09-10-2010, 02:20 PM | #1 |
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Join Date: Jan 2009
Location: glenmora. la
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fuel mileage
I have a 72 that will be running a 5.3 with 295/45/20 tires on the back, when I am done with restro. What kind of mileage is the 5.3 liter guys getting? What gear ratio are you running? I am hoping to get in the 18-20 range will that be possible?
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65 Chevy C10 Short Fleet BBW 6.0L/4l80E 68 Chevy C10 SWB 6.0L/4L80E 84 Chevy C10 SWB 5.3/4l60E QA1 Suspension |
09-10-2010, 02:32 PM | #2 |
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Re: fuel mileage
I'm getting a consistent 18-19 in town, and 20-21 on the highway.
I run 3.42 gears and a 28" diameter tire. You would need about a 4.11 gear to turn the same RPM @ 75 mph.
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Bob 1970 Chevy K10 LWB "Goldie" 350/TH350 next project!! 1981 Chevy C10 LWB 355/TH350 - My son's truck LS SWAP FORUM! Tons of LS swap info here! PLEASE CLICK HERE TO SUPPORT THE GREATEST BOARD ON THE NET! CLICK HERE FOR THE FAQ INDEX by KRUE Last edited by glock35ipsc; 09-10-2010 at 02:36 PM. |
09-10-2010, 02:40 PM | #3 |
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Re: fuel mileage
I do have a 4.11 rear end right now but was thinking that was to low for mileage the reason I was asking. I have a 4L60 transmission also.
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65 Chevy C10 Short Fleet BBW 6.0L/4l80E 68 Chevy C10 SWB 6.0L/4L80E 84 Chevy C10 SWB 5.3/4l60E QA1 Suspension |
09-10-2010, 09:05 PM | #4 |
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Re: fuel mileage
Glock,
I don't get your math, the 295/45-20 is only ~31 in. diameter. MS2335, I get 18-20 back and forth to work with a 6.0 L LS2 and I am working on getting it over 20. I think the key is getting the high gear RPM< as low as possible. I am running 1800 at 70 mph in my 65 (3.73 gears with 2:1 overdrive in 6th). I run the exact same gearing in my LS3 Vette and get 22 mpg on the same route. The difference is mainly aerodynamics as near as I can figure. Our trucks have at least 4 times more drag than the Vette. TR
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1965 C10 SWB Fleet Two owner LS2 Swap Thread http://67-72chevytrucks.com/vboard/s...d.php?t=413880 |
09-11-2010, 10:30 AM | #5 | |
Next project: 1970 K10
Join Date: Feb 2004
Location: Fort Collins, Colo 80524
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Re: fuel mileage
Quote:
My tire is 28", and with the 3.42 gear I'm turning about 2200 rpm at 75 mph. According to my trans/gear/tire calculator, his 295/40-20 would need to run a 4.11 gear to achieve a similar rpm @ 75 mph. That is, of course, is from memory (which is sketchy at best ). My spreadsheet is on my puter at work, so I don't have access to it right now.
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Bob 1970 Chevy K10 LWB "Goldie" 350/TH350 next project!! 1981 Chevy C10 LWB 355/TH350 - My son's truck LS SWAP FORUM! Tons of LS swap info here! PLEASE CLICK HERE TO SUPPORT THE GREATEST BOARD ON THE NET! CLICK HERE FOR THE FAQ INDEX by KRUE Last edited by glock35ipsc; 09-11-2010 at 10:31 AM. |
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