6 Speed/3.42 Rear Axle Ratio: Red-line MPH question...

[6 Shooter]

I've ran my 6 Speed/3.42 Rear Axle Ratio to red-line in 1st and 2nd, with the following results. :cool​

1st - 53 MPH
2nd - 78 MPH
3rd - 105 MPH
4th - ? MPH
5th - ? MPH​

If anyone has ran their 6 Speed/3.42 Rear Axle Ratio to red-line in 3rd, 4th and 5th, please fill in the question marks. ​

​

Thanks . . . . . .
6 Shooter

 

[DRTH VTR]

?????

On the strip, I have to shift my Z06 into 4th before I get to the finish line. I cross at about 113MPH. There is no way my Z06 will do 100MPH in 2nd.

Red line in 5th is about 175MPH

 

[6 Shooter]

Drth - I'll check the 2nd gear red-line out on the way home tonight...

Z06
Gear Ratios
1st - 2.97
2nd - 2.07
3rd - 1.43
4th - 1.00
5th - 0.84
6th - 0.50
http://www.corvetteactioncenter.com/specs/z06/2002z06.html​

Coupe/Convertible
Gear Ratios
1st - 2.66
2nd - 1.78
3rd - 1.30
4th - 1.00
5th - 0.74
6th - 0.50
http://www.corvetteactioncenter.com/specs/c5/2000/2000specs.html​

 

[DRTH VTR]

Dwayne-

If you get one very good reading (eg 3000 RPM in 2nd + Z MPH), you can do all the rest with math and a calculator.

Z MPH times redlineRPM/3000RPM = MPH at redline in 2nd.

MPH at redline in 2nd times 1.78/1.30 = MPH at redline in 3rd.

etc. This ignores wheelslip, etc.

Jim

 

[6 Shooter]

Drth - I corrected the 1st post in this thread per my trip home tonight!

 

[6 Shooter]

Speed versus RPM calculator

Calculator Equations:

For those who are curious about the calculations, here are the gory details of the speed versus engine RPM calculations:

Each revolution of the engine is reduced by the transmission gear ratio.. each revolution of the output shaft of the transmission is reduced by the rear-end ratio... and each revolution of the tire makes the car move a distance equal to the circumference of the tire. Pretty simple really.

Let's go thru the calculations step by step:

If the engine speed (for this example) = 6000 revolutions/minute

then the driveshaft speed = engine speed divided by tranny gear ratio R1 = ( 6000 / R1) revolutions/minute

and the rear axle speed = driveshaft speed divided by rear-end ratio R2 = ( 6000 / (R1*R2) ) revolutions per minute (where * indicates multiplication, and / indicates division)

So, the rear tire will be making 6000 / (R1*R2) revolutions each minute, causing the car to move forward (2*pi*r) * ( 6000 / (R1*R2) ) inches/minute (where r is the loaded tire radius in inches, and 2*pi = 6.28).

That is, the car will be moving ( 6000 * 6.28 * r) / (R1*R2) inches per minute.

Since 1 mile = 5280 feet = 63,360 inches, and 1 hour = 60 minutes, then the conversion from inches per minute to miles per hour is ( 60 / 63,360 ).

So, if the engine is turning 6000 rev/min then the car must be going (60 / 63,360) * ( ( 6000 * 6.28 * r) / (R1*R2) miles/hour.

Now, let's plug in the numbers... for my car, the transmission gear ratio R1 = 0.73 in high gear, the rear end ratio R2 = 3.62, and the loaded tire radius r = 10.9 inches, so the car's speed at 6000 RPM will be:

(60 / 63,360) * ( ( 6000 * 6.28 * 10.9) / (0.73*3.62) ) = 147 miles/hour

Rewriting that all into a tidy form:

(0.00595) * (RPM * r) / (R1 * R2) = vehicle speed in miles/hour

where:
RPM = engine speed, in revolutions/minute
r = loaded tire radius (wheel center to pavement), in inches
R1 = transmission gear ratio
R2 = rear axle ratio

Tire Expansion:

There is a potential for error in these calculations with bias-belted tires due to centrifugal force expansion of the tire at high speeds, but that effect is generally negligible for radial-ply tires due to the circumferential belts used in their construction. To get accurate results, racers using bias-ply tires should check with their tire supplier to determine how much the tire radius will change at various speeds.

http://wahiduddin.net/calc/calc_speed_rpm.htm

 

[c5y2k]

I think you forgot to take into account color.

 

[6 Shooter]

I think you forgot to take into account color.

WOW - I almost forgot that Millennium Yellow adds speed!
​

L8TR - D

 

[schmaltzr]

I seem to remember that the top speed of a standard c5 is somewhere in the 172 mph. I've also heard that it cannot be done in 6th gear, but is attained in 5th gear. About 2 days ago I saw a demonstration on youtube.com where some guys took a corvette (it looked like a c5 Z06 dash) and they drove it on a 3 mile airport runway in Germany. The entire time all you saw was the tach and speedometer and an indication of what gear they were in. The top speed of this 'vette got near redline in 5th gear at 200mph. The engine was struggling to reach that speed, but it made it.

 

[schmaltzr]

I found it again here is the URL http://youtube.com/watch?v=ip2NJRbneF4. It was a Z06 and it was only 190, nog 200.

 

[KANE]

WOW - I almost forgot that Millennium Yellow adds speed!
​

L8TR - D

And stickers.... can't forget the stickers. It is all part of ricer math.

(sticker+manufacturer)(size of sticker+type of vehicle)
1/2 B x H​

:L

 

[04 Commemorative]

My brother in laws old 68 Mustang GT 390 used to go to 60 in first gear!