Injector questions?

I was over 300hp with the old motor and almost certain I am about 30hp more with this new one and 24's are working just fine. Just so you know killercanary is also using the same 24's that I do and I think that he will agree that they will be enough for a 302 based street car with bolt on's.

go with the 30's. I had a dyno test and found out actually how lean I was running with an older setup than I have now and with 30's it was just perfect I would go with them by the way I bought mine used no problems.

I am in the process of building the same combo as you and have researched this a lot. I've decided that the 24's are the way to go. I am planning on a AFPR, too. I think that the 24's might be a slight bit small, but a bit more pressure will correct for that. Adding pressure makes the injectors perform as if they were bigger. This will also improve atomization of the fuel, which, I believe, is helpful during idle. It's possible that an injector running at very small pulse width's can not have enough 'open' time to develop a good spray pattern. The 30's seem too large. They would make for even smaller pulse widths at idle (to emit the same amount of fuel as 24's), and perhaps poor atomization. I theorize that this helps to cause poor idle quality. Obviously, there are many factors that work with each other to cause problems. Hopefully going with the 24's will help to lessen those factors and work toward a better idle quality.

Rick

It is hit and miss with used ones. I got my 30's used, and they sat too long, and I had to pay to have them reringed and flowed. I since sold them to my friend, and they are fine. I bought my 36's used, and only had them out for about 1 month. Kept them capped and in a air-tight plastic bag.

RC

mo_dingo said:

HP=(Nc X Injector X Dc)/ bsfc

8cyl x 24lb x 85%(.85) duty cycle/.5 = 326.4 FWHP or 277.44 RWHP

You should be about 290 rwhp w/ a good afr setup. Check out killercanary's setup on the main FAQ. You will be running the injectors over 85% duty cycle, which severly shortens the injectors life.

You can get away with it, but I wouldn't want my car down because I decided to save a few bucks on injectors. I know the 30's are a jump in price, so it's your choice.

btw, 8*30*.85/.5 = 408 FWHP or 346.8 rwhp.

290rwhp = 60% duty cycle w/ 30's

JMO
Scott

Click to expand...

Scott

I'm using 30's for the same thought process you have shown here.

HOWEVER

Even though 24's are close on the top end you can do the afpr thing and crutch them up a bit as many have done.

The 30's at idle and at small pw's can be a problem causing a rich condition.

I use a Tweecer so no fear of lean on the top end or need of afpr or too rich at idle.

IMHO, If I did not have a tuning device or chip I think 24's & up the pressure would be the way to go.

Later
Grady