[Z06] Drag racing question regarding shift points
Thread Starter
Le Mans Master
Joined: Oct 2000
Posts: 5,474
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From: raleigh, nc
Drag racing question regarding shift points
I am wondering if I could improve the track times by shifting into 2nd at 6000 rpms rather than at redline. I asked this because it seems I always have some severe wheel hop going into 2nd and was wondering if I could eliminate this by shifting at 6k. How much ET do you think I am losing with having severe wheel hop going into 2nd. I would appreciate anybody shift points they are using on stock tires
[Modified by Y2K253SS, 8:04 AM 11/4/2002]
[Modified by Y2K253SS, 8:04 AM 11/4/2002]
Melting Slicks
Joined: Nov 2000
Posts: 2,380
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Re: Drag racing question regarding shift points (Y2K253SS)
Short-shifting seemed to help JWSchmidt3 with his wheel hop issues: http://forums.corvetteforum.com/zerothread?id=426468
JC
JC
Melting Slicks
Joined: Oct 2000
Posts: 2,524
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From: Stamford CT.
Re: Drag racing question regarding shift points (Y2K253SS)
I am wondering if I could improve the track times by shifting into 2nd at 6000 rpms rather than at redline. I asked this because it seems I always have some severe wheel hop going into 2nd and was wondering if I could eliminate this by shifting at 6k. How much ET do you think I am losing with having severe wheel hop going into 2nd. I would appreciate anybody shift points they are using on stock tires
[Modified by Y2K253SS, 8:04 AM 11/4/2002]
[Modified by Y2K253SS, 8:04 AM 11/4/2002]
Thread Starter
Le Mans Master
Joined: Oct 2000
Posts: 5,474
Likes: 80
From: raleigh, nc
Re: Drag racing question regarding shift points (Power Shifter)
I can't remember by the redlines you are referring to. I usually shift when i see the needle between the 6000 mark and the thick red line
Drifting
Joined: Jul 2002
Posts: 1,320
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From: Duncanville Texas
Re: Drag racing question regarding shift points (Y2K253SS)
There is 500 RPM between what you are talking about.
I had sever wheel hop issues.....get more traction.
Did you lower your car? That is normally where the problem comes in, and you could lose a good .2 sec from wheel hop depending on severity!
I had sever wheel hop issues.....get more traction.
Did you lower your car? That is normally where the problem comes in, and you could lose a good .2 sec from wheel hop depending on severity!
Safety Car
Joined: Oct 2001
Posts: 3,504
Likes: 25
From: Insert Wittty Comment here
Re: Drag racing question regarding shift points (z0sense)
Short shifting cost me time. About .3seconds and 3 mph.
I shift at 6200 - 6300. The rev limiter is at 6600. I carry 3rd as far as I can, and this seems to net me my best times.
I haven't seen any wheelhop after I lowered the car, as it seems to reduce the rear spring rate a bit.
The only times I have ever gotten wheelhop is on the cheesy asphaly outside of HRP. I can go out there in the street and get wheelhop if I side step th clutch. Before I lowered the car it seemed a bit worse. Lowering the car seem to soften it a bit.
But, I haven't had any real problems, as long as the car hooks, which it always seems to do. I have only seen wheelhop in htese cars when wheelspin is involved. If tires aren't spinning, they aren't hopping either.
I shift at 6200 - 6300. The rev limiter is at 6600. I carry 3rd as far as I can, and this seems to net me my best times.
I haven't seen any wheelhop after I lowered the car, as it seems to reduce the rear spring rate a bit.
The only times I have ever gotten wheelhop is on the cheesy asphaly outside of HRP. I can go out there in the street and get wheelhop if I side step th clutch. Before I lowered the car it seemed a bit worse. Lowering the car seem to soften it a bit.
But, I haven't had any real problems, as long as the car hooks, which it always seems to do. I have only seen wheelhop in htese cars when wheelspin is involved. If tires aren't spinning, they aren't hopping either.
Team Owner
Joined: Mar 2000
Posts: 27,231
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From: Houston TX
Cruise-In III Veteran
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Re: Drag racing question regarding shift points (J-Rod)
So the verdict is to short shift the 1-2 shift at about 6000-6100 rpms, shift 2-3 around 6300rpm, and go full fledged on the 3-4 shift?
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Melting Slicks
Joined: Oct 1999
Posts: 2,181
Likes: 421
From: Ponte Vedra Beach FL
Re: Drag racing question regarding shift points (Ryan Bell)
That doesn't sound like a verdict to me. There is no reason to short shift at all unless you're powershifting. If you're lift-shifting,might as well take it higher...you don't need the 200 rpm "cushion" to allow for the brief climb in revs during a powershift. And even then, 6000 seems a little low.
I think the verdict is 6200-6300 for 2nd and 3rd gears shifts, and 6400+ for the shift to 4th.
