shifting.........

black91turbo

Formerly black87turbo
Apr 27, 2006
1,064
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Jacksonville, FL
Hey guys!!!! i was just wondering what needs to be done to determine my optimal shift points. I heard that I need a dyno first!? i have no clue so i thought i would ask. thanks guys
 

swaq

posts++;
May 24, 2005
1,351
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Oregon -> Arizona
www.SwaqValley.com
I believe the key thing is area under the curve. If you look at a dyno graph you'll want to see what range of rpms will result in the most area. It's just a simple calculus concept really. Of course, you'll also have to know how much you rpms will drop at each shift.

The short answer is near the redline.
 

ChadMKIII

Yup, Thats The G/F
Jul 14, 2006
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Bay Area, Ca
I think it depends, for one, on turbo or non turbo, and where your redline actually is.

Judging by your user name, I'd say you have a turbo, which, according to Scheaff in the Reference section makes peak power (230hp) at 5600rpms.

Now, I've heard that some of these have a redline at 6250 and others at 6700 (I think). Mine is a 91 turbo, redline at 6250. Running it to redline would still not have a huge drop off. I would assume the 6700 redline would really run you way past your high powerband.

So, all that to say Marc looks about right on, perhaps you might even want to shift a bit earlier than that if your car is stock, like 58-5900, or if you have done some good mods your powerband may have increased well above that, to the actual redline or possible further.
 

toyotanos

What will we break today?
Staff member
Super Moderator
Nov 29, 2008
2,841
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Coon Rapids, MN
As has been said before, it depends a lot on your power curve. My power band is relatively high, but it still drops off. While I will happily rev the engine to 7500rpm, it isn't making power up there. I usually shift at 6700-7000 so I don't drop out of boost, as well as having my power and torque still. Not that it is fine-tuned by any means, I need to get a transmission that stays together before I can quantify this thought process.

Take a look at this sheet and see why I do what I do.


Edit: Here's my older dyno graph before I felt comfy spinning the engine that high, back then I shifted right before redline ~6400rpm.
 

Insidious Surmiser

Formerly 89jdm7m
May 12, 2006
2,172
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Oceanfront
I haven't even hit the limiter in my current 89 turbo.... I'm scared to try.... reason being, my tach is WAY off, but I know what rpms I'm turning.... makes me wonder if my CPS is fucked, possibly resulting in an absurdly high rev limit. (way too high)