Mister Bally

Interesting article: http://www.borgwarner.com/en/enews/P...nsOrBelts.aspx

MP4.2+6.0

I was suspecting I might find some commercial interest bias, but it seemed pretty straight up. I liked the honesty and implication that belts essentially were trading cheaper initial cost to the manufacturer to higher lifetime maintenance cost downstream.

I remember when belts came in to the VW group family w/ the original Rabbit and the original Audi Fox (grand, grand daddy of the Audi 80's and ultimately the A4) in the early 70's and just as the Arab oil embargo and OPEC hit. Sold back then as another greatest thing since sliced bread, though it was more the simple OHC design that was relevant, at least relative to the gen 1 Audi motor (Super 90 and then 100LS) that was a very basic chain driven cam in block and push rod set up. Back when I used to rebuild motors with very simple tools...

Only thing I didn't see mentioned that I wondered about some is very rapid change in motor speeds where I might guess a belt system could have an advantage, assuming it had lesser rotational mass. Of course high and fast rev change think is about the antithesis of a pretty low rev limit W12 in my world, or my C5 4.2 for that matter. I also look at the current Audi chain systems, the W12 probably the most extravagant, and they have some of that stereotype elegant but likely overly complex Germanic style to them. Not sure this was the true "build it and forget about it" life of motor think the article was suggesting. Also owning a simple (by comparison) current gen Mini with a piece of junk plastic guide system and a hair's breath away from recall tensioner that variously just flies out of the block or that some dude on a French assembly line couldn't be bothered to torque properly doesn't uniformly win my chain endorsement either.

Mister Bally

The nice thing about the early OHC engines is that they were non-contact design. Replace belt upon inspection showing cracks or when it breaks and you get towed to a shop. Nothing beats the Type 1 Boxer engine. Cam & crank joined with teeth on gears. No chain, no belt, no failures.

mishar

Though perfect for Formula 1, that system is not so good on the long run. Because of ever changing torque it tends to develop uneven wear and create clanking sound. It is also too expensive for OHC or DOHC systems.

Edd W

Correct, most Mini's are a Peugeot engine and I have to say whilst I love France and spend a lot of time there, I do not like their style of car engineering at all. The only Peugeot I have ever owned - a 405 GTX