How are you supposed to shift when racing

fast

1st gear, then 2nd gear, then 3rd gear, then 4th gear....

Shift as fast and as accurately as possible.
Depending on your cars "personality" stay ON THROTTLE while shifting.

I stay abuot 1/2 - 3/4 throttle while shifting.
When I do this I increase my ETs by .2 - .3 compared to getting off-throttle to shift.

Also, shift at peak hp or somewhere near there.

Also, shift at peak hp or somewhere near there.
That is not correct from what I understand.
It is certainly not correct for a turbo MR2.

Shifting has to do with Torque, not Horespower.

My understanding is that to find the optimal shift point (I posted this in another thread. copy/pasted here):

Please feel free to post anything that contradicts the following information. I am merely sharing what my research has found.
Nothing below is written in stone (As far as I know )

Shift point information:

http://www.lingenfelter.com/shiftpoint.asp

http://www.allpar.com/eek/hp-vs-torque.html

http://realbig.com/miata/miata/1995-12/910.html

Using the formula on the third link, my car should be optimally shifted well beyond redline ... and I do shift at redline.

Formula:
Lower gear ratio / higher gear ratio X RPM at peak Torque = Shift RPM

Using the same formula for a stock CT26 MR2, I get shift points:
1st --> 2nd = 6595 rpms
2nd --> 3rd = 5643 rpms
3rd --> 4th = 5595 rpms
4th --> 5th = 4915 rpms

Hope that helps.

Notice how the following both have the peak torque at the same RPM?

276 HP CT26
http://www.turboforum.net/dyno/imag...ins/dyno276.jpg

161 HP CT26:
http://www.turboforum.net/dyno/imag.../redmr2dyno.gif

Same turbo, same shift points :thumb:

That is not correct from what I understand.
It is certainly not correct for a turbo MR2.

Shifting has to do with Torque, not Horespower.

My understanding is that to find the optimal shift point (I posted this in another thread. copy/pasted here):

Please feel free to post anything that contradicts the following information. I am merely sharing what my research has found.
Nothing below is written in stone (As far as I know )

Shift point information:

http://www.lingenfelter.com/shiftpoint.asp

http://www.allpar.com/eek/hp-vs-torque.html

http://realbig.com/miata/miata/1995-12/910.html

Using the formula on the third link, my car should be optimally shifted well beyond redline ... and I do shift at redline.

Formula:
Lower gear ratio / higher gear ratio X RPM at peak Torque = Shift RPM

Using the same formula for a stock CT26 MR2, I get shift points:
1st --> 2nd = 6595 rpms
2nd --> 3rd = 5643 rpms
3rd --> 4th = 5595 rpms
4th --> 5th = 4915 rpms

Hope that helps.

Notice how the following both have the peak torque at the same RPM?

276 HP CT26
http://www.turboforum.net/dyno/imag...ins/dyno276.jpg

161 HP CT26:
http://www.turboforum.net/dyno/imag.../redmr2dyno.gif

Same turbo, same shift points :thumb:

I said somewhere close to that.

Peak torque maybe or peak horsepower. But my comment on that shift point beyond the redline...I also think is wrong. Shifting an engine higher than its redline will generally loose torque in its torque curve at a certain point, something like a saturation point. Thats why I said close to the peak.

mycivic look at this dyno:
http://www.turboforum.net/dyno/images/mattjenkins/dyno276.jpg

Torque Peak is at 4000 rpms and Peak HP (nothing to do with shifting) is around 4200 rpms. I gaurantee you the optimal shift point for THAT car is what I posted above:

1st --> 2nd = 6595 rpms
2nd --> 3rd = 5643 rpms
3rd --> 4th = 5595 rpms
4th --> 5th = 4915 rpms

That is no where close to 4000 - 4200 rpms.

It is quite possible that the "ideal" shift point is beyond redline.
That is the case with my turbo car.
I would love to increase my redline to reach it, but I would need to make sure the engine could stand more rpms.

mycivic look at this dyno:
http://www.turboforum.net/dyno/images/mattjenkins/dyno276.jpg

Torque Peak is at 4000 rpms and Peak HP (nothing to do with shifting) is around 4200 rpms. I gaurantee you the optimal shift point for THAT car is what I posted above:

1st --> 2nd = 6595 rpms
2nd --> 3rd = 5643 rpms
3rd --> 4th = 5595 rpms
4th --> 5th = 4915 rpms

That is no where close to 4000 - 4200 rpms.

It is quite possible that the "ideal" shift point is beyond redline.
That is the case with my turbo car.
I would love to increase my redline to reach it, but I would need to make sure the engine could stand more rpms.

I still cant see what your trying to point out. Lets use the last figure as an example. An ideal engine when revved higher will produce more hp or torque. But there is no "IDEAL ENGINE" that can just go on revving to say 15K rpm and not reach a saturation point. What I am trying to say is that (In my opinion) its best to shift "NEAR" peak power (hp or torque) because if you go past this, the "TORQUE CURVE" will start to go down. So generally, you make less power even when revving high. With your example that you gave, shifting at say way past 4000 rpm, you make less power beacuse of the saturation point. So you wont pull as hard.

