Quote:
Originally posted by John Monnin
I think it is the timing issue that has caught everyone attention.
Because it shouldn't work, people don't believe him.
I believe it works on his car him I just think that we just don't quite understand why.
The other reason this caught so many people attention is because it is the only mod he had. A lot of people have gutted the MAS , at the same time they installed bigger injectors, or bigger turbos, or new intake or new exhaust...
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I've actually though of most of these possibilities.
I've decided that using the stock MAF allows the ecu to use certain parameters that do not need to be changed due to HP increases. In fact, some stock parameters are better left alone in many cases. I'm sure the engineers put a lot of thought into the drivabilty and smoothness aspects of the VR4 that some aftermarket MAF systems may diminish or eliminate entirley from the maps. Timing is one of the ones you want to keep a close eye on! . If you don't want knock, you don't want to go way beyond 22 degrees of advance up top. With my stock virgin MAF, my timing went over -29 at times, and that was not a good situation. Ever wonder why the car likes to run rich? Because running rich suppress the knock caused by the excessively advanced timing. Better to run leaner and have slightly less timing from what I've determined ,on this car in particular.
This mod allows more air to enter with less air restriction. Just like any larger MAF, it decreases spool up, which gives the car a snappier feeling, and more overall HP pretty much everywhere across the power band.
Since the Karman readings are lower now (even though there is more flow in theory) the ECU is somehow fooled into reducing the timing. I can't be bothered trying to figgure out why. I probably couldn't anway.
My Karman readings would peak near 2850, but at 2700 they would show a huge dip in flow and make the car go very lean between 5800 and 6400 rpm (13:1). That may be where others have fragged there engines. Just a thought....
Now my max HZ are 2700 @ 7200 rpm. The lower overall airflow value somehow is pleasing to the ECU and tining curve. I also found it was easier to tune a flat A/F reading with the gutted MAF. The MAF reads the increase in airflow smoothly all the way to redline with no spikes or dropoffs as before. So you effectively increase the gross flow accuracy and potential of the MAF. Using a wideband really gives you the edge . You can really feel this as it manifests itself as smoother throttle response and less jerkyness that the high correction factors on the AFC at lower rpmps cause. Keep in mind with 550 injectors, I'm at -15 now as opposed to -31. That will effect the low and partial throttle performance in a positive way.
My timing advance is roughly 6 degrees less advanced . Why it would work on my car and not others as John would suggest is possible is beyond me. I'm no engineer, but I know what works, and I know cause and effect.
The ONLY thing that may effect this mod is the Alamo IC's and pipes I have, flowing many more CFMs than stock units. So it's possible the gains I've experienced may not be as significant with stock IC's and piping to the CFM / restriction loss. Also really big injectors are gonna hurt your performance, mainly if they are too big for your needs. That's a biggy IMO.
Whatever the f*ck.... It works!
