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The Gord
08-27-2005, 07:47 PM
I have a 99 Cobra and like everyone else has asked what gear ratio to go with. So last night I made a chart using stock specs for a 99 cobra comparing MPH vs. RPM with different gears (calculator from slowgt.com) What RPM will yield the best gas mileage? I read on this site that the IRMC opens the 2nd intake ports at 3250 in the 96-98. Does my 99 have the same setup?

I hope the chart helps anyone else with gear change questions. Lastly, I dont know how to post this excel chart, but will if it would be helpful.

tcrews
08-28-2005, 12:19 AM
No, the '99 and up Cobra's do not have IMRC plates. You have have different type intake/head setup that didn't require the use of primary/secondary ports.

As an FYI my MPG changed about 1 mpg switching from 3.27 (stock) to 4.10 gears.

Lumpydogs
08-28-2005, 10:19 PM
I didn't see any significant change in my MPG when my '01 Cobra went
from 3.27 to 4.10

Then again, I don't drive the Cobra for gas mileage. :what:

The Gord
08-29-2005, 08:44 AM
yeah, im either going to go with 4.10 or 4.30. I worry about the 4.30 b/c after a stroker rebuild Ill add a twin screw of a ton of NOS. thanks for the replies.

WOPONY98
08-29-2005, 10:40 PM
yeah, im either going to go with 4.10 or 4.30. I worry about the 4.30 b/c after a stroker rebuild Ill add a twin screw of a ton of NOS. thanks for the replies.
If you plan to put a blower or NOS I wouldn't put 4:30's in the car unless you plan to use this car at the strip alot. You will be more traction to the tires and more out of your blower or Turbo if you use 3:55's or 3:73's. The car will make insane power off the line and you will be going through the gears way to fast to make any difference. If you also plan to drive this everyday 4:30's suck for long drives. Just my opinion and something to think about.:thumbsup:

Yellow98Snake
09-27-2005, 07:09 PM
My MPG dropped quite a bit when I switched from 3.27 to 4.30's. I did manage to get over 26 MPG on the highway once with the 3.27's.

Now I am lucky to hit 22 MPG on the highway. I average about 21 MPG now.

Your results WILL vary.....

InfamousSVT
09-28-2005, 12:57 AM
If you are going twin screw and nawwwsss then I'd stick with the 4.10's :D

flynfink
09-28-2005, 08:53 AM
My MPG dropped quite a bit when I switched from 3.27 to 4.30's. I did manage to get over 26 MPG on the highway once with the 3.27's.

Now I am lucky to hit 22 MPG on the highway. I average about 21 MPG now.

Your results WILL vary.....

I agree, but..

I drive mine long distances on the superslab and back hwy's and the 4:30's are fine. not a huge diff. between them and 4:10's. But, she sure does wanna cruise at 80 :thumbsup:

MARK BELL
09-28-2005, 02:09 PM
I switched to 4.10's in my 97, and did see a milage drop, but the smiles made it worth it. Gear swap is one of the quickest, cheapest mods I have done.