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Gearing for a blower?

958 views 2 replies 3 participants last post by  camaroman7d 
#1 ·
Hey guys.
With my 6-71 blown Gremlin I think the 4.56 gears may be a bit much. I have a 2 speed glide, slight over stock convertor(2000 rpm) a 2900lb car, 31X18.5 rear tires.
I want some low end, but want to be able to cruise without burning up the engine. My cam is 2200-5700 rpm's to.
Any ideas on my gearing I should choose? HG
 
#2 ·
HemmiGremmie said:
Hey guys.
With my 6-71 blown Gremlin I think the 4.56 gears may be a bit much. I have a 2 speed glide, slight over stock convertor(2000 rpm) a 2900lb car, 31X18.5 rear tires.
I want some low end, but want to be able to cruise without burning up the engine. My cam is 2200-5700 rpm's to.
Any ideas on my gearing I should choose? HG
Although most will suggest something in the 3.7-1 ratio; I'd go with around 3.5-1 with the Powerglide. Should still take off from a stop very well and cruising RPM won't be so bad.
 
#3 · (Edited)
Blown engines do not need a lot of gear. With a roots blower you will have more torque and bottom end than you can imagine. Steep gears will only hinder traction and burn more gas. Depending on how tall a tire you are running. With a car that light and a stall that tight I would probably go with something in the 3.42 range (even with a glide). I hope that powerglide is built to handle abuse, because it is going to see some serious torque.

I ran 4.11's with a 26" tall tire and over drive. That was too much gear for that short of a tire with a blower. My current car has 28" tall tires and I went with 4.11's again with OD. I hope that's not mistake, I probably should have gone with 3.7*'s.

Royce

Edit: Ooops I just saw you are running 31" tall tires. You may be able to get away with 3.90's. It really depends on your goals for the car.
 
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