S2 port velocity

[Shelbyguy]

what is a good turbo that will perfrom on the street on a built stage2 motor. i have S2heads and a custom sheetmetal intake. i want a fast spool and a decent amout of powe.....so enough too keep the port velocity up where it should be. i realize that the S2 heads may be too big for my needs but i got the motor given to me and budget is tight (cant affod new heads...need money for turbo)

 

[Mac in SD]

Briefly: I've got a 274 S2-headed engine with great big ports, 2.125 intake/1.625 exhaust valves. I also have a 9-inch NLU converter, about 3300 stall. I cammed my motor very conservatively - 222/218 hydraulic roller. Here's what I found out.

1. A 60-1 with .81 A/R will be almost uncontrollable from a dead stop up to 50 mph (on BFG radials.) Responsive, for sure. But just nuts.

2. My current 76 BB Q-trim turbo with a .69 A/R is still very responsive, and will generally light the tires up at will with 15 psi. I'm thinking of stepping up to a .81 A/R.

Don't be intimidated by the S2 heads. And DON'T feel like you're "stuck" with them. They don't crack, they run cool, and they sure do look bitchin'. Just make sure you don't over-cam it.

And if you feel any need to dispose of that sheet-metal intake, drop me a line.

 

[NJTurbo]

Originally posted by Mac in SD
Briefly: I've got a 274 S2-headed engine with great big ports, 2.125 intake/1.625 exhaust valves. I also have a 9-inch NLU converter, about 3300 stall. I cammed my motor very conservatively - 222/218 hydraulic roller. Here's what I found out.

1. A 60-1 with .81 A/R will be almost uncontrollable from a dead stop up to 50 mph (on BFG radials.) Responsive, for sure. But just nuts.

2. My current 76 BB Q-trim turbo with a .69 A/R is still very responsive, and will generally light the tires up at will with 15 psi. I'm thinking of stepping up to a .81 A/R.

Don't be intimidated by the S2 heads. And DON'T feel like you're "stuck" with them. They don't crack, they run cool, and they sure do look bitchin'. Just make sure you don't over-cam it.

And if you feel any need to dispose of that sheet-metal intake, drop me a line.

Why are you stepping up to a .81AR Also send me a PM i am curious to see what you paid for your 76BB Thx

 

[GNSCOTT]

Mac, I'm guessing here but I would say The bb tubo allows you to run a bigger ex housing w/out sacrificing spool, the bigger ex. housing will allow you to flow more air and make more power w/ less boost. The ex. housing is the key to the turbo. Jack Cotton and Cal have proved this by running in the 8's with 76 turbos.

 

[Mac in SD]

Scott's got it. If I've got (more than) adequate spool-up, then I can give up a little to get more top-end with less back pressure with the .81 turbine housing. On my old stock block with a 60-1, going from a .58 (don't ask) to an .81 got me 4 mph in the quarter with no other changes.

When I had that 60-1 on the Stage II, I think it made more power than the 76 is making at the same 15 psi level. Now, I also know that the 76 isn't anywhere near its sweet spot, and that much more than 15 psi with the 60-1 would be close to overspinning it. Admittedly it's a seat-of-the-pants dyno, but I can borrow the .81 to try it out.

 

[KendallF]

Take the damn thing to the track already! Better yet, wait until I come out that way again and we'll go blow it up together.

 

[Mac in SD]

Originally posted by KendallF
Take the damn thing to the track already! Better yet, wait until I come out that way again and we'll go blow it up together.

I know, I know....