BOTTLE ROCKET

iTrader: (4)

I've read a LOT of post on the benefits of SD to MAF with FI. I really would like to keep my MAF, AS LONG as it's not a restriction.
What I'd like to know, is whether or not there are any 600+rwhp cars out there running a STOCK size LS1 MAF.
I am doing the final MAF tuning, and if there is going to be issues with restriction, I need to address it now.
I have a H/C with a fast 90 / LS2 (90mm) with a P1SC1 and will run about 9 psi.
Who out there is running a stock MAF FI car over 600hp?

BigRich954RR

iTrader: (1)

I had 658RWHP with a maf but also had a F1C procharger pushing the air though it

ChevyChad

iTrader: (50)

On my old P1/ 346 combo, I made 632 rwhp thru my stock screened MAF. It was beyond maxed out tho.

conan

iTrader: (5)

I just switched to a SD tune about a month ago when I had a retune done. My MAF was maxed out at 500+ rwhp.

BOTTLE ROCKET

iTrader: (4)

What causes the difference? Some making over 600, and some at 500?


On my old P1/ 346 combo, I made 632 rwhp thru my stock screened MAF. It was beyond maxed out tho.

What is the "symptoms" or problem that arise as result of it being maxed out?

conan

iTrader: (5)

Big rich, and chevy chad are both maxed out by far. The amount of air that is going through the MAF is way more then GM ever built it for. I have read some bad threads about peoples MAF failing or too maxed out and the engine goes lean and then boom Also and I dont know that much about tuning but my tuner showed me the fuel table (i think) of the 1 bar map VS the 2 bar map and its double the size and more fine tuning can be done.

MIGHTYMOUSE

iTrader: (59)

you can make a thousand hp while having a maf on the car, but it wont be helping calibrate for the air past it's max output frequency the computer can read (11,250/12000) i forget.

kp

iTrader: (34)

I'm still using a MAF, stock without a screen they will max out (stop reading) around 500hp or so. I do a simple resistor trick that alters the output (similar to a MAF translator) that lets it read to about 700 (flywheel) hp. The flow numbers arent accurate of course but its easily tuned around.

One day I'll do a 2 or 3 bar SD tune but the car runs and drives so nice and is super consistent at the track so I just leave it, mostly because I'm lazy. I dont think it would be any restriction with a P1SC really, I'd probably yank the screen or get some aftermarket MAF ends. I ran a stock descreened MAF years ago with a P1SC on a stock motor around 9psi and it didnt max out, that was around 500rwhp, over that you have to start fooling things. A lot depends where th MAF is too, moving it a couple inches can make a big difference once you take the screeen out.

ChevyChad

iTrader: (50)

MM is correct. The MAF can only read so much before it maxes out. The stock computer can only read slightly higher than the MAF can. So it does you no good to get a MAF that can read a higher limit, because odds are, if you max out the flow limit of what the MAF can read, you'll max out the limits of what the computer OS can read as well. After that point, you have to add fuel in the program based strictly off RPM. This is a bandaid approach. It can work, but its pretty much blind to the amount of air coming in. Its a bandaid way to tune. Ideally, you want to be adding fuel based off the amount of air coming in. Thats where a MAP can be helpful because you can get a 2 or 3 bar MAP and then add fuel based on pressure rather than RPM. This is a much better way to go about things all around.

ChevyChad

iTrader: (50)

Thats an interesting trick I've read about a few times. What resistor do you use, and how easy is it to tune around? Sorry, I'm not a tuner, but I'd like to know

kp

iTrader: (34)

Its easy enough to tune around, you just solder a resistor across one of the MAF elements, I happened to have my old MAF I used from about five years ago and I forget what value I used. I had to put a variable resistor on it and find the correct value. All it does is skew the readings, I wouldnt do it with a turbo car, but since a blower is very linear its easy to tune around.

These days its just easier to do an SD tune on a 99+, we were doing the resistor thing before LS1edit was available so its pretty old school. Plus I had to do it with my old 98 since there was no 2bar available at the time. When one was finally available I tried it and it never worked out well, had huge IAT fueling/cold start issues that were not acceptable to me.

I plan on doing a BS3 eventually on this car so I dont want to waste too much time fooling with an SD tune, not to mention it runs just fine as it is..

BOTTLE ROCKET

iTrader: (4)

I have the MAF descreened, and it is located immediately after the Y-tube coming from the dual intercoolers. It is as far from the TB as I can get it.

The tuner that I was going to take it to for final tweaking, estimates that I should be around 630-640rwhp when complete.

I have a Delphi MAF (85mm I think) that came with the kit, but I didn't use it because it has the built in IAT, which I have mounted right before the TB and AFTER the meth injection.

It almost sounds like the only choice for ABSOLUTE saftey (no leaning out) is to go SD, which I really didn't want to do unless there was no no other choice.

mike13

iTrader: (27)

When you max out the maf do you throw a code? maf over voltage or something similiar?

kp

iTrader: (34)

If it goes super lean when the MAF fails it simply will stop making power, thats better than than going just a little lean.

A MAP sensor can fail (or hose pop off) and the same thing can happen in SD. Only absolutely safe way to do it is leave it stock

BOTTLE ROCKET

iTrader: (4)

Would it be worth going to one of the Lingenfelter 100mm MAFs to eliminate the "no read problem?
Has anyone tried them?

Proxses

Going to larger diameter MAFs will only change the frequency it outputs when you reach the max airflow level of 512 g/sec.

Some people have also scaled everything down to retain the MAF, but this too has the issue of loosing resolution.

WS6 GreeN

Why not just get a 2 bar MAP sensor and the 2 bar OS upgrade with HPTuners? From what I've read, you can use the MAF below 105kpa and anything above that, it uses strictly the VE table. So you can sort of have the best of both worlds if you get the VE table dialed in above 105. I'm pretty sure I read one of the HPT guys posting that over on the HPT forums.

qqwqeqwrqwqtq

All of HPT's SD operating systems are designed to be used in SD mode only, no maf.