Warrtalon

iTrader: (6)

Kevin, yes, that is probably th emain issue: shift point. You're probably always getting 1.6s, because you are apparently trying to **** close to 8000rpm? I shift around 6500 out of first, because I have no power whatsoever in 1st after that point. I am not sure why people would want to shift anywhere near 8000rpm on the stock turbo in 1st gear, but maybe that explains the crazy 60's but so-so ETs. If you shift at 6500, you might see a 1.70 60' with an ET that is a tenth better...

ezhangin

I don't drag race (at least not yet!) but I can attest to that working. Really, I think the stock turbo makes the most horsepower around 6500 rpm anyways.

Warrtalon

iTrader: (6)

Well, you don't have to think...it actually does according to dyno sheets. The higher the boost you run, the lower the RPM you hit peak WHP, too. Cams raise the effective powerband usually (as can cam gears), but it's rare to not see a significant drop-off in power by 7500rpm on the stock turbo, and in 1st gear, it's even more drastic.

kjewer1

iTrader: (4)

The issue is not so much power drop off after a particular RPM, as it is will being at a lower RPM in the next higher gear result in more torque at the wheel. Acceleration, or thrust, is directly tied to torque. HP:Weight effectively determines trap speed, but taking advantage of lower gear ratios longer can lower ET. Looking at recent dyno charts HP peaks at 7200 RPM and drops only 20 by 8000. TQ falls off significantly though of course. [edit>] The TQ and HP on my chart do not cross at 5252, so I am not sure the scaling is right on this graph, and peak HP @ RPM is not given. The drop is only 20 hp regardless. [/edit]

I haven't thought about most of this stuff in a long time, so I reserve the right to be wrong I am willing to try to shift at a lower RPM to see what happens, but last time I went through this on the EVO I'm pretty sure there was no advantage. On the 2g with the T25 I went a solid half second faster by dropping shift points to 6500 in all but first gear (wider spacing on DSM gearing almost always makes winding first out worthwhile), but that turbo is extremely small, about half the size of the EVO 16g (~24 lbs/min vs 42). I may try this Friday night just to see again what happens though.

When I brought up the 1-2 shift I was refering more to the time it takes to execute the gear change than the RPM it takes place at. Speed can not increase in between gears, it will at best hold steady and not slow down (though I have seen that on extremely slow 1-2 shifts, I suck at life). Looking at my logs there is a solid .4 second period of zero speed increase. People like Curt Brown that shift the 1-2 so fast that I can hardly find it in most of his videos have a significant advantage here! My situation is that I can 60 foot as well as I want, but the 1-2 shift is still going to hurt the ET to MPH ratio, thanks to a shyte shifting transmission. Perhaps shifting the 1-2 at say 7000 rpm, despite potentially not being very helpful in itself, will allow a faster 1-2 shift resulting in a net gain? Only one way to find out I guess. I'll post back if I get enough runs to *** around with this Friday night.

EVOONYOASS

iTrader: (2)

I found shifting the 1-2 before 7000 rpms yielded better times also. I use to shift at 7500 and it yielded crappier times with the same 60'.

Depending on what your logs say, I would try between 6300-6800 rpms.

kjewer1

iTrader: (4)

Well, that settles it. I'll try it.

In addition, after reading the alignment info Dave posted and seeing how bad my car tracks (even on the dragstrip, which should be flat, when over ~100 mph) with the Advans back on (as of saturday at the SO ), I believe I found a local performance shop that will do quarter mile oriented alignments. So I've got a couple things to test Friday night. The redneck racing that goes on on Fridays can significantly reduce the number of runs I get though, which isn't going to with getting consistent back to back comparisons. It will also be interesting to see if there will be a significant change to 60' times with these changes.

icantdrive75

iTrader: (8)

As far as shift points...I keep making power till my rev limiter, so I just try to shift before I hit it.

Warrtalon

iTrader: (6)

Yeah, with the GT35r, you will make tons of power up top at high rpm unlike the rest of us...

Ang Wen Yan

+10000

Spooldyou

iTrader: (52)

I agree Most of my trouble is the 1-2 shift, i find myself Slowly shifting into 2nd cause i dont want to grind a gear or mistshift, But that could be a simple adj. seeing that i have an ACT clutch, or a full out tranny rebuild from shep. Lets hope its just a clutch adjment issue, im not feeling having my tranny rebuilt at this time, maybe next season.

Warrtalon

iTrader: (6)

I would say it's the clutch, not the tranny. Despite all my racing and tons of drag launches, my 1-2 is still smooth as can be with no notchiness or grinding when racing. It only grinded or locked out when I had the ACT.

justchil

iTrader: (44)

^ Agreed. I've cut down a good amount of time changing my 1-2 shift technique. I'm going to try shifting around 6500-6800 tonight to see if that helps even more. Best 60' I've cut so far is 1.64 with Kuhmo's (34/32psi) launching at 6k.