It's a tough choice. I've driven two almost identical trucks (4wd dually) and one had a TBI 454 and the other the 6.5 TD. The 454 maybe felt slightly faster when empty but the TD did a little better when hauling.......the biggest difference was the fuel economy. The diesel got about 25% better empty, and almost doubled the fuel economy when pulling a large trailer.
I would also tend to think that a stock 6.5 TD would feel all around stronger than a stock TBI 350.
On the fuel mileage of K5's in general, I would think that averaging 16-18 mpg in a completely stock gas Blazer (street tires, no lift, etc...) would be extremely good. Heck, a new style truck with a more efficient engine and much better aerodynamics can barely get that mileage. Maybe with the right mods a TBI 350 in an old K5 could get that, don't know.......but that would be very good mileage for what is basically a rolling barn door. Start putting a lift and bigger mud tires on one and it would be pretty hard. Now keep in mind I'm talking about average fuel economy, not what somebody got while cruising at a steady 55 mph for 2 hours on the highway.
When my Blazer was completely stock minus the slightly larger mud tires, it got around 16-18 mpg in average mileage with a stock 6.2 and 700r4 trans. Honestly I think that somebody claiming 20+ mpg on a 6.2 truck with 40" tires might be exaggerating a little, but again I don't know for sure. That's just really good mileage for the overall truck and tire size.
I would also tend to think that a stock 6.5 TD would feel all around stronger than a stock TBI 350.
On the fuel mileage of K5's in general, I would think that averaging 16-18 mpg in a completely stock gas Blazer (street tires, no lift, etc...) would be extremely good. Heck, a new style truck with a more efficient engine and much better aerodynamics can barely get that mileage. Maybe with the right mods a TBI 350 in an old K5 could get that, don't know.......but that would be very good mileage for what is basically a rolling barn door. Start putting a lift and bigger mud tires on one and it would be pretty hard. Now keep in mind I'm talking about average fuel economy, not what somebody got while cruising at a steady 55 mph for 2 hours on the highway.
When my Blazer was completely stock minus the slightly larger mud tires, it got around 16-18 mpg in average mileage with a stock 6.2 and 700r4 trans. Honestly I think that somebody claiming 20+ mpg on a 6.2 truck with 40" tires might be exaggerating a little, but again I don't know for sure. That's just really good mileage for the overall truck and tire size.
Fuel consumption/mileage won't be too bad if I stay close to home....could 6.5 later eh?
