Precision 7175/7275 on SII Motor?

[thrlskr]

Looking to possibly change out my existing Turbo for quicker spool and more lively street action. Current Turbo is a PTE 76HPSRH ball bearing, cast wheel.

Anyone have experience with the ball bearing 71-72/75 and transient nature on the street? Am I wasting time and money? Set-up is on center SII with SII heads and solid roller.

Thanks,

Bill

 

[bison]

I think you'd be going after little gains in spool since the hot side is the same. What ex housing, headers and crossover diameter are you running? Also try reducing the lash some. It will increase exhaust pressure a little and help spool


BPE2013@hotmail.com

 

[thrlskr]

Its the .96 housing, custom hand built headers wth 1.75 primaries and 2.5 inch crossover. I'm going to order a PTC from Dusty which should help over the 3400 I'm running. Cam is a Conleys spec grind 234 and heads are out of the box SII alums with clean-up work.

I thought about the 7168 4 bolt but was worried it would just blow the tires off.

 

[bison]

Your primaries and crossover are way too large for a street application on a v6 unless it's about 1600hp and are probably requiring 600-800 more RPM to spool. Dropping to a 68 turbine will choke flow that combo a lot. If you're not racing it will help with spool but the headers are what's making your turbo laggy.


BPE2013@hotmail.com

 

[thrlskr]

After re-measuring my headers they are 1.5 inch primaries and 2 inch cross over...going to order the converter and see how it goes. Its a brand new combo with maybe 50 miles on it.

 

[Reggie West]

If you are wanting a street car I would switch exhaust housings.

Try an .81 or .86 if they have it. Bison will know more than me.

And I do think the right converter will help you out as well

You have monster heads, you just have to get the turbo working sooner ( lower rpms ).

Is this is a 4 bolt turbo or 3 bolt?

 

[hemi8]

Bison, what would be a good primary tube diameter for the stage 2 heads on a street car?

Mike

 

[bison]

Bison, what would be a good primary tube diameter for the stage 2 heads on a street car?

Mike

It would depend on the mass flow and intended power band. The usable rpm range with typical stage 2 heads is high 5000's to high 6000's. What one calls street compared to another is two different things.


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