GTM Performance Engineering 1000HP MAF CALIBRATIONN -ANOTHER MILE STONE

NewYorkJon34

Any updates on the GT-R manifold conversion kit?

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Vince@R/T

Congrats on the numbers!!!


I'm assuming you are using 2 UPREV GT MAF's in 3 in tubes?

SAM@GTM

Thank you

There is one source for those after market maf sensors, These are the same sensors that UPrev, AAM, AMS uses, We are just applying our own Calibration on them .

Sam

gabe3d

Great work Sam and I'm glad to see that things are moving ahead the way you envisioned them.

Nixlimited

This is no doubt an important achievement for the monster HP cars out there. Technically speaking, though, is there ever a way to get stock-type resolution with a MAF that still has the same voltage range and resolution (i.e. 0-5V in .01V increments)? Seems to me that no matter what, if you are pushing more air over the same range, then every increment (e.g. .01 volt) is going to represent a larger amount of incremental airflow such that your resolution is lower between those increments, right? My guess is that this is all academic, but it's always something I have been curious about. Is speed density / MAP metering any better when you get into these high HP applications?

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phunk

^^^ the ECUs interpolation inbetween set voltage increments should sort through that.

IMHO speed density is only great for one thing, being bullet proof. It has no proper ability to compensate for physical changes that effect volumetric efficiency, as its tuned directly assuming a specific and static VE.

But when I say I think the speed density is bullet proof, i mean that literally. You could blast a hole in the intake manifold and the engine will idle sky high but the engine will still be able to run and function! where a MAF car, any leaks between the MAF and the cylinders can potentially shut you down or make the engine undriveable.

Aside from that, the only down side I really see to a MAF setup is the restriction of the MAF itself, but i think that these modern ones are probably completely neglible in restriction.

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SAM@GTM

The relationship between voltage and airflow is not linear. Therefore, at low air flow you can still have good resolution. These MAF sensors are calibrated to have still a good resolution at low voltage 0-3V where most of the drivability and normal driving happens. In comparison to the factory ECU, it's not much different. The compromise in the resolution is only in the upper limit of the sensor. Besides, when you are at WOT, the resolution is not as critical as long as you are not maxing out the MAF's or Load Tables.

FYI, the 370Z system has a very sophisticated logic which depends on the two MAF sensors as well as the two MAP sensors. So yes the 370Z does have two MAP sensors in addition to the two MAF sensors. One is used mainly for atmospheric pressure compensation and the other is used as a switch between VVEL engine rpm control and throttle body engine rpm control. In the event that the MAP sensor for the brake booster goes below a certain threshold, it will switch to the throttle body control to make sure that there is sufficient manifold vacuum so that the brake booster can do its job.

We're very fortunate that the 370Z has dual MAF sensors so we are not completely compromising driveability and I'll bet if you take that 1000bhp Z on a test drive and test out the driveability, you'll think it was stock. I hope that all makes sense.

For the speed density vs. MAF, MAF tuning is always more precise and accurate since we're tuning based on how many grams per second of air is going into the engine. At lower altitude, you get more air, and at high altitude you get less air. The key is to have the right MAF curve that translates the amount of air going into the engine to the ECU. With speed density/MAP tuning, it's almost impossible to do on the 370Z because the VE changes so dramatically due to VVEL.

I was able to tune the G37 via a speed density system with an F-Con Vpro, but it was more of a workaround than a true tuning solution. Really it took me almost 80hrs just to get a good starting point for the car to even run. This was back in the days when there was no UpRev option and the VQ37VHR wasn't even available to the general public yet. It was an absolute nightmare, but I had no choice and got through it. It really makes me appreciate MAF tuning so much more.

phunk

^^ lol i hadnt even thought about that situation with speed density tuning with the VVEL. but it makes total sense since the manifold pressure/vacuum does not precisely correlate to engine load with this engine.. sounds like a bad time overall.

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SAM@GTM

One other very important point I would like to make is that the MAF voltage (and location) has a direct impact on the automatic transmission line pressure. Therefore, if you relocate the MAF without the proper tuning, your line pressure can be adversely affected.

SAM@GTM

You mean good times

Sam

KaienZ34

Brain splode....and i like it. Keep up the great work Sam.

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Ron

What are the benefits of using these upgraded MAFs on a 450-500 rwhp Z?

Mike@GTM

There really isn't a benefit at those power levels as the stock MAF's are capable of handling the airflow just fine.

Think of it like this: if you have a stock car, there's no point in putting in bigger injectors right? Same thing with the upgraded MAF's...they only provide a benefit at high horsepower levels (600+whp).

Ron

Thanks Mike, I figured so but I read this from a vendor's website and got confused

Mike@GTM

That is true if the forced induction designer fails to compensate for the higher airflow of the turbo/supercharger by increasing the diameter of the MAF tubing. Of course you can only increase the diameter so much before you start running into other issues (fitment, resonance, turbulence, etc.).