tuning...how do the high HP guys do it??

[NebTurboST5]

My question resides in the fact that I am going to be close to maxing my maf on the G/cyl end with my fixed afc i think and im not even going to be making 500 horse at the wheels. so how are the guys running the huge injectors getting away with it?

[Fivefingerdeathpunch]

Mind fart, whats a AFC??

Most guys just go to a bigger/different MAF sensor. Like a LS1 maf.

[NebTurboST5]

Mind fart, whats a AFC??

Most guys just go to a bigger/different MAF sensor. Like a LS1 maf.

air fuel controller

[GTPpower]

Darkhorizon just runs a stock tune.

I believe you may need an adjustable controller at that point.

[BillBoost37]

Or you do the math and scale your injectors and airflow. I believe I saw DH talk about that as well. Simple math in that case.

[NebTurboST5]

Or you do the math and scale your injectors and airflow. I believe I saw DH talk about that as well. Simple math in that case.

i figured this is probably what people were doing just wondering if it messed up any of the load calculations.

[91parkave]

Half ifr double stoich

[darkhorizon]

Half ifr double stoich

No. That doesnt solve the maf sensor issue.

Plain and simple you need to run a maf that outputs ~11000hrz at your peak airflow. After that you may run into the issue of maxing out the largest number available in the maf table (511 in dhp). To get around that max number issue you will push your injectors up and pull the whole maf table down by the same percentage.

There are many ways to get a maf sensor setup to flow the amount you need at low enough hrz. I do it electrically with a converter (zzp fixed afc) that takes the output from the maf and pulls a fixed amount of frequency from it. You can also modify the maf mechanically by putting it in a larger tube so it sees less air or a modification to the maf itself to limit the amount of air it will see.

Op. You have a fixed afc which is good for 800ish hp on a stock maf. You just need to push the injectors up and pull the whole maf table down.

[NebTurboST5]

Roger. i havent really started tuning it yet since getting it back together. im just basing this all off the loose assumption that after adding the fixed afc and removing the modified maf the idle hertz has increased significantly. i know its not linear etc. so its probably not an issue for me at this point.

I am running 60's so you are saying i tell the computer that they are 66's that i would then scale the maf table down 10%?

[darkhorizon]

you would "tell" the injectors that they are much smaller, but yes thats the idea.

[NebTurboST5]

i got ya so say i have 60# injectors i punch in 30 into the injector table. and scale the maf by 50%

[SnowFlake]

Wait.. you're maxing out a fixed afc MAF but you're on 60# injectors?

[GTPpower]

He's not running E85 though.

[SnowFlake]

Makes me wonder even more how he's maxing out a fixed AFC MAF.
I was able to run 28psi through my engine without maxing the MAF and I had the AFC at 80.

[GTPpower]

Maybe he's making more power than you.

[SnowFlake]

Could be lol

[NebTurboST5]

im not maxing the maf i just thought that i might be and was curious. so far the highest i have seen is 10250 on the table.

[NebTurboST5]

i had my old modded maf set up for 11375

[darkhorizon]

Wait.. you're maxing out a fixed afc MAF but you're on 60# injectors?

no, he is maxing out the max G/s value in the maf table. Not the maf.

[turtleman]

If you're hitting the g/cyl limit in the tune, you have no choice but to counter-scale the fuel side (IFR) so you stay in bounds of calculations. AFC (raw frequency limit) is a totally separate thing so you need to have that figured out first and then you can scale maf vs IFR how ever much you anticipate you need. So if you have a fixed freq AFC, the first thing is to make a base maf table to work with that. Unfortunately that part is not a simple multiplier (because the maf table in the first place is not linear). The best way I know of to get to the right place there is with a polynomial plot formula. PRJ paul was kind enough to give me an excel document that produces a new maf table for you with your desired scale factor. That's the trickier part. If you are already ok with your base AFC-modified maf table then you just scale the maf table down in proportion to the injector flow rate and then you have maf numbers that are understated (which is what you need) and injector flow rate numbers that are overstated but it all works because you're lieing the same amount both ways.