Injector size?

[Smokedawg]

What size injector should I be running with the current mods. Keeping in mind that I will also be adding nitrous in about a year around 125 shot. Thanks

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347 Stroker Motor: Balanced, A9P Computer, Cobra Transmission, Extrude Ported and Polished Upper and ported Lower, GT40 Milled Ported and Polished Heads, B303 Cam, BBK 1 5/8 Headers, Holley Fuel Regulator, March Underdrive Pulleys, Electric Fan, Accel Performance Coil, Accel 300+ Racing Wires, Ram Air, K&N Filter, 79mm Mass Air Unit, FlowMaster Exhaust w/BBK Offroad H-Pipe, Hurst Short Throw Shifter, 3:55 Gears, Ram Clutch, Cross Drilled Rotors, High Tolerant Painted Calipers and Drums.

[302 LX Eric]

I would say that 24#'s are the minimum for your 347 N/A. With the N20, you probably will need 30#'s or even 36#'s to be safe.

Good luck,
E

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1991 5.0 LX Coupe - 38,000 miles

13.17 @ 106.14 mph w/ 2.138 60'

[Rick 91GT]

I would say 30#ers would be a good choice. Have you done any dyno pulls with it yet?

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Check Out My Site 91GT,Holley SysteMAX II Kit-Heads 2.02" x 1.60" port matched to a 1262,Anderson N-61,24#,76mm C&L,Full MAC exhaust 1-5/8" Long tubes,2-1/2" O.R H-Pipe,2 1/2" cat back, No A/C or PS or emissions, 12" K&N Filter,RNH PERFORMANCE Ram Air,Ron Davis Radiator,Full Suspension,S&W 8pt "X" brace,JAZ seats,3:73's,Welds..etc,4:30's and 31 splines coming very soon!

[Smokedawg]

No dyno pulls yet.. I was waiting til I got my fuel system up to par. I will as soon as I get my injectors and AFR on. Do you think the 30's will be to much? If i get the 30's i will keep the pressure down til i get the N20.

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347 Stroker Motor: Balanced, A9P Computer, Cobra Transmission, Extrude Ported and Polished Upper and ported Lower, GT40 Milled Ported and Polished Heads, B303 Cam, BBK 1 5/8 Headers, Holley Fuel Regulator, March Underdrive Pulleys, Electric Fan, Accel Performance Coil, Accel 300+ Racing Wires, Ram Air, K&N Filter, 79mm Mass Air Unit, FlowMaster Exhaust w/BBK Offroad H-Pipe, Hurst Short Throw Shifter, 3:55 Gears, Ram Clutch, Cross Drilled Rotors, High Tolerant Painted Calipers and Drums.

[Piston]

I would go with 30lbs on a 347 for sure. I got a N/A 302 and I am using 24lbs but would definately put higher inj in for a 347. I got a formula that shows what an injector will support HP wise. I will post it if I find it and remember....

[Smokedawg]

Thanks for all replys..I went ahead and got the 30's..Now does anyone know whats a good N20 kit to buy?

[Kenn]

Glad to hear you went with #30's. I just read the post, hence I didnt get to give you my input prior to your purchase. Anyway most of the fast N/A 302 cars in TS and PS are running the #30's, so your 347 should need them. I would start them off in the 40psi range with the vacum line off. If you go wet system for your nitrous you dont have to worry about your injector size, dry you do. I used to run GT40 heads/intake, custom cam and ran the Bag of Nitrous dry kit with #24 injectors on a 302 with great results. Good luck to ya. Oh, check out www.stangcrazy.com and ask some of them guys in the RS class what kit they recomend.

[Smokedawg]

Ok. Thanks Kenn

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347 Stroker Motor: Balanced, A9P Computer, Cobra Transmission, Extrude Ported and Polished Upper and ported Lower, GT40 Milled Ported and Polished Heads, B303 Cam, BBK 1 5/8 Headers, 30lb Bosch Injectors, Holley Fuel Regulator, March Underdrive Pulleys, Electric Fan, Accel Performance Coil, Accel 300+ Racing Wires, Ram Air, K&N Filter, 79mm Mass Air Unit, FlowMaster Exhaust w/BBK Offroad H-Pipe, Hurst Short Throw Shifter, 3:55 Gears, Ram Clutch, Cross Drilled Rotors, High Tolerant Painted Cal

[Mean50]

A good nitrous kit is the adjustable one from The Nitrous Works company. It is a wet system and is only around $500.

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89 LX Coupe
306, 10:1 compression, Holley Heads, Intake, and Cam package, 70 mm Throttle body and Mass Air, 30 lb injectors, 255 lph fuel pump, 1 5/8" full length headers, Flowmaster 2 1/2" American Thunder Cat back system, Centerforce dual friction clutch, 4.10 gears
50-175 hp Nitrous Works kit, 5" Auto Meter Shift Light

Is it true what I was told.....that to find out what the minimum size for your needed injector is take 1/2 of your HP and divide it by the # of cylinders? Is there benefit to having a larger injector or fuel pump than needed, or will it have an adverse effect???

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'90 LX 5.0; 12K original miles (no sh*&); 3.55 gears; pulleys; Edelbrock Performer Heads;
BBK shorties; MSD 6AL ignition system; Motorsport E303 cam; 75 MAF; 70 TB; Eibach spring kit;
Southside sub-connectors; K&N cone filter charger; Hurst shifter; fiberglass cowl hood; A/C-less;
rear seat-less; cat-less; Flomasters; Corbeau racing seats (fronts); 12.513 @ 108 mph

[xspeed02]

Oh I got this... Let me go dig in my Muscle Mustangs and Fast Fords ...

Retyping this from an article John Hunkins wrote:

Calculating fuel demand, injector size and fuel pressure for any engine is a fairly straightforward affair that we've covered on several occasions, but we'll review it once again here. First, estimate the total engine fuel demand by multiplying the estimated horsepower by .55. This will give you the fuel requirement in pounds per hour for an engine with a brake-specific fuel consumption of .55. Next, divide this total fuel demand by the number of injectors (eight, in our case), and tack on an extra 15 percent for safety.

The number you have just arrived at is the target injector size. If the number is in between two existing injector sizes (and it likely will be), you'll want to go to the smaller size and raise the fuel pressure to make the difference. You don't want to go up to the next size and cut fuel pressure, because this hurts fuel atomization and combustion efficiency.

Hope that helps. The article was actually taken from his Under Pressure Column, which he mainly talks about Supercharging... But this part should be the same for every car I believe. I hope.