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When to shift based on powercurve? (Drag Racing)


thorne

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In the past I've always made peak power close to redline so I shifted @ redline. I'm not sure if thats the best option now. Is it better to shift sooner and come back into the higher TQ area of the power band or run it to redline.

 

No matter what I have to shift into 5th due to short gearing.

 

Here's my current power curve

http://www.40roll.com/mywagon/mywrxvsmyg35.jpg

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What are the Gear Ratios in the Trans? You want to base your shift RPM on the percentage of RPM drop after each shift. You want the after-rpm shift to land right at the beginning of the powerband.

 

This...gear spacing is important. need to consider cost / benefit of how far past peak power you shift in comparison to where the next gear lands in both the power and torque curve.

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http://www.columbusracing.com/forums/picture.php?albumid=738&pictureid=7181

 

Gear Ratios Shift RPM RPM after Shift

3.083 0

2.062

7500 5016

7000 4682

6500 4347

6000 4013

5500 3679

 

1.545

7500 5620

7000 5245

6500 4870

6000 4496

5500 4121

 

1.151

7500 5587

7000 5215

6500 4842

6000 4470

5500 4097

 

0.825

7500 5376

7000 5017

6500 4659

6000 4301

5500 3942

 

 

 

I would say shift at 7K.

Edited by Patterson
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What are the Gear Ratios in the Trans? You want to base your shift RPM on the percentage of RPM drop after each shift. You want the after-rpm shift to land right at the beginning of the powerband.

Exactly. With gear spacing in mind, I would till shift right at redline. The VQ's engines like to rev a bit, and if you shift at 7, you'll land at about 4500-5000, which is part of their happy spot.

 

For the Subi, it's a bit different since it's turbo-charged. You want to shift at the highest RPM point possible (relative to where it's making power) to keep the turbo spinning as fast as possible for the next gear. Looking at that graph you could take it to at least 6500rpm and be golden.

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How fast can you go in 4th if you would rev it to 7000?

 

When I had my RA gearset I would run 4th off the limiter and come through the traps at 112. But I was making less HP and TQ than you.

 

So previously on my 2.0 thats how I did it. I stayed in 4th and hit the rev limiter and ran 12.3@112 (@333awhp 333awtq). But I'm trying to go 11's this year.

 

Sounds like i need upgraded cams...

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For what its worth, the 90's WRC Imprezas all shifted well before redline.

 

I shaved a little more than 0.2 seconds off my 1/4 mile time just by shifting from 1st to 2nd at about 5k or so which I think put me between 3k and 4k once I hit 2nd. This is with a 4EAT and a TD04 (stage 2 @ 19.5 psi) though. If only I could do the same for 2nd to 3rd, I should be able to break 13.5 and 100 mph pretty easily.

 

Based on Patterson's math, I say shift @ 5500-6000 in every gear.

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Get a better driver

Hence this thread trying to improve my driving. Launching should be fine once i swap tires I used to cut 1.8's almost every time. I've also got the ability to do No lift to Shift now so that should help.

 

Like I said wasn't sure about shift points. I feel like I should shift 1-2 2-3 and 3-4 @ ~6500

 

and run 4th to 7000 and shift if need be.

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