Looking for a heads up on what to expect when the 383 fires up. This is an 89 Vette with the 7165 ECM. MAF is ported. I expect the MAF to max out at 4000 or so RPM. What provides the proper fuel beyond that? PE vs RPM? Or does it just start to lean out as you increase RPM? Hopefully I won't have to convert to a 730 speed density ECM to kake this thing run right.

Thanks a bunch

 

Yes, you can use the AFR vs RPM (in WOT) do handle differences in the upper RPMs.

As far as what to expect, in theory you should be AOK. Many times MAF guys with heads and cam on a 350 will decrease the MAF error table so that it doesn't throw a code. But, your 383 will be pulling more air in so you shouldn't have to worry about it. If by chance you do throw a code then just post here and we'll tell you how to fix it

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.587 @ 107.97mph (1.710 60ftr) on the long runner setup.
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels. Stock Wheels. No Weight Reduction.
Gunning for NA 11's with the MiniRam II and Hooker LT Headers.
-=ICON Motorsports=-

 

Thanks for the reply. Good info nad I love havign a place to ask these questions. Now another one for you. I am using GMEPro software. I do not have a table named ARF vs RPM. I have one called PE vs RPM. The units are listed as %change at various RPM's. What I don't know is what the base units are or where they are. I noticed on someone elses bin, he changed the values from 3600 to 6400 from -7.81% to -.78%. Any comments?

 

Thanks for the reply. Good info and I love having a place to ask these questions. Now another one for you. I am using GMEPro software. I do not have a table named AFR vs RPM. I have one called PE vs RPM. The units are listed as %change at various RPM's. What I don't know is what the base units are or where they are. I noticed on someone elses bin, he changed the values from 3600 to 6400 from -7.81% to -.78%. Any comments?

 

89Vette,

I have modified this table in the past and can tell you that changing the value from -7.81 to -7.8 will do almost nothing. You'll probably have to make significant changes at each RPM ... between 2-10% depending on RPMs and the head/cam combo you are using.

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.587 @ 107.97mph (1.710 60ftr) on the long runner setup.
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels. Stock Wheels. No Weight Reduction.
Gunning for NA 11's with the MiniRam II and Hooker LT Headers.
-=ICON Motorsports=-

 

Your readign too fast! LOL He changed it from -7.80% to -.78% What is this subtracting from?

 

This is subtracting from the pulsewidth at those given RPMs.

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.587 @ 107.97mph (1.710 60ftr) on the long runner setup.
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels. Stock Wheels. No Weight Reduction.
Gunning for NA 11's with the MiniRam II and Hooker LT Headers.
-=ICON Motorsports=-

 

Thanks. That makes sense. Do you think I'll be ok with 30 pound injectors?

 

89vette,

30lb injectors will work AOK. But, you need to set the injector constant in the PROM to adjust for it. Right now I am running SVO 30lb injectors (red top) and am running 45psi of fuel pressure at the rail and have the injector constant set to 33lb/hr.

SVO injectors are rated at 37psi and GMs injectors are rated at 43.5 psi. This makes Ford 30lb injectors = 33lb GM injectors.

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.587 @ 107.97mph (1.710 60ftr) on the long runner setup.
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels. Stock Wheels. No Weight Reduction.
Gunning for NA 11's with the MiniRam II and Hooker LT Headers.
-=ICON Motorsports=-

 

This board is great! I think I'm gettin a chubby!
I gotta get the hardware an do this stuff myself. I haven't had the need until now, but the new heads arrive soon and the cam change will require some tweaking of the fuel curve, so I'M GONNA DO IT ALL BY MYSELF! hehehehe.

------------------
Karl Hunter
Hunter Motorsports
Vancouver, B.C. CANADA