Quote:
Originally Posted by b454rat
LS trucks didn't get great mileage, why would think they would do better in a truck shaped like a brick?? The newer trucks have better aerodynamics than older ones, that has alot to with mileage. Weight and gearing plays in too....I got hi teens in my brick shaped 4 door tahoe with the stock 205k Tahoe doing 90....
|
I disagree with this. There's not much difference in aerodynamics between a 1970's truck and a 2000's truck. Look at a 2012 Silverado HD. There's nothing aerodynamic about it!
Most of the aerodynamic drag comes from the rear of the vehicle. As you drive, a dreadful "windstorm" occurs behind your truck, creating a pocket of low pressure. If you had a hypothetical vehicle with one end completely blunt and the other end tapered out to a fine point, the blunt end should go first. When a vehicle travels through a mass of air, that air splits apart a lot more cleanly than it comes back together again. By having a long tapered rear, you're allowing the air to recombine cleanly after you pass through it.
This phenomenon is not lost on vehicle designers. Every small SUV has a downward slope to the rear roof-line. This is an attempt to taper the back of the vehicle. The new Tesla truck is obviously targeting this tapered rear as well.
I've heard many accounts of folks getting much higher mileage in swapped vehicles, compared to the same engine in the donor vehicle. Most of these cases involved a lowered c10. A few were in slightly jacked k10's though. Enough so, that it's safe to say that the weight reduction made a difference.
Another difference that shows up, is in the engine tune. Tunes are always compromises between Emissions, Economy, and Performance. Many tuners will completely ignore emissions, and focus on the other two.