G3 rpm/gear ratio

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1973Barracuda

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those that have done the swap, what ratio are you running? I have read different things as far as the rpm the g3 will be happy cruising at.

I am ready to pull the trigger on a rear end, but want to buy once(hopefully).

I thought I wanted a 3.55 or 3.23 to keep highway rpms down, but read it may be unhappy there.

Thoughts?

6.1
46rh
27 inch tire
 
those that have done the swap, what ratio are you running? I have read different things as far as the rpm the g3 will be happy cruising at.

I am ready to pull the trigger on a rear end, but want to buy once(hopefully).

I thought I wanted a 3.55 or 3.23 to keep highway rpms down, but read it may be unhappy there.

Thoughts?

6.1
46rh
27 inch tire

What tranny OD ratio are you running?

My 6.1 SRT8HEMI manual tranny has a 0.70 OD with 3.91 gears. In hindsight, a 3.55 gear would have been better for me - but depends on what you want to use the car for. You can calculate RPM with different setups using this: HyperMart

Jim
 
.69 overdrive.

I have figured the rpm thing, what I don’t know is where the engine is happiest.

1800 at cruise on the highway sounds great until you find out it is a dog there.
 
.69 overdrive.

I have figured the rpm thing, what I don’t know is where the engine is happiest.

1800 at cruise on the highway sounds great until you find out it is a dog there.

The 6.1 is no dead dog!!!! The torque curve is very flat - especially at lower rpm.. eg
300 ft-lbs @1200 rpm
325 ft-lbs @1600 rpm
340 ft-lbs @2000 rpm
350 ft-lbs @2400 rpm
 
those that have done the swap, what ratio are you running? I have read different things as far as the rpm the g3 will be happy cruising at.

I am ready to pull the trigger on a rear end, but want to buy once(hopefully).

I thought I wanted a 3.55 or 3.23 to keep highway rpms down, but read it may be unhappy there.

Thoughts?

6.1
46rh
27 inch tire
I'm running 3.89 with NAG1.
 
I have a 0.63 6th, 3.91 and 28.4” rear tires. I have no problems with highway crusing torque. If I started from scratch, 3.7x in the axle would be a hair better for me.
 
Goody, you must cruise at really low rpms.

With 3.55 I think I was looking at 1800 at 80mph I think.
 
Goody, you must cruise at really low rpms.

With 3.55 I think I was looking at 1800 at 80mph I think.

at 65mph I am about at 1,900rpm, 2,300rpm at 80...

If you had 3.55s, 0.69 OD and turned 1,800rpm at 80mph, you would have to have a 36" tall tire...the correct calculation is 2,368rpm using the 27" tall tire you reference earlier.
 
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at 65mph I am about at 1,900rpm, 2,300rpm at 80...

If you had 3.55s, 0.69 OD and turned 1,800rpm at 80mph, you would have to have a 36" tall tire...the correct calculation is 2,368rpm using the 27" tall tire you reference earlier.

Ran the numbers again. You are correct.
 
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