Injector size for 355CID @ 450hp+? And other question.
 

What size injectors do I need and do I need to run a higher preasure fuel pump to handle 450-500hp 355CID? Also, I'm having a hard time finding a fuel injected intake that the runners will match up to my Dart Pro 1 cylinder heads. Anyone have any suggestions without having to spend a grand.

Re: Injector size for 355CID @ 450hp+? And other question.
 

I'd go with 42lb injectors

Re: Injector size for 355CID @ 450hp+? And other question.
 

I run 30 lb SVO's with my setup. Only at 15 on the pulse width on the injectors at WOT. And I have right at 400 RWHP N/A.
HVY SS

Re: Injector size for 355CID @ 450hp+? And other question.
 

For 500 flywheel HP, you should be running at least a 36# injector. Unless you have a very efficient tune, you will be over 90% duty cycle on a 30# injector, even allowing the 5% extra capacity in the SVO's at 43.5psi fuel pressure.

If you're talking 500rwHP, you'll need the 42's.

Re: Injector size for 355CID @ 450hp+? And other question.
 

Here is a good formula for finding out...

lbs/hr = (max HP) x (brake specific fuel consumption) / (no. of injectors)

I think that is right...

ShibbyZ

Re: Injector size for 355CID @ 450hp+? And other question.
 

I would go 36 or 38.

Re: Injector size for 355CID @ 450hp+? And other question.
 

It's not quite right... it ignores duty cycle.

(flywheelHP x BSFC) / (# cylinders x duty cycle)

Example:

(500 HP x 0.46 #/HR/HP) / (8 cyl x .85 DC) = 230 / 6.8 = 33.82 #/HR

A BSFC of 0.46 #/HR/HP would represent a fairly efficient tune. Some sites recommend a BSFC of 0.50 for NA engines and 0.60 for blower and (dry) nitrous engines. 0.50 is a bit conservative.

Re: Injector size for 355CID @ 450hp+? And other question.
 

Ok thanks for all the help guys, sounds like i'll need 42lbs injectors then. What about the intake question?

Re: Injector size for 355CID @ 450hp+? And other question.
 

oops, forgot duty cycle has an effect too. Atleast it is cleared up now :thumb:

Re: Injector size for 355CID @ 450hp+? And other question.
 

should i upgrade my injectors?

i have a 355 huge cam and stock heads/intake and 150-175 shot but i do have abigger fuel pump!

Re: Injector size for 355CID @ 450hp+? And other question.
 

Is your nitrous system wet or dry? You don't need larger injectors for a wet nitrous system. You would size your injectors based on the engine's NA HP. Given the mods you list, you probably should have something larger than a 24# injector..... although I'm not sure a "214/224 comp cam" is "huge".

Re: Injector size for 355CID @ 450hp+? And other question.
 

im osrry the cam thats in the new 355 is a 238/242 565/579 lift

Re: Injector size for 355CID @ 450hp+? And other question.
 

This is off topic, but what kind of gas milage do you get/plan to get? manual or auto?

What kind of milage did you get with the 210/224?

Re: Injector size for 355CID @ 450hp+? And other question.
 

i was getting bout 245-265 miles per tank!

maybe a 10-12 drop

Re: Injector size for 355CID @ 450hp+? And other question.
 

10-12 mile drop from the whole tank? That is like a 1 mpg drop. Good to know what is going to roughly keep the same milage. I plan on doing a 224/224 .525/.525 ZZ409, if those are the right specs....hopefully I'll have some good milage still.