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glock35ipsc · 08-03-2010, 10:49 AM

I can only speak for the 5.3, but considering my setup is:

4L60E trans (2wd), 3.42 gear, 28" diameter, .70 O/D ratio, at 75 mph = 2155 rpm

Yours should be:

700R4 (same gear ratios as the 4L60E), 4.56 gear, 35" diameter, .70 O/D, at 75 mph = 2298 rpm

I get 20-21 mpg on the highway. You should expect a little less than that due to the height of teh truck, tire diameter, friction loss from the transfer case, etc. At least I am assuming with a 6" lift and 35's that it's a 4wd.

08-03-2010, 10:49 AM	#3
glock35ipsc Next project: 1970 K10 Join Date: Feb 2004 Location: Fort Collins, Colo 80524 Posts: 6,684	Re: What kind of mpg should I expect after a engine swap? I can only speak for the 5.3, but considering my setup is: 4L60E trans (2wd), 3.42 gear, 28" diameter, .70 O/D ratio, at 75 mph = 2155 rpm Yours should be: 700R4 (same gear ratios as the 4L60E), 4.56 gear, 35" diameter, .70 O/D, at 75 mph = 2298 rpm I get 20-21 mpg on the highway. You should expect a little less than that due to the height of teh truck, tire diameter, friction loss from the transfer case, etc. At least I am assuming with a 6" lift and 35's that it's a 4wd. __________________ *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; 08-03-2010 at 10:52 AM.