Z31 Introduction

[z31]

Intercooler install.:icon_bigsmurf:

[z31]

My track times at Interstate dragways, Sabin MN Sunday August 8:

My two best runs on 10lbs boost was
[email protected].... 2.02 60ft
[email protected].... 1.99 60ft

My 4 best runs on 12-13lbs boost was
[email protected] 60ft
[email protected] 60ft
[email protected] 60ft
[email protected] 60ft

My best run at 15lbs boost was
[email protected] 60ft

12-13 lbs boost
http://www.youtube.com/watch?v=JF76ETa951Y
http://www.youtube.com/watch?v=DCWa6BlQKQ0

15 lbs boost
http://www.youtube.com/watch?v=B0f4jqPBE20

Race weight was 3500lbs 58mm turbo, drag radials on E85.
Ported and polished heads with 270H cams 3in exhaust.

[weshole]

What rpm's you shifting at Jason?

[z31]

weshole;314771 wrote:
what rpm's you shifting at jason?

6000 rpm

[weshole]

Why so low?

[z31]

weshole;314774 wrote:
Why so low?

6200 is where the cam drops off in power.

[z31]

The car has a basic tune in it, so the tuneup is not ideal. I'm gonna have the car dyno tuned to fine tune the timing and fuel to gain some power in all RPM ranges. Hopefully i can get another 50 horse out of it with timing and fuel adjustments and a little more boost.

[weshole]

z31;314779 wrote:
6200 is where the cam drops off in power.
I cant imagine the drop off is that drastic that you wont still pull hard if you rev higher.

[PSiedTSi]

weshole;314797 wrote:
I cant imagine the drop off is that drastic that you wont still pull hard if you rev higher.

Agreed. Holding the previous gear a little longer can help you get into your mid range power in the next gear. It may also be beneficial to adjust shift times in every gear.

[z31]

Ya, i guess i could try going to 7000 rpm next time im at the track.

[weshole]

I think your car is faster than you showed and it sure seemed that you were definitely shifting way too soon.

[Grr]

that car drops 100hp from 6200-7000. His tq peak is about 4400, shifting any later than 6200 would be a complete waste of time and slow the car down alot.

[PSiedTSi]

what RPM does he drop to when it shifts?

[Grr]

about 4400, shifting at 6200 is about perfect. It really needs a bigger turbine and more cam, but the turbine and housing is killing a solid 40hp up top

[z31]

I have been thinking about this. I took a look at the rpm drop on each shift, and this is what i came up with:

gear 1-2....1700 rpm

gear 2-3....1100 rpm

gear 3-4....800 rpm

gear 4-5.... 500 rpm

This is a dyno sheet of the same setup in another z31. The only differance is im using e85 at 15 lbs of boost with 9:1 compression pistons and, he is using 93oct at 20 lbs of boost with 7.8:1 compression pistons.

[weshole]

Im assuming the Green is the HP and the blue is the TQ. If that's the case, theres a lot more rpms avail.

[beachbum_jon]

judging by that dyno graph, and given that your car makes the same power at the same rpms, shifting at 6200 is about perfect IMO. Why go past that when your power drops off, when you can shift and be right back in the power again?

[z31]

weshole;314903 wrote:
Im assuming the Green is the HP and the blue is the TQ. If that's the case, theres a lot more rpms avail.

Yes.

[Bookem]

weshole;314903 wrote:
Im assuming the Green is the HP and the blue is the TQ. If that's the case, theres a lot more rpms avail.

I'm guessing since Jason has higher compression and less boost his power band is lower rpm just a bit more power.

[z31]

Im currently installing manual trans number 3