Intake: Super Victor (or GMPP for rectangle port heads if needed)
Turbo: T6 80MM, GT4780 / PT4780 or similar (80mm is the limit)
Transmission: RMVB TH400 or RMVB 4L80 (no electronics in the 4L)

Goal: 3250lb race weight, high 8's in the desert with just the 80mm.

I had originally planned on a 415ci LS3 with either AFR 245's or Trickflow 235's, however I am reading now that I should be considering other heads and smaller displacement to take advantage of the small turbo I am stuck with.


So, I ask you tech...

What ci motor would you build, and what heads would you put on it knowing the above, and mostly WHY do you say that. I am a technical person so I like to know the ins and outs of why something does or does not work.

Thanks!

 

402 with room to grow, the better the heads are the more power you'll be able to make with less boost, I'd stick with the Edlebrock supervic and a pair of Performance Inductions 245s.

 

370-PI ls7 4.0 or 245's

 

Why are you guys saying the smaller cubes?

 

the smaller turbo will make more power on a smaller engine.On a large engine you will run out of airflow.

 

Gotcha.

I saw your post on YB also about the heads also. Do you sell PI products?

 

Yes,sir-number one PI distributor.

 

What is the deck thickness on the PI heads?

 

0.75

Small motor and $$ heads or big motor and cheap heads.
I think the 402 and $$ heads will out run what an 80mm can push
Guys are doing 9.3ish on 370's with AFR 225's and PT88.
Big motor may also need a bigger turbine than your listed turbo. You'd need to ask Jose on that one.

There's a guy on TTF that's going 9.40 in 4400 lb truck & 383sbc with only cal tracs for suspension mod and AFR 195's.
Best chance with the 80mm is a 370 and mid size PI cathedral head.
It should have no problem running off the map w/ some rpm.
The smaller setup should get the compressor up in the higher PR section of the map for max compressor capacity.
But it's easier to change heads later than a crank so the 4xx motor has is pros too.
It's kind've a balance with CID and boost w/the 4 bolt head.

 

9.40s with an 88? i just went whats roughly 9.teens on a 76 with as cast TFS heads, and I dont think thats anywhere near what it should be when its working right. In a class limited, smaller turbo deal, I dont think the heads matter much. A killer set of heads on such a setup mayb make more power at a lower "boost reading" but if you turn it up, does the motor or the tuner care if your running 16.5 psi or 19 psi? All in is all in.

Personally I went the route of saving money on the heads, and putting it in the turbo, the ultimate determinate of how much power its going ot make.

4 bolt head vs small/big engine, boost doesnt lift heads does it? Cylinder pressure does, low or high boost 1000 hp is a certain cylinder pressure Id think. Tuning window and spooling window will be smaller with smaller engine yes. You run out of turbo with a 80mm on a 370 no problem, mines choked I know

 

9.40 w/80mm 16-17psi at 4400lbs nothing done but cal tracs......needs valvetrain or bigger turbine, not sure which and pretty expensive fix for a 9sec street truck that tows a boat. Dropping 1000lbs off that combo would be in the 8's easy.....
9.30 is with an T4 based 88 370 street car. -98Z28Cobrakiller
OP is in the desert so running off the map will add even more heat to the air.
More guys lifting at 20+ than 15.....but an 80 will flow more air at 20+ than 15.
Tune lifts more heads than boost and you know it.
Based on your comments and agreement on the 370
The 370 with as cast 220's and a 234/238 cam should about max an 80mm out.
But I'd like to see someone doing 8's with as cast TFS 220's first.

If I had the coin, I'd get the PI heads no matter what.....still might, but I have reservations on
spending that much on heads and keeping a stock crank.