Best highway RPMs - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Thealien · 02-04-2021, 06:06 PM

I am installing an LS3 engine and a 4L70 transmission. I do believe the overdrive in the 4L70 is .70. I have installed 275 40 20 tires with a 28.5” diameter in my 2 wheel drive Blazer. The truck has an open differential with 3.08 gears. I am trying to decide if I will eventually go to 3.73 or 4.11 gears. What is the most comfortable and efficient RPMs for an LS3?

3.73 should run about 22XX and the 4.11 should be about 25XX. If I can I “may” install a taller tire in the future if it will fit?

Thanks
Mark

02-04-2021, 06:06 PM	#1
Thealien Senior Member Join Date: Jun 2007 Location: Pine Ridge Florida Posts: 4,126	Best highway RPMs I am installing an LS3 engine and a 4L70 transmission. I do believe the overdrive in the 4L70 is .70. I have installed 275 40 20 tires with a 28.5” diameter in my 2 wheel drive Blazer. The truck has an open differential with 3.08 gears. I am trying to decide if I will eventually go to 3.73 or 4.11 gears. What is the most comfortable and efficient RPMs for an LS3? 3.73 should run about 22XX and the 4.11 should be about 25XX. If I can I “may” install a taller tire in the future if it will fit? Thanks Mark __________________ Click on my Not really a build thread, yet NOT SO RUST FREE RUST FREE BLAZER LS ENGINE SWAP INFORMATION THREAD BOLT RESTORATIONS 4l60 to an NP205



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