Stock MAF specs

[FlaBouy]

OK guys, let the lessons begin...

What is the Stock MAF range in HZ and lb/min on a 5.3L? As Allen was so quick to point out, my current tune is showing injector duty cycles of 105 to 107% @ 20 ms on 42 lb injectors and MAF freq readings at 12000 @ 5500 and sucking 60 lbs/min. At what limit will the stock MAF be maxed out. I just bought HPT so be easy on a brother (cult memeber).

Thanks

[chrisj6]

13500 hz is the fail frequency, and 57.58 lb/min or 512 g/sec. Also, if that runs out I dont think you will be getting a different maf, I think the next step would be a speed density tune (mafless).

Chris

[FlaBouy]

So you think the Vortech S/C on a crap tune is already beyond the limit of the stock MAF..... I saw above 57.58 prior to every shift point. I assume Allen will take care of this or suggest a work around, so in the meantime, where do I go to read up on this new fangled contraption you call a "speed density tune"

BTW thanks for the info. I definitely know my place is behind the wheel and not in the PCM right now...

[Tim Z]

speed density is a set of fuel table programmed in to the pcm, old tuned port injected covettes and camaros used this from 90-92 cause it was cheaper to produce over the previous MAF systems, the MAF usually didnt require program changing when adding cams or heads cause it sensed more air bieng needed by the engine, but in some forms of racing cars are using speed density maps that they might change throughout the race to fine tune there engines while racing, i guess you get a more precise tune for the conditions with speed density, but it doesnt self adjust like mass air flow systems do,which is why gm went back to them i think. im no tuning expert by any means , but i have studied tpi swaps and did 3 of them and worked with both of them.

[FlaBouy]

Well at some point I want to add a cam and slp rockers to help it breathe better. I guess I better address this prior to any more mods(headers, high flow cats, cam, etc.)

Thanks for the info

[RedHeartbeat]

My 93 corvette LT1 had speed density and worked flawlessly though the custom programmed tune, by Street and Performance, would not pass emissions testing on a stock engine. The speed density system used the MAP and air temp sensors for air flow measurements. Nothing fancy about that setup plus you'll get to lose the ugly MAF in the engine compartment.

[chrisj6]

Well in a since tim is right. Speed density runs mainly off of the VE table (volumetric efficiency). Unless you have a special OS from hptuners or whatever software you use, when you enter speed density the pcm will only use the low octane table, so that takes away the advantage of a dual tune. This table is actually an airflow calculation and monitors how much air the engine is actually digesting.

www.hptuners.com, so to the forums, there are some experienced tuners there to help answer your questions. And yes, Allen will be able to work around this. His tunes are as good as they get!

Chris