A correctly installed quality gear drive makes zero noise. None. One part of the article I didn’t agree with. I don’t use paper to set the gear lash, I use a dial indicator and it set the lash at .002 and send it. I’ve used them for years on the street and not once has anyone asked if I have a gear drive. They don’t ask because they can’t hear it.
As for the harmonics, I can say I’ve never found an SAE paper or any other peer reviewed article on a fixed idler gear drive transferring harmonics. Not one. I asked a guy on SpeedTalk years ago to show me a detailed paper with an analysis of gear drive harmonics using a fixed idler gear drive and he posted a paper where they tested a chain, a floating idler gear drive and a belt, but nothing on a fixed idler.
I’m open to reading any decent paper(s) on gear train harmonics as it relates to fixed idler cam drives to change my mind. 30 plus years of running them says I’ll never find it.
As for the power loss...I can’t say. You’d need several days on the dyno to sort it out. I do know a friend was running a gear drive and he almost couldn’t sleep at night because he was worried about his valve train getting killed, even though we looked at both our stuff every winter and never saw a thing.
So he sprung for a belt, thinking he’d find some ET in it and nothing. At the end of the year, we took the engine apart and it looked the same. He was shifting at 8000 and it was a stick car.
