Fuel Compsumption 396 4L80E - Page 2 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**c30** · 10-23-2025, 02:56 PM

Had an old chevy c20 with 396, manual granny tranny and not sure what the rear gear was, but it was a stump puller.
When it came to mileage, we joked that it was measured in GPM not MPG.

68 C10 Driver · 10-23-2025, 05:24 PM

Quote:

Originally Posted by ahoke

Appreciate the helpful comments.
Standalone controller for the transmission. Not sure the actual gear ratio. Was getting about 18mpg with a 350/th350 in my '72 C20.

I hope you can get the mileage you are looking for...I have only had big blocks in cars and I only remember the MPGs being around 15.

My C10 build will have a 4 bolt 350 with a Muncie 4 speed M20 with 3.08 rear end gears. I am hoping for 17 hwy.

Best of luck on your project!

MARKDTN · 10-24-2025, 04:20 PM

Quote:

Originally Posted by HeavyHauler

Yeah but you are higher in the rpm range with any LS stuff.

Torque curve on a 6.0 is pretty flat between 1500 and 4500. Not sure what you mean?

10-23-2025, 02:56 PM	#26
c30 Active Member Join Date: Feb 2015 Location: chicagoland Posts: 108	Re: Fuel Compsumption 396 4L80E Had an old chevy c20 with 396, manual granny tranny and not sure what the rear gear was, but it was a stump puller. When it came to mileage, we joked that it was measured in GPM not MPG.



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