MAP / MAF / Grain of Salt...

[Ward]

You guys do relize that 255 g/sec is only about 300 HP ?
Ward

On Mon, 29 Mar 1999 09:30:31 -0800, Mark Romans wrote:

> Tpis also says a modified maf will flow 750 cfm and I have flowed one on
a
> superflow 600 and modified maf flowed 796 cfm (589cfm at 11").  I show
255
> grams/sec (Which is the max it will measure) at 4600-4700 rpm's.  As long
as
> peak torque is below the max flow you should be able to tune the engine
to
> run fine with a 165 ecm.
> Mark
> -----Original Message-----
> From: Andrew K. Mattei <amattei at mindspring.com>
> To: gmecm at esl.eng.ohio-state.edu <gmecm at esl.eng.ohio-state.edu>
> Date: Saturday, March 27, 1999 8:44 AM
> Subject: Re: MAP / MAF / Grain of Salt...
> 
> 
> >Frederic Breitwieser wrote:
> >>
> >> For my engine, 431 stroked cubes and 10lbs boost max, I was
> >> hoping it was okay.  I still don't "get" which is better,
> >> MAP or MAF for my boosted application.
> >
> >Unfortunately, I'm not qualified enough to jump in to the MAP vs MAF
> >debate. ;) Nor do I wish to start one...
> >
> >Here's what I *know*. The MAF sensor that accompanies my 165 ECM is a
> >Bosch unit, with a 2 3/4" opening (3 1/8" OD, 2 3/4" ID). The
> >restrictions inside include the large heat sink fins (which some people
> >shave for performance), and the loop for the wire sensors. I'm not sure
> >of the "maximum flow" through this unit, but my "guesstimation" would be
> >in the range of just under 600 cfm. (I have a book that quotes TPIS as
> >saying that it "is capable of flowing only 529 cfm stock" - of course,
> >they sell modified MAFs, so, take with a grain of salt...). While this
> >would likely get your 431 rolling, it would prove to be a restriction
> >later down the road.
> >
> >Now here's a thought (one from the peanut gallery - or as Bruce would
> >say, "Sleepy says..." ;^D ). Has anyone ever tried two MAF sensors? This
> >book I have ("How to Tune and Modify Chevrolet Fuel Injection", Ben
> >Watson, Motorbooks Series) states that the Bosch MAF gives a signal
> >range of 0-5 volts output based on airflow (low->low, high->high) (not a
> >frequency based unit like the later Delco 2 found on LT1/LT4 cars). Some
> >creative circuitry (op amps) could combine the two MAF signals in to one
> >for the ECM... That is, if you max out the initial MAF. Just a
> >thought... Of course, I'm still on my first cup of coffee... <G>...
> >YMMV...
> >
> >FWIW, I can't decide whether to go MAF or MAP either... I have my 730
> >ECM sitting on top of my 165... Probably go MAF, because that's what my
> >wiring harness is set up for... I have a lot more work before I actually
> >get the thing running, though...
> >
> >-Andrew (ported my heads this week, though ;^D) M
> >
> 





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