I know there's already another thread on this but I didn't want my question to get lost since they both have so many posts.


I hear a lot of folks saying that optimum shift point is just below the rev limiter but, shouldn't the optimum shift point be just above the max power rpm?

The way I always thought of it was if you make max power at 6000 then shift at 6200 just so you can catch the next gear in the power band.

And I say 6200 because even though your HP is dropping beyond where you make max power it's more than likely still more then you would make at the rpm you would enter the next gear in...


Mike

 

On an M12 tranny, a shift at 6500 will put the engine to 4500 in the next gear. There is more torque at 4500 than say 4200 (where you'd be is you shifted at 6200).

As for shift points, a lot of experimentation has been done and opinions vary.

My view is "just before the limiter" yields best results for me with my driving style.

What is best for each driver will vary by the speed of their left leg...the two-direction movement that governs the speed of a shift. If your left leg is slower than mine, you will need to begin the shift a little earlier.

Ranger

 

Ranger: Great video. Have seen it before & it's amasing. I think I have memorized your launch technique. Am going to take the Z or Sacramento tonight & give it a try. This will be on 3:42's just got the 4:10's and they're still in the box until make some changes to accept the potential damage from high revs. Thanks Again, Harley

 

Ahh...that's what I was waiting to hear. I was more use to the LS1 on my Z28.

But I forgot that the LS6 is a whole different animal.

Thanks,
Mike

 

Here is a quick take on this; using the information I have gathered on this site it appears that the optimal shift point should occur at the red line. For each shift there is about a 1.43% increase in gearing (1.43 for 1-2, 1.44 for 2-3 and 1.43 for 3-4).

It appears that most stock dyno plots are pretty close. Obviously this is WHP but it will suffice for analysis. Most show the vehicle making about 285 WTQ @ 6500 RPM. Now for the math, take the shift RPM and divide it by the gearing reduction percentage to determine the approximate RPM after the shift:

6500 / 1.43 = 4545 RPM

Since there was a gearing reduction the WTQ has also effectively dropped. Looking at the plots it appears that 345 WTQ is typically available at 4500 RPM. Reduce this by the gearing change percentage:

345 / 1.43 = 241 Effective WTQ

So, holding the gear as long as possible and utilizing the gearing should be the most effective since more torque is available when gearing is taken into account.

For example, on my daily driver, a B5 S4 with just the GIAC X Chip, it made about 300 WTQ and 250WHP. At the track, holding it to redline was not the best bet as torque drops off quickly. The gears in the S4 are not spaced evenly so the shift for each change was different. The gearing increase for the 1-2, 2-3 and 3-4 are 1.85%, 1.53% and 1.27% respectively. When shifting at redline the car was running mid/high 13's at about 101 - 102 MPH. When applying the correct shift points to the engine's output and the gearing I was able to drop the time to 13.1 @ 106.6 and was somewhat repeatable with respect to the launch.

Point being, each gear needs to be considered when trying to determine the optimal shift points. However, with the Z06 it is much simpler due to the relatively flat curve; hold it as long as possible in each gear.

 

The optimal shift point is 1500 ABOVE your peek HP. That way when you shift, you will drop 1500 RMPs, you will be AT your peek HP.

so if yout rev limiter is 6650 rpms and your peek HP is 5800 like most stock ZO6s then your optimal shift point is 7300 RPMS.

But wait your red line is 6650 i.e. shift point is at red line.

Need to do a dyno and see where your peek HP is.