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Auto Racing/Changing Gears
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Question
I have a 79 Merc Cougar with a 351 5.8L engine. I want to increase it's overall performance, especially torque and horsepower. A mechanic has told me I should change the gears from 2:47 to 3:90. What are the advantages/disadvantages to doing this? I'm concerned my money could be better spent elsewhere. Thanks.
First off the chanage in gear ratio will have no effect whatsoever on torque or horsepower. To do that you have to modify the engine which is expensive these days.
It will however enhance your acceleration, and detract from your fuel mileage. I am going to guess that your MPG figure will be reduced by about 25% So if you are getting 15 MPG now you can expect about 11.5 MPG after the gear change. The other change will be in your top speed capability which will also be reduced by quite a lot.
For a street car ? I wouldn't do it.
Dan Liddy
Sarasota, Florida
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Dan Liddy
Expertise
Anything concerning race cars, 20 years competition experience, Senior Competition Driver Instructor , car builder, mechanic, welding, fabrication, tuning , engine modifications, set up, suspension design. Specializing in Datsun/Nissan products. Please submit questions about RACE CARS ONLY. No street cars, no video game scenarios Thank you.
Experience
I have been racing for 20 years, I have been the Central Florida SCCA Regional Championship points for 5 years running, and won the championship in my class 2 times. During my first start in the 60's I won many solo awards and the State Championship Drags. I serve as a senior instructor for SCCA, and have taught in Mercedes AMG events at Daytona, and Dodge Viper Days at Sebring International. I have been in the thick of the competition for all of my career. At one time or another I have driven race cars at speeds nearing 195 MPH. It's quite a ride !
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