Fuel Injectors - F-Body Online

Dragonsys · 03-27-2007, 02:47 PM

I think I need to upgrade my fuel injectors for the fuel pressure that I'm running.
I'm running 50 psi, but I'm unsure as to if I need 19#, 24# or 30# injectors.
If the info I'm seeing so far is correct...

Here is what i have
Stock Size - ??? (According to the Accel catalog, stock injectors for '89-92 5.7 are 21#)
19# SVO seem to be recommended for a stock engine
24# for 43.5psi fuel pressure

so, would the extra 6.5psi I'm running require the extra 7lbs, or would 24lbs still work fine for me?

19Stroked89 · 03-28-2007, 05:35 AM

Your fuel injector size is more related to the fuel requirements of your engine not so much how much fuel pressure you have. If you have done any mods to increase air flow into the engine( bigger cam, higher cc heads, and so on) then yes you could go bigger on the injectors. But if you havent done many mods to increase air flow then theres really no benefit in going bigger on your injectors in fact you will probably have trouble with bogging from to much fuel. Another thing to keep in mind is if you go much bigger on the injectors you may need a different chip to run them. So if stock is 21# you should be fine with 24#.

Dragonsys · 03-28-2007, 11:09 AM

Well, I'm getting ready to install a LT4 HotCam..
I already have a pcm4less chip, I just need to get it reburned. I'm waiting until I have everything installed (or at least ready to install) before I send it to them.
My full list of mods is here - http://www.fbodyonline.com/vbpicgall...p?do=view&g=15

19Stroked89 · 03-28-2007, 04:13 PM

Okay here is a good formula to help figure the best size injectors for ya. The basic principle is that you will use about .5 lbs of fuel per hp at WOT. So just for an example say you had a 350 hp engine you will multiply 350 x .5 which is 175 lbs of fuel. Now divide the 175 by 8 which is 21.875 then divide that by .8 which is 27.34. So in this case 30# injectors would be perfect.

If you know what hp you are running punch it into the above formula and that will get you pretty darn close.

Dragonsys · 03-28-2007, 04:32 PM

no, all I have is an estimate on the HP

19Stroked89 · 03-29-2007, 04:29 AM

Thats really the only accurate way I know to be sure your getting the right injectors for your engine is by using that formula. Otherwise your just making a guess and could be cheating yourself. If your gonna spend money for these parts why not be sure your getting the best bang for your buck.