what injectors should i go with for my 331???

juiced_94gt · Aug 11, 2007

Well two of my 24lb injectors took a dump i tested the harness and its two bad injectors causing a huge misfire well it's a 331 with AFR 185's a track heat manifold, TFS stage 2 cam, 80mm LMAF and will eventually get a at least a 75 shot of spray...it's my daily driver so do bigger injectors equal more gas?? should i stick with 24's for a 75 shot?? are 30' or 36's a better choice?? I will go to steve at powertrin on monday to get my chip re-flashed for whatever i need.

sage2k · Aug 11, 2007

30's or 36's
I have a 302 with trickflow kit and its maxing out my 24's

Grn92LX · Aug 11, 2007

Wet or dry kit?

I would do 30's if its a wet kit and 36's if its a dry kit. My 30's are near maxxed out.

DDSTANG94 · Aug 11, 2007

juiced_94gt said:
Well two of my 24lb injectors took a dump i tested the harness and its two bad injectors causing a huge misfire well it's a 331 with AFR 185's a track heat manifold, TFS stage 2 cam, 80mm LMAF and will eventually get a at least a 75 shot of spray...it's my daily driver so do bigger injectors equal more gas?? should i stick with 24's for a 75 shot?? are 30' or 36's a better choice?? I will go to steve at powertrin on monday to get my chip re-flashed for whatever i need.

i dont think 24ers were adequate for what ur running now..and if u throw nitrous in the mix its going to be problems..i would say 36#ers..

Stanger007 · Aug 11, 2007

If you're getting the chip flashed, go big.

Wes

5spd GT · Aug 11, 2007

Grn92LX said:
I would do 30's if its a wet kit and 36's if its a dry kit.

I have to agree here.

Get a tune either way...

BlackVert · Aug 11, 2007

+1 on the 36s

gcomfx.com · Aug 13, 2007

If you are getting a tune.... and you have the LMAF. Why not go with 42s and be done with it? That's what I'm running. Don has been able to tune it first a little lean, then a little rich. Next tune should be on the money. And I'm ready for a super charger down the road. All I have to do it slap it on the car. T/B, Mass Air, injectors... it's all ready to go.

juiced_94gt · Aug 13, 2007

gcomfx.com said:
If you are getting a tune.... and you have the LMAF. Why not go with 42s and be done with it? That's what I'm running. Don has been able to tune it first a little lean, then a little rich. Next tune should be on the money. And I'm ready for a super charger down the road. All I have to do it slap it on the car. T/B, Mass Air, injectors... it's all ready to go.

Supercharger with flat top pistons???

gcomfx.com · Aug 13, 2007

Super charger with a stock engine? Nitrous on stock hypertectic pistons?

I'm not talking about 30 psi or anything.

blkcobra50 · Aug 13, 2007

36# or 42#

I have 42's on my 331. AFR is where it should be w/proper tune of course.

final5-0 · Aug 13, 2007

I do wanna say I think John could not find 36's a while back
for his 347 combo

Grady

DDSTANG94 · Aug 13, 2007

right HERE>>>>http://cgi.ebay.com/ebaymotors/8-36...012QQitemZ220138059488QQrdZ1QQsspagenameZWDVW

5spd GT · Aug 13, 2007

I know Accel makes 36lbers, but I like the Ford Racing ones myself...(bias)...

So in that case, get 42lber's with a tune

Fuel Injector Selection:

Injector HP Ratings: divide flow rating by .5 and multiply the result by the number of injectors. The following examples use a 100% duty cycle. These ratings are for N/A engines and at the flywheel.

Example:

19 lb injectors/.5 = 38 - 38 x 8 = 304 HP
24 lb injectors/.5 = 48 - 48 x 8 = 384 HP
30 lb injectors/.5 = 60 - 60 x 8 = 480 HP
36 lb injectors/.5 = 72 - 72 x 8 = 576 HP
42 lb injectors/.5 = 84 - 84 x 8 = 672 HP

The preferred duty cycle is about 85% maximum, so for a safety factor multiply the final figure times .85.

304 HP x .85 = 258 HP for 19lb injectors
385 HP x .85 = 326 HP for 24lb injectors
480 HP x .85 = 408 HP for 30lb injectors
576 HP x .85 = 490 HP for 36lb injectors
672 HP x .85 = 571 HP for 42lb injectors

Remember that the above ratings are at 39 PSI. Increasing the pressure will effectively increase the flow rating. Example: a 19 lb injector will flow 24 lbs at 63 PSI, and a 24 lb injector will flow 30 lbs at 63 PSI.

See http://users.erols.com/srweiss/ to get the calculators used in these examples.

Courtesy of jrichker...

Guero · Aug 13, 2007

If your going with 30lbers im selling mine....

The Green GT · Aug 13, 2007

42's with a tune. It will give plenty of room to grow.

final5-0 · Aug 13, 2007

I also prefer FMS/Bosch

All inj's are not created equal :Word:

Another thing about that excellent info David gave us

Those HP ratings are Flywheel ... NOT ... RWHP

Grady

5spd GT · Aug 14, 2007

Good point, I always forget to add that 'note'...because that changes things a bit

Edited...

final5-0 · Aug 14, 2007

Several times I've been contacted with a request of why I feel 19's will not
feed all that much power.

The most important thing to keep in mind I tune at stock pressure so that
is my point of reference.

Peeps are so quick to say ... "19's will feed 300 horses"

Look at that info David provided

304 flywheel hp

258 with the 85% duty cycle

258 x .85 for a 15% drive line loss = 219 rwhp

See why Ford put 24's on the Cobras

Grady

5spd GT · Aug 14, 2007

I see, I see

what injectors should i go with for my 331???

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