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Discussion Starter #1
The following chart shows the optimum shift point for maximum acceleration in gears 1, 2, and 3.

The colored dots show the shift point for a gear; and the matching dot, the corresponding RPM for the following gear (provided my math is correct).



Basically, for maximum acceleration, the 1-2 shift should be at ~6200, the 2-3 shift at about ~5800, and the 3-4 shift at ~5700.

This roughly parallels the anecdotal accounts of shifting at 5700 yielding the best results.

The data is derived using CP-E stock run. Different dynos will yield various results. However since it is known that this dyno is roughly the mean run from a number of runs, it provides the best sample we have. For the most part, curves (which is all that really matters for this exercise) are generally going to remain the same even between dynos.
 

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Not neccessarily..
It looks clean. I just wish I had my old DOS Program we used to set up the tranny for the tracks and the suspension.
Then I could compare that to the DYNO run.
Knowing the Bore/Stroke, Wet Wieght, HP/TQ and Gearing, this program would crunch #'s to give best shift points.
Then we could even put in the Drag, Face surface, rear surface, tire patch, and width/hieght of vehicle to pull best shift for max G's in turns.
 

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I've never seen anything put together like this, and I'm impressed. I will be following these shift points when I take my MS6 to the track May 12th, may even try em out on the street and see how it goes :)

Thanx!!
 

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Excellent graph. I"m not quite sure it'll work well though. From what I recall when I shifted at 6000 in first to second, the rpms were already at 4500-5000.

It felt as if I shifted twice within a second.

Will definitly have to look at it from now on.

Jason
 

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great work Sigma :)
 

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Nice info. Hard to look at the tach and shift exactly at 5700 and 5800 since the car Revs so damn fast. lol
 

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Nice work. Agrees with my shiftpoint excel ss. I plot axle torque vs mph for ea gear, a bit easier to read. Anyone with excel, pm me your email address for a copy. Can use for other cars.
 

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thanks alot.
 

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Discussion Starter #12
Excellent graph. I"m not quite sure it'll work well though. From what I recall when I shifted at 6000 in first to second, the rpms were already at 4500-5000.[/b]
My math could very well be wrong on the corresponding RPM going into the next gear. Usually I'd sniff-test something like this, but without an MS6 of my own, I can't do that.
 

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Just went out and tested it out. SHifting at 6200 in 1st put me at 4800 in 2nd, and at 6000 in first, 4500 in 2nd.

Give or take a couple hundred rpm.

Couldn't get the 2-3 shift. I'll check that out tomorrow.

Jason
 

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RPM in next gear should be based on the ratios of the primary gears.

rpm2 = rpm1 x GR2/GR1

final drive ratio does not matter for shifts in gears 1-4 (FD=3.941)

mazda-usa lists MS6 gears box ratios as:

1=3.538
2=2.238
3=1.535
4=1.172

for 1st to 2nd, GR2/Gr1= .633

so a 6200 shift drops to 3900 rpm, not 4800 rpm

If Jason's numbers are correct, then the ratios listed by mazda are not.
 

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If I shift at 6200... my rpm's are back near 5 grand in 2nd... so 4800 sounds about right..
[/b]
That can't be right. 1st and 2nd cant be so close. It would mean you can either go up to 47mph in 1st gear and 73mph in second or 39mph in first and 47mph in second. :sarc:
 

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They are very close. This is why I made the argument for wanting more high rpm gains then mid rpm gains as the car is frequently above 4500 rpm.

jason
 

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Discussion Starter #18
RPM in next gear should be based on the ratios of the primary gears.

rpm2 = rpm1 x GR2/GR1

final drive ratio does not matter for shifts in gears 1-4 (FD=3.941)

mazda-usa lists MS6 gears box ratios as:

1=3.538
2=2.238
3=1.535
4=1.172

for 1st to 2nd, GR2/Gr1= .633

so a 6200 shift drops to 3900 rpm, not 4800 rpm

If Jason's numbers are correct, then the ratios listed by mazda are not.
[/b]
Well I'm glad to see that my math isn't exactly incorrect since you get the same results as I do. Something is off though.

The gear ratio of 2nd is over 30% lower than that of 1st. You can't shift at 6000 and end up at 5000 when your gear ratios are that far apart. That means the gear ratios are all fuggered up.
 

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I'll see if I can tape it tonite and show you.

Jason
 
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Sigma
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