What's better A timing chain setup or a gear drive setup

[Tom68]

Would you mind (if you can find the paper) taking a look at it and letting me know what gear drive(s) we’re tested?

TIA

Keeping in mind I think Roush may have had or has interests in the Hy-Vo, think I found a link a year or so ago.
Don't know if you can identify the gear drive, they only tested one, don't believe the brand was mentioned.

1996

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[ClassAct]

Would you mind (if you can find the paper) taking a look at it and letting me know what gear drive(s) we’re tested?

TIA

Keeping in mind I think Roush may have had or has interests in the Hy-Vo, think I found a link a year or so ago.
Don't know if you can identify the gear drive, they only tested one, don't believe the brand was mentioned.

1996

20221001_212110.jpg

20221001_212116.jpg

That is a Pete Jackson or Pete Jackson knock off gear drive. That is not better than a chain. The fixed idler gear drives are far better, but I’ve never seen any testing of one of those verses a timing chain or belt. I’m going to test a Milodon fixed idler gear drive verses a timing chain next year. I’ll post the results.

[Little Mouse]

You won't see an aluminum head or block, a chain, a needle bearing or stud rocker system on anything made to last.

[Tom68]

You won't see an aluminum head or block, a chain, a needle bearing or stud rocker system on anything made to last.

So Iron headed Side Valves were made to last then ?

[Alaskaracer]

I run a belt on my current setup, going back to a gear drive. There is a lot of bs out there about them. First off, Pete Jackson or similar gear drives are junk...pure junk.....secondly, the whole "gear drives transmit damaging harmonics to the valve train" is a bunch of bs as well. I've had the opportunity to talk to the engineers at Milodon and recently RCD about this....MYTH! Fixed idler, full cover style gear drives don't transmit anything more to a cam than a chain or belt.....if they were such an issue, the high end exotic cars wouldn't run gear trains.

[Alaskaracer]

That is a Pete Jackson or Pete Jackson knock off gear drive. That is not better than a chain. The fixed idler gear drives are far better, but I’ve never seen any testing of one of those verses a timing chain or belt. I’m going to test a Milodon fixed idler gear drive verses a timing chain next year. I’ll post the results.

Several years ago Hot Rod or Car Craft magazine did a belt drive, timing chain, gear drive comparison. They used a Jesel belt, Cloyes chain, and a Milodon gear drive. The gear drive won hands down. One thing they did find was the belt would retard cam timing as rpm increased, facilitating a need to advance the cam 2-4* to account for this. Higher spring pressures make this worse. Belts stretch, period...and that costs power. More and more serious engine builders, especially supercharged stuff are going with gear drives....Belts are still very prevalent but aren't being used nearly as much as they used to be. Belts only real advantage is being able to easily change cam timing and swap cams if needed. But, if you're having to adjust cam timing at the track to get better performance, you either didn't tune it properly on the dyno, or it's the wrong cam....

Just my measly $.02, if that even matters.

[ClassAct]

I run a belt on my current setup, going back to a gear drive. There is a lot of bs out there about them. First off, Pete Jackson or similar gear drives are junk...pure junk.....secondly, the whole "gear drives transmit damaging harmonics to the valve train" is a bunch of bs as well. I've had the opportunity to talk to the engineers at Milodon and recently RCD about this....MYTH! Fixed idler, full cover style gear drives don't transmit anything more to a cam than a chain or belt.....if they were such an issue, the high end exotic cars wouldn't run gear trains.

I’m going to test it and post my results just because. I won’t have a belt drive unless someone wants to donate one for a SBM, but I’ll do a Milodon fixed idler against a chain.

[Little Mouse]

You won't see an aluminum head or block, a chain, a needle bearing or stud rocker system on anything made to last.

So Iron headed Side Valves were made to last then ?

Have you put 1 million 500 thousand miles on an engine and the gear drive system still good as new, the solid roller cam and its lifters like new, same crankshaft never been out of the engine same original head same block, have you ran 23 pounds to as much as 35 lbs a boost on aluminum for 1 million 500 thousand miles. I owned 15 class 8 engine' you don't see any crap like aluminum used, chains or needle bearing junk. What a junk air cooled engine have to do with anything. You want an air cooled engine for your daily driver pickup. Chains, belts don't last have to be replaced. If we just have to talk motorcycle engine a sportster since 57 till now has had 4 individual cams all gear driven and they were that way before 1957 in the kh flat head. 400 lbs seat 1100 open will wear out any chain or belt in no time.

