1FSTZ71

iTrader: (11)

Think 36# injectors and 12-15psi would be plenty? I plan on running a kenne belle boost-a-pump inline with my factory pump. I think that would be enough for what I'm looking for don't ya think? Think I could leave the stock cam in it too and just change the springs to attain those numbers? I have Corvette 241 heads on it right now. everything else is stock. Once the motor goes I planned on boring it out and swapping cranks to do an iron block 5.7 setup with forged rods/pistons, but not yet, still trying to get my 69' going lol.

BlackGMC

iTrader: (31)

So is 20 psi possible on a 4.8 since it is a smaller motor?

1FSTZ71

iTrader: (11)

semms so with a dead-on tune and good gas lol. I don't think I want to push it THAT high yet

1FSTZ71

iTrader: (11)

So think just head studs will be fine, worth changing out rod bolts? Don't plan on spinning higher than 6200rpm

parish8

iTrader: (6)

you dont need rod bolts if your not going to spin it up high.

the 42lb marine injectors would be a decent step and bolt/plug right in. i dont know for sure how far they would take you. if you have plans of pushing it you might want to go bigger. a camed 4.8 with good exhaust at 15psi might be too much for 42's

the stock pump is good to around 400rwhp. with a boost a pump i would think 450rwhp at least but no idea exactly how much hp that would be good for. 15psi might be pushing it for a stock pump with a boost a pump.

not sure of your experience level. if your going to push things you need to know how to tune and watch the scan tool and be able to control yourself when the scan tool tells you to take it easy. a person without the desire to learn how to tune and the self control to take small steps would be the wrong person to push a nearly stock 4.8. when i was running 15-20psi on my 4.8 i rolled around much of the time with a laptop hooked up in my truck and kept close tabs on things. if you screw up one time you will break a piston and it only takes a sec for that to happen.

1FSTZ71

iTrader: (11)

So you think the stock cam should be fine and around 15psi you think Marine injectors will hold up with stock cam? I've built alot of nitrous motors (fuel injected and not) and had a supercharger on the 5.7 that is currently in my truck and did the tuning on that myself (my first time trying), never had detanation problems, ran a lil rich but went mid 14's on 7psi with stock everything except for headers, no cats, exhayst, 4.56 gears, but on 33x13.50 super swampers. This will be my first turbo build (going to be turboing my 69' as well). I don't trust myself enough to do the first tune on it but have friends at XXX motorsports here in town that tune 1000hp EFI cars that could tune it and assist me. I plan on running a wide band and my laptop in the truck so I can keep look out for stuff. I'm not looking to make it a drag truck, mainly for street driving and pulling with some fun at the track and off at times. My truck was awesome with the blower, surprised alot of people especially with the big tires haha.

parish8

iTrader: (6)

here are some charts i have for my completely stock 4.8 with a t76. the gtech runs were on a cold night and i have found my gtech corection factor is .3sec and 5mph so drop(it is .3 slower than the chart says) all those 1/4mile et's by that amount. with sticky tires and loading it higer on the launch i am sure a true high 11sec run is posiable on a totaly stock 4.8. with valve spring you could take the motor to 6000rpm and the numbers would hold prety good up there.

parish8

iTrader: (6)

here is another neat gtech from just a few weeks later when i got the 408 in. the 408 is camed with stock 6.0 heads.

1FSTZ71

iTrader: (11)

Awesome graphs man. So at 10psi on pump gas made 428 and 445, that's pretty awesome. I'd truely like to run right at 10-12, 15+ on race gas at the track. I'll probably do a tune on pump gas on the dyno then one on race gas and save the file to upload for the track. Alright well next week I'll be ordering my flanges, piping, valve springs, and start building my kit.

PPI Typhoon

iTrader: (1)

Hey Parish, was that T76 using a .96 a/r on the exhaust housing?? I'm gathering parts for putting an LSx motor in my Typhoon with my T76 Q-trim and wondered how it would be on a 4.8 (leaving the motor purchase until last). Obviously as it is on a 4.3 right now, it's pretty laggy even with a .85 a/r exhaust housing. But being a BB turbo, it's not really all that bad.

Have any opinions on if I would need to swap that exhaust housing out on the 4.8?? I know I certainly would with a 5.3 or higher. The plan is a 6.0L eventually with twins, but I might as well use my T76, and it sounds like you've had a lot of good luck with that setup.

Thanks in advance.