I am a newbie when it comes to EFI tuning so be patient with me
I have been reserching the site and felt that some of the experienced tuners here may have some recommendations for me as I seek to get this beast tuned.
I had been in contact with Chuck at coW but it looks like it will be a while before I can get the car to him. I am using a local guy that has been recommended but I'd like to understand some basics before I take the car to him.

Now for the good stuff...
Fresh 396 LT1 stroker with the following:
Comp Cams 306
Scoggin Dicky stoker kit (.030 over, forged crank etc)
Stock LT1 Intake
38lbs Injectors
Long Tube Headers
2 1/2" Flowmaster Exhaust
3:70 gears
Stock Computer
6 Spd
SLP Cold Air Induction

IMO the car has no idea what is going on due to the stock computer... runs very rich (I'm sure those injectors aren't helping) and is terrible at low speed and RPM. The motor had NOS and apparently pulled 551 RWHP on the dyno with Spray. WOT is no problem and the car pulls hard.
I would just like to understand what type of baseline info ie. recommended injector size etc for this set up so I can see if this tuner is going down the right road.
The only other thing I can think of is that they are running a cooler that stock plug due to the previous NOS set up.
Any words of wisdom would be appreciated.

Chuck

 

Anybody?

 

Hi Chuck,

Let's see if I can help getting some discussion going on your 396...

It's helpful to post your cam specs because no one really wants to look them up based on a vendor number. The overlap will tell how difficult it's going to be to getting the fuel under control.

I spent a long time with closed loop tuning when I first had my 396 installed. Closed loop tuning helps to understand what's going on with computer control but ultimately I made my best gains while tuning open loop and running it full time. In my opinion it's easier to tune to a target AFR than tune around 14.7. To get max hp/torque you should run richer than 14.7 anyway. I'm running between 13.5 (idle) and 12.5 depending on what time of year (temperature).

Things I did:
increase spark advance at idle (eliminate glowing headers) and at high RPM high vacuum
decrease fuel at high vacuum conditions and at idle
increase (MAP) decel fuel cutoff (due to less vacuum)
disable closed loop and use WBO2 sensor
and misc table, constants changes (RPM vs PE mode, PE mode SA, PE mode fuel, etc.)

At what fuel pressure is the 38 lbs specified?

 

Thanks for chiming in...
I'm really at a disadvantage here as I did not rebuild the motor... previous owner.
The cam specs are:
230 / 244 duration, .510 / .540 lift 112 LSA. 1.6:1 rockers that takes the lift to .540 / .570.
I'm somewhat puzzeled at the injectors. The previous owner said that 38lb injectors (Racetronix) were recommended in the stoker kit from Scoggin Dickie... from what you are saying and from what I've read that may be way too much.
This car is running the stock computer which is obvious as too why it runs so poorly. It idle's at about 1000 RPM and you can smell nothing but fuel... it's worse than my BB '67 Chevelle SS. At low speed it really chugs... like it wants to go but can't... WOT seems fine and it pulls very hard.
I assume that once I get it looked at on Friday that I will be in a much better position but I'm also dreading trying to pass emmision testing... from what I have read, the cam may be a big problem getting this motor to pass.
Anything else I should know?

 

What year is your car?

 

1992

 

You'll also need to change your cylinder volume and injector flow rate.

Do you have any tuning software or chip burner? If not, you could use one of the forums supporting tuners to get you close.

 

Maybe the original owner got rid of it because they didn't know how much effort was involved in getting the computer controls right. Don't freak out, it may seem overwhelming right now but it's not that bad. There are ways to pass emissions and right now you probably won't. While you're waiting to line up a tuner you should start the learning process. The cam specs aren't too bad.

Make sure you know what fuel pressure you're running and if it's set at 50 psi turn it down for now. Changing to smaller injectors in the interim is not really a major deal. With a monster like that a wideband O2 sensor is a must. Even if you get a tuner to help you, the more you know about the fuel/spark management the more efficient your machine will perform. You can tune to 14.7 (closed or open loop) for emissions and run another program open loop for performance.

Your 92 is a speed density system and it sensitive to outside temperature. I run a different program in the summer than in the winter. The Corvette service manual explains all the sensors, show were they are and what they do...a valuable resource. Be careful when running WOT since it's the stock program, you may be lean at the top end even though you're rich at idle.

Burning chips is timing consuming and a hassle in my opinion. It's so much better hooking up the laptop to the emulator (EEPROM to flash conversion) and downloading a program without removing a chip. Once you get the hang of it and see the incremental improvements you'll have a real sense of accomplishment.

These are somethings you should consider purchasing:

WBO2+display (TechEdge)
laptop (doesn't have to be fast)
datamaster-monitoring software (Winaldl is free though)
tunercat-edit your program software
emulator (romulator, prominator, ostrich)

Keep in touch and let us know your progress.

 

You may already know this but:

Some standard injector sizes are 22, 24, 30, 36, 55 lbs/hr.

36 lb/hr injectors typically flow at:

34.5 lb/hr @40 psi fuel pressure
36.6 lb/hr @45 psi
38.6 lb/hr @50 psi
40.4 lb/hr @55 psi

30 lb/hr injector flow at:
28.8 lb/hr @40 psi
30.5 lb/hr @45 psi
32.2 lb/hr @50 psi
33.7 lb/hr @55 psi

The point is that you can run 36 lb/hr injectors at 40 psi or 30 lb/hr injectors at 55 psi and get about the same flow. I suspect you have 36lb/hr injectors at 50 psi.

 

Well everybody... sorry it's taken me this long to get this info posted.... but the Blue Beast hit the road at the end of October! Although she's away for the winter now... I thought I would share a couple of quick video's of how she's runnin.
Bottom line was we figured out that most of the problem was the injectors... they were just too big! Replaced them with 30lbs and had a custom tune done... and she's a real weapon now. Car runs great... not all that great under 2500RPM due to the cam but get on her and look out!

Enjoy these....

http://vettetube.com/view_video.php?...0e8d4cc25129f9

http://vettetube.com/view_video.php?...06feb59a8bdc52