[2010reddevil]

Originally Posted by Bhobbs

DOHC engines should make more hp/l as a function of their design. Handicapping the LSx at 5.3 liters makes no sense because it is negating the biggest benefit of the OHV arrangement. If you are stuck with displacement caps, like racing or government regulations, then DOHC makes more sense because it will always make more power for the same displacement. If the only concerns are weight and packaging, then I believe OHV is the better choice. For the same power, it will be generally smaller and lighter while making more torque than a similar DOHC engine.

Again, the Engine Masters capped displacement. There is no way a OHV engine can compete at the same displacement. Why limit the LSx to 400 cu in when there are factory LSx in the 427 range and aftermarket blocks in the 500+ cu in range? That's going to put the LSx at a big disadvantage. If they had done the same challenge but limited rpm to 7000, then the Ford guys would lose their minds because DOHC is better for spinning at high rpm.

The rules didn't limit displacement size, they had a minimum displacement of 400 cu in. That was how they tried to handicap the Mod Motor. They knew it would require some enginuity to make a Mod Motor with that many cubes. You also realize that despite having a ridiculous bore/stroke ratio and being handicapped with a very undersquare engine, the Mod Motor still mopped the floor with the LSx. There were plenty of LSx builds that were well over 400 cu in. The point is that both have their merits. You talk about power vs weight/size. OK, let's use that for arguments sake and compare any pushrod V6 to any similar displacement dohc V6. There is not one single pushrod V6 that will match or beat a dohc V6 in terms of power vs size/weight. Same goes for I6 and I4. Why do Superbikes use dohc when there are plenty of pushrod designs out there? It's like Harley Davidson, their real performance bike is a dohc v-twin. Even Victory motorcycles use a 4v sohc. Again, both deign have their merits with the pushrod engine being simpler in some ways and more compact, but not necessarily lighter. If you are truly trying to get the most power out of a given engine displacement, 4v>2v.