Experience needed

[Highway Man]

I have done a few light mods to my 92 LT1 which consist of magnaflow cat-back exhaust, ditched the stock resonator and had an x pipe put in its place and opened up the stock air box and put in a k&n filter and I am getting ready to put in some comp cams 1.6 roller rockers with new springs ect. By the way my car runs like a champ. It starts right up and idles smooth with good power up the rpm spectrum. I have considered going to a 52mm throttle body and some headers but not yet. Anyway at what point should I consider maybe upgrading my injectors or any other components and I am already planning to get a tune. I know this is a blanket question but I would appreciate any advice or suggestions perferably based on experience. Thanks!

 

[boomdriver]

IMO, others may not agree,
but with what you are doing/planning I think a small step up in injector size is justified, especially knowing that you can reduce the inj flow rate with the Bosch-III design by simply dialing down the pressure. Adjustable fuel regulator.
I have similar mods, bored so mines a little bigger displacement and breaths better and I went up 4 lbs/hr. I actually could have gone up 6 to 10 after seeing the results that I got out of a 4 lb/hr increase. I run those at over 50 psi and get a good clean burn. If i dropped the pressure I would go down to the stock flow...or close. If you only go up a few lbs there is enough "wiggle room" thru the pressure that you;re safe and not in danger of being stuck with a rich un-tunable engine.
Save your "tune" for last and resist the urge to do other things after you get a tune...unless you;re ready to go get another. This practice is so common that some tuners sell 3 paks of tunes...for a good price. They know that most guys can't leave it alone and will need to come back again soon.

Your ECM will probably be able to compensate and live with 2-6 lbs/hr bigger injectors without having to be retuned. Any more than that would definately require a tune so the engine was not getting over dosed with fuel. O2 sensors would freak out...everything would go to hell in a hurry.

 

[Hib Halverson]

Once your header installation is complete will you run cats or not?

As for the question of injectors and a 52-mm TB, I'd get the rockers, the springs and the headers on then run the car on the chassis dyno and see where you are as far as injector duty cycle and air flow.

At WOT/high RPM, if your sustained injector duty cycle is over 85% then you probably will need "bigger" injectors and the one to use is the LT4 unit. As for the bigger throttle body, if you need one--ie: at the top of the power curve the engine is air flow restricted--it will be obvious from the dyno results.

Larger injectors and bigger throttle bodies are not power adders unless the engine needs the extra fuel and air.

 

[Highway Man]

Good stuff

This is good stuff guys-thanks a lot!. Besides myself perhaps someone else will benefit from the information shared here. I am already forming a plan on how I want to pursue this. I have looked at headers both shorty and full length and I think for me the shorty headers with cats would be the best route. I know I would get more hp gain with the long tubes but I am reluctant to get into possible sensor issues. Then again some people are of the opinion that the stock exhaust manifolds have good enough flow that not much would be gained by going with shorties and wouldn't start to realize much of a gain until I got into the higher rpm range. Anyone else want to chime in?

 

[Highway Man]

Thanks for the feedback

I think what I'm going to do at this point is go ahead and install the 1.6 rockers ect. and see how the car runs then if all is well headers with cats will probably be my next step. I think I'll forgo the 52mm throttle body unless results warrant it and I'll be surprised if they do. I am going to keep my eyes on those injectors though as I don't want to burn the engine up from being too lean.
Thanks guys!