I never refered to an "ideal" engine. I refered to the ideal "shift point".
I offered a fairly accurate formula for calculating that.

For my turbo MR2, with my T3T4 turbo, my ideal shift point is well beyond redline.
The MR2 turbo I used in the example has the OEM turbo and it's ideal shift points are much less than mine (as noted)

The problem with making a blanket statement like "shift at or near peak torque" is that does not take into account gearing.
The equation I offered does just that.

My dyno is here:
http://jekylandhyde.madpowaz.com/hydedyno.jpg
Notice my peak torque is around 5200 rpms.
I gaurantee you that is not my ideal shift point ... nowhere close.
My ideal shift point is well beyond 7200 rpms (my rev limit).

Max Toqrue is only one part of the equation.
To determine the ideal shift point, you would want to know:

Peak Torque
Max RPM
Tire Diameter (gearing)
Differential Ratio (gearing)
Gear RAtio (gearing)

http://www.rapidline.com/screens/pcchshif.gif

I never refered to an "ideal" engine. I refered to the ideal "shift point".


I know you were reffering to the ideal shift point as you were saying. But lets also take into account that if you do shift at that "IDEAL SHIFT" point, there is no "IDEAL ENGINE" that can do that. You will loose power after peak power. Thats why I said in my first post that (In my opinion still) its best to shift somewhere near peak power.

Here are two interesting shift point calculators:

http://www.prestage.com/Tech+Info/Drag+Racing/1121.aspx

http://www.bgsoflex.com/shifter.html

I haven't played with them yet to see how accurate they are, but notice they both incorporate gearing.

I know you incorporate gearing and all other factors but its still not wise to shift at the ideal shift point. You also have to take into cosideration the capabilities of the engine, like redline and the fuel cut-off point. If you do shift at that Ideal shift point...you "MAY" destroy the engine because the engine cant handle revving past the redline or fuel-cutoff point.

But lets also take into account that if you do shift at that "IDEAL SHIFT" point, there is no "IDEAL ENGINE" that can do that.
For a given engine with a given transmission with specific gears and specific tire diameter there is an ideal shift point. It is something that can be calculated.

Thats why I said in my first post that (In my opinion still) its best to shift somewhere near peak power.
Just because you see a dyno graph "fall off" doesn't mean that it is the ideal time to shift for maximum acceleration.
You have to take gearing into account.

I know you incorporate gearing and all other factors but its still not wise to shift at the ideal shift point.
If your goal is maximizing acceleration, then it is wise to shift at the ideal shift point if it falls below the redline of your engine.
See the graphic I posted? ... it asks for the redline point ofr a reason.

On the stock-turboed MR2 graph I posted, the ideal shift point is around 5500 rpms. With my T3T4 turbo on the same engine my mathematical ideal shift point is beyond redline ... obviously I can't shift there. So my ideal shift point IS redline (7200 rpms).

If you do shift at that Ideal shift point...you "MAY" destroy the engine because the engine cant handle revving past the redline or fuel-cutoff point.
Then I wouldn't describe tht point as ideal!

I see your point. I understand what you are trying to say. But it still doesent take into account the engine...where it cuts-off. Even though you shift at redline, you still may not be getting the most out of acceleration. You may actually be accelerating slower if you shift past peak power.

Hey, does anybody else have another opinion? This is kinda getting interesting.

The formula I posted using the stock-turboed MR2 I got shift points:
1st --> 2nd = 6595 rpms
2nd --> 3rd = 5643 rpms
3rd --> 4th = 5595 rpms

The calculator I posted from:
http://www.bgsoflex.com/shifter.html
Gave me:
1st --> 2nd = 6130 rpms
2nd --> 3rd = 5553 rpms
3rd --> 4th = 5524 rpms

Just becuase "torque" falls off on a dyno sheet does not mean that is time to shift.

The trick here is to keep your engine in the meaty part of the torque curve, as your acceleration curve will match your torque curve - meaning if your torque peak is at 3000rpm, that's the RPM your car accelerates the hardest. How do you keep the engine in the best part of the curve? Shift when you will be at an RPM where the car will make more torque AFTER you shift than in your current gear. This may sound confusing, but I will give some examples to help demonstrate this. Gear ratio is important because you need to know what your RPM's will drop to once you shift. EXAMPLE : If you're at 6500rpm in first, you need the gear ratio to know what RPM that will translates to once you shift to 2nd.

Well what do you know! You bracket the HP peak. HP after the shift is the same as HP before the shift. Now we know shifting at the torque peak isn't the answer, and neither is shifting at the HP peak.

From this site:
http://www.datsuns.com/Tech/whentoshift.htm

Using the calculator, and if it says that shift way past redline, is not ideal. I still believe that its near peak power.

Each of us obviously have our own opinion on what the ideal shift point is. And it seems that none will give in to another. So lets leave it at that and see what other people think is the ideal shift point.

mycivic, see my last post. We posted about the same time and I think you may have missed it.

Using the calculator, and if it says that shift way past redline, is not ideal.
If the math states that your target shift point is beyond redline, then redline is your ideal shift point.

