ok, i searched for and found some info about this in the forum, but i'm still confused about some things:

1) what good is knowing where peak hp is? peak hp for the evo is at 6500 rpm, yet, as we all know too well, acceleration tails off at ~5000 rpm. seems to me that knowing where torque peaks is much more important. which brings me to my next question.

2) why is shifting at or near redline better than shifting at ~5500, where you will be closer to the powerband in the next gear? maybe i'm oversimplifying things, but this makes sense to me: if your goal is to accelerate as QUICKLY as possible, and your maximum acceleration occurs in the 3500-5000 rpm range, wouldn't you rather be in the 3500-5000 range than 5000-7000? i know finding the optimal shift point is involved and requires analyzing the gear ratios, etc., but my "seat of the pants" analysis seems to blatantly contadict what the charts say. i don't know what the stopwatch says either, as i've never had any timed runs.

 

You shift at redline so in the next gear you will not have to regain boost.

If you shift at 5500, then in your next gear you will be brought down to say like 3000RPM, and then you will have to regain boost again. This is why when you launch an AWD car you must rev it to around 5000RPM and then your gonna have boost when the car takes off. You wanna be driving the car at full boost as much as possible.

 

The best way to find the best shift point is to dyno your car. My car looses power after 6800RPM so I shift at point of peak power before cars power drops. I was able to trap 106MPH in the 1/4 mile shifting at 6800 vs 7400 giving me a 101MPH trap. You want to take your car to its highest RPM before the power dips

 

I know it is not rocket science, but there is a formula that uses torque peak, rpm, gear ratio, etc. to approximate your optimum shift point... to drop you in the sweet spot of your torque curve. I've long since forgotten it.

 

You need to do some datalogging or hit a dyno.

Our 1 -> 2 shift seems to work better shifting a lil lower since 2nd gear is only like 2 grand lower than 1st. I had better trap speeds doing that.

A lot will also depend on your mods. A car with an intake/exhaust will be able to rev higher with power than one with out. So really, you need to get some data logging done. Else, hit up your local track and do CONSISTANT runs (meaning similar launches, even if it's just a normal clutch engagement) and change your shift points.

Good luck

 

If you think about it also, they get the peak numbers from a stock car, and that has the boost taper starting at about 5500rpms or so. So if you get a boost controller that holds 19-20psi all the way to redline, then your power band should move up some to the higher rpms. Just a thought.

 

The above mentioned WAS based off your torque peak... common sense would dictate that one would have to have a means to measure it.

 

Give this a try to help determine your optimal shift points

http://www.prestage.com/carmath/dynochart.asp

You will need your dyno chart and the following gear info to do this:

1st 2.928 40 mph @ 7000 RPM
2nd 1.950 60 mph @ 7000 RPM
3rd 1.407 83 mph @ 7000 RPM
4th 1.031 114 mph @ 7000 RPM
5th .720 155 mph @ 6650 RPM (est.)
Reverse 3.416
Final 4.529

 

Interestingly enough I just tried that link I posted and it told me my optimum shift point according to my dyno results are 7000rpm for each gear

Your best shift points are:
Best shift point for the 1-2 shift is 7000 with a LOSS of 44 Lb/Ft of torque.

Best shift point for the 2-3 shift is 7000 with a LOSS of 12 Lb/Ft of torque.

Best shift point for the 3-4 shift is 7000 with a LOSS of 13 Lb/Ft of torque.

Best shift point for the 4-5 shift is 7000 with a LOSS of 13 Lb/Ft of torque.

 

Just get your evo on the dyno and watch when your hp stats to drop off, shift at that pt and you will trap higher.

 

Acceleration is Force/Mass. The get the maximum acceleration you either increase the Force or lower the Mass.

The force that matters most for us is the force to the ground aka (torque to the ground). To get the best acceleration we need to maximize the force put to the ground as we shift through the gears. While it is true that as our engine RPM increases our torque decreases but due to transmission gearing and final drive ratio we will push the engine beyond it’s peak torque curve to maximize the use of the gearing ratio as well as to ensure that we don’t drop the rpm down to a weak spot once we shifted.

