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460 c6 37's. what gears?

14K views 31 replies 18 participants last post by  rhauf 
#1 ·
This is my first post since getting my 79 xlt ranger. It has the 351m c6 in it now with 3:50 gears. Its gonna get street driven a lot with occasional trips offroad and to the woods for camping/hunting. Maybe a 500 mile weekend trip here and there. I'm working on my 460 build right now and I'm building the motor to hit 500ftlbs torque below 2000 rpm. The c6 is notorious for sucking fuel but I'm keeping it anyway with a stock converter. My thinking is that with a torquey 460, stock converter with stock gears my RPM's will be lower and I can get better milage( I'm not hoping for much I know it's a 460)

my question is will the 3:50's get me better fuel milage wih a motor that has 500ftlbs of torque below 2000 RPM's. I'm thinking like a diesel guy!

Thanks.
 
#5 ·
The engine is on the garage floor right now. Lol. I've been following some builds on the 460 forum and a 545 stroker is just the ticket for gobs of torque down low. I figured with this much torque I could get away with higher gears. For offroad I'm looking at the 205 doubler. I've built a few jeeps but a 79 bronco has always turned me on and now I own one!
 
#9 ·
I have 3.55 in mine and a stock c6 converter. It's pretty darn nice. Don't need an overdrive to get decent mileage and the 460 has plenty of torque to take off even with a moderate load. I've pulled a trailer through soft fields in high range just fine. 4lo is still fast enough for the sand too.
 
#11 · (Edited)
JBG's hard-copy parts book has a gear ratio chart, showing rpms and tires. I just checked and they don't have it online, just hardcopy. The chart shows what gears to run for the optimum rpm range for the best fuel economy.

I'm got 35s...460...C6...Holley Truck Avenger....running 4.56.
I get 5 mpg.
 
#12 ·
I know the gear charts are accurate for getting back to stock RPM's and such. But this is not gonna be a stock engine. For crawling work ill be running a 205 doubler.

What RPM's would I be at with 3:50's 37's and 60mph? Like I said, I'm building the engine to have peak torque very very low.
 
#14 ·
RPM = (Speed * Transmission Gear Ratio * Final Drive * 336) / Tire Diameter

Roughly 1900 RPMs.


Black_mamba said:
Roomate has a 429 in his ranger with 4.11's and 38's and is changing to 3.55's. On the highway he's at 3,000 rpm with the 4.11s
How fast is he going? If that's accurate, you'd need to do 80+ to get those RPMs with those tires and gears.
 
#13 ·
I'm running 4.10's and 37's with a stock 351w and the cruising RPMs are a little better than with 35's but not by much I can give a solid number but I'm thinking right a round 2500 @ 65. I've got good enough power but I don't need to go fast anyway and it will pull a 5% grade with the cruise on loaded at 70MPH and still walk off and a leave land rover.
 
#16 ·
Thanks for the input. 1900 RPM's sounds great! That's will help with planning the rest of my engine build. Not that I'm drag racing but some of the drag guys that go from a standard 460 up to a stroker will put in higher gears and have a better et's. Apparently with massive amounts of torque down low higher gears can net better acceleration. I've been doing my homework on this and was looking to see If its been done for a driver.
 
#27 ·
4.56's are going to have it wound pretty tight. Bigdumbford was running 44" boggers on 4.10's with a 460.

85MPH will put you somewhere around 3500RPM with 4.10's not that you will plan on doing that all the time but just letting you know. You need to add converter slip to the gear/tire chart which on mine seams to be around 450RPM +/- 50

If you already have 3.54's in there run them and see how you like it. Hughes makes a converter that is supposd to not have as much final drive slip which would make for better mileage.
 
#32 ·
4.56's are going to have it wound pretty tight. Bigdumbford was running 44" boggers on 4.10's with a 460.

85MPH will put you somewhere around 3500RPM with 4.10's not that you will plan on doing that all the time but just letting you know. You need to add converter slip to the gear/tire chart which on mine seams to be around 450RPM +/- 50

If you already have 3.54's in there run them and see how you like it. Hughes makes a converter that is supposd to not have as much final drive slip which would make for better mileage.


your converter adds 450rpm? at highway speeds? there's something wrong with that converter. a stock converter, up at 2000+ RPM shouldn't be adding more than about 200 MAX
 
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