I have a 91 Z28 and was debating bigger injectors. I know the stock ones are 19#, but I would like 32# or so, do I need a differant PROM?, If you go for a 24#, could you get away without changing the prom ? I have a Hyper Tech thermal master chip, is that going to be enough for a smaller size injectors? 1991 Z28 1LE car, 5.7L K+N, air foil,chip,3"cat back system with 2 chamber flowmaster,bullet proof 700R4 running 105 in the 1/4, not positive of the time, but thats about mid 13's?


[This message has been edited by badgmc (edited January 31, 2001).]

 

Oh boy, are a lot of people going to resopnd to this and it won't be pretty.
First are you still running with a stock intake? How about the cam, stock? the heads, are they stock also?
If you say yes to these questions then DON'T EVEN THINK OF BIGGER INJECTORS!
If your engine is a 5.7L then you have 22# injectors NOT 19#.
Second unless you have MAJOR mods you don't need to upgrade your injectors, may be get them cleaned and flow matched.
Third, there is a guy on the boards called Glenn91 something, and he can tell you more about the prom and the relation to injectors and the pulse width needed to have the right flow.
There has been a lot threads on injector size so do a search and that will help you understand about this a lot better.
Remember BIGGER is NOT always better.
Good Luck!

 

First, sorry to hear that you purchased a Hypertech chip; my condolences. I won't get you all upset, but those "off-the-shelf" eproms don't do much.

Second, if you want to change your injectors on a basically stock engine (I'm only going by your listed mods, don't take offense) you MUST compensate through the eprom. Hypertech chips just don't do that. You would either need to get a custom chip from someone like Ed Wright or make your own (my personal preference).

I have no idea why you would even consider an injector as big as a 32#. That was a mod in the mid eighties when people thought "more fuel" was the secret to more power on EFI cars. Totally wrong. A 32# would be necessary for something like a 383 or 400 with a supercharger.

But one of the problems encountered by large injectors (even when you compensate within the eprom), is that you can only get the pulse width shorten so much, and then encounter low rpm driveability problems.

Please don't take this as a flame, but you only have some minor bolt-ons and quite frankly you are probably running rich as it is. I don't notice any headers or an AFPR on your car (probably not listed). But that's ok, you obviously want to make your car run better and faster (with better gas mileage to boot).

You are at a perfect place to start learning about burning your own eprom. Most people wait until they NEED an eprom, and have nothing to use as a good starting point and have to combat a "learning curve" with not knowing where to start just to get the car running half decent, let alone running optimally.

Go to this article https://www.thirdgen.org/newdesign/tech/promintro.shtml and read it a couple times and go to every link on the article. Then go to the PROM Board and set the "Show topics" to 1 year (its not that long, but it gets everythign) and read all the oldest posts and read forward to the most recent.

It will answer 99% of all the questions you would have about "burning your own" PROM, and then you can start burning your own eprom that will be better than ANYTHING you could buy...and be in a position to make some good mods (heads, cam, and intake) and take full advantage of those parts.

It will be a hell of a lot cheaper than buying 8 injectors and your car will be a lot faster. If you were to put 24# (let alone 32#), and not adjust the eprom, your car would have been a lot slower.

What other mods do you have on your car by the way?

[This message has been edited by Glenn91L98GTA (edited February 01, 2001).]

 

YOU THA MAN GLENN!!!