Quote:
Originally Posted by cumminclouds
Like the title reads I am considering starting a swap, I am looking into a moderate LS3 + 6l80 4x4. With the 1st gear of the transmission being 4.06 and the 6th being .66 I am going to put a 3.06 ratio in my diff.... The new Camaros with a LS3 weigh in around 4,000lbs. my truck with a full tank weighed in at 4,800lbs. Would I be able to get good MPG (14-20) and would it still have good enough power to get off the line quick. By moderate I mean cleaning the throttle body + a good tune.. I typically ride on the interstate around 80 and am looking at trying to make it a road trip truck. Thanks
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I'm not sure how efficient the LS3 would be for you but shouldn't be much (if any) worse than the 6.0 I used.
The 6L80 idea sounds neat, with the low first gear you could run that high rear gear you mention and still squirt around town nicely and maintain low highway rpm in overdrive. Your issue might be an adapter for the transfer case though....keep in mind.
I did a 6.0/4L60E swap in my 72 blazer 4x4. The 3.06 first gear helps it get moving, and I ran 3.07 rear gears for a while along with 33" tires, wasn't bad really for a 4600 lbs truck. I wanted more squirt so I swapped both diff's to a 3.73 gear. It lays rubber, runs strong, and I consistently get 17 mpg around town and 22 mpg highway. It's not a variable displacement engine,,,just a very sharp tune by yours truly. It's my daily driver as well as our family SUV and vacation vehicle, so I also had long road trips in mind when I built this thing.
It cruises along very nicely at 75 mph....Could go 80 I guess if you wanted to but 70-75 is fast enough for me
You could probably do better on MPG than mine if you went with the 5.3 since there is a sizable difference in cubes (325 vs 364) but I wanted the grunt from the 364 and I knew with tuning I could squeak some mileage out of it anyway....Guys telling you 15 mpg tops are probably running stock tunes that need some serious tweaks. The stock truck tunes in these things suck,,,,,badly.