Shifting

[djet820]

When your'e doing the 1/4, when do you shift? I've noticed a lot of people go pretty close to redline. And wht kind of technique do you use for road and drag racing? Just slam it into the next gear, double clutch, heel-toe, so on.

edited it, damnit i'm dumb lol.

[David]

heel toe is for downshifting, probably not the best technique for drag racing;)

[stu]

Heh heh, double clutching is for old cars with no synchros and is for DOWN SHIFTING. If you try to double clutch during a drag race you are just slowing yourself down. Oh yeah, Heel-toe is for down shfiting as well. Just shift quick, smooth, and at the same place everytime if you want to be consistent and win races.

[DrJones]

shifiting is for suckers. If you really want to street race like us hard core true real racers you just throw it in first and go. Everyone knows you get the most power in first, so use it. Shifting is for the gay cars that can't handle all that power all at once....

[djet820]

I thought double clutching was for regular shifting too. Because you clutch to get it out of the gate then clutch again to get it into the next one.

[Mario]

On my particular car, I shift at 6.5k RPM's just because anything above that is just coasting speed and at 6500k RPM's on the b20a's, you catch just above 4k on the next shift to keep your secondary runners open so you are still in the powerband.

[Mark_H]

Ideally in a drag race you want to shift just before your rev limiter(assuming your car is fuel injected). The purpose is to be as high in the RPM range as possible when shifting into the next gear.
Mark

[Skaterkid]

I shift as fast as I can right at 8200 (although my tach reads 7700) to just miss the rev limiter and be right in the sweet spot for power in the next gear.

For drag racing shift as fast as you can at the highest rpm (some exceptions; Foci).

For road racing shift as high as you can, and heel/toe to get smoot downshifts for corners.

[GimPin]

I shift at 9500 RPM right before the fuel cut....

[prkrnt]

there are 2 goals when shifting for street or drag racing.

1. Do not go past your peak HP range. For example on my accord (F22) the redline is like 6600, but the HP peaks at 5800.

2. You want to make sure that when shifting to the next gear that you are still in your main power band.

When running a 1/4 mile run you should try and rev your engine to around 2000 - 3000 RPM's before you launch. Just make sure that you don't rev too high that you loose traction. If you are running turbo then definately you will want to rev high enough so that you can build some boost before you launch.

[djet820]

My car is fuel injected and the redline is set at 6500 (according to the cluster). But I have shifted at 7000 rpms before and no rev limiter kicked in. And how do I know what my powerband is?

[prkrnt]

what year make and model?

[marcrx5]

correct me if I'm wrong, but double clutching and heel toe shifting are the same things. This should be used in auto cross or on the street, but like everyone else said, that is for down shifting. For drag racing, you want to shift as high as you can, unless your power band sucks ass and drops really low at top end. This isn't common, so most people just shift right below fuel cut.

[David]

double clutching had something to do with old cars, you would push in the clutch let go then try to match the RPMs to the wheel speed put it in gear then push the clutch back in again.

I dont know why you did it I just know thats how you did it.

[djet820]

91 teg

[Bedlam]

The Evo falls on its face if you get too close to redline..its more beneficial to shift like 700-500 rpm before you get there..that little turbo is pretty much out of its "happy" range at that many RPMs..it really depends on the car.

-Bedlam

[stu]

Double clutching is different than heel-toe shifting. However, you usually heel-toe whilst double clutching.

[Mario]

Originally posted by GimPin
I shift at 9500 RPM right before the fuel cut....

:cry: Yea, I can barely make it to 7 grand... oh well, once I get the h22a.... 8200 baby. :D

[chris_venturini]

Originally posted by 4g63_KickAss
double clutching had something to do with old cars, you would push in the clutch let go then try to match the RPMs to the wheel speed put it in gear then push the clutch back in again.

I dont know why you did it I just know thats how you did it.
double clutching in older cars (and still in semis) is used to keep the engine and the clutch plates turning at the same speed when they engage. This was used in vehicles that lacked effective syncromesh. It is also ussed when downshifting using the heel toe technique

The heel toe technique is used to match the rpms when downshifting. Im sure everyone knows what its like to downshift and have your rpms raise and your engine lurch forward causing an "engine brake." IF this happens while approaching a turn it could potentialy be enough to cause your car to spin. (weight shifted to the front end of the vehicle) This is why heel toe shifting is used when racing, or any other situation for that matter. The brakes are applied and at the same time the driver "blips" the gas with his heel to match the rpms.
http://www.boomspeed.com/_scuba_/heeltoe.jpg

[Skeptron99]

wut about pwrshifting?... is it transmission friendly? :confused: :(

[chris_venturini]

Originally posted by Skeptron99
wut about pwrshifting?... is it transmission friendly? :confused: :(
NO

[djet820]

If I remember correctly...power shifting is horrible. It'll also burn your clutch soooo badly.

[chris_venturini]

a friend of mine with a cougar went through two sets of 2nd, 3rd, and one fourth gear syncro because he power shifted all the time. Dont do it, it's bad news.

