[james christopher]

I have a fuel question what size injectors?

[95opal]

42lbers and a 255 pump will do ya

[james christopher]

Thank you its hard to find detailed info, maybe you can tell t/b size and maf size. I have a 1995 mustang GT,I found a good deal on a 1994 mustang gt with a brand new 347 build most everthing is there. I paid just over a 1,000 for the car with a stroker.

[Bullitt95]

Originally Posted by james christopher I have a fuel question what size injectors?

Is that N/A or with forced induction?
Is that 450hp at the crank or at the rear wheels?

Realistically I'll assume it's 450hp at the crank (390rwhp) and N/A so the optimum injector size would be 36lb/hr. The 42lb injectors would be appropriate if it was 450rwhp and N/A (tall order on a 347). Either way a tune would be mandatory.
I'd go with a 75mm TB, 80mm MAF, and a 255lph fuel pump.

[95opal]

agreed in NA form 36rs would be fine. But for one they dont make them anymore and two you should always leave room for growth. Why buy crap twice. makes no sense
WIth the right combimation of parts a 347 can and will lay down those numbers.

[Bullitt95]

Originally Posted by 95opal agreed in NA form 36rs would be fine. But for one they dont make them anymore

If that's true then 42lb injectors would be OK, but the computer will need to be reprogrammed with a reduction of the injector duty cycle to prevent the engine from running overly rich.

[james christopher]

Its going to take alot to make the 450 h/p I will have the car tuned after i get done and the breakin period is over. Thank you

[Bullitt95]

450 crank HP = 390rwhp

There are several 347's out there putting down at least 390rwhp so it's within reach. It's just a matter of selecting the right combination of parts.

[cobramanphil]

I agree that it is always better to have room to go. Before I swapped out motors I always thought that 42lb injectors would be enough. I was soooo wrong. Even without the blower belt attached/running those injectors were barely enough to run n/a on my car up to 4000rpm. So I swapped them out for 60lbs and changed my tune. After a year or so..I stepped up the blower speeds and then guess what...those 60lbs with aftermarket fuel rail/lines/aeromotive fuel pump is running lean again and i then moved to 80lb injectors which gives me more reasonable duty cycles at my shift points (6500rpm). If I were smart about it I would have jumped to 60lb injectors from the start and saved on the bucks buying 42 pounders (easily could have triimmed the 60s in my tune).

The whole point is that one can easily modify the fuel tables/trim/MAF transfer if running big injectors on a combination that probably does not require that large of an injector..it is just in the tune and I see no ill affects about doing it this way.