CFM's? PSI?

[rockjeep]

Ok so i've got a 360 with 9.5:1 pistons, melling cam, headers and a performer intake. How many CFM does this thing need to have? I'm currently running a tbi unit off of a chevy with stock 350 injectors which should be around 55 lbs. Is the tbi going to cut it? Right now I don't think I'm getting the full potential of this motor. I've yet to get the computer tuned as the only source I can find for that is a chassis dyno which will require me to bring the jeep to them and god only knows how much that will cost. Any advice?
Thanks,
Bobby

[ironman_gq]

the tbi should be able to fuel the beast adequately but you may need bigger injectors. in my opinion the dyno time would be well worth it as they will get you dialed in perfectly and be able to set you up with the right injectors. there are some companies that will flash a computer to feed your engine if you send them all of the specs and requirements for your engine which will be much closer to what you need than the stock chevy programming.

[tufcj]

I'm running a 350 TBI on my 360 with 291-C heads (about 9:1), with the original injectors. I have a Howell closed loop system, running a PROM they custom burned for my cam/intake/exhaust/compression. I haven't dyno'd it, but have never felt any seat-of-the-pants difference from the Holley I had which was dialed in with a dyno.

Bob
tufcj

[rockjeep]

they chassis dyno guy says it'd be 550.00 so that's not an option. My issue is I don't really know what I should expect as far as the power goes. I just want to make sure it reaches it potential, and maybe its there I just am not sure. I know with 42"s and 4.10 gears in 2wd it takes it a second to get going, but that's not a huge deal for me as I'm mostly in 4lo with a 4:1 x case gear. hum guess I'll just have to keep playing with it.

[tufcj]

With 42s and 4.10s, performance isn't going to be stellar. It would be similar to 3.23 gears and a 30" tire. When you take into account the added unsprung weight of a 42" tire and wheel, you need even more gear. Ever weigh a tire/wheel combo? It may be triple what the stock setup weighed.

I'm running 4.27s with 37s and it isn't enough. I have 4.88s on the shelf waiting to go in.

Bob
tufcj

[rockjeep]

Yeah I know but I don't think even in 4 lo with a 4:1 x case gear it was making full power. And trust me I know 42's weight a lot. I had to mount them on my steel beadlock wheels. Now my old 38's seem so light compared to them. I hope to get this crap dialed. It works good but I want it to be perfect

[tufcj]

What's your crawl ratio? Mine is about 70:1 with a T-18 and Dana 300 (6.32 x 2.62 x 4.27), it will go to about 80:1 with the 4.88s. I have Detroits in both ends, and it will sit at idle and spin all 4 if it can't find traction.

Bob
tufcj

[rockjeep]

Well i've got an tf 727, not sure on the first gear ratio. Don't get me wrong this thing has some serious low end torque. I have manual brakes and you have to hold them tight or they will not hold at idle. I'm starting to think I just need to get it tuned. My biggest complaint is if I just stomp the throttle it feels as if the tbi is not keeping up with the demand of the motor.