Brett SS

Hey Guys,

I am currently getting a 383 stroker built and we are looking at getting around 520-530fwhp. It will probably reach peak power around 6000-6200rpms and I won't spin it past 6500rpms. My question is whether the stock 28.8lb injectors will be enough to support this engine or whether I will need to upgrade to larger ones.

I have got 50lb injectors second hand off another guy but if the standard ones will be enough I can sell them to someone else who would benefit more from them and I can put that money to other use.

Thanks,
Brett.

needmoremoney

i would say NO. I would think you would want something like the FMS 30LBs'ers (whick is like 34LBs for our fuel pressure.)

Jorday

I would replace them.

A lot of people here will recommend increasing the injector size when running a moderately modded 346 ci engine. I use 42.5 for my 6800 RPM heads/cam 346 ci combination.

Reboot

iTrader: (5)

30# SVO Injectors are a safer bet. I will be running those in a couple of weeks when my 383 is done being built.

I bought a set of flow matched injectors from Summit. All of them are rated at 30.8lbs at 39.15psi. This is 37.48lbs at 58psi.

Brett SS

Thanks for the replies guys.

After searching through some other posts I came across this one and in it Colonel states that he was able to support his 422ci engine which was 480rwhp using only the 26.4lb injectors :

https://ls1tech.com/forums/fueling-injection/105937-26-29-ls6-injectors.html

Did the people that upgraded their injectors do so because they were starting to run lean top end?

Colonel

You're talking about somewhere in the neighborhood of 465 RWHP. Your stock injectors will do that.

Brett SS

Thanks Colonel, when we do some testing on the engine dyno I will see whether we start to lean out and if it doesn't the stock injectors will stay in.

H82BBad

I ran out of injector tuning on my 383 today. Mine is a 2000 so I think the pump is weaker and the injectors are smaller.

Brett SS

Interesting, was it leaning out top end or was just your duty cycle at 100%?

Also does anyone know if he would have the 26.4lb or 28.8lb injectors in his car?

BigBake

He would have the 26.4lb variety. The 98, 01 and 02 had the 28.8lb injectors.

H82BBad

it made peak torque @ 3700 rpms. I had to 25% more pe vs rpm fuel to get it to 12.6:1 @ peak torque.

After that hp climbed real quick then flatlined at 5600 rpm's.
@ 5600 the richest I could get it was 13.7:1
This is on a very stingy mustang dyno that I always use for tuning. When I was just heads and cam and running 11.30's it showed I made 338 rwhp. Now it is showing I make 370
Tq has picked up over 100 ft lbs.

Shinobi'sZ

I had 28's and they barely supported 430rwhp on my H&C car....346cid. With the 383 or any stroker you are going to need more fuel. Do you really want to be running stock injectors at 90%+ duty cycle...You would be better off with some larger injectors...See what your AFR is like at 6500 rpms...if you can maintain 12.9-13.0 at redline you should be ok.

383ss

iTrader: (14)

with my 383 stroker, I just started running out of fuel with 457rwhp and stock injectors in my 99.

Colonel

He has 28.8 lb/hr injectors. If they can't keep a 13.3:1 or richer mixture at 465 RWHP (assuming 55 PSI or better), I'll buy all of ya'll a coke and a smile.

383ss's testimony supports this. His 26.4 lb injectors carried 457 RWHP before they even started to run out (I bet the PSI had dropped a bit as well which was part of the problem.) 457/26.4=17.31x28.8=498.54 Keep that PSI up where it's supposed to be and they'll handle even more.