Gears & RPMs

[1998Venom]

I'm considering swapping my stock gears in my stock 98 Cobra. I plan significant future mods, however, plan to maintain NA.

Granted that I drive 50:50 city:highway, I'm curious as to RPM increase at highway speeds. To those running lower gears, waht RPMs are you running at 70MPH?

Thanks.

 

[charged98cobra]

If you wanna do a gear swap in a street car go with 4.10's.

At 70 mph in 5th I am running 2,400rpm at 60 it is around 2,100 rpm's.

Your shift points change.

1st 35mph
2nd 64mph
3rd 92mph
4th 127 mph
and, you can now use 5th gear to climb to 150-160mph!!

4.10's make a big difference in the feel of the car. As far as gas milage goes. I get about 300 miles per tank. if you have any other q's feel free to ask.

 

[URDONE]

Not really sure what it is at 70, but I am at 3,000rpms at 80 mph in 5th gear with my 4.30s. I would go with 4.30s if you are going to stay N/A.

 

[blk96SVT]

Ditto on what URDONE said above. 4.30's!

 

[MatchStick]

Originally posted by blk96SVT
Ditto on what URDONE said above. 4.30's!

Another vote for 4.30's. :rockon:

 

[1998Venom]

Thanks for the feedback.

I've known for years that our cars run better with shorter gears, however, was always hesitant. I shall not fear the gear!

I've been leaning towards 4.10s, and will now consider 4.30s as well. The only comment is that I've read on another string is that with 4.30s, the car sounds like its staging for a 1/4 mile run while at highway speeds. While driving in the powerband at all times would be fun, the noise may become a pain, and expensive!

 

[URDONE]

How would it become expensive.

 

[1998Venom]

The expensive comment is specific to gas consumption.

 

[SnkBit]

Ditto on what URDONE said above. 4.30's!

They are awsome!:rockon:

 

[Wylde Horses]

I'm at 2800 rpm with my 4.56s. You can guess what ratio I would suggest.

As for this:

Originally posted by 1998Venom
The expensive comment is specific to gas consumption.

That reasoning is incorrect. I average around 20 mpg, which is just slightly less then when I had my 3.73s (1 to 1.5 mpg less). On a recent 200 mile trip, I averaged 23 mpg, and I wasn't babying it by any means. I get better mileage then half the cars I pass. :rockon:

 

[MatchStick]

Originally posted by Wylde Horses


That reasoning is incorrect. I average around 20 mpg, which is just slightly less then when I had my 3.73s (1 to 1.5 mpg less). On a recent 200 mile trip, I averaged 23 mpg, and I wasn't babying it by any means. I get better mileage then half the cars I pass. :rockon:

I agree completely. As far as the noise goes, with 4.30's my Cobra is quieter than my 95 was with 3.73's. They keep it out of the 2200 rpm drone.

 

[96cobra96]

charged98cobra,
How do you get 300miles to the tank?

 

[blk96SVT]

Originally posted by 96Cobra96
charged98cobra,
How do you get 300miles to the tank?

Very carefully, I did it last summer with my 4.30s

 

[juiced96snake]

here's another vote for 4.30's

 

[1998Venom]

Thanks for your input.

I found the following chart on stangnet, and can't confirm its validity, however am posting for everyone's benefit:

Gear Ratio 3:27 3:55 3:73 4:10 4:30
Speed RPM
45- 1290 1401 1472 1618 1697
55- 1577 1712 1799 1978 2074
65- 1864 2023 2126 2337 2451
75- 2150 2335 2453 2697 2828
85- 2437 2646 2780 3056 3205
95- 2724 2958 3107 3416 3582
105- 3011 3269 3435 3775 3958
115- 3298 3580 3762 4135 4337
125- 3585 3891 4089 4494 4714
135- 3871 4203 4416 4854 5091
145- 4158 4514 4743 5213 5468
155- 4445 4825 5070 5573 5845
165- 4732 5137 5397 5933 6222
Gear Ratio 3:27 3:55 3:73 4:10 4:30 4.56
Speed in
Gear
1st- 47 43 41 38 36
2nd- 80 74 70 64 61
3rd- 119 110 105 95 91
4th- 159 146 139 127 121 115
5th - 237 218 208 189 180 170