I still believe that its near peak power.
Each of us obviously have our own opinion on what the ideal shift point is.
This has nothing to do with "believing" or "opinions".
I am offering you facts - from physics.
It is your choice what to do with them.

There are hundreds of sites out there that will back my statements.
I have offered no opinions.

I dont know what else to say...

I still cant see past why it has to be way past peak power when it starts to drop in the torque curve.

The trick here is to keep your engine in the meaty part of the torque curve, as your acceleration curve will match your torque curve - meaning if your torque peak is at 3000rpm, that's the RPM your car accelerates the hardest. How do you keep the engine in the best part of the curve? Shift when you will be at an RPM where the car will make more torque AFTER you shift than in your current gear. This may sound confusing, but I will give some examples to help demonstrate this. Gear ratio is important because you need to know what your RPM's will drop to once you shift.

This, however makes more sense to me.

Hey mycivic, think of it this way:

Think of maximum turque over and range of rpms ... not just the peak point.

EXAMPLE:
Let's say your engine+tranny make it's most power from 4000-5500 rpms.
Let's say your peak TQ is at 4800 rpms.
What if you shift at 4800 and your rpms drop to 2000 rpms?!
UG....
You are not "in the power" for THAT gear. You want to shift when you drop down into the "meat" of the next gear.

You want to keep your car in the max power range.

Hey mycivic, think of it this way:

Think of maximum turque over and range of rpms ... not just the peak point.

EXAMPLE:
Let's say your engine+tranny make it's most power from 4000-5500 rpms.
Let's say your peak TQ is at 4800 rpms.
What if you shift at 4800 and your rpms drop to 2000 rpms?!
UG....
You are not "in the power" for THAT gear. You want to shift when you drop down into the "meat" of the next gear.

You want to keep your car in the max power range.

Ok, I get it now. I may have been wrong with what I said. I stand corrected with what ever wrong that I mentioned earlier.

No worries man... we are all here to learn and your questions pushed me to learn more today.

Thank you for that. :)

Same here.

Slight "Disclaimer" to the individual that referred to the Lingenfelter site.

I just thought I should add this guys.

(Quote from LPE)
"When determining proper shift points it is also important to consider the safe operating speeds for your engine. Consult your owners manual or your engine builder when selecting shift points. Shifting after the redline or past the safe operating speed of the engine can result in premature engine wear or damage."

I just thought I should get that out of the way. In the quest for that last .05 at the traps people tend to overlook this little gem of wisdom.

Slight "Disclaimer" to the individual that referred to the Lingenfelter site.

I just thought I should add this guys.

(Quote from LPE)
"When determining proper shift points it is also important to consider the safe operating speeds for your engine. Consult your owners manual or your engine builder when selecting shift points. Shifting after the redline or past the safe operating speed of the engine can result in premature engine wear or damage."

I just thought I should get that out of the way. In the quest for that last .05 at the traps people tend to overlook this little gem of wisdom.

He mentioned that too when we were having the argument. It is not advisable to shift past redline because there is no ideal engine that can be capable of that. That is why there is a redline. If the "Ideal Shift Point" is way past redline...then the next best thing to do is sihft near redline and not past redline.

THe way I understand it is you wait until the point when you shift you will be back in a higher toque/hp range. for instance, if you are at 5600 rpm and you upshift and now you are making less power that is bad, but then you hit the 6100 mark and your upshift will make you more power.

fast

just playing, technically, if you want the best shift point, get to a dyno, find out where the highest possible horsepower is made, and keep going, you need to find the spot where you can shift, and "fall onto" max hp. thats what drag racers do anyway

Powershifting is the best way. Keep your throttle down while u shift. Be VERY!!!! careful not to keep ur clutch down while ur gas pedal is down too LONG or else....YOUR GONNA BLOW UR TRANNY and BURN UR CLUTCH DISCS!!!!!

Powershifting is the best way. Keep your throttle down while u shift. Be VERY!!!! careful not to keep ur clutch down while ur gas pedal is down too LONG or else....YOUR GONNA BLOW UR TRANNY and BURN UR CLUTCH DISCS!!!!!
"powershifting" huh.......good luck on changing your clutch....alot!

As drag1320 stated, take it to the dyno.The is the best way to know here your optimal shift points will be. You'd be suprised how some cars don't make as much power all the way up to redline as they do a few hundred rpms lower.

This past weekend, for the first time, I completely "flat footed" the 3rd --> 4th shift.
I stayed 100% throtle and shifted extremely fast.

Everything was 100% smooth - no jerk ... it was perfect. IT also netted me back-to-back new personal best times. 11.74 followed by a 11.73.

Previosuly, I always tried to stay on some level of throttle while shifting ... but not 100%.
It felt good :)

Real men powershift their cars, no if, ands, or buts. It will make your go faster in the 1/4 too as long as you aren't revving to high past peak hp. However, there are obviously some real risks, ie destroying your tranny, frying your clutch, or blowing your motor if you miss a shift. Fox mustangs were famous for blowing up the stock T5 tranny when powershifting. But, with that you can pick up probably .2 sec ET in the 1/4 vs. moderate shifting.