Need Advice on Gears, etc

[RalphP]

Hope the experts will chime in. I think I am on the right track but would like to hear what you think!

My car made 800/760 (corrected) on a mustang dyno. I'm running about 11 lbs boost but it is somewhat slow to build given my rear mount setup and 60-1 turbos w/.63 A/R housings. I don't get full boost in 1st gear with my 3.90s and also not in second, it hits full boost for about the last 1/3 of 3rd and the last 2/3 of 4th.
Unless I power shift, and then I can have full boost in 2,3,4 because the blow-off valve never opens. But I'm not the greatest shifter and still working on my power shifting.

Launching in 1st, my best was 11.80 (don't laugh - the DA is over 9000 here) and trap about 129 with no power shifting. About 1.8 60 ft.

So last night I tried launching in second and I power shifted 3rd and 4th. That got me 11.50 @ 136 with a 1.95 60 ft. The car was flat in 2nd but went like crazy in 3rd and 4th. And I went through the traps on the rev limiter in 4th. Rick at STS is trying to help me get a 2-step rev limiter working and he says I will be able to leave the starting line already on boost. That should help with the flatness in 2nd (or 1st).

But with my 3.90's 1st gear is pretty worthless - it winds up faster than the turbos can spool and I don't need it.

The thing I like about the 2nd gear launch is I only have to shift twice...

Lembo says put the 3.42's back in. Then I have to shift 3 times.

So my choices are to do nothing and see what happens when I get the 2-step working and practice my power shifts.

Or go to 3.42's or to some other gears and still get the 2-step and practice power shifts.

BTW, last week I messed up and left in 3rd. The 60 ft was 2.4 but it went 100 in the 8th in one gear and the ET was 11.8 @ 130

What I want is to run in the 10's.

I know it's kind of an unusual case for most of you guys, given I have STS rear mount turbos and I run at high altitude....

I'm inclined to follow Lembo's advice, but please tell me what you think.

[Ernie King]

I think Jim is on the right track with the 3.42's,, it would allow you to ne in a gear longer so it would build boost If I'm right on that.. I'm not a turbo guy..

Ernie

[MikesZ06]

Not sure I can give much advice about the boost in first, but I can tell you that I would never make it through the traps without banging the rev limiter with 3.90's (and my rev limiter is set at 7500).
Now my situation is somewhat diffent because my top end is limited by the stall convertor but the overall result may be similar.
I'm running the 3.42 and may someday have to switch to a 3.30.

Mike

[RalphP]

Originally Posted by MikesZ06

Not sure I can give much advice about the boost in first, but I can tell you that I would never make it through the traps without banging the rev limiter with 3.90's (and my rev limiter is set at 7500).
Now my situation is somewhat diffent because my top end is limited by the stall convertor but the overall result may be similar.
I'm running the 3.42 and may someday have to switch to a 3.30.

Mike

Thanks Mike: It is clear that I could cure all my ailments with an auto too.... But I just like the 6 speed and want to keep it.

[MikesZ06]

Originally Posted by RalphP

Thanks Mike: It is clear that I could cure all my ailments with an auto too.... But I just like the 6 speed and want to keep it.

Don't get me wrong Ralph, I wasn't recommending an auto. I was just commmenting that the taller gears might help your passes at that power level.
Believe me, the T-400 doesn't solve all your problems. Except for using the trans-brake at launch, the shifting is pretty much the same as a four speed manual.

Mike

[RalphP]

Originally Posted by MikesZ06

Don't get me wrong Ralph, I wasn't recommending an auto. I was just commmenting that the taller gears might help your passes at that power level.
Believe me, the T-400 doesn't solve all your problems. Except for using the trans-brake at launch, the shifting is pretty much the same as a four speed manual.

Mike

Mike: I didn't misunderstand - just a comment. Anyway, the auto would be good because I could leave on boost and stay on boost. Right now, if I take my foot off the gas pedal when shifting, then the blow-off valve dumps all the boost in milliseconds. If I power shift it stays up on boost all the way - huge difference! The auto would do that for me - I could keep my foot to the floor all the way. What I wish I could get is a slick SMG!!

And I agree that the taller gears will help. It is just a question of "Which" taller gears.

[Ernie King]

Ralph, I got to thinking that 3.42 gears would be ok, I'm not sure what your rev limiter is set at, but when I had a six speed with 3.42's I was able to carry the car in 3rd gear.. this was with a rev limiter set at 6800.
I think anything above that would cause you to shift into 4th.. Which just means another shift. Don't know about the 3.15's if that would be better..
Something to think about...

Ernie

[RalphP]

Originally Posted by Ernie King

Ralph, I got to thinking that 3.42 gears would be ok, I'm not sure what your rev limiter is set at, but when I had a six speed with 3.42's I was able to carry the car in 3rd gear.. this was with a rev limiter set at 6800.
I think anything above that would cause you to shift into 4th.. Which just means another shift. Don't know about the 3.15's if that would be better..
Something to think about...

Ernie

Thanks Ernie: I was thinking 3.42's but expecting I will need 4th. I'm pretty sure I won't be able to go over 130 in 3rd.