Not a flame war here, Just explain the physics and mechanics of this-. A certain person claimed a BB chevy, NA, will outpull a "Turboed" diesel of the same timeline (pre 2000). So lets do a somewhat fair comparison. 6.2 OR 6.5 TD vs a BBC NA (454). Figures for a mid 90s 180-hp, 6.5-liter V-8 (diesel) 400ft lbs (99 claims 215hp/430tq) 255-hp, 5.7-liter V-8 (Vortec, 210 for the TBI) 290-hp, 7.4-liter V-8 (Vortech, Dont know what it is for TBI version). Correct these figures if you can. Anyways, to the point of the question. Assuming a 6% Grade for 5 miles, I think the claim that any NA motor, be it gas or diesel, will make it with any grace. In my opinion it is a simple calculation- Less air= less Power. As altitude increases, the amount of oxygen decreases. Less power. Take two equally power rated engines. lets say they both have 300hp/300tq at sea level. But one is a NA and one is Turboed. The turboed one will make more power at altitude than a NA would. Exactly what altitude this becomes important, i can't tell you but I know it does make a difference. Does the 6.2 NA make as much power as a BBC of the same year? no. Does the 6.5TD of the same year? Comes very close at SEA LEVEL. On a major hill climb, the turbo should deliver a consistantly denser charge of air, which will help maintain the highest possible power output. The BBC, being NA, as the hill climb increases, will begin to starve for air. The diesel will starve too, but the forced induction will help it keep its breath longer. The other consideration is, in hill climbs, being able to properly select a power band is more important in a diesel than in a gasser. So being geared properly and tranny gear selection become important as well. If the theory I've stated is wrong, please explain.