I think the verdict is 6200-6300 for 2nd and 3rd gears shifts, and 6400+ for the shift to 4th.
Safety Car
Joined: Oct 2001
Posts: 3,504
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From: Insert Wittty Comment here
Re: Drag racing question regarding shift points (Tracy)
Nope, the verdict is to get as many RPMs as you can without hitting the limiter.
The motor makes power to 6800, so shifting at 600-6100 is too low. I'd shoot for about 6300-6400 on every shift.
The motor makes power to 6800, so shifting at 600-6100 is too low. I'd shoot for about 6300-6400 on every shift.
Melting Slicks
Joined: Oct 2000
Posts: 2,524
Likes: 0
From: Stamford CT.
Re: Drag racing question regarding shift points (J-Rod)
The verdict should be to do what works best for you in your own car. I think trying to get a difinative answer to what's best is futile. My car's best way changes with weather and track conditions and so does yours!! I make a guess on launch rpm the first run and adjust from there. The shift point that most often gives the best et's IS 6250 with power shifts, most of the time ANY THING over 6300 on any power shift has yealded slower et's. Yes if you want to push 3-4 to a higher rpm it may yeald more mph but in my car it usualy costs et to do it. Any one that says there power shifting at 6500 without touching the limeter needs better glasses to read there tach, because it isen't reading 6500, and power shifting at 6400 costs et in my car as a general rule. Shifting at 62-6300 is not short shifting IMO it's the BEST SHIFT POINT for quick runs, in my car, and probably yours if you power shift. Ric
Le Mans Master
Joined: Jun 2001
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From: Admit Nothing, Deny Everything, Make Counter Accusations.
Re: Drag racing question regarding shift points (Power Shifter)
I'm with Ric on this one. Find what works best on your car for your style of driving and then stock with it. This will vary from car to car & driver to driver.
Race Director
Joined: Sep 2000
Posts: 11,309
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From: Valley Ranch, Texas
Re: Drag racing question regarding shift points (rbartick)
I'm with Ric on this one. Find what works best on your car for your style of driving and then stock with it. This will vary from car to car & driver to driver.
:yesnod: You have to be flexible to race cars, it goes with the territory. :cheers:
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 31
From: Central Florida
Re: Drag racing question regarding shift points (Y2K253SS)
What consistently works best for me is to shift at the highest possible rpm without kissing the limiter. I do this to put the engine rpm after the shift at about 4500, where the Tric is producing a +9 rwtq advantage (dyno measured) compared to the stock air box.
I rarely kiss the limiter, perhaps one run out of 15.
When I shift lower, my ETs suffer.
Obviously, you need a fast clutch foot to do this...just one of the reasons I pump iron. ;)
The speed of a shift really is limited by the speed of the leg which must move in two directions. In contrast, the arm moves in only one direction.
I'm running the stock shifter.
Ranger
I rarely kiss the limiter, perhaps one run out of 15.
When I shift lower, my ETs suffer.
Obviously, you need a fast clutch foot to do this...just one of the reasons I pump iron. ;)
The speed of a shift really is limited by the speed of the leg which must move in two directions. In contrast, the arm moves in only one direction.
I'm running the stock shifter.
Ranger
Melting Slicks
Joined: Oct 2000
Posts: 2,524
Likes: 0
From: Stamford CT.
Re: Drag racing question regarding shift points (Ranger)
What consistently works best for me is to shift at the highest possible rpm without kissing the limiter. I do this to put the engine rpm after the shift at about 4500, where the Tric is producing a +9 rwtq advantage (dyno measured) compared to the stock air box.
I rarely kiss the limiter, perhaps one run out of 15.
When I shift lower, my ETs suffer.
Obviously, you need a fast clutch foot to do this...just one of the reasons I pump iron. ;)
The speed of a shift really is limited by the speed of the leg which must move in two directions. In contrast, the arm moves in only one direction.
I'm running the stock shifter.
Ranger
I rarely kiss the limiter, perhaps one run out of 15.
When I shift lower, my ETs suffer.
Obviously, you need a fast clutch foot to do this...just one of the reasons I pump iron. ;)
The speed of a shift really is limited by the speed of the leg which must move in two directions. In contrast, the arm moves in only one direction.
I'm running the stock shifter.
Ranger
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 31
From: Central Florida
Re: Drag racing question regarding shift points (Power Shifter)
...I ask, because your talking about the in and out with the clutch, limiteing speed of shift?. and last but not least, are your recomendations for full on power shifts, or some thing else?...
During a shift, the clutch leg must depress the clutch and then release it. That entails movement in two opposite directions. The elapsed time of that movement will alway be longer than the time required to slam the shifting arm in only one direction per shift, a movement that is futher assisted by the momentum of torso for those who practice "violent shifting." Movement of the throttle foot, if any, is much shorter and therefore quicker. And, while the movements of these three limbs must be coordinated, the clutch leg will (always) be the slowest.
