MAF sensors ok for supercharger?

[Guest Anonymous]

Novice question--

My LT1 has a MAF sensor. Theoretically even though I'm sticking on a supercharger the computer should still be able to give the right a/f ratio based on the MAF readings right? I don't need to convert to MAP do I?

I realize that the fuel table will have to be changed and injectors upgraded once I turn the boost up to where it is supposed to be, but I just wanted to make sure that MAF was ok with forced induction.

[BLKMGK]

MAF sensors calculate ingested air based on measurement unlike the MAP sensors that infer the amount of air based upon readings and lookup tables. IMO MAF sensors work well in forced induction apps. If the injectors are big enough and you don't max the MAF sensors output it shoudl be able to provide sufficient fuel without bumping fuel pressure to the moon etc. That's been my experience on FORDS anyway.

 

My Mustang once used 9th injector and at another time used one of those additional fuel pressure things who's name I've just forgotten The 9th injector setup had "issues" and the pressure riser would surge and do nasty things liek completely close off my return line sending fuel pressure to the moon. I spoke to friends and read up on th eEEC and determined that the MAF woudl do the job. Slapped in a set of 30lb injectors and never had to fiddle with fuel pressure again - it ran well. The MAF was calibrated for those injectors though.

 

I'm NOT sure that it will work this easily with a GM. I'm not sure if their MAF sensors are available recalibrated or if the ECU must be changed (ECU change is a BETTER way to go). Recalibrating the MAF is actually NOT a good idea but I won't go into that - it's done by some and works well but the ECU is the correct way to go.

 

Honestly I'd suggest you talk to the blower manufacturer and try to find some folks actually running blowers to get their experiences. That computer should be plenty sophisticated and can be reprogramed if that's needed. I don't think you "must" switch to MAP.

[Guest Anonymous]

I think you're talking about an FMU..

That's what ATI recommends and normally supplies with their supercharger kits. I don't want to use an FMU though. I want to just reprogram the computer. But your point about maxing out the MAF sensor worries me.

I guess I can always wait and try it out. I'm sure I can figure out how to monitor the MAF output / resistance (whichever way it works) during a few test runs to see if it is peaking before wot.

[BLKMGK]

Yes, thank you - couldn't recall that and it was killing me!

 

IMO maxing the MAF shouldn't be too bad a problem. Some of the Buick guys do it though and I know some of the Mustang guys have - it pops the Check Engine light However if you're using a recurved MAF the range should be greater.

 

When they recurve they change the resistance of the circuit - at higher air flows it reads higher resistance. That way the stock curves don't fire the injectors as much - they fool the engine into thinking it's getting less air but the bigger injectors are able to handle the additional air with the lower air pulsewidth. Clear as mud?

 

That works GREAT except for a few little problems - low airflow over the sensor means a reading nearly in the noise level and can cause idle issues unless the motor is moving more air than stock. The other BIGGER issue is the spark curves - those are also based upon airflow and TPS. You end up using different parts of the spark curve than you might want since it thinks the airflow is lower. Make sense?

 

Anyway, tread lightly and slowly. I believe what you wish to do is correct and that an FMU is a bandaid. If you've got the correct sized injector and it's not HUGE then stock fuel pressure and modified pulsewidths should be the way to go....

 

[ October 22, 2001: Message edited by: BLKMGK ]