SladeX

A thought occurred to me on the way we shift our manual cars at the track.

2.66 1.78 1.30 1.00

1-2 = 67%
2-3 = 73%
3-4 = 77%

For example, you shift at 5500 rpm you end up at 3685 rpm on the 1-2 shift, but on the 2-3 shift you end up at 4015 rpm. 3-4 leaves you at 4235.

Ideally we want to end up right in our peak region for torque, while we have a good "flat" torque curve, 3700 is just outside that peak region, while the 2-3 and 3-4 are bang on. Also being that in stock form our HP peaks usually hit around 5300 rpm, this seems almost perfect.

What I'm wondering is, by holding 1st a little longer, say a 6000 rpm shift, and then shifting lower for the 2-3 and 3-4, could a few tenths be shaved? How many of us have already figured this out without thinking too much about it from feel, and how many people are actually loosing time from shift lights?

I'll try it out next time at the track, but I could have sworn that while playing around with my shift points, one of my miscues actually turned out faster than sticking to a single traditional shift point...

WS6TransAm01

iTrader: (13)

By racing many many stock internal F-bodies I found out that shifting it at 6000 to 6100 rpm in every gear will give you the most MPH and best ET.

Ideally you want to shift a little after your peak HP. Once you are moving, the torque curve you saw on your dyno sheet plays very little part in your MPH and ET.

Trust me, with your stock Camaro, shift at 6000rpm.

cjay

iTrader: (2)

Wouldn't the rear gear ratio figure in to the equation? Seems like that 3 - 4 shift point takes a while to get there. I find myself trying to get into 4th gear by the 1000' mark no matter where the rpm is. With the 3.42 gear it takes too long. Probably need more gear, huh? My car runs enough mph for 12's(107) but the et's off(13.15).
CJay

WS6TransAm01

iTrader: (13)

The rear end gearing would only bring up your 1-2 shift faster and cause you to shift earlier wile going down the track. It will not change the amount RPM drop from gear to gear.

Rear end gear ratios only shift the entire rpm band.

Imagine the rpm band through all the gears as a saw-tooth wave. Changing the transmission gearing will effect the size of the "teeth" of the wave, making the rations closer [smaller drops from a shift] or farther [bigger drops from a shift]. Changing the rear and gear ratio will shift the entire saw-tooth wave left and right, it will not change the size of each individual "tooth" of the wave.

Stang's Bane

iTrader: (22)

Excellent description!!

WS6TransAm01

iTrader: (13)

thanks, its easy to see once you figure out the mechanics, plus I have the experience of going from 3.42 to 3.73 to 4.11 to 4.56 gears over the years.