MN6 to 3.90s question
Thread Starter
Drifting
Joined: Jan 2004
Posts: 1,987
Likes: 24
From: Texas
MN6 to 3.90s question
I'm doing heads and cam in my 2000 FRC. I can change the ratio from my stock 3.42's to 3.90's for a decent amount of money.
Mostly my car is just a DD, but I do go out to the 1/4 mile a few times a year..
For you guys that have/have driven the 3.90's verses the 3.42's what did you think? Will this be a good of change as I'm hoping for?
Mostly my car is just a DD, but I do go out to the 1/4 mile a few times a year..
For you guys that have/have driven the 3.90's verses the 3.42's what did you think? Will this be a good of change as I'm hoping for?
Safety Car
Joined: Jan 2001
Posts: 3,879
Likes: 3
From: Hobart, WI
I have had 3:90s since I was basically stock. They are great on a MN6 since you always have that 5 and 6 OD. One of the best mods you can do. If you are not going to mod too much maybe even 4:10?
Melting Slicks
Joined: May 2000
Posts: 2,974
Likes: 5
From: CenTex Texas
If you're stopping at H/C (ie no stroker or FI) then go with 4:10's. I did my H/C over 4 years ago and got bored with the performance after a couple of years....and not wanting to dump tons of $$$ for big cubes or FI i decided to add 4:10's and an aluminum flywheel and all i can say is "WOW", the SOTP perfomance will put a 
on your face.
on your face.
Race Director
Joined: Mar 2001
Posts: 11,405
Likes: 26
From: Whippany NJ
CI 6-7-8-9 Veteran
St. Jude Donor '08-'09
NCM Sinkhole Donor
Originally Posted by towercontroller
4:10s work really well with H/C set up. That set up for me anyway, was perfect
If your not doing FI, go 4.10s, its the best gears for MN6 cars. (every gear is matched perfectly in the tranny)I was on the fence too between 3.90 and 4.10s Im so happy I went with 4.10s!!
Oh yeah, im still 31mpg highway not that it matters for a Vette anyway.
Last edited by Ikester; Jun 22, 2006 at 01:14 PM.
Thread Starter
Drifting
Joined: Jan 2004
Posts: 1,987
Likes: 24
From: Texas
Awesome, I think I'm going for the 4.10's. How quickly will I be shifting out of 1st? Do I need to do the hardened output shaft or brace? Again, not much dedicated racing, but I will run it every now and then...
Thanks
Thanks
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Race Director
Joined: Dec 2000
Posts: 19,304
Likes: 85
From: San Diego CA
I believe that you may also need to bump up your rev limiter if you go 410s and plan on doing the 1/4-mile. Otherwise, you'll be shifting into 5th gear and THAT would be no fun.
Also, track guys recommend against 410s so if that is a possibility, you might inquire further.
Also, track guys recommend against 410s so if that is a possibility, you might inquire further.
Le Mans Master
Joined: Dec 2003
Posts: 5,561
Likes: 448
From: Atlanta metro Ga.
Originally Posted by FroDaddy
3.90's were perfect for me; I had 3.42's before. Make sure you account for your exhaust drone at certain RPMs and calculate it out with the 3.90's. Just something to think about!
Melting Slicks
Joined: Jan 2004
Posts: 3,138
Likes: 37
From: Burbank. CA.
Originally Posted by see5
With a MN6 and 3:90s you will have almost the same final ratios as a Z06 with just a bit lower 1st. Can't beat that.
Steve
Last edited by mountainbiker2; Jun 22, 2006 at 06:47 PM.
