sbcbuilder

Many people think that more power is the answer. All the power in the world is no good if you can get it to the ground.

Wheelspin is also a factor, many drag racers want a little wheelspin to help launch the car. Road racers do not want any wheelspin as it could cause problems depending at what part of the course you are in.

Then there are the choices of transmissions, standard or automatic,
Manufacturers are giving the buyers more gears in both standard and
automatic as well as sequential transmissions.

I have been doing some searching and reading on different final drive ratio and what seems to be the best for ME, the best for one person is not always the best for another. So the point of this little thread is to discuss and show what effects all the available final drives have..

Just a quick note or two before I start ... In drag racing the idea is to put as much power down while traveling the distance of a 1/4 mile and ultimately the more times we can reach peak HP the quicker the car will be. If we could use all 5/6 gears, crossing the trap box at peak HP/RPM in 5th/6th gear, this would be the ultimate. But in most street cars it would be unrealistic do to the fact that we would have a horrible cruising RPM and a 6200 rpm Rev limited top speed of about 100-120mph. In road racing/auto-x the best gear ratio all depends on the track and once again the more times we can hit peak HP in a straight the faster we accelerate but we don't want to end up with a weird shift point causing a time lengthing up or down shift.

Lets compare Z06 vs ZR1.

Z06 1st gear - 2.66 ZR1 2.29:1
Z06 2nd gear - 1.78 ZR1 1.61:1
Z06 3rd gear - 1.30 ZR1 1.21:1
Z06 4th gear - 1.00 ZR1 1:1
Z06 5th gear - 0.74 ZR1 0.81:1
Z06 6th gear - 0.50 ZR1 0.67:1

Shift rpm 6500
Final drive 3.42
Tire size 335/30ZR18
Diameter 25.9"
Width 13.5"

Z06: ZR1:
1st = 55 mph 1st = 45 mph
2nd = 82 mph 2nd = 74 mph
3rd = 112 mph 3rd = 105 mph
4th = 146 mph 4th = 129 mph
5th = 198 mph 5th = 159 mph
6th = 293 mph 6th = 187 mph

Range of gear
Z06: ZR1:
1st 0 - 55 mph 1st 0 - 64 mph
2nd 55 - 82 mph 2nd 64 - 91 mph
3rd 82 - 112 mph 3rd 91 - 121 mph
4th 112 - 146 mph 4th 121 - 129 mph
5th 146 - 198 mph 5th 146 - 183 mph
6th 198 - 293 mph* 6th 183 - 244 mph*

* Vehicle top speed is a theoretical number. Variables such as horsepower, traction, wind resistance, tire growth, etc. have a considerable effect on your vehicle’s actual top speed.

RPM Drops
Z06: ZR1:
1st to 2nd = 2150 1st to 2nd = 1930
2nd to 3rd = 1753 2nd to 3rd = 1615
3rd to 4th = 1500 3rd to 4th = 1128
4th to 5th = 1690 4th to 5th = 1300
5th to 6th = 2108 5th to 6th = 1625


RPM Drops
RPM drops are the decrease in engine RPM as you shift to a higher gear. These numbers assume you change gears at the Upshift RPM you entered. Contrary to what you might think, the RPM drops between gears will NOT be equal. Rather, the RPM drops will diminish as you get into the upper gears. To understand this, realize your engine can overcome a 2500 RPM drop when shifting from 1st to 2nd gear without much trouble, but that same RPM drop when shifting from 3rd to 4th would make the engine fall flat on its face.

Percentage of Pull

Z06: ZR1:
2nd 11.4% 2nd 15.0%
3rd 12.8% 3rd 16.7%
4th 14.2% 4th 14.1%
5th 21.6% 5th 20.3%
6th 39.9% 6th 33.9%


A transmission feels like it has "even pulls" between gears when the
percentage MPH pulls are roughly equal from one gear to the next.
Now also factor in power to weight ratio, the different driver styles of driving and skill, you can see just how hard to build a perfect car. There are so many factors.

Here is the gear ratio calculator here:

http://weddleindustries.com/gear-calculator