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

[lifted4.0]

hey guys, im wondering if these injectors are gonna pop right into the engine that im rebuilding in the basement, http://cgi.ebay.com/ebaymotors/ws/e...arms=tab=Watching&item=360086640222&viewitem=

thanks

 

[Yellowsplash]

Your not going to need anything that big.... You might want to add some info on that "engine in the basement".

 

[Wicked_Sludge]

+1

it depends on what kind of horsepower figures your going to put out. how much boost? how much nos? wet or dry?

 

[lifted4.0]

looking for about 400 at the crank. 9-10 psi of boost off a eaton m90 with w/m and a 50 shot max of nitrous dry

i have 30 pound injectors in the basement, but i didnt think those would be sufficent

 

[turbo cat]

the 30#ers- should be fineand go wit ha wet kit. you don't wanty a bigger injector than you need otherwise the motor will have a hard time trying to tune the idle and it may not even idle that great.

 

[Wicked_Sludge]

30lb injectors are NOT enough to support 400HP even if you had 8 of them (i forgot to ask, is this a v-6, or v-8 your working on?). your better off to have too large of an injector than too small (turbo cat should know a thing or two about this)...although sizing the injector properly would provide the best results.

 

[turbo cat]

Too large of an injector creates unstable fuel flow due to at idle when little fuel is needed. This is why the Ford GT uses two 42# injectors per cylinder. A 4.0 ( I assume this will be a 4.0) at 9-10lbs of boost will be around 300hp at the crank roughly. I didnt do any big calculations but 30-40#s should be in range somewhere in there. im not a nitrous guy but I belive wet kits are setup to deliver fuel along with the nitrous so theres your fuel for when your on the bottle.

At 90% duty cycle at 45psi 24lb injectors are rated good to 384hp roughly. So tell me that 30lbers are not good to 400?

 

[Wicked_Sludge]

he said he was looking for 400 at the crank and a dry shot. 30lb injectors would probably be fine for 300 HP on a wet shot (which supplies its own fuel)...but hes going to lean out if he pushes it over that or runs a dry shot.

id rather sacrifice idle quality than burn through pistons.

 

[turbo cat]

At 90% duty cycle at 45psi 24lb injectors are rated good to 384hp roughly. So tell me that 30lbers are not good to 400?

 

[Wicked_Sludge]

whats your BSFC to get that number? .1?

or are you talking about a v-8 now?

and i always use a maximum duty cycle of 80%. that leaves room for things like a tired fuel pump, clogged injectors or fuel filter, etc. thats the number ford and SVT use.

400 HP out of a v-6 will need at least 37lb injectors. 28lb-ers for a v-8.

 

[turbo cat]

whats your BSFC to get that number? .1?

or are you talking about a v-8 now?

and i always use a maximum duty cycle of 80%. that leaves room for things like a tired fuel pump, clogged injectors or fuel filter, etc. thats the number ford and SVT use.

400 HP out of a v-6 will need at least 37lb injectors. 28lb-ers for a v-8.

90% will be fine for what hes using the truck for. Actually Im jumping the gun here anyways more info about his setup is needed. We don't know what hes sliding into that motor. On a DD street/strip truck how long will he be at redline. Also how far will he rev. Now Im not an expert on the subject but one thing I do know is you do not want a bigger injector than necesary. 42#ers may be needed but more info about the setup is also needed. honestly i would skip the dry setup for a wet setup and sue the 30# injectors but hey RIP 4.0

 

[Wicked_Sludge]

again, its better to have too large of an injector than too small. its better to run rich than lean. rich will cost you fuel economy. lean will cost you a motor.

but i agree, more info (especially number of cylinders) is needed.

 

[lifted4.0]

cylinders- 6

going to the dyno tommorow...gonna get those numbers up right when i come back, im pretty sure that i have 300hp at the crank right now..at 6lbs

going into the engine are forged pistons at probably 9.4:1 ratio, and ported and polished heads...

 

[Wicked_Sludge]

for 400HP out of a 6 cylinder, id snag up those 42lb-ers. thats about dead perfect for what you want at 80% duty cycle with an assumed BSFC of 0.5 or so. your dyno run will tell you more.

if your leaving the boost where it is then they are way overkill.

 

[Yellowsplash]

The BSFC can move from .5 to more towards .6 on forced induction (in this case s/c) applications. Can I ask what engine will be pushing this amount of power, a 4.0 SOHC? What fuel pump, fuel pressure, and target air/fuel ratio are you planning on running?
I assume you are running a SOHC that has a mechanical returnless fuel system with a base pressure of atleast 60 psi. I also assume a .6 BSFC, and 80% max duty cycle...a 42lbs/hr injector would be sized perfectly with some excess room for error (indicated lower fuel pressure, lower duty cycle, and higher BSFC).