BB 67GTQ .85 vs. BB 70 GTQ .63

[aquickv6]

How much difference between these two Precision turbos?

Street manners?
Spool?
Converter?
HP?
1/4 mile capability?


231 109 motor with the basic roller cam and good head setup, THDP 3.5, in a full weight TR.

I think there is about $850 price difference.

 

[John Wilde]

How much difference between these two Precision turbos?

Street manners?
Spool?
Converter?
HP?
1/4 mile capability?


231 109 motor with the basic roller cam and good head setup, THDP 3.5, in a full weight TR.

I think there is about $850 price difference.

The 67 should be a better street trim IMO.
-67 should spool at least 200rpm sooner
-3000-3200 spool should be fine -Talk to Dusty Bradford who is a PTC Dealer
-780HP in theory
-Don P has gone 10.0s @ 135 plus in his TSM Car

The 70 should be a better race only turbo IMO.
-70 should spool at least 200-400 rpm slower
-3400-3600 spool should be fine -Talk to Dusty Bradford who is a PTC Dealer
-850HP in theory
-Dave B has gone 9.2 @ 146 plus in his TSM Car
-Most guys using this do better with a stroker motor.

 

[aquickv6]

Thanks John. Are they both still in the sweet spot at 30 psi?

 

[bison]

Thanks John. Are they both still in the sweet spot at 30 psi?

This would depend on cam, heads, and cubes. More rpm would be better for the 70 at higher boost. It will be more efficient and make more power than the 67 wheel at high boost and high rpm. I wouldnt doubt that the 70GTQ has been pushed a lot more than 30 psi in some TSM applications either.

 

[aquickv6]

I thought the .63 exhaust housing and full BB would really let the 70 GTQ spool quick on the street. It seems like the two would be very close in this configuration.

 

[bison]

I thought the .63 exhaust housing and full BB would really let the 70 GTQ spool quick on the street. It seems like the two would be very close in this configuration.

Id still go with a 3400 at zero psi for optimum spool with the .63/70GTQ BB.