MBC Racing

iTrader: (3)

can someone tell me the proper way to adjust for the larger injectors? I have a 2000 m6 Z with cartek heads and cam. I have heard there are a few ways to do this, but some of them have problems with the A/F ratio being really lean for a couple thousand rpm when you initially hammer the car and then they correct to 13:1 at the upper rpms. However, I heard the they will eventually go lean in the upper rpms also after the computer learns. Not sure if this is true or not, but need to find out.
thanks
Brad

NoGo

iTrader: (2)

The lean mess, I believe is caused by differences in the SVO injector offset compared to our stock table. The stock table works fine, but some of the LTerms are pretty crappy at times (ie when you first hit it, and also coming off of the gas).

To properly scale your injectors, use the following formula.

Injector Flow = Rated Flow * SQRT((Your psi + Intake psi) / Rated psi)

Injector Flow: How much your injectors will really flow for that given pressure (intake pressure)

Your PSI: How much fuel pressure your car has. For a stock car this is 58.015 psi or 4 BAR

Intake PSI: How much pressure in the intake. This value is represented by Kpa (kilopascals) on your injector scaling table.

Rated Flow: The flow that the injectors were rated at. For your case it would be 30 lb/hr

Rated PSI: The pressure that the injectors were rated at. For SVO 30#'s this pressure is 39.16 or 2.7 BAR.

Sooooooo.....

Convert Inlet Pressure Kpa to PSI.
KPa * .14503 = PSI

Here is an example of the calculation for first cell in your Injector Scaling table.

Injector Flow = 30 lb/hr * SQRT((58.015 psi + 0 PSI) / 39.16)
Injector Flow = 36.51 lb/hr

Our PCM tables are in Gram/Sec, so we have to convert the 36.51 lb/hr to gram/sec.

36.51 lb/hr / 3600 sec = .01014 lb/sec
.01014 lb/sec * 453.6 g/lb = 4.6007 g/sec

Or you can just go to http://ls1edit.slowcar.net/faq.html and use ChrisB's table if you aren't a numbers guy.

Good Luck,
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MBC Racing

iTrader: (3)

Thanks for the info. I will have to see what is in my PCM and go from there.
Brad