injector size

[WFOranger]

A friend of mine just bought a rebuilt 5.0 long block from another friend. It has mildly ported E7 heads and a comp cam with 512 lift on both exhaust and intake and 220 degrees duration at .050. He has an 89 gt we are going to swap the motor into. It already has BBK long tubes, X-pipe, and Bassani cat back. My question to you is what size injectors should we use? Stock is 19 lb/hr if i am not mistaken so i was thinking 24 lb/hr would work fine. Any and all input would be welcome. We need all the help we can get.

 

[795.0pacecar]

The 19s will be fine but if you're worried 24s will work also.

 

[RYC CUKR]

I ran the stock 19 lbers on my 93 which had TFS stage 1 cam, GT40P heads, TFS trackheat intake, 70mm TB, 76mm MAF and full exhaust with no probs. I would be comfortable with the stock injectors provided they are in good working order but if you are not comfortable with them you could step upto the 24s

 

[4G-KDMP]

go with the 19s and you'll be fine.

 

[mike93lx]

you can go with either, you just need to have a Mass Air meter calibrated for them.

if you just slap 24's in a motor with a 19# MAF, it will run like crap.

 

[5spd GT]

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

You'll be fine with 19's if you increase fuel pressure, or if he has the money just put in the 24's with a matching MAF. That is if your/his budget allows.