tbi injector size

Flingarrows · Post by **Flingarrows** » Mon May 29, 2006 9:16 am

i have a gm tbi from a 5.7 L 8cyl (has blk orange marking on the injectors) i am going to put this on a 4.2L inline 6. can i use these larger injectors without suffering in performance or fuel economy, or should i get different injectors?

RNash · Post by **RNash** » Tue May 30, 2006 7:12 am

You control your performance and fuel economy with your tuning, but the biggest potential problem with injectors that are too large is lack of idle control (if the injectors are too large they will be idling at a very small pulse-width and hard to control because the opening and closing times will have more effect on how much fuel is injected than the pulse-width control.).

According to this chart:
http://thegebharts.com/msindex.html
Your 2 injectors are 55 lb. each and should be good for up to 190 HP.
GM TBI injectors are a little under-sized, so I think they should work for your 4.2 L.

Roger

Flingarrows · Post by **Flingarrows** » Wed May 31, 2006 3:09 am

Thanks for the reply Roger