EFI tunning question

[Guest y2kindyz]

I The following is my full engine combo I have in my 82 camaro Pace car: Stroked 350 SBC bored .040, stroker kit 385ci, 6†rods and SRP forged Pistons, Canfield Heads 23-500-65, SLP Cam p/n 51010(dur @ .050 - 224/232, (the cam is installed at 0 deg) 1.5 Rocker - .490/.510 - Lobe Sep - 112deg, retro-fit roller lifters, 24# injectors, TPIS Mini-Ram, and the stock throttle body. I have a FAST bank to bank EFI Management system. I am using the inlet tube off of a firebird that makes a 90 deg turn to the right into a 3â€pvc that connects to a large K&N filter in the location where the battery sits on the passenger side.

I had a 700R4 and 3.23 gears I ran a 12.79 @105MPH on a 26†ET Street. Swapping the 700R4 for a 6-speed and some 4.10’s.

I have a buddy running a 406SB with AFR heads and the same cam and intake and he is hitting 112MPH in the ¼ mile.

I have a good tune on the car that is not too aggressive. Timing is 36deg WOT and the A/F Ratio is set to 12.6 @ WOT. I don’t feel the car pulling very hard past 5000rpm. I have been wanting to get a bigger throttle body, but after reading GrumpyVette’s “do you need a 58mm Throttle Body†I am wondering if it would help.

Can anyone maybe give me some insight on how I may increase HP. The motor torque feels good and strong. Do I need to increase timing? Would a bigger throttle body help? Any advice and suggestions is appreciated,

Thanks,

Oscar

1982 Indy Pace Car

[RTz]

In my opinion, the most prudent thing to do is to take it to a dyno shop and tune, tune, tune.

 

12.6 AFR's might be a little on the fat side for an NA motor. Dyno will tell you what the motor likes, including ignition timing. If nothing else is gained, at least you'll have solid ground with which to assess future changes.

 

You might be getting ignition drop-out... what ignition system are you using?

[Guest y2kindyz]

Thanks Ron,

 

I forgot to include that info. Ing. System includes: MSD Digital 6 box, MSD dist. and a Blaster II coil, Crane Wires W/ground strap and AC FR3LS plugs. BTW, I am using the Canfield heads on my combo, not the AFR's. But I figure they are pretty close. I will bump up the A/F ratio next time out. Is 13.2-13.5 a good target?

 

Thanks again,

 

Oscar

[RTz]

...and a Blaster II coil

 

Is this the internal HEI coil or an external conversion? Most internal HEI's wont 'do' much RPM.

 

 

I will bump up the A/F ratio next time out. Is 13.2-13.5 a good target?

 

Mixtures are dependent on many variables. I've seen a huge change in 'correct' mixtures with a simple swap in injector style. Its impossible to give you anything other than a guideline. In my experience, I often find 13.0 to 13.3 (NA) to be pretty close, BUT its not always a truism, and further, I find what the engine likes can be RPM dependent, or at least, more *sensitive* to the ratios being 'correct' in one range vs another.

 

My point is that the way to find this is on a dyno.

 

A distant second is very careful, methodical use of data-logging. External variables are more difficult to control with data-logging, but I've had good results in the past. The premiss is to overlay the RPM graphs and compare the rate of change of RPM's. Assuming no wheel spin, consistent road gradient, etc, etc, you'll know if the engine liked the change and what RPM it improved the power. You can do sweeps, shifting the entire map, richer or leaner, and compare the RPM plots. Disseminate, and try again. Its laborious and inefficient... better bet is the dyno.

[Guest y2kindyz]

It is a an external coil. What is your thoughts on the throttle body? Do you think more air is needed or is it just that I am running to fat to make the HP at the top end?

 

Thanks for the great idea to data log and check the RPM rate change with different A/F ratios. I can try it on the street in 3rd, logging a few seconds at WOT. I will check my last couple of logs from the track and compair thise too.

 

Thanks again,

 

Oscar

[RTz]

It is a an external coil.

 

Are you confident that you have adequate dwell/discharge settings?

 

What is your thoughts on the throttle body?

 

The 52mm TB is probably justifiable.

 

Thanks for the great idea to data log and check the RPM rate change with different A/F ratios. I can try it on the street in 3rd, logging a few seconds at WOT. I will check my last couple of logs from the track and compair thise too.

 

3rd should work. Just be mindful of using low gears... the car may go through the RPM bands more quicklly than the O2 can respond, giving you a misleading indication.