Calculating shift points
Thread Starter
5th Gear Member
Joined: Apr 2005
Posts: 3,584
From: CT
Calculating shift points
Has anyone sat down with their dyno graph and a program to figure out their optimal shift points? I used a program called SpeedCalc and it basically calculated them at redline. I thought might have missed something so I did the calculations using a spreadsheet and basically came up with the same thing. Is it pretty much a given with a centrifugal blower that your best shift point is going to be at or very close to redlne in every gear?
This is my dyno graph. It is a comparison graph with and without meth. Use the top curves. As you can see, the bulk of my torque is made up top. Shifting at redline keeps me in there. That makes sense, right?
This is my dyno graph. It is a comparison graph with and without meth. Use the top curves. As you can see, the bulk of my torque is made up top. Shifting at redline keeps me in there. That makes sense, right?
6th Gear Member
Joined: Oct 2003
Posts: 8,635
From: North Cackilacky
RE: Calculating shift points
Your curve is pretty flat around 4800-6k, that's a good thing. There's not reason why you should shift before that point as you're not losing much power at all and, like you said, it's keeping you right in your powerband.
Thread Starter
5th Gear Member
Joined: Apr 2005
Posts: 3,584
From: CT
RE: Calculating shift points
ORIGINAL: 98LS1
Your curve is pretty flat around 4800-6k, that's a good thing. There's not reason why you should shift before that point as you're not losing much power at all and, like you said, it's keeping you right in your powerband.
Your curve is pretty flat around 4800-6k, that's a good thing. There's not reason why you should shift before that point as you're not losing much power at all and, like you said, it's keeping you right in your powerband.
It's going to be weird trying to drive my STI to its fullest potential. The torque curve is completely different than that of my Mustang and from what I understand the optimal shift points vary from gear to gear. I'll be able to figure it out once I get my dyno results.
3rd Gear Member
Joined: Nov 2004
Posts: 905
From: Bayside, New York
RE: Calculating shift points
ORIGINAL: BicketyBam
Has anyone sat down with their dyno graph and a program to figure out their optimal shift points? I used a program called SpeedCalc and it basically calculated them at redline. I thought might have missed something so I did the calculations using a spreadsheet and basically came up with the same thing. Is it pretty much a given with a centrifugal blower that your best shift point is going to be at or very close to redlne in every gear?
This is my dyno graph. It is a comparison graph with and without meth. Use the top curves. As you can see, the bulk of my torque is made up top. Shifting at redline keeps me in there. That makes sense, right?
Has anyone sat down with their dyno graph and a program to figure out their optimal shift points? I used a program called SpeedCalc and it basically calculated them at redline. I thought might have missed something so I did the calculations using a spreadsheet and basically came up with the same thing. Is it pretty much a given with a centrifugal blower that your best shift point is going to be at or very close to redlne in every gear?
This is my dyno graph. It is a comparison graph with and without meth. Use the top curves. As you can see, the bulk of my torque is made up top. Shifting at redline keeps me in there. That makes sense, right?
My high HP is at 6500 RPM (458) But my torque at 6500 rpm is only 301.
Given that, were is the better shift point: 5100 rpm 413HP/479TQ or 6500 rpm 458HP/301TQ? I say go with the high Torque curve.
Thread Starter
5th Gear Member
Joined: Apr 2005
Posts: 3,584
From: CT
3rd Gear Member
Joined: Nov 2004
Posts: 905
From: Bayside, New York
RE: Calculating shift points
VERY INTERESTING!!! So I was thinking along the right direction. The thing is to find out where the peak torque curve is in each gear. Then to shift just under the peak TQ. So if my peak torque is 479@5100 rpm, I should shift at 4500 rpm. My torque curve is going up rapidly and the engine will be thriving at that point.
There is a lot of trial and expermentation involved to find out the curves for each gear. I don't know if a dyno can do that? If if can, you have it made. I run an automatic. Computer controlled. Under full throttle, It shifts at 6400 rpm. My red line is set at 6550.
Of course with a manual, this is very possible.