Safety Car
Joined: Jan 2001
Posts: 3,879
Likes: 3
From: Hobart, WI
Originally Posted by mountainbiker2
Almost true. First, Second and Third are real close to the Z06 gearing. 4th gear is alot different. Not sure about 5th & 6th
Steve
Steve
RPM 1st Gear 2nd Gear 3rd Gear 4th Gear 5th Gear 6th Gear
600 4 7 9 12 16 23
800 6 9 12 16 21 31
1000 7 11 15 20 26 39
1200 9 13 18 23 32 47
1400 10 15 21 27 37 55
1600 12 18 24 31 42 63
1800 13 20 27 35 48 70
2000 15 22 30 39 53 78
2200 16 24 33 43 58 86
2400 18 26 36 47 63 94
2600 19 29 39 51 69 102
2800 21 31 42 55 74 110
3000 22 33 45 59 79 117
3200 24 35 48 63 85 125
3400 25 37 51 67 90 133
3600 26 40 54 70 95 141
3800 28 42 57 74 101 149
4000 29 44 60 78 106 157
4200 31 46 63 82 111 164
4400 32 48 66 86 116 172
4600 34 51 69 90 122 180
4800 35 53 72 94 127 188
5000 37 55 75 98 132 196
5200 38 57 78 102 138 204
5400 40 59 81 106 143 211
5600 41 62 84 110 148 219
5800 43 64 87 114 153 227
6000 44 66 90 117 159 235
6200 46 68 93 121 164 243
6400 47 70 96 125 169 251
6600 49 73 99 129 175 258
6800 50 75 102 133 180 266
Team Owner
Joined: Mar 1999
Posts: 22,025
Likes: 192
From: At the beach in little Rhody
I seem to remember reading somewhere that the 3.90 gear set was a weaker set. Have done a search and can't find it. Anyone have any information on this? I am debating 3.73 or 3.90, but in either case will have DTE do the setup
Pro
Joined: Jan 2003
Posts: 526
Likes: 0
From: Tampa fl
I love the performance of the 4.10's but one more thing to consider is you will be doing alot more shifting. It seems that I am running 1 gear higher in all driving conditions which equals about 25% or more shifting all the time. I have recently started skipping gears and now the original "skip shift" 1 to 4 actually makes sense with the 4.10. The performance gain is very good. I find myself using the steering wheel to hang on for dear life because it pulls so hard at the top of 3rd gear!
Race Director
Joined: Mar 2001
Posts: 11,405
Likes: 26
From: Whippany NJ
CI 6-7-8-9 Veteran
St. Jude Donor '08-'09
NCM Sinkhole Donor
Originally Posted by mainagent
Awesome, I think I'm going for the 4.10's. How quickly will I be shifting out of 1st? Do I need to do the hardened output shaft or brace? Again, not much dedicated racing, but I will run it every now and then...
Thanks
Thanks
You will shift quick out of first, but with 4.10s theres no need to keep in first gear long anyway, 2nd will bite harder anyway. 3rd gear, just hold the F on!
PS- 4.10s were recommended to me by ECS, who am I to argue with the pros?
Last edited by Ikester; Jun 22, 2006 at 10:12 PM.
Burning Brakes
Joined: Aug 2000
Posts: 889
Likes: 0
From: DFW tx
I have the 4.10's with h/c. I do a ton of shifting, sometimes 3 shifts to get thru an intersection. Put it this way, you are driving in 5th gear at 45 mph. If I did it again, I would do 3.90's or 3.73's.
You will still get decent gas mileage on the highway ~ 28 or so going 70 to 80, but around town you will feel it. I do mostly city driving on the way to work and average 11.8 mpg.
The 4.10's work great when you are taking off from a stop (if you can get traction), but they don't seem to pull as hard at speed. Not sure if it is because I am used to the power of the h/c now, or if the gears keep the car in peak power range for a shorter amount of time.
You will still get decent gas mileage on the highway ~ 28 or so going 70 to 80, but around town you will feel it. I do mostly city driving on the way to work and average 11.8 mpg.
The 4.10's work great when you are taking off from a stop (if you can get traction), but they don't seem to pull as hard at speed. Not sure if it is because I am used to the power of the h/c now, or if the gears keep the car in peak power range for a shorter amount of time.
Thread Starter
Drifting
Joined: Jan 2004
Posts: 1,987
Likes: 24
From: Texas
This forum rocks... Theres some good stuff mentioned above...
Now I'm leaning toward the 3.90 since I drive in the city a ton, but the thought of having to hang the F... on in 3rd makes it tempting..
thanks for the heads up on the output shaft.
Anything else you can think of keep it coming please.. I love knowing all the pros and cons of a decision...
Now I'm leaning toward the 3.90 since I drive in the city a ton, but the thought of having to hang the F... on in 3rd makes it tempting..
thanks for the heads up on the output shaft.
Anything else you can think of keep it coming please.. I love knowing all the pros and cons of a decision...
Burning Brakes
Joined: Sep 2005
Posts: 1,141
Likes: 1
From: Kona, Treasure coast Hawaii, Florida
same boat as you but i think i might go with 4.10's since i like it to pull hard.. also with a h/c power doesnt come to the higher rpms so the higher gears will get you up in the rpms faster.. either way tell us how they feal