The Evo’s final drive ratio is 4.53:1 and Gear Ratios are:
1st 2.93
2nd 1.95
3rd 1.41
4th 1.03
7th 0.72

Below is a chart based on my interpulation of the torque from Vishnu’s dyno of a baseline stock EVO and it’s torque to the ground at various RPM.

The RPM drops will be proportional to the gearing. 1st to 2nd: .66 2nd to 3rd .72 3rd to 4th .73 4th to 5th .70

For example, if you shift from 1st to 2nd @ 7000 RPM you will drop down to 4620 RPM.

Based on the numbers below… it does not make sense to shift earlier than redline in 1st gear because when you look at the high rpm numbers in 1st gear, they’re all higher than your 2nd gear numbers. Sure your torque is dropping but with a 13.26:1 ratio you’re getting good acceleration.

Let’s say you shift @ 7200 RPM in 1st Gear, your RPM will drop down to about 4700 RPM in 2nd gear. So you continue to drive up your 2nd gear… If you look at the numbers in 2nd gear.. it drops to 1210 at 7200 RPM. Yikes! If you look into the middle of 3rd gear, there are some higher numbers there. Based on this chart, I would shift from 2nd to 3rd gear somewhere between 6800 and 7200 RPM. 7000 is probably a good number, it will drop your RPM back down to about 5000 RPM. The torque to the ground @ 5000 RPM in 3rd gear is more than torque to the ground @ 7200 RPM in 2nd gear so you will get better acceleration if you shift before 7200 RPM in 2nd gear. The same situation applies to 3rd gear. If you take 3rd gear to redline you are losing power to the ground, the optimum shift point looks like it’s somewhere between 6800 and 7200 RPM. Same thing for 4th to 5th gear.

RPM TORQUE (1ST 13.26) (2ND 8.83) (3RD 6.37) (4TH 4.67) (5TH 3.26)

2400 96 1273 848 612 448 313
2800 108 1432 954 688 504 352
3200 132 1750 1166 841 616 430
3600 162 2148 1430 1032 757 528
4000 200 2652 1766 1274 934 652
4400 204 2705 1801 1299 953 665
4800 201 2665 1775 1280 939 655
5200 198 2625 1748 1261 925 645
5600 180 2387 1589 1147 841 587
6000 171 2267 1510 1089 799 557
6400 165 2188 1457 1051 771 538
6800 150 1989 1325 956 701 489
7200 137 1817 1210 873 640 447

A car's torque curve and gearing ratio will determine optimum shift point for best acceleration.

 

Very nice information, it is writeups like that one that keep me coming on this site looking for more information. It gives me the final idea that they set a 7k redline for a damn good reason, and shifting later(unless your setup supports it) will not help your performance. Although shifting earlier will hurt your performance goals.

 

It can be summarized like this:

You want to shift at the point when, taking gearing into account, you will be putting more torque to the wheels in the next gear than you are in the current gear.

If you have the torque curve in a gear and then overlay onto that the torque curve of the next gear (rescaled appropriately), it turns out that even on a stock EVO this point comes near 7000rpm (in lower gears). With even minor modifications, this point comes near or after stock redline. This is why most reflashes raise rev limits: not because there is a ton of torque past stock redline, but there is still more torque in that gear than in the next one.

The graph below is three torque curves in 5th gear, overlayed on top of three torque curves in 4th gear. The vertical axis represents wheel torque (relative scale). The horizontal axis represents RPM's in 4th gear. You can see that the tuned curves' torque does not ever fall below the next gear torque (prior to redline), while the stock torque curve crosses the next gear's torque curve around 7200rpm, indicating a good shift point.

 

are you trying to tell me my butt is wrong? seriously, this is a lot of good info, thanks.

 

Now nobody wants to talk about your butt...