injector size and brand for S/C'd nitrous ranger

[AKBroncoII]

Still considering it though.

 

['93BajaSport]

wait a min i did the math for my 3.0 and at 15psi boost for 300 hp on 6 cylinders at 80% duty cycle (fords safety margin is 85%) i need 42# injectors.

The numbers sound right, but boost doesn't factor into the sizing of injectors. All you need is the BSFC, number of injectors, and brake horsepower.

Just look what Turbo Cat has done with his setup

 

[98blownranger]

when you figure you injector size, remember that you fuel pressure is about 70 psi, the injectors are rate for flow at at much lower pressure, so a 30lber will put out more fuel on your returnless system

 

[rurouni20xx]

how much psi fuel pressure?!? i realize that the amount of boost isnt a factor i just threw that out there as a complete number for my figuring when i figured it. 70 psi is a lil high, 35-55 is the normal range if im not mistaken. granted were talking a returnless system here so i dont know, mine has a return w/ a regulator and constant pressure fuel pump. cranking up the fuel pressure does help but the injector duration etc across the rpm range is altered, you can underfuel at lower rpm and over fuel a hair at upper rpm, its best to size the injectors properly and keep the voltage w/in range that way you know your getting the right amount of fuel at the proper time. def dont want too small of an injector however then the duty cycle at higher rpm is pegged and you could underfuel too much and lean the piss out of it at 70%-100% throttle under acceleration. the only other way i could see getting around larger injectors is a secondary injector rail tha kicks in on a relay when tps senses beyond 70% above 3k rpm or something, def tuned tho.

 

[98blownranger]

a ford returnless system is set to run 68-72 psi

 

[lifted4.0]

i ordered the pistons through Super six..and i think they go through wiseco?

 

[AKBroncoII]

What did you pay for them?

 

[lifted4.0]

805 shippedd

 

[V8RangerBoy]

A V6 will fall on it's face if you try and make 400hp on 30lb injectors. Don't even try it. The MINIMUM I would start with would be a 50lb. You might squeak it out with 42's and an adjustable fuel pressure regulator, but even then I would be leery. Injectors are only designed to work within a reasonable range of pressures. This is why FMU's reaked so much havoc on cars. People would throw a super-restrictive FMU on to gain fuel flow and viola, injectors would fail shortly thereafter.

300hp is attainable on 42's. You're right in the ballpark there.

 

[shadetree]

805 shippedd

I hope they have a lower compression ratio than the 9.4 you are currently running. Superchargers don't like higher ratios as they make their own. Detonation and pre-ignition is not your friend. 8:1, is good, certainly not more than 8.5.

There is more than one way to skin a cat. Joe Morgan made 400hp on a mostly stock 2.3 using stock injectors (35lb), but he ran two Ford truck fuel pumps. He used nitrous to launch the Pinto.shady

 

[lifted4.0]

compression ratio was thought about for a while, while rob on RPS is running 333whp at 10psi through his stock internals at 9.7:1...with no detonation...and basa was running 9.0:1 and he said it slowed the truck down a great amount...i ffeel that 9.4 will be perfectly fine

 

[turbo cat]

as long as you can tune it higher compression isnt a bad thing unless your running huge amounts of boost. Mild boost 9-9.5 cr is good. with a 8 cr and low boost the power numbers would be lower than expected.

 

[shadetree]

higher compression isnt a bad thing unless your running huge amounts of boost. Mild boost 9-9.5 cr is good. with a 8 cr and low boost the power numbers would be lower than expected.

Operative words "as long as you can tune it." Higher compression gives a little more low end torque. He is running a positive desplacement blower, not a turbo, so spool-up is not a consideration, and the power should be there.

Lower crs' allow a slightly larger chamber, more space for a heavier mixture charge, plus, he may want to be able to run regular gas.shady

 

[turbo cat]

yes but unless he is pushing over 9psi on that blower a lower cr isnt necesary. There are a lot of motors that have a 10cr wit hpositive blower pushing 9lbs into them.

 

[shadetree]

Here is a rule of thumb chart. shady