Injector question - Lucas 5207009 Vs. Bosch 0.280.150.934 ...

[turbokinetic]

Hey guys, I have a question about injectors. The engine in question is a Buick LG3 3.8SFI engine which will be getting a n/a to turbo conversion.

My curiousity is up, because of one thing. The stock injector for the LG3 engine is a 17 Lb injector. The owner of the car installed Lucas 30 Lb injectors without any programming changes. The engine runs normally, not overly rich. I'm not sure if they are NEW or remanufactured.

In the past, I installed Bosch 28 Lb injectors into another completely stock LG3 engine and it ran pig-rich (which I expected). I then tuned it for the 28 Lb injectors and has plenty of room to make boost without fuel issues.

So I am concerned that the injectors installed in the engine (the Lucas 30's) are somehow not delivering the same fuel that the Bosch 28's deliver.

Option 1 - Lucas 5207009. I have been told this is 30Lb. Currently in the engine. Was installed because original 17's died from sitting too long with old fuel in them.

Option 2 - Bosch 0 280 150 934. This is a 28 Lb injector. These are stock for a 1995 Supercharged L67 3800 engine. Have these on hand but not installed in engine.
Previous LG3 - went from 17 to Bosch 28 - ran awful until tuned. After tuning runs like new.
This LG3 - went from 17 to Lucas 30 - runs OK without tuning change?

Do you think I have something "strange" going on here?

What I don't want to do is waste a lot of time tuning it and find out in the end that the injectors are not what they claim to be, and I have to start over on the tune. Other than this, I don't care which ones we use. It would be easier to keep the Lucas ones because they are already in the engine.

Sincerely,
David

Ps - this is a 1986 LeSabre Grand National that's getting boosted.

 

[TurboDave]

I'll get you thinking even more by answering your question with a question:

Does common sense really tell you that you can go from a 17# injector to a 28-30 without any other changes and have the engine run properly????? The answer should be obvious.

 

[Chuck Leeper]

What Dave said^^^^^^^^^^^^^^
Did you check the FP that's running w/ the bigger injs?

 

[turbokinetic]

Thanks for the replies! Yes, I do think common sense says something is up.

Will check the FP next chance I have to work on the car. If fuel pressure is correct, I'll probably install the Bosch units and stop worrying.

 

[87GN_70GS]

Maybe the engine management system for this LG3 (whatever that is) is such that it always remembers the fuel compensation for changes to configuration/operating conditions/etc. So in other words, the first time the bigger injectors were installed (by prior owner), it spit and sputtered until it learned. But from that point on, it stored that adapted cal and would run fine (unlike our ECM which would be rich until closed-loop).

 

[turbokinetic]

Scott, the LG3 is the naturally-aspirated version of the 3.8SFI engine. It has a virtually identical ECM to the Turbo Regal.

I think I found out why it is able to run with these injectors. There is also a Hotair Turbo Regal MAF installed on the LG3. So the MAF and injectors were both oversize.

It's not a problem because it's going to be a 7730 ECM with speed density anyway. I just want to make sure injectors aren't bad.

LG3 engine:

Sincerely,
David