Quote:
Originally Posted by bp944
So I did some math and with a 944 5th gear in the turbo trans I will be running 60 mph at 2000rpm. So I think I should be okay with gear ratios. It's not amazing but it's better than the 2600 rpm I was told.
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2000 is alright, but could be better, considering the engine size. 35mpg might not be possible with that big of an engine, since (I think) the Corvette struggles to get 35mpg at relatively low speeds with even less highway rpm. Small 2L engines turning high 2000s at 60mph get low-mid 40 mpg, with a giant V8 you're effectively cutting an already low load in half, which will really kill your efficiency.
If you're willing to cut some displacement with a smaller crank and longer rods (which might let it rev higher but I don't know anything about how rev happy you can make a pushrod motor), then it would certainly help. I still think it's best to grab a 6 speed gearbox for the smaller spread between ratios (better acceleration, more choices of low speed cruising gear around town), and increase the final drive so you get better fuel economy and so you don't spin out in a cloud of smoke when you try to gun it in 1st. With a powerful large displacement engine like that a longer final drive will still keep your low speed acceleration at pretty insane levels, since there's just so much power.