Mileage before/after LS swap?
 

Random wondering: What is the mileage people get after they install an LS V8 in their Blazers compared to what they had before with the 4.3L?

I bought my 2002 2wd 2 door blazer 4.3/5speed with around 197K miles. I drove it for about 3k miles and I was averaging about 18-20 mpg.
My swap setup is a 5.3 with a 224/224 camshaft, built 4L60E with a 3200 stall converter and I have about 7k miles on this setup. I now get about 22-24 Mpg on the highway but only around 14 around town due to the converter.
My blazer has the factory 3:42 gears, 28in tires and weighs about 3800lbs.

If the LS engine is tuned well, you can get very good mileage because its not working hard.
Even with the gen 3 5.3 you are only adding 1 liter to the engine displacement, but stock they are over 100hp more than the 4.3.

Actually, I suspected as much with the larger engine not having to work so hard.