[Tom68]

You won't see an aluminum head or block, a chain, a needle bearing or stud rocker system on anything made to last.

So Iron headed Side Valves were made to last then ?

Have you put 1 million 500 thousand miles on an engine and the gear drive system still good as new, the solid roller cam and its lifters like new, same crankshaft never been out of the engine same original head same block, have you ran 23 pounds to as much as 35 lbs a boost on aluminum for 1 million 500 thousand miles. I owned 15 class 8 engine' you don't see any crap like aluminum used, chains or needle bearing junk. What a junk air cooled engine have to do with anything. You want an air cooled engine for your daily driver pickup. Chains, belts don't last have to be replaced. If we just have to talk motorcycle engine a sportster since 57 till now has had 4 individual cams all gear driven and they were that way before 1957 in the kh flat head. 400 lbs seat 1100 open will wear out any chain or belt in no time.

I have no idea what you're talking about. Not in this post or the one before.

[Jeff Lee]

I run a belt on my current setup, going back to a gear drive. There is a lot of bs out there about them. First off, Pete Jackson or similar gear drives are junk...pure junk.....secondly, the whole "gear drives transmit damaging harmonics to the valve train" is a bunch of bs as well. I've had the opportunity to talk to the engineers at Milodon and recently RCD about this....MYTH! Fixed idler, full cover style gear drives don't transmit anything more to a cam than a chain or belt.....if they were such an issue, the high end exotic cars wouldn't run gear trains.

I’m going to test it and post my results just because. I won’t have a belt drive unless someone wants to donate one for a SBM, but I’ll do a Milodon fixed idler against a chain.

Did that test ever happen? See my recent post on ST regarding HP loss on Gear Drive. Thanks.

[frnkeore]

No talk about 2 gear drives?

I used to sponsor a Open Comp car that used a John DeLong direct gear drive (rev rotation cam). I always thought that would be the best gear drive, longevity wise, with the least hp lose.

Then I was reading a thread here on ST about crankshaft dampening and gear drives were put down because it was said, they cause to much detrimental cam harmonics????

[Tom68]

Then I was reading a thread here on ST about crankshaft dampening and gear drives were put down because it was said, they cause to much detrimental cam harmonics????

Blame HP Books, S.A Design etc that everybody grew up on.

Some of the best historical engines had gear drives.

No idea what this is but it has lots of gears.

[Ken_Parkman]

The question cannot be correctly answered without understanding the effectiveness of the damper and is the engine operated in a range where a critcal crankshaft exciting order lines up with a crank torsional vibration mode. You will have rpm points where the excitation and modes do line up, the question is where, how bad, and are you running the engine there. Then the next question is does the crank damper control it and keep the torsional vibration amplitude peak to peak under control.

If the answer is the crank is subject to significant torsional vibration a gear drive will be worse. In F1 they invented torsional dampers in the gear drive to fix that and not transfer it to the cam, probably there is one in that mess of gears in the picture above. IF you have a crank torsional signature you should probably run a belt.

It is a system so there is no one size fits answer. The OEM's have the engineering for this, the aftermarket usually does not.

[hoffman900]

Then I was reading a thread here on ST about crankshaft dampening and gear drives were put down because it was said, they cause to much detrimental cam harmonics????

Blame HP Books, S.A Design etc that everybody grew up on.

Some of the best historical engines had gear drives.

No idea what this is but it has lots of gears.

Every F1 and Indy Car engine in the last 45+ years has had a gear drive.

Cosworth figured this out 60 years ago and there are modern takes on it plus quill drives. Honda has a few papers on reducing angular velocity variations in their F1 engines from 20 years ago.

Cosworth style damper, quill drive that grabs the cam along its length, weighed cam gears, locking the cams at the rear, dampers on the read of the camshaft, etc.

Billy Godbold has shared data on the measured flucuations on a Pro Stock engine.

[hoffman900]

Some screen shots:

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