Max speed per gear with 4:10s
06-21-2009, 04:57 PM
#1
Thread Starter
Join Date: Jul 2007
Location: Delaware
Posts: 38
Max speed per gear with 4:10s
Does anyone know the maximum practical speed per gear with 4:10s? I'm very comfortable with the 3:55s and have no problem dropping it into 1st at 30mph or 2nd at 55mph, but I don't want to hit the rev-limiter if I try to do this after I get the 4:10s installed next week, that would be very embarrassing. Thanks for any input.
06-24-2009, 01:56 PM
#2
3rd Gear Member
Join Date: Jan 2008
Location:
Posts: 530
I made an excel spreadsheet recently, but I can't upload it. Copy and pasting ruins the formatting.
Here is your top speed in each gear with 4.10s and a 765 revs/mile tire, with a max engine speed of 6000rpm
Gear top speed (mph)
1 34
2 57
3 87
4 115
5 169
Basically, 4.10s are good for drag racing and crap for everything else. The gearing is too short for auto X or road course driving as well as highway driving. I'm seriously considering going back to 3.55s
Here is your top speed in each gear with 4.10s and a 765 revs/mile tire, with a max engine speed of 6000rpm
Gear top speed (mph)
1 34
2 57
3 87
4 115
5 169
Basically, 4.10s are good for drag racing and crap for everything else. The gearing is too short for auto X or road course driving as well as highway driving. I'm seriously considering going back to 3.55s
Last edited by Vapour Trails; 06-24-2009 at 02:00 PM.
06-24-2009, 03:58 PM
#5
Thread Starter
Join Date: Jul 2007
Location: Delaware
Posts: 38
Thanks for the answers, that's exactly what I was looking for.
But if you run 4:10s with an 11psi Whipple blower (a few months away hopefully), you might (if you're lucky) have to go into 5th gear to finish the 1/4 if the max speed is only 115mph? I thought 5th gear was just used for overdrive, that doesn't seem very practical? Or do you just hope you don't hit the rev limiter before you cross the line? Should I stick with the 3:55s if I plan on getting the blower relatively soon?
But if you run 4:10s with an 11psi Whipple blower (a few months away hopefully), you might (if you're lucky) have to go into 5th gear to finish the 1/4 if the max speed is only 115mph? I thought 5th gear was just used for overdrive, that doesn't seem very practical? Or do you just hope you don't hit the rev limiter before you cross the line? Should I stick with the 3:55s if I plan on getting the blower relatively soon?
06-24-2009, 03:59 PM
#6
Thread Starter
Join Date: Jul 2007
Location: Delaware
Posts: 38
Thanks for the answers, that's exactly what I was looking for.
But if you run 4:10s with an 11psi Whipple blower (a few months away hopefully), you might (if you're lucky) have to go into 5th gear to finish the 1/4 if the max speed is only 115mph? I thought 5th gear was just used for overdrive, that doesn't seem very practical? Or do you just hope you don't hit the rev limiter before you cross the line? Should I stick with the 3:55s if I plan on getting the blower relatively soon?
But if you run 4:10s with an 11psi Whipple blower (a few months away hopefully), you might (if you're lucky) have to go into 5th gear to finish the 1/4 if the max speed is only 115mph? I thought 5th gear was just used for overdrive, that doesn't seem very practical? Or do you just hope you don't hit the rev limiter before you cross the line? Should I stick with the 3:55s if I plan on getting the blower relatively soon?
06-25-2009, 07:49 AM
#8
2nd Gear Member
Join Date: May 2009
Location: K-town RP Germany
Posts: 235
here is a nice rpm/speed calculator that i have used in the past, love it. Its great for playing with rear end gear ratios. to see how it plays with your speed.
http://www.smokemup.com/auto_math/mph_range.php
http://www.smokemup.com/auto_math/mph_range.php
Last edited by dagamore; 06-25-2009 at 08:30 AM. Reason: what the link was there the whole time :shifty eyes:
06-25-2009, 08:26 AM
#9
Retired Mod
Join Date: Jan 2007
Location: Long Island, NY
Posts: 7,658
06-25-2009, 12:59 PM
#10
3rd Gear Member
Join Date: Jan 2008
Location:
Posts: 530
take your gear ratio and multiply it by the final drive for the overall ratio
1st gear 3.38 * 4.10 = 12.61 (so the engine turns 12.61 times for each wheel revolution)
Take max engine speed and divide by overall ratio = 6000/12.61= 476 wheel rpm
Take 476 and multiply by 60 to get revolutions per hour = 476*60= 28560
Divide wheel revolutions per hour by the tire revs per mile = 28560 / 765 = 34 mph @ 6000 rpm
Put that all in an excel spreadsheet and you change make changes easily.
1st gear 3.38 * 4.10 = 12.61 (so the engine turns 12.61 times for each wheel revolution)
Take max engine speed and divide by overall ratio = 6000/12.61= 476 wheel rpm
Take 476 and multiply by 60 to get revolutions per hour = 476*60= 28560
Divide wheel revolutions per hour by the tire revs per mile = 28560 / 765 = 34 mph @ 6000 rpm
Put that all in an excel spreadsheet and you change make changes easily.