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Old 07-23-2022, 04:40 PM
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GTOKIDRH GTOKIDRH is offline
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Join Date: May 2006
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Quote:
Originally Posted by geeteeohguy View Post
What b-man said. But, how are you with the current performance? I was getting 15-16 mpg at 65 mph in my '67 GTO with a TH400 and a 3.36 rear gear. When I changed to a 2.56 posi 12 or so years ago, the numbers went to 21 mpg at 75-80 mph. The car now sips gas, keeps up with the Hondas, and runs cool. Since it's a road-tripper and cruiser, I would NEVER think of installing a 3.36-3.55 gear in it again. Just saying....with regular gas at $5.49 a gallon where I am, I'll take the extra 6 or 7 mpg's and 15 mph all day long.
It's a turd LOL! Granted it weighs 4500 lbs but if i were to guess 0-60 about 10 seconds. Mashing the go pedal at speed and it downshifts it basically just makes a lot of noise lol. Not worried too much about mileage. It's not a daily. I've never tried calculating the mileage but I know it isnt great.
My '67 4 spd GTO had a 3.08 when I bought it. Eventually I put a 3.55 in it. Great gear! I'm currently running a 5 spd Tremec TKO-600 and 3.73 12 bolt. With this setup just cruising the GTO gets around 15 mpg. The engine is mildly built making about 475 hp.

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