So does anyone have a chart comparing injector flow rates to horsepower?

I'm finally re-assembling my car and it's going to need bigger injectors. Is there any other variable to consider besides "the car will probably make x amount of hp"?

For your info it has some stock LT1 castings with about as much porting as can be done to them, though I don't remember what they flow. The cam is a Comp nitrous/blower grind @.50 220-230 on a 114lsa. The motor is a 355 with 8.9:1 compression. Long-tubes with 3inch cat-back.

Not sure if there is any other relevent info. How many hp per cylinder can 1 lb/hr support at an appropriate duty cycle?

Thanks,
Jeremy

 

~.55lb/h/hp. So, 24lb injectors are good for ~55hp/injector. Multiplied by an 80% duty cycle, ~45hp. So, ~340hp for 24lb/h injectors.

Rich

 

Given the ultralow compression I take it you bought this cam for the blower end of it's recommendation rather than nitrous???

How wild are you going to go. If you search the net you can find calculators, I have access to a paid subscription one if you give more details I can run it.

 

I see low compression and a "nitrous/blower" cam..... but I don't see a blower on the list. Is there going to be one? Rich appears to have assumed you have one in his recommendations.

 

Yeah, I did make that ASSumption

 

Actually I bought it for the nitrous side of the cam. I should have mentioned the shortblock belonged to "Wingnut" and I will eventually put it back to its turbo origins. Right now, however, I just want to run it N/A with a ~250 shot.

96capricemgr: What kind of details do you need to run that calculator?

Thanks for the fast responses guys,

Jeremy

Edit: I found a calculator online, looks like I need ~33lb/hr injectors. I had guessed it would be between 30-36.

 

For a normally aspirated motor with a wet shot, multiply the normally aspirated (no nitrous) flywheel HP by 0.07 to get your injector size.

Example.... 400 flywheel HP x 0.07 = 28 #/Hr

That assumes a fairly efficient tune and an 85% duty cycle.

If you are thinking about a dry nitrous system, where the injectors have to supply the fuel, you have to know the specifics of the system to size the injectors... e.g. does the system increase fuel pressure when you spray?

 

Now that's information I can use. I was planning on using a wet shot (direct port fogger) and I figured that because it supplied fuel I wouldn't have to have bigger injectors. What if I run a dedicated fuel system for the nitrous with Methynol or some race gas?

 

Can you mill the heads and use a thin gasket to get some compression out of it 8.9:1 is like 80s smog turd level compression.

 

I don't really want to. When I have some money I will put together a turbo kit for the car, which is what the motor was designed for. If I wanted to run N/A forever I would swap out the pistons though, but it's probably not going to happen.

You're right though, I don't expect this car to be the fastest with compression that low. Another 15psi ought to bring those cylinder pressures up nicely though