Accessory Drive Losses

[Stubby79]

Most engines would be fine. If it isn't a harmonic damper, it isn't doing anything useful beyond driving the accessories. A harmonic damper will have a ring of rubber in it.

None of the small engines I've had in my cars have had a harmonic damper, afaik. I can only confirm a couple of GM V6s that I've had that did.

[Isaac Zachary]

A lot has to do with engine speed. The old air cooled VW's don't even have counterweights on the crankshaft nor a harmonic dampener.

I do remember one VW guru recommending a weighted pulley for performance reasons.

[Ecky]

Originally Posted by Stubby79

Most engines would be fine. If it isn't a harmonic damper, it isn't doing anything useful beyond driving the accessories. A harmonic damper will have a ring of rubber in it.

None of the small engines I've had in my cars have had a harmonic damper, afaik. I can only confirm a couple of GM V6s that I've had that did.

It is - both are.

[Piotrsko]

Originally Posted by Isaac Zachary

A lot has to do with engine speed. The old air cooled VW's don't even have counterweights on the crankshaft nor a harmonic dampener.

The cranks have counterweights, them roundy things at the ends of the journal.
There's even a limit as to how much con rod weight you can use, and I have had shops drill the cranks when I got I beam rods. I agree, they dont have dampners because the crank is short and beefy so doesn't flex much.

[freebeard]

Crankshaft length is shared by a V-4. The boxer [four] has an inherent balance compared to a V or inline arrangement.

[Isaac Zachary]

Originally Posted by Piotrsko

The cranks have counterweights, them roundy things at the ends of the journal.
There's even a limit as to how much con rod weight you can use, and I have had shops drill the cranks when I got I beam rods. I agree, they dont have dampners because the crank is short and beefy so doesn't flex much.

Peformance aftermarket VW cranks have counterweights. But the stock ones do not.

Originally Posted by freebeard

Crankshaft length is shared by a V-4. The boxer [four] has an inherent balance compared to a V or inline arrangement.

Good point from you both!

You can ignore the rest, it's just me bragging.

I did balanced the heck out of my Type 1 dual port engine when I rebuilt it. I had the crank (stock without counterweights) dynamically balanced along with the flywheel, clutch plate assembly and even the pulley. Then I took and got all the pistons, pins and bearings within a fraction of a gram of each other and also suspended the connecting rods over two scales so I could balance each rod end so all the small ends and all the big ends also weighed exactly the same.

I've seen the same engine in a friend's Super Beetle bounce all over the place just idling. My engine ran smooth as butter, which is one reason the guy who bought it was so impressed.

[freebeard]

When I built up a stroker 1776 I did basic balancing but added a heavier Gene Berg (IIRC) 8lb lower pulley. It was intended as a truck engine. I see the Hot VWs Mileage Motor went with a lightened flywheel. I believe the original John Karcey build went heavier:

He started with a 76mm crank and 77mm pistons = 1415cc, stock 1300cc heads with some "mild " port work flycut .120" to get 9.0:1 compression, dual solex/Kadrons with custom machined 25mm venturies and a 100 main jet, and a 009 dist. A 12 volt 180mm flywheel (heaviest flywheel VW made), and yes a modified 62 Jag front crank pulley that weighed 10 lbs. He used a WEB cam (no specs given)

https://www.thesamba.com/vw/forum/viewtopic.php?t=97269

[cRiPpLe_rOoStEr]

I don't remember when it was the last time I saw a harmonic dampener. Even some 3-cyl engines are kept deliberately unbalanced from the factory.

[hayden55]

Originally Posted by cRiPpLe_rOoStEr

I don't remember when it was the last time I saw a harmonic dampener. Even some 3-cyl engines are kept deliberately unbalanced from the factory.

Must be a small engine thing? Everything for the most part has harmonic balancers or internal balance shafts here in the USA.

In Toyota fashion the Prius has a harmonic balancer with belt grooves in it and it doesn't even have an accessory drive. Probably because it already existed and worked.

[Ecky]

I want to say Honda didn't install them on their D15 engines, but the slightly longer stroke D16 (and every engine of larger displacement) got one.

I had to check, and the Insight's 1.0L 3 cylinder has a harmonic damper. That surprised me a bit as I imagine it's probably an accessory loss, turning some crank motion into heat.

Maybe all timing chain motors have one? I could see a belt as providing some damping.