Shift Points

[FoMoCoSHO]

So I've been thinking about the best shift points for our cars and I decided to play with a calculator. For reference, I used SHO-TYM's dyno (Thanks SHO-TYM!) on page 5 of dyno results. I used stock diameter wheel size and the PP gear.

After going through that I went on the hunt for an EXCEL based formula which I did find and can be found here...The forum wouldn't let me attach the excel file.

http://www.modularfords.com/threads/161757-Shift-Point-Calculator

Looks like redline is the correct shift point based on my data entry.

Discuss.

 

[FoMoCoSHO]

This is good news for another reason.

The higher shift point will have us shifting into a higher RPM, moving away from the naughty fuel starved area of the curve.

 

[SHOdded]

Do these calculations allow for "slop", time to shift, longevity considerations, etc?

 

[FoMoCoSHO]

Do these calculations allow for "slop", time to shift, longevity considerations, etc?

I think they are all basically calculating power by gear x torque vs rpm.

You wouldn't have all that tranny slop if you'd get rid of that edge and get a tuned sho. 

 

[FoMoCoSHO]

If I can find some more readable dynos I will run some more numbers. Many in the thread seem to be missing.

 

[FoMoCoSHO]

LME XSPORT dyno found here....

http://www.ecoboostperformanceforum.com/index.php/topic,2059.30.html

1st pic is with the 3.16 final drive

2nd is substituting the 2.77 for comparison.

Looks like 3.16 final drive would need to engage the paddle for a 3-4 short shift.

 

[FoMoCoSHO]

For the non PP 2.77 guys, I wonder if the MYCAL and SCT can set different shift points for different gears?

 

[ajpturbo]

For the non PP 2.77 guys, I wonder if the MYCAL and SCT can set different shift points for different gears?

With sct i dont think the end user options have the capability to adjust gear shift points but in the tune you can adjust shift points by gear

 

[FoMoCoSHO]

For the non PP 2.77 guys, I wonder if the MYCAL and SCT can set different shift points for different gears?

With sct i dont think the end user options have the capability to adjust gear shift points but in the tune you can adjust shift points by gear

I can change it globally but not by gear.

Good to know it can be changed by the gear in the tune.

 

[ajpturbo]

I would say the shift points should be the same for all gears and should be judged from a dyno curve...the reason the power changes for each gear is most likely due to being at different boost levels ....the gear itself shouldnt really have any effect on power but different boost will and incidentally most logs ive seen show widly different boost levels by gear....my take on it anywho...i shoot for 6k every gear

 

[BiGMaC]

FoMoCo... Best answer to the question you asked me is here:
http://www.ecoboostperformanceforum.com/index.php/topic,2054.msg91452.html#msg91452

 

[FoMoCoSHO]

Thanks BigMac, according to the dyno you made power to about 6750 and I'm just trying to figure out how you made it there with a 6500 RPM redline and whether or not that RPM is safe.

 

[FoMoCoSHO]

I would say the shift points should be the same for all gears and should be judged from a dyno curve...the reason the power changes for each gear is most likely due to being at different boost levels ....the gear itself shouldnt really have any effect on power but different boost will and incidentally most logs ive seen show widly different boost levels by gear....my take on it anywho...i shoot for 6k every gear

I agree, and these numbers are plotted off of provided dynos.

I did not think about the varying boost levels, are you saying that on turbo cars if you were to dyno by gear that the curves might look a bit different? That definitely throws a wrench into using a straight math calculator.

Another way to figure this out is to log accelerometer data through the 1/4. In my mind, that is probably the most accurate way to figure this out due to so many variables.

For fuel challenged cars it would seem having that cam spin faster after the shift with a higher shift point should be part of the equation as well. Trying to figure out the max safe operating RPM has been impossible so far.

 

[BiGMaC]

Thanks BigMac, according to the dyno you made power to about 6750 and I'm just trying to figure out how you made it there with a 6500 RPM redline and whether or not that RPM is safe.

I have no proof either way... We did do 9 dynos that day, I really don't have the need to push that hard in daily driving. Not sure what the weak link at over-rev would prove to be.

 

[ajpturbo]

I would say the shift points should be the same for all gears and should be judged from a dyno curve...the reason the power changes for each gear is most likely due to being at different boost levels ....the gear itself shouldnt really have any effect on power but different boost will and incidentally most logs ive seen show widly different boost levels by gear....my take on it anywho...i shoot for 6k every gear

I did not think about the varying boost levels, are you saying that on turbo cars if you were to dyno by gear that the curves might look a bit different

It depends on the car....unless the car has a sophiticated boost control system or aftermarket electronic boost solenoids, often turbo cars will run different boost for various gears...sometimes intentional sometimes because of lack of functionality of the controller

The stock tunes also have torque modifiers based on output shaft speed . Those will affect the desired tip values that correlate to boost..from the logs ive seen here boost in gears 1-2 are a good bit different than 3-6...and i can tell you based on the tunes ive seen it wasnt intentional but more from a lack of understanding of the tables