stick car 4 speed best shift points

[Eric Merryfield]

Have dyno sheet, peak tq is at 5800-6000, HP at 7000. Have racepak.

Not sure if there was any tried and true methods. Seems to like 8000. I know autos are totally different due to torque convertor multiplication and the 3 speed.

Sitting at a shop, getting ready to pack up for trip to the grove.

Thanks

Eric

[bigfoot584]

Really no one could answer this question better than yourself.
You need to shift at different points and track the change with
the time slips.
I know it's not what you wanted to hear.

[Mike Taylor 3601]

Originally Posted by bigfoot584

Really no one could answer this question better than yourself.
You need to shift at different points and track the change with
the time slips.
I know it's not what you wanted to hear.

As he said trial and error.
As starting point I would try going to 2nd. about 6800-7000, 3rd about 7500-7700 and 4th. 7500-7700 4th may like going on up to about 8000, that is where I would start for base line and see what it likes from there,a lower ratio 1st gear will like to be shifted sooner than a taller 1st.how much difference in ratio on other gears will determine how far you need to stretch those gears out,more difference=high shift point.
Mike Taylor 3601

[weedburner]

If you have a Racepak, just make a few runs at different shift points to get some data, then you can change the individual "0" set points on the runs to visually compare the different shift points. By changing the "0" set points, i'm talking about syncing the runs to a much later point other than 1st movement of the car. I like to pick a common driveshaft rpm that occurs after any tire spin but before the lowest shift point, like maybe set them to "0" at 2000 driveshaft rpm to compare all the 1/2 shifts. After you overlay the runs, you can expand the graph with the "+" button to make it easier to see which shift point added driveshaft rpm at a faster rate. When you are done comparing 1/2 shifts, change the "0" points to a common driveshaft rpm that occurs before the 2/3 shifts and compare those.

[joespanova]

Shifting at power peak should drop RPMs back to torque peak.
I don't know if contemporary stick cars work this way though , since anymore most , if not all , current stick cars use a clutchless trans.


BTW.........If you ain't clutching at the gear change , using a clutch assisted trans , you ain't a real stick racer.


Contemporary clutchless trannys can make a stick racer out of my grandmother.

[Robert Simpson]

I would use the g-meter on the racepak. I would look at the g-meter at every gear change. If it is still accelerating, before the gear change, then shift higher at that gear. If the acceleration fell off some before the gear change then shift sooner. It is some trial and error but you have a good source to get the data.

[Mike Pearson]

When I ran a stick in my super stock car years ago with a 327 It liked high rpm at the launch. Typically it would be at 9500 rpm leaving the line and shift points at 8000. It also liked a real light flywheel 13 lbs was the lightest I tried and was the fastest by about 2 tenths. Back then we used the clutch at every gear change.

[Aubrey N Bruneau]

Perhaps just MY thought on it... ? ? ? ... but I don't see it so much as "trial and error" ?
The "blessed" dyno sheet should help us SOMEWHERE !
Personally, I study the torque / horsepower curves ( we all know that single peak numbers don't do much, if there's no "support" before and after ). I calculate % RPM drop at each gear change. Then apply that operating range to my dyno numbers, and determine what start / finish RPM points, show the highest average HP between them.
To me ?... just mathematics. Also, as I see it, the greater the drop in RPM, the higher the shift point would have to be, in order to remain in the best average HP.
The only "trial and error" after this, would be to possibly drop your shift RPM by a couple hundred, to help the engine fall into the thick of it's torque curve.
I dunno ?... again, just my thoughts.

[Bill Unruh]

Originally Posted by joespanova

.....If you ain't clutching at the gear change , .... you ain't a real stick racer.
Contemporary clutchless trannys can make a stick racer out of my grandmother.

WOW! Sounds like someone has clutchless shift envy.

---Bill.

[joespanova]

Originally Posted by Bill Unruh

WOW! Sounds like someone has clutchless shift envy.

---Bill.

LOL , Yeah sure pal.
Hardly.
It's the truth.