you sure your tuner didn't tell you 10lbs and you somehow misheard him as 20lbs?

 

I've been running 12 psi for the last couple years on a stock bottom end. The tune is very important IMO. I'm almost at 150K miles on the engine, and the last 30K or so have been at 12 psi.

 

thats what i was wondering. 20psi should yeild a **** ton of power.

 

these gm engines are tough, i pulled out my 4.8l with 130k miles on it and put in a iron 5.7l, and took the old 4.8 and put in on the engine dyno at school on twin turbos and boosted it to 31lbs and broke the dyno and the engine was still together

 

here is a dyno sheet for a pull in 2nd. gear only when we were tuning. it shows 13.8lbs. of boost showing 491RWHP + 437RWTRQ. This was before I added the longtubes(no cats) and alky kit with alky pump and in dash controller. I am looking for the new dyno sheet and will scan and post it. yes its 19.8lbs of boost now. with heavy meth assist. I use about 1 gallon of meth per tank of gas! slowhawk performance has a website check it out. there is another avalanche with a 5.3 that he built with a little less power and it post in the 12's at new england dragway. not bad for a 8000lbs truck. but remember the cpu has been wiped and this is a completely custom tune.

 

this is using a P1C procharger which is running at max capabilitys now. If I want to go higher I will have to swap it out for a D1 or better. The D1 will allow me to add another 8lbs. of boost. however now im worried that might be to much for the stock bottom end. I do have a dyno sheet for the current setup im running.Im tring to find where the wife put it. anyone who would like to see the truck is welcome and can go for a ride. I live in swansea MA. I take great pride in the building of this truck it took two years to get it right and I love to show it to people and take them for a run just to see the expression on their faces.

 

there are some engine pictures in the garage section

 

as for the 20lbs. of boost reply. from the dyno sheet above you can see that 14lbs. of boost yeilds 491RWHP and 20lbs. yeilds 565RWHP. this = 21RWHP for each pound of boost added. talk to some tuners and this is right on par in higher levels.

 

It just doesn't seem like enough power from 20psi. The 5.3 truck that hellbents10 tuned put down over 700tq at the wheels on 35s.

http://www.streetfire.net/video/stev...ake_644102.htm

Bill (trever1t) has a 5.3 truck that dynoed at something like 575 at 11-12psi without the nitrous.

Hell, even I am putting down over 500 at the wheels at 10psi, and I know my tune isn't right because I am new to tuning lol.

If its really running 20psi of boost, something doesn't seem right. Especially that 460ft-lb number...

 

Agreed, 460rwtq seems waaaayyyyy too low for 20psi. Hell, I put down 407rwtq at 6psi on stock manfolds, cats and a very conservative tune. If I added 14psi, a cam, meth and longtubes and only gained 53rwtq, I would be pissed.