Charley Hoyt

On the track do you shift near redline or at a lower point in the power band? I have been shifting near redline...but yesterday I was on the track with a car that was very similar to mine that was able to pull slightly away from me on the straights. Both cars are C6 Z51's with stock (unmodded) engines...The only difference being that mine is a convertible with Z06 body panels and wheels/tires. I also have a roll bar so aerodynamics could be a part of it. Not sure if it was an aero issue, shift point issue, or if my engine is getting tired (I hope not).

Thanks for the help,
Charley

rustyguns

some engines have a little more HP than others, none are exactly the same. I have seen 15 hp difference on a dyno with same models

63Corvette

My opinion, for what it's worth, is that while you're on the track, you should try some different braking points, different lines, and most important, try to conserve momentum, like a spec Miata. So try to short shift here and there, use a higher gear, and then DRIVE the car thru the corner in the higher gear with lower RPM and use your stopwatch to see what works for you

davidfarmer

depends completely on the car....in the LS6, the crossover point (ie the point where torque at the rear wheels between gears crosses) is actually above redline, so maximum acceleration is achieved by shifting at redline. This may not be the case in the LS2/LS3 engines.

You can overlay a rear-wheel-torque in each gear vs speed to see where ideal shift points are........ There is no universal answer!

autoxer6

Running with the top down will increase drag and lower top speed.

96CollectorSport

If you have Z06 wheels and tires you will have a little more rolling resistance as well as more mass in your driveline (rear wheels and tires) so I would expect the other car to accelerate faster. Your car should have more grip with the larger wheels and tires so you'll have to make it up in the corners.

Gary2KC5

I agree with Joel (hi Joel)...also your wider body mods make a bigger object to punch through the air with...remeber when Bill Elliot was kicking everyones *** in NASCAR back in 1985-7 until they figured out their cars were much narrower than the others...hence today's cars that only have different headlight decals.

VetteDrmr

I think it's more about the driver. The other driver could be getting better corner exit speed than you do; a little adds up.

Have a good one,
Mike

AU N EGL

Aero makes a huge difference. Run with the top up at all times.

Wider looks cool but may not really faster. And too wide of a tire can also be a challenge to top speeds.

SouthernSon

You need to know the max torque RPM and max HP RPM. One generally likes to be somewhere between the two when shifting. Then consider your rear end ratio for useful rev limits and you'll begin to see where shifts make the most useable power.

Solofast

The optimum shift point for the LS engines is 1 rpm below where the rev limiter kicks in....

For the L-98, it is 4500 rpm, or just before you hit the wall of jello...

redtopz

In general with LS engines, it's probably best to shift close to the redline as Solofast mentioned so you get into a greater torque range in the following gear. For my LS6, I just raised the redline a couple hundred rpm to help achieve that going from 3rd to 4th.

As far as getting pulled down the straight, I doubt it was shift points that caused it. It was probably more a factor of who got on the throttle sooner coming out of the previous corner and who had better aerodynamics down the straight (which would be the coupe). Or the other car simply makes more rwhp, which is possible too.

It's pretty dramatic how much difference carrying speed and getting on the throttle early coming out of a corner will help speeds down the following straight and make more powerful cars wonder how the heck a "slower car" can keep up with them. It's happened to me from both perspectives .

kmagvette

Corner exit speed can not be emphasized enough. I have had C6 Z and Viper pilots ask what I have done to my engine...and not like the "Timing chain and damper" answer. Folks are too concerned about horse power and dyno numbers; the cheapest performance upgrades lie in your suspension setup and seat time...suspension will not help much without the seat time.

When I am going in a straight line I try to shift at 6K since it is HDPE and no sense thrashing the engine for no real gain. If I am accelerating hard out of a corner in 3rd and I end up between 6K and red line at exit, then the corner exit determines my shift point.

Charley Hoyt

Thanks for all of the help. All great input. My exit speed and lines were very similar to his while I was behind him, although, it is possible that he managed his momentum better.....I don't know? I also agree that aero is probably playing a part in this. I was definitely faster in the corners...but, he was able to pull away on the straights. I will work more on getting on the throttle sooner. That is one of the things I really like about this sport, there is always so much to learn.
Charley

brkntrxn

In addition to corner exit speed, another variable is how quickly the two of you shift. From my drag racing days, I can definitely tell you that power shifting and speed shifting are worth tenths in the 1/4 mile. The same is true on a road course.

To answer your original question, in my C5Z06 I shift at redline. When I get a tune this winter, I will get the rev limiter bumped up and shift even higher. It is all about maximizing the area under the curve. Some opinions say to maximize the torque, others say to maximize the horsepower. I am of the latter.


-Kevin

Jason

.1s behind is fender to quarter at corner exit but a car length at 150mph.

mashinter

Both are correct...to maximize torque at the rear wheels, maximize horsepower from the engine.

LeMans05C6

As stated a few times already sticking between the peak torque and Hp area will probably net you a good general starting point. I have an LS2 and pushed it close to redline sometimes but not all the times. Depends where your driving and what temps you see.

If you car gets too hot you will be losing power no matter what RPM you shift at. Keep it cooler and youll run faster too. Were not out there trying to win medals all the time so experiement and see what feels best for you and the car.

63Corvette

To put this in dragstrip perspective, If 2 identical cars ran identical times, but car "A" left exactly 0.1 seconds before car "B", the difference would be almost impreceptable. However, by the end of the strip, assuming a terminal velocity of only 100mph, the difference would have grown to 14.7 feet, or about a car length, because 100mph is 147feet per second, so 0.1 second is 14.7 feet. It often SEEMS that one car pulls another down the straight when it's only an illusion caused by speed and relative place on the track.

shifter77

Max power on most zo6 is 6200 RPM.