dhuggett1001

New to forum and to turbo vehicles so bear with me. I have a 5.3 with ported 799 heads, tc78 .96, isky cam, north texas 4l80e, circle d 3200 single disc and I run on e85. Had it dynoed on e85 and put down 598whp on 19 psi. I was expecting close to 700whp or is that just wishful thinking. The tuner told me I need a multi disc converter to lock up on dyno and a better turbo any input would help can I reach 700whp with what I have. I know I will be purchasing a new converter soon that's my next purchase. Thanks.

Atomic

iTrader: (42)

What does it run at the track? Trap speed with a known weight is a much better test of power than a dyno.

dhuggett1001

Never been to track truck weighs 4479 with me in it. scsb

black00chev

iTrader: (2)

That sounds pretty good to me. Maybe the tune needs some more tweaking?

If you figure 20hp per psi, that's roughly a 400hp increase on boost alone. So it doesn't really seem too far off but sounds like there's a little left on the table considering the heads and cam.

dhuggett1001

Oh ok I was just curious seems like there's a tee people making close to that on pump with similar set up and and a few of those are the 4.8s. I also made 518whp on pump at 12psi so I think that's y I expected more at 19 on e85. I was recommended at precision 76/75 from the same shop would that make that much difference.

George C....

Should gain more then 20hp per psi with a LS motor on e85

dhuggett1001

So should I expect going from 12 lbs to 19 lbs that's 7 more lbs at 20hp a lb is 140 more hp from pump to e85 that's around 650-660? That's seems like where I would have expected.

gamble686

iTrader: (3)

Agreed that is ricer math if I have ever heard it. Efficiencies are a much better explanation. In a perfect world if you have a perfectly efficient build you would double your power for every added atmosphere(about 14.5-15psi)over NA. If that isn't the case then you are looking at an efficiency issue. Example if my stock NA 5.3 makes 200rwhp it should make roughly 400rwhp on 15lbs. If it doesn't then there are factors at play of all types. Let's say your 5.3 makes 300rwhp NA. Then at 21lbs you should make roughly 725-750rwhp if it was a perfect setup in a perfect world. Clearly something is holding you back. Either the boost isn't being delivered efficiently or it's not a very powerful motor setup.

George C....

Example my 5.3 makes 540/550 on 12 psi from a maxed out procharger on 93 with small amount of meth
500 alone on 93

My old TT 5.3 on 9 psi it made 575rwhp on pure 93


Dig deeper you have something going on

kbracing96

iTrader: (26)

You're probably out of turbine wheel. That TC78 only has a 68mm turbine. Your back pressure is probably though the roof at 19psi of boost!