[cby1]

Can those of you who've driven STi's more than this new owner help me with this...I am used to cars that you run just about to redline to get the most out of them (e.g., my MR2 Turbo).

The STi doesn't seem like that kind of car - seems like you want to shift a little earlier, like 5000-5500...but what do I know?

I wanna set the shift alarm at the optimal point to train myself to shift around there...

Thanks.
Chris

 

[STI_XB9R]

I would have to do the math but each gear would have its own shift point.

The way to figure it is to calculate the torque at the wheels for the gear that you are in then for the rpm drop to the next gear and the torque at the wheels for that lower rpm. If the number is lower for the next gear you need to shift at a higher rpm. If is the same then this is the perfect rpm to shift. If it is higher shift sooner.

 

[4MLA1FN]

i was thinking last week to create a graph like this, but i haven't seen a hp or torque curve for the sti. have i missed it? i was actually going to use the hp curve as the reference, but you suggested torque, which i think is right. (he says, hoping not to open the ubiquitous hp vs tq thread.)

 

[ldivinag]

follow this thread this GOD dude started in clubwrx.net:
http://www.clubwrx.net/forums/showt...181b05&threadid=27403&perpage=20&pagenumber=1

and his graphs:
http://www.godspeedinc.com/images/DynoHPBC.jpg

 

[amdmaxx]

What sunroof?

i got sti graph.. will email upon request.. Or I'll host when I get a chance..

 

[amdmaxx]

Here it is

 

[twg]

Please verify: pass-through rear seat or not?

To find the optimum shift points, you need a raw tq (where the gear multiplier isn't compensated for, which a normal dyno does) vs speed in all 6 gears.

What you'll see is a big hump for gear 1, a wider but lower hump for gear 2, and even wider and lower hump for gear 3 ...etc. Where these graphs intersect is the optimal shift pt.. if the graphs do not intersect, that means the optimal shift pt is at redline...

 

[WRX_Mundi]

Arguably you really need to use a accelerometer with your car actually moving, not a dyno test. That would then count rolling resistance, aero drag, aero cooling including intercooler, and so forth. Then you'd get a graph of acceleration in each gear for each rpm, from which you could calculate the shift points which would give you maximum acceleration. But that's hard to do without a car, some time, some equipment, and some free space to run the car in.

But given just trying to max out the torque from a dyno graph, here are my attempts at guessing optimal shift points. These are approximate for a number of reasons -- Subaru's data isn't that precise, it will not precisely match a given car (as seen by God's data), assuming stock tire sizes, and I'm being a little sloppy.

1-2 5300rpm (27mph)
2-3 4900rpm (38mph)
3-4 4900rpm (51mph)
4-5 5000rpm (68mph)
5-6 4800rpm (91mph)

God's dyno graph is much more peaky than Subaru's, and peaks at something like 3600 rather than 4000. Hence the calculated shift points come earlier, though because of the awful peak, you're better off shifting later than earlier. Anyway, I get a 1-2 shift of about 4800rpm, a 2-3 of about 4500rpm, and so on. 400-500rpm earlier, though again his graph has a huge slope from 2250 to 3300 or so, while the slope from peak at 3600 down to about 5250 is gentle, so shifting a few hundred rpm early would hurt much more than late.

I'm actually a bit surprised that the shifting comes so early (5000rpm or so, given a 7000rpm redline). The short ratio gearbox also means shifting often for max power -- not much over 10mph before shifts. I'll have to really get used to such a different behavior -- I'm used to shifting at 6000+ rpm with 20+ mph between shifts (and in the Miata, after 2nd gear, 20mph takes a while). I also see a lot of people recommending very high shift points -- this keeps the car in a better horsepower band, but doesn't maximize torque. Not sure why the difference between theory and practice.

 

[Ken Reich]

in my experience,the fastest acceleration would be achieved ,by shifting the car at an rpm in each gear so the rpm drops to just below peak torque,it will accelerate the hardest on each gear change :wink:

 

[WRX_Mundi]

in my experience,the fastest acceleration would be achieved ,by shifting the car at an rpm in each gear so the rpm drops to just below peak torque,it will accelerate the hardest on each gear change :wink:

According to 2Fast 2Furious, shifting at any point is like adding afterburners -- if you want to go faster, just shift -- no matter how, when, or why, you'll be pressed back in the seat and the world will blur from the extra acceleration. Oh, and if while looking at your competition, you see them gaining or passing you, grimace and then press down on the throttle the rest of the way since for some reason you were in a race and were only running half open down a straight. :roll: I don't even want to get into the 90mph capable reverse gear...

Joking aside, if you are at torque X in the current gear and will be at torque Y in the next gear, you would want to shift whenever Y > X (complicated by any upcoming turns, shifting time, tachometer error, tachometer delay, etc.). This should end up having every gear pass through the peak torque area. If you wait until Y is right below peak torque, this might be giving up something. But then I think you knew this from your wink...