There is a lot of trial and expermentation involved to find out the curves for each gear. I don't know if a dyno can do that? If if can, you have it made. I run an automatic. Computer controlled. Under full throttle, It shifts at 6400 rpm. My red line is set at 6550.
Of course with a manual, this is very possible.
Thread Starter
5th Gear Member
Joined: Apr 2005
Posts: 3,584
From: CT
RE: Calculating shift points
ORIGINAL: janine
VERY INTERESTING!!! So I was thinking along the right direction. The thing is to find out where the peak torque curve is in each gear. Then to shift just under the peak TQ. So if my peak torque is 479@5100 rpm, I should shift at 4500 rpm. My torque curve is going up rapidly and the engine will be thriving at that point.
There is a lot of trial and expermentation involved to find out the curves for each gear. I don't know if a dyno can do that? If if can, you have it made. I run an automatic. Computer controlled. Under full throttle, It shifts at 6400 rpm. My red line is set at 6550.
Of course with a manual, this is very possible.
VERY INTERESTING!!! So I was thinking along the right direction. The thing is to find out where the peak torque curve is in each gear. Then to shift just under the peak TQ. So if my peak torque is 479@5100 rpm, I should shift at 4500 rpm. My torque curve is going up rapidly and the engine will be thriving at that point.
There is a lot of trial and expermentation involved to find out the curves for each gear. I don't know if a dyno can do that? If if can, you have it made. I run an automatic. Computer controlled. Under full throttle, It shifts at 6400 rpm. My red line is set at 6550.
Of course with a manual, this is very possible.
Shift when you will be at an RPM where the car will make more torque AFTER you shift than in your current gear.
This is the program you can use. http://home.comcast.net/~ndmac/SPCal.zip
It takes a lot of inputed data in order to run properly. You have to read the readme.txt file to understand. Great program though.
5th Gear Member
Joined: May 2006
Posts: 3,427
From: CA
RE: Calculating shift points
ORIGINAL: BicketyBam
I think you missed something.
If you shift at peak torque, you will be shifting at a point that puts you at a lower torque figure in the next gear. That's not good. You should shift after peak torque, but how far after is the key and it can vary by gear depending on the torque curve.
This is the program you can use. http://home.comcast.net/~ndmac/SPCal.zip
It takes a lot of inputed data in order to run properly. You have to read the readme.txt file to understand. Great program though.
ORIGINAL: janine
VERY INTERESTING!!! So I was thinking along the right direction. The thing is to find out where the peak torque curve is in each gear. Then to shift just under the peak TQ. So if my peak torque is 479@5100 rpm, I should shift at 4500 rpm. My torque curve is going up rapidly and the engine will be thriving at that point.
There is a lot of trial and expermentation involved to find out the curves for each gear. I don't know if a dyno can do that? If if can, you have it made. I run an automatic. Computer controlled. Under full throttle, It shifts at 6400 rpm. My red line is set at 6550.
Of course with a manual, this is very possible.
VERY INTERESTING!!! So I was thinking along the right direction. The thing is to find out where the peak torque curve is in each gear. Then to shift just under the peak TQ. So if my peak torque is 479@5100 rpm, I should shift at 4500 rpm. My torque curve is going up rapidly and the engine will be thriving at that point.
There is a lot of trial and expermentation involved to find out the curves for each gear. I don't know if a dyno can do that? If if can, you have it made. I run an automatic. Computer controlled. Under full throttle, It shifts at 6400 rpm. My red line is set at 6550.
Of course with a manual, this is very possible.
Shift when you will be at an RPM where the car will make more torque AFTER you shift than in your current gear.
This is the program you can use. http://home.comcast.net/~ndmac/SPCal.zip
It takes a lot of inputed data in order to run properly. You have to read the readme.txt file to understand. Great program though.
Thread Starter
5th Gear Member
Joined: Apr 2005
Posts: 3,584
From: CT
RE: Calculating shift points
I somewhat agree. But most people do not know the exact shift points that will give them the best overall ET with all other things being equal. Shifting by the seat of your pants or at redline may not be the optimal shift points for a given car. That's what I am talking about, not just knowing when to shift. I've been driving a stick for 22 years. I think I got the daily driving part down.