interesting, they show no hp loss with a gear drive. what does it do to hurt valvetrain life?

There seems to be a lot of opinions on the topic, don't know how many people have actual proof of what they are posting. Best answer I read was, it all depends on application. Cummins puts gear drives in all of their motors, for what that's worth.

Cloyes or Comp billet double roller will handle just about anything thrown at it. If you want the noise of a blower,put a blower on it.

And I guess if its in car craft it has to be true...

It has to do with harmonics being trasferred from the crank to the valvetrain. While I dont have any testing data, I was under the understanding that gear drives transfer the most harmonics, chains come in second, while belts absorb all and transfer none to the valvetrain.

All today's diesels are gear drives but its not apples for apples. Have you seen the timing set in a diesel even a 4cylinder Isuzu? Big difference than what people are putting on their gas motors.

And years ago I did see with my own eyes a back to back dyno pull on a sbc it was 30 hp on a dyno.

I think all newer diesels run the injector pump off the front of the engine, I know several guys a while back dynoed race engines and showed loss of H/P on all, like Vinny said, belt transfer the least amount of harmonics back thru the engine...now Bob M. can probably give you the best info here...

International / ford don't run injector pumps and timing set is in the back of the motor. But it's not an apples for apples the harmonics in the two are different and diesels don't spin any kind of rpm. The timing sets in a diesel are totally different the gears are massive and the teeth on them are totally different compared to what is being put on a gas motor. If a gear drive was the answer I think General Motors would have put them on there motors a long time ago. And I'm sure GM put alot more money into R&D than Pete Jackson put into his gear drive. For that matter sine we are talking about boat motors why doesn't Mercury put them on there high dollar stuff?

I'm sure it's not cost effective for GM to use a $500 Milodon gear drive when a cheap chain and gear will do the job.

I don't think it's cost effective for anyone to pay $500 for a gear drive when a cheap chain drive will do.