Well I have been reading as much as I can on injectors and I am starting to think my 37# racetronix maybe to small for my 383 stroker motor. I am running a good size solid roller and I should be over 500hp at the flywheel. What do you guys think?

My calcs show a 35# for 500hp, 38.# for 550hp, and 42# for 600hp.

Thoughts?

-Dustin-

 

Check your duty cycle with a scanner.
Below 85% duty, don't worry.
Above 85% time to upsize.

 

Your "calcs" appear to be based on a BSFC of about 0.476 #/HR/HP and an 85% duty cycle. If you make more than 525 flywheel HP, or don't have an efficient tune, you may be encroaching on the 85% DC with 37 #/HR injectors. You'll probably be OK to 560HP if you want to push it to 90% DC, but the higher the DC, the harder its going to be on the injectors, and the greater the liklihood that the flow rate or spray pattern will be affected. With a really efficient tune and efficient combustion chamber design, you could see a 0.450 BSFC and that would give you even more head room with the 37's.

 

For 500+ hp it would be pushing the injectors in my opinion. You could go with a lot higher one for not that much more. I see 42's for $300 and 60's for $379 and you could sell your old ones for a decent price and upgrade.

 

I'm running the racetronix 50lbs on my 383 and pushing 580 to the wheels.

 

Injector size is determined by flywheel HP, not rwHP. I was going to back into the flywheel HP, assuming the 700R4 shown in your signature, but then I noticed that you are running "edelbrock intake and carb"....... sort of confusing.

When stating an injector size, you also need to state the fuel pressure.

 

Just for reference, my 396 with heavily ported heads and a GM 847 cam maxed the stock 24# injectors this weekend at 5500rpms.

I have 39# flow-matched Terminator injectors to swap in... once I do I'll get a dyno sheet and see how much the stock injectors were really putting out at 100% duty cycle (though they were an old set so they may be a bit less than expected).


37# injectors may be fine for your application, although you will have to rev higher to make the same hp as my 396, which reduces the available pulse width per revolution so you may be fighting duty cycle.

What PCM are you running? I assume its not stock (7000 rpm limit) due to the a solid-roller cam.

 

I got some 42# FMS matched set. Used with about 5k miles on them. PM me if you are interested.