[prkrnt]

Originally posted by djet820
91 teg

The peak HP for the '91 teg is 6000 RPMs. Assuming it is the stock engine.

[Mark_H]

Originally posted by djet820
91 teg

Honda OEM tach's are often times WAY off, especially at or near redline. Atleast I've noticed that on several that I've driven, and heard it all the time on H-T.
Mark

[hsunchen]

Just to clarify the pic (very helpful, thanks for doing that) that chris_venturini posted, it is also possible to heel and toe with the just the left and right sides of the BALL of your right foot. I think this is much easier.

This is the real reason pedal pads kits are made (to made the gas and brake pedal close enough to facilitate this technique) - they weren't originally just dress-up items.

The reason most production cars don't have the pedals close enough for easy heel/toe is because jackhole morons and people with big feet would step on the gas together with the brake and then sue the manufacturer.

Maybe some of you older members will remember how Audi suffered the "unintended acceleration" lawsuits in the early 80's with their 5000-series cars . . . didn't help that they caught on fire and were basically junk too.

On shift points for drag racing - if you want to do figure optimal shift points accurately, there is math involved with gear ratios and torque peaks. You want to shift at a point that will drop the revs as close to the torque peak in the next gear as possible. I don't know remember how to calculate that stuff, but it was covered in an old issue of SCC. I just wanted to dispel the general myth of "the higher the better."

Also I think occasional power shifting (shifting without fully lifting off the gas) is OK on a good smooth tranny like a Honda. I've done it several times at the track in my Integra and CRX. No damage or long term effects so far. It might help your 1/4 mile time ever so slightly on a NA car, maybe a noticeable amount with a turbo car if it helps keep the turbo spooling.

I would never do it with my MR2 (notchy bitchy transmission) and probably not with any DSM tranny . . .

[djet820]

Originally posted by prkrnt
The peak HP for the '91 teg is 6000 RPMs. Assuming it is the stock engine.

At club clash that's what I shifted at and got an 18.7...same with when I went to T&Ts. But when I shifted at 6500 I got an 18 flat and 17.8.

[gothemperf]

The purpose of shifting gears is so that you can have more torque available to accelerate. The gears multiply or reduce the torque that is sent to the differential, but have speed limits because of this. Notice below how 1st gear sends the most torque to the wheels, but has the lowest achievable top speed, where as 6th gear sends the least amount of torque to the differential but has the highest achievable top speed. The S2000 is an extreme case of what happens with many newer performance cars, the torque doesn’t fall of drastically enough so that one would want to shift to a lower, “torqueier” part of the power band with a taller ratio gear to continue accelerating with the torque present in the lower gear before the shift. If someone knows where we can get a crankshaft dyno chart for a motor that produces a lot of torque at low engine speeds and then drastically falls off at higher engine speeds, we can redo this to find out how we would change gears with that motor.

S2000 example:
http://us1.webpublications.com.au/static/images/articles/i9/0911_3mg.jpg
Here is a dyno graph of an F20c, displaying crankshaft horsepower. I was unable to find one in hp/tq but a kw/nm will make do for illustrative purposes.

Gear Ratios
1-3.133
2-2.045
3-1.481
4-1.161
5-0.971
6-0.811

RPM/Torque___1st___2nd___3rd___4th___5th___6th
1000/150nm 470nm 307nm 222nm 174nm 145nm 122nm
1500/175nm 548nm 358nm 259nm 203nm 170nm 142nm
2000/180nm 564nm 368nm 267nm 209nm 175nm 146nm
2500/185nm 580nm 378nm 274nm 215nm 180nm 150nm
3000/190nm 595nm 388nm 281nm 221nm 184nm 154nm
3500/192nm 601nm 393nm 284nm 223nm 186nm 156nm
4000/195nm 611nm 399nm 289nm 226nm 189nm 158nm
4500/195nm 611nm 399nm 289nm 226nm 189nm 158nm
5000/197nm 617nm 403nm 292nm 229nm 191nm 160nm
5500/198nm 620nm 405nm 293nm 230nm 192nm 161nm
6000/200nm 627nm 409nm 296nm 232nm 194nm 162nm
6500/202nm 633nm 413nm 299nm 235nm 196nm 164nm
7000/205nm 642nm 419nm 304nm 238nm 199nm 166nm
7500/208nm 652nm 425nm 308nm 241nm 202nm 169nm
8000/207nm 649nm 423nm 307nm 240nm 201nm 168nm
8500/199nm 623nm 407nm 295nm 231nm 193nm 161nm
9000/185nm 580nm 378nm 274nm 215nm 180nm 150nm

We can observe that because of the location of torque peak that its not possible to shift so that there is more torque available in the next gear than at redline, therefore it would be advantageous to shift at redline anyway so that the maximum amount of distance can be covered before “losing” accelerative torque with an upshift(also the power band stays strong till redline so no major amount of momentum will be lost going to redline either).

[chris_venturini]

heres on that drops off gradually
http://www.nissantalk.com/registry/users/Ramses/images/lg_dyno213chart.jpg