Regarding my powershifting, it all depends on the hook of the track on any particular day/pass. Some days the hook is great and sometimes it just won't take strong shifts to 2d and 3d. I normally powershift the 3d-4th.
I certainly don't recommend powershifting across the board. Each driver needs to do his/her own "risk vs reward" analysis. Assuming the track has the hook to sustain powershifts, which some rarely do and none do all the time, then is shaving a couple tenths in the 1320' ET worth the risk of damage to the tranny??
For myself, if I find great track conditions and great air this Fall and have a shot at a pass in the 11.5s, then I'll powershift all the gear changes and see what happens.
Ranger
[Modified by Ranger, 6:15 PM 11/8/2002]
Melting Slicks
Joined: Oct 2000
Posts: 2,524
Likes: 0
From: Stamford CT.
Re: Drag racing question regarding shift points (Ranger)
...I ask, because your talking about the in and out with the clutch, limiteing speed of shift?. and last but not least, are your recomendations for full on power shifts, or some thing else?...
Hey Ric,
During a shift, the clutch leg must depress the clutch and then release it. That entails movement in two opposite directions. The elapsed time of that movement will alway be longer than the time required to slam the shifting arm in only one direction per shift, a movement that is futher assisted by the momentum of torso for those who practice "violent shifting." Movement of the throttle foot, if any, is much shorter and therefore quicker. And, while the movements of these three limbs must be coordinated, the clutch leg will (always) be the slowest.
Regarding my powershifting, it all depends on the hook of the track on any particular day/pass. Some days the hook is great and sometimes it just won't take strong shifts to 2d and 3d. I normally powershift the 3d-4th.
I certainly don't recommend powershifting across the board. Each driver needs to do his/her own "risk vs reward" analysis. Assuming the track has the hook to sustain powershifts, which some never do and none do all the time, then is shaving a couple tenths in the 1320' ET worth the risk of damage to the tranny??
For myself, if I find great track conditions and great air this Fall and have a shot at a pass in the 11.5s, then I'll powershift all the gear changes and see what happens.
Ranger
Hey Ric,
During a shift, the clutch leg must depress the clutch and then release it. That entails movement in two opposite directions. The elapsed time of that movement will alway be longer than the time required to slam the shifting arm in only one direction per shift, a movement that is futher assisted by the momentum of torso for those who practice "violent shifting." Movement of the throttle foot, if any, is much shorter and therefore quicker. And, while the movements of these three limbs must be coordinated, the clutch leg will (always) be the slowest.
Regarding my powershifting, it all depends on the hook of the track on any particular day/pass. Some days the hook is great and sometimes it just won't take strong shifts to 2d and 3d. I normally powershift the 3d-4th.
I certainly don't recommend powershifting across the board. Each driver needs to do his/her own "risk vs reward" analysis. Assuming the track has the hook to sustain powershifts, which some never do and none do all the time, then is shaving a couple tenths in the 1320' ET worth the risk of damage to the tranny??
For myself, if I find great track conditions and great air this Fall and have a shot at a pass in the 11.5s, then I'll powershift all the gear changes and see what happens.
Ranger
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 31
From: Central Florida
Re: Drag racing question regarding shift points (Power Shifter)
I said in my earlier post what I try to do, which is to shift as close to the limiter as I can without kissing it. Sometime before the end of the season, I'll try to hook up some data capture hardware and measure my actual shift points. If I get that done, I'll post the results in a spread sheet for multiple runs. Nothing beats real data.
Melting Slicks
Joined: Oct 2000
Posts: 2,524
Likes: 0
From: Stamford CT.
Re: Drag racing question regarding shift points (Ranger)
I said in my earlier post what I try to do, which is to shift as close to the limiter as I can without kissing it. Sometime before the end of the season, I'll try to hook up some data capture hardware and measure my actual shift points. If I get that done, I'll post the results in a spread sheet for multiple runs. Nothing beats real data.
Race Director
Joined: Aug 2000
Posts: 10,649
Likes: 31
From: Central Florida
Re: Drag racing question regarding shift points (Power Shifter)
Ric, I really don't want to see this thread degenerate into endless nitpicking. I said what I have to say that is useful. What I do seems to work for me. I have posted my target shiftpoints before, only to have you write that they are not accurate. No good purpose is served by going there again.
I wish you well and good luck at the track this weekend. Hope the weather is good to you. :)
Ranger
[Modified by Ranger, 7:49 PM 11/8/2002]
I wish you well and good luck at the track this weekend. Hope the weather is good to you. :)
Ranger
[Modified by Ranger, 7:49 PM 11/8/2002]