Big Injectors......

[Hi-psi]

Guys,

Of all the large injectors, which are the most linear in flow? Which are the easiest to burn chips for? Thanks.

75lb/hr Delphi
83lb/hr Siemens
84lb/hr Delphi
95lb/hr Delphi

 

[SubZero350]

Originally posted by Hi-psi
Guys,

Of all the large injectors, Which are the easiest to burn chips for? Thanks.

75lb/hr Delphi
83lb/hr Siemens
84lb/hr Delphi
95lb/hr Delphi

None of the above.

Unfortuneately, I have found it difficult to burn chips for the 75lb injectors on the 7148 ECM. This is because the ecm is built only to accomidate up to 60 lb/hr injectors in the programming. Another factor would be the lack of speed/processing power of the 7148's CPU. The owner of this car that has the 75 lb'ers decided to get a chip from Red to start with. Boy, did that thing run rich at idle. Sure, it ran 'ok', but liked to load up and glaze over cylinder walls while it was at it. I had to back off on the MAF tables heavily below 20 g/s just to get the INT and BLM to come back to normal. In doing this, the car has now developed an off-idle or "tip-in" lean hesitation. Time for a faster ECM. I am waiting on the release from TunerCat for the ability to program 94-95 3800 SC computers. These systems are much faster and more flexible than the old C3 systems of the GN. Besides, an 8192 baud data stream would be so much better than 160.

 

[JayC]

That's pretty interesting considering I have 83# injectors in several cars with the stock ECM and they work fine.

 

[SubZero350]

Well, I just was offering my experience for some advice. Sounds like you are running an engine combination that might be a little more forgiving with the stock ECM. If you are indeed running 8.0:1 compression, T-63E turbo, 218/218 cam, low-impedence 75lb injectors, stock MAF sensor, and are able to attain 128 BLM and INT counts at all times, please point me in the right direction.

 

[JayC]

I was actually running a 276 CID Stage II engine with Champion R aluminum heads, Hydraulic roller cam, T76, 8 inch converter, etc. As for keeping 128 BLMs and INT at all times, I have my own philosophy on that based on 11 years of doing chips for these cars. As long as I can keep the BLM and INT "in play" and not too far out of whack then I'm happy with that.

And BTW, if you're using Tunercat to set the injector constant, you should try hex editing it instead. I believe Tunercat has a limit on the adjustment you can make which isn't actually the true ceiling of the injector constant. I'd need to double check again to make sure of that but I think its the case.

Finally, there are other ways to recalc the fuel without using the injector constant at all. I've done 50# chips with stock constants and they work okay. There are just a lot of different approaches that you should take a look at if you want to be proficient with this stuff.

 

[TurboDave]

Jay makes some good points. As I've been trying to preach for years, attaining 128 INT and BLM all the time just isn't going to happen, and is for the most part not only impossible, but totally impractical. As long as they are "in play" (Jays words), the system is doing it's job.
Heck, even Neal here in San Diego has had success running 90+# injectors in the stock ECM running a STG II engine setup.

 

[Hi-psi]

Jay,

What would you charge to do two custom chips for one of the large injectors listed above? You can PM me or e-mail at TTA799@home.com

 

[SubZero350]

Originally posted by TurboDave
Jay makes some good points. As I've been trying to preach for years, attaining 128 INT and BLM all the time just isn't going to happen, and is for the most part not only impossible, but totally impractical. As long as they are "in play" (Jays words), the system is doing it's job.
Heck, even Neal here in San Diego has had success running 90+# injectors in the stock ECM running a STG II engine setup.

I was not attempting to suggest that perfect 128 BLM or INT counts were going to be attainable. I was merely saying that it would be nice to have 128 counts. My original question still stands to Jay: Will you please let me know a better way of tuning the combo I am working with since you seem to know more about it than me. Thank you.

The problem I have is that this friend I am working with wants to build the car to run mid-10s and drive it on the street also. The other problem is that the turbo and cam he is using was intended to be used with a front-mount intercooler which he can not yet afford so we are forced to work with what we have. He wants all this plus seat-of-the-pants throttle response and gas mileage with a 3000 non-lock-up stall. In my opinion, it is just too much to ask of a computer system designed in the late 70's early 80's.

But as I said before I am open to any suggestions, short of abandoning my friend, in order to rectify this problem.