3.42 vs 3.90
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Instructor
Joined: May 2005
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From: Bradenton FL
3.42 vs 3.90
I'm thinking of putting 3.90 in place of by 3.42. I know there has been a lot of discussion about 4.10 vs 3.42. I think 4.10 too much for me. So if you guys that has the 3.90 give some feedback it would much appreciated. My mods are heads/cam, FAST intake, Magnaflows, Melrose coated headers, Random tech high flow cats with x pipe, MSD wires, Honker CAI, thermostat, NGKs, and underive pulley. Will get dynoed next week. Thanks in advance
Tech Contributor
Joined: Jul 2002
Posts: 14,950
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From: St. Louis, MO
St. Jude Donor '08
I'm thinking of putting 3.90 in place of by 3.42. I know there has been a lot of discussion about 4.10 vs 3.42. I think 4.10 too much for me. So if you guys that has the 3.90 give some feedback it would much appreciated. My mods are heads/cam, FAST intake, Magnaflows, Melrose coated headers, Random tech high flow cats with x pipe, MSD wires, Honker CAI, thermostat, NGKs, and underive pulley. Will get dynoed next week. Thanks in advance
Tech Contributor
Joined: Mar 2003
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From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
You cannot feel any difference between 4.10's and 3.90's. The ONLY reason to opt for 3.90's is if it is a track car that will exceed red line in 4th gear or mid 130 trap speeds. If it is a street car, get 4.10's.
Instructor
Joined: May 2006
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From: Atlanta Georgia
After I got 4.10's I was really surprised that it was not nearly as aggressive as it seems like it would be. I would have been completely disappointed if I went with anything less than 4.10's for a street car.
Drifting
Joined: Sep 2004
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From: North Carolina
Pro
Joined: Mar 2006
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From: Pa
My car has heads/cam etc........I also have 4.10's. Great combination. I'm currently in the high 11's.........shifting to 5th isn't even an issue. I red line at 134-135 in 4th gear and can cruise in 6th at 2100rpm and 70 mph....go for the 4.10's
Burning Brakes
Joined: Feb 2006
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From: Miami FL
I would say that it depends on if you have the Z51 option or not. I have a C6 and just installed 3.90's with the Z51 and it's all I can manage on the street. I can't imagine a steeper gear in this car. I guess it depends on your power output. I can't even squeeze the throttle 60% without the tires starting to blow away in 2nd gear. 3rd gear is dependent on surface and weather. It got down into the 40s a couple weeks ago and I can break 3rd gear loose on a roll. It's back up to 70-80 and I can squeeze 3rd again as long as there aren't any breaks in the road etc.
I'm also running a 305 street tire. You've got quite a bit of mods. I dyno'd 470-480whp. I don't know how much I've lost through the gears, but I'm sure it's still in the 460-470 range.
I guess it has nothing to do with the fun factor, but rather how useless the car is becoming on the street. 4th gear is a blast though.
Dougie
I'm also running a 305 street tire. You've got quite a bit of mods. I dyno'd 470-480whp. I don't know how much I've lost through the gears, but I'm sure it's still in the 460-470 range.
I guess it has nothing to do with the fun factor, but rather how useless the car is becoming on the street. 4th gear is a blast though.
Dougie
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Tech Contributor
Joined: Mar 2003
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From: Colorado Springs, CO
St. Jude Donor '08-'09-'10-'11
I would say that it depends on if you have the Z51 option or not. I have a C6 and just installed 3.90's with the Z51 and it's all I can manage on the street. I can't imagine a steeper gear in this car. I guess it depends on your power output. I can't even squeeze the throttle 60% without the tires starting to blow away in 2nd gear. 3rd gear is dependent on surface and weather. It got down into the 40s a couple weeks ago and I can break 3rd gear loose on a roll. It's back up to 70-80 and I can squeeze 3rd again as long as there aren't any breaks in the road etc.
I'm also running a 305 street tire. You've got quite a bit of mods. I dyno'd 470-480whp. I don't know how much I've lost through the gears, but I'm sure it's still in the 460-470 range.
I guess it has nothing to do with the fun factor, but rather how useless the car is becoming on the street. 4th gear is a blast though.
Dougie
I'm also running a 305 street tire. You've got quite a bit of mods. I dyno'd 470-480whp. I don't know how much I've lost through the gears, but I'm sure it's still in the 460-470 range.
I guess it has nothing to do with the fun factor, but rather how useless the car is becoming on the street. 4th gear is a blast though.
Dougie
You didnt lose any power with gears. It isnt friction, ect....that made it dyno less; its how the dyno takes the reading.
I could break the tires loose in any of those 3 gears regardless of having 3.42's or 4.10's. The power level is wrong for the gears not the other way around. Get gears first and stop adding power when you cant get it to the ground anymore.
Cartek is in the tens with Z51 and gears and 470rwhp. Lots of 3.42 cars with 600rwhp are in the 11's.
Last edited by SpinMonster; Feb 24, 2007 at 10:41 AM.
Tech Contributor
Joined: Jul 2002
Posts: 14,950
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From: St. Louis, MO
St. Jude Donor '08
I didn't go 410 though since my buddy with a 440 rwhp C5 Z06sometimes hits his rev limiter at the traps with his 3:90 car and we both run the short M/T DR's (those short 26" tires make a difference in your calculations, don't forget that). Then again he ran a 11.15 at 126 with his setup and sometimes gets 127 which I doubt I'll be able to do. That's the difference between a great driver and a mediocre one. It makes all the difference.
Last edited by Joe_G; Feb 24, 2007 at 12:43 PM.
Drifting
Joined: Jul 2006
Posts: 1,492
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From: WA
I got a spreadsheet for ya to check out ....it's a tire/wheel and gear calculator:
http://corvette.krocko.com/tire_and_...a_corvette.xls
http://corvette.krocko.com/tire_and_...a_corvette.xls
Melting Slicks
Joined: Feb 2002
Posts: 2,935
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From: Anderson, SC
St. Jude Donor '06-'07-'08
I got a spreadsheet for ya to check out ....it's a tire/wheel and gear calculator:
http://corvette.krocko.com/tire_and_...a_corvette.xls
http://corvette.krocko.com/tire_and_...a_corvette.xls
Thread Starter
Instructor
Joined: May 2005
Posts: 196
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From: Bradenton FL
you guys are great on your feedbacks. Thanks again. I'm going to think about it for awhile. And I do have the Z51. I will dyno my car next week , see how much I have, than decide what gears.
