Stock 4.8 802RWHP but valve float now
 

Stock 4.8 engine
26 PSI on C16 made 802 RWHP but now I cant rev this thing past 6000 RPM. I guess thats right around 1000 hp at the crank through my TH400 and PTC converter.

My goal was to run faster than my old Turbo V6 with a stock Ls1 4.8. I almost did. The 4.8 finally went 6.5 @ 23 psi but the old v6 went 6.455. Although the 4.8 went 107 mph in the 1/8 and the V6 only went 105 so it looks like Im making more power anyways.

I ordered valve springs, trunion kit and push rods so I can rev it past 6k at 26 psi.

My question is has anyone DONE a turbo 4.8 if so what cam did you use.

a member here "stock48" used a isky triple 12 cam with great success.

6.50 @ 107mph with 802whp?

Doesn't sound right?

Yeah your right. my pass at 26 PSI, 802 rwhp would only rev to 6000 and my converter is too loose so the converter was trying to catch up to the motor but slipping. My data log showed 6000 rpm steady like a rev limiter. Too much intake manifold pressure causing valve float. It went slower at 26 psi 6.8 @ 104 mph. At 23 psi it would rev to 6800 and the converter was not slipping at much. I leave off the brake @ 5000 but can stall upto 5500.

I did a junkyard 5.3 with some 243's on my friends Silverado and went with our boostaholic 2 cam and pulled 823 RWHP. His truck ran 10.50's at 134 MPH full weigh plus added weight of roll cage

My car @ 8:35
Murder Nova @ 4:15 from Oklahoma

Was thinking same thing when I read this. Should be 114-116 somewhere in that mph. But I see you explained Rev limited to 6000 and auto trans woos.

What turbo is that?

Turbo is an s475. i machined the big flange off and welded a stainless v-band to it

I also have this turbo. I'm making 21psi on my ls1 with it. Good turbo for the money.

Great turbo for the money. This is my first LS motor and I am very happy with my swap from the Buick turbo v6. I get alot of Buick haters but you cant go wrong with a craigs list 300 dollar 4.8. And I had it delivered to my shop too!!!

http://i430.photobucket.com/albums/q...ps92c49e27.jpg


10 psi 525
18 psi 680
26 psi touched 802
The RPM scale was calculated from the rollers. 5250 dosent cross at the right point on some runs

mine just did 561 at 15psi so yours makes more power than mine..

100% stock motor ? springs cam etc, head bolts ....etc ?

yep everything in the long block is completely stock. Head bolts, gaskets, cam springs, ect. Everthing... Only edelbrock intake manifold and stainless headers I built. with a s475 turbo. And my tune.

I do have a comp behive spring kit ON THE WAY and the trunion kit with comp push rods. I will install them this week and hopefully next Sunday make some passes @ 26 psi PLUS now that I know what kinda timing this thing likes on C16

And to think I sold my '05 long block 4.8 with 34k miles for $650 recently..... F*ck. would've rather seen how bright it would burn now instead....

i would use the Brian Tooley dual valvesprings, or PAC springs before i would use the comp cams behives (they tend to break faster than stock springs)