v8 pushrod vs v8 dohc??

[240VZA]

on paper engineering-wise, which is the better design? which can give more hp for the same size? which is easier to maintain (lasts longer)? which is the cheaper design? i ask because i wanted to know the differences between the ls1 gm engine vs japanese/european ohc designs. thanks for your comments.

[DeathToRice]

OHV - usually shorter and narrower than OHC, no bulky chains are required, and the valve cover can be shorter. Cheaper to design and build than OHC engines. The cam is housed in the center of the block, otherwise wasted space, so it is more space efficient. The smaller size also translates into more room in the engine bay, and as small as cars are these days that is a good thing. OHV engines have proved to be perfectly reliable, thanks to modern day roller technology. OHV is more suited for low end power, and does not have the RPM capability of OHC engines.

OHC - more bulky than OHV, as I stated before. The cam(s) require chain or belt drive, that adds complexity, and weight, and also makes the engine wider and taller than an OHV. OHC engines are more expensive to design and build than contemporary OHV. They do have higher RPM capabilitys, though, and can provide better economy and driveablility in high power applications, especially with todays modern variable valve timing.

As far as reliablilty goes, I would say they are both about the same, with todays roller valvetrains. The LS1/2/6 are great engines with enormous power potential, provided you are good at tuning with a lap top.

check out www.ls1.com www.ls1tech.com www.ls2.com fore more information.

[nbw]

Car and Driver: Pushrod finally gets its due
AutoWeek.com


hope that helps

[1g1yy]

Nobody ever mentions modifications. Many of us who have Corvettes or other cars with V8's like to mod our engines with hotter cams, heads and so on. With an OHV design these mods are relatively affordable, available, and extremely effective! Try finding aftermarket heads and cams for an OHC design -- and then if you do find any, price them! And price the labor for a swap!

Oh, you're thinking that with an OHC design you shouldn't need to mod the engine with a head and cam package? Well, it depends on how much power you can be happy with. Just check the power levels that guys are getting out of LS1's with a head and cam package! As far as I'm concerned you can keep your overcomplicated, bulky, heavy and pricey OHC engines!