitted, steps are on the way to optimize the ECU calibration.

    • First a typical chip will be fitted to study the effect of how these items actually fuel these engines and how this correlates to the torque generation.

    • As I am not a fan of desktop calibrations, the vehicle will be recalibrated on both fuel and spark over the entire speed load range.

    Keep watching this space.;)
     
    Last edited by a moderator: Oct 23, 2017
  2. Ess Three Forum Member

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    Superb stuff there! :thumbup:
    Thanks for posting.

    Did you do any testing of the fully modified airbox with a standard vs K&N panel filter?
    I found a slight, but repeatable, gain there.

    Overall though, I found the same...modified airbox works the best overall.

    Interestingly, the modified airbox you tested is the opposite to mine - I have the port in the lower section and the upper just smoothed. Similar results on the dyno though.


    Is that TB standard?
    Looks like it's had the ramps removed?

    That would have been an interesting swap too...I pick up another geniune, and repeatable, gain by swapping standard to modified TB.
    Ramps removed and smoothed gave a gain with no ill affects. Taking the casting right out and really working it have no more gains over the simple smoothed, and makes the throttle a tad jumpy on my car. No matter.

    I'll look forward to following your next steps.
     
  3. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    Last edited: Sep 13, 2009
  4. vw_singh Events Team Paid Member

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    Good work there Toyotec. :thumbup:

    Separating the truth from fiction. :clap:

    Gurds
     
  5. tshirt2k

    tshirt2k Forum Junkie

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    Good stuff. :thumbup: Would like an airbox for mine but space is a issue.
     
  6. Ess Three Forum Member

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    As said in the post there was no improvement when the K&N panel was swapped with the VAG item. The VAG item was new so this may have been the reason why. There was also no improvement w/o a filter. If there was it may have beem lost to test noise.
    I actually tested this condition 3 times.


    I read that as you tested the K&N vs Std in the standard airbox.
    I would have perhaps expected a fully modified airbox to find a slight gain from a K&N, where a standard may not.
    Certainly it seems that way from the testing I've done.


    I did that test too. Installed the modified bottom half with the extra hole with the std top half and these was a loss of torque compared to the complete modified unit, similar to when the halves are swapped around. In this condition the engine made the same torque trace as a pod filter. Smoothed boxes should have reduced turbulance in the airbox and would have have a positive influence on torque, but I did not have the time to further refine the airbox.

    Makes sense.
    I doubt one modified airbox differs from another by too much anyway, the basics are the same, smoothed of turbulence causing objects, larger volume with the hot air stuff binned and bigger inlet.


    Yes the throttle is smoothed and the inlet is matched. There is a slight increase in shuffle during light (traffic) tip-ins. Not that Joe-public would notice. I would have expected with the unmodified throttle, the torque ramp up from part load would have been faster then clip at a lower figure at WOT then drop out at an earlier engine speed.

    Sorry, I just spotted that in your original post.
    I thought it looked to be.

    I've tried 3 different 'attempts' at opening the TB up / including port matching (including really opening the casting up on a lathe) and I've never found anything gain wise from going further than that one...except more shuffle.


    The only other inlet option I tried was a home-brewed 75mm CAI with a large cone filter mounted behind the front bumper, in the airflow from the drivers side vent. This gave odd results in that it seemed to hold onto the peak power/torque longer than the modified airbox - but was noisy...Saxo noisy. So I binned it and went back to a modded airbox - as I have after trying every other form of inlet!
     
  7. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    OK. Maybe the OE filter suppliers have improved their filteration material as I can conclude there was very little pressure drop between 'no filter', std new VAG item and the new K&N panel. If there was I would not think you could tell this apart when on the road. All conditions had the same torque traces.
    I would expect at 10K miles the STD unit would be a problem.
     
    Last edited: Sep 13, 2009
  8. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    You could if you really wanted to. It was a bit tricky to fit an early Corrado VR6 unit to the WOLF R. But it was fitted in the end. Used all my brain cells on that piece of hardware :lol: :lol:
     
    Last edited: Sep 13, 2009
  9. paultownsend Forum Member

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    im glad i went with this option on my mk2 abf. would there be any benefit with using a different intake boot? its ribbed where it bends. surely it should be smooth for airflow?
    something like a mix of match of samco type hoses?
     
  10. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    The duct is actually has a larger crossectional ID than the throttle body. The improvement maybe so small that you would never feel it on the road!!
    Would be a good idea to test and see. If I had one at the time it would have been thrown into the test schedule.
     
  11. Ess Three Forum Member

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    I have tried it, with a home fabricated adaptor...
    No gains in the ass-dyno.
    No gains on the calibrated chassis dyno either.
    No surprise really!

    [​IMG]

    It's a pity I didn't know you were planning the testing, or I could have sent you a few bits to try (Inlet hose, 'Big' TB, different design of modded airbox etc).


    For reference, and to help anyone planning on having a go: (Toyotec, if you want these pics removing, just say...I don't want to take the thread off course)

    The CAI I fabricated and tried:
    [​IMG]

    Std TB vs Mod'd TB:
    [​IMG]

    Different modded airbox:
    [​IMG]

    [​IMG]
     
  12. Toyotec

    Toyotec CGTI Committee - Happy helper at large Admin

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    You would have gained some more airflow by adding a velocity stack to the top half as the air in the box does not flow straight. This would have increased the torque thoughout the rev range but more the post 4500rpm.
    I was to run a test with just the modified top half by itself, but sanity @11pm sort of took priorty!
    The square edges of the top half inlet tend to cause a bit of disruption to airflow. Hence the simple and cheap modification of cutting the factory velocity stack where the taper begins and fitting with a 180 degree bellmouth.The length of the velocity stack would influence how long the torque would stay high with engine speed.
    I have in the past crudely modified these boxes by just removing the VW tapered velocity stack and opening the bottom half towards the drivers fender arch and have felt more ar*e torque. Perhaps this should have been another validation test that could have been done.

    Main thing is for 10 quid, the home made modification gave a 9lbft increase over open throttle. And all that was required was a velocity stack, some creativity and to make an extra hole to the bottom half.
    For 70 quid an induction kit would have given about 7lbft increase.
    You could argue that 2lbft delta at the end of the rev range is nothing to be felt. But 60 is !:lol:
    .
     
    Last edited: Sep 13, 2009
  13. Ess Three Forum Member

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    It's hard to see in the pic, but it's smoothed and profiled with a Dremmel.
    There's afair bit of plastic there to have a go at.
    Not as good a job as fitting a proper bellmouth, but not a square edge either.

    Regardless, as you say, it's pretty much free of cost and gives a bigger gain than a fancy induction kit. :thumbup:
     
  14. Nige

    Nige Paid Member Paid Member

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    Great detailed report. Thanks for taking the time to do it and share the results !
     
  15. Matt82

    Matt82 Forum Addict

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    for the most BHP you need over 200k miles too
     
  16. Mike_H Forum Addict

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    Great work as always - I'm off to buy an OEM air filter for the track car!
     
  17. Matt82

    Matt82 Forum Addict

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    with a cotton or foam one you still ahve to buy the oil for them. waste of time
     
  18. dubDREAD

    dubDREAD Forum Member

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    very illuminating

    keep it comin
     
  19. monkeyzoo Forum Member

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    Can you describe in more detail exactly what mods were done to the air box?
     
  20. eatonmk2 Forum Member

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    Here's some pics of what I did.:thumbup:

    [​IMG]


    Also blocked off the hot air feed at the back of the bottem part. Removed the small bit that sits behind the headlight and open'd that up and fitting a cold air feed pipe that goes to the front bumper, plus cut a 3" hole next to the oem one as it's right behind the headlight,
    [​IMG]

    [​IMG]

    [​IMG]

    [​IMG]

    Smoothed off the wall around the new Jenvey air horn.
    [​IMG]
     
    Last edited by a moderator: Oct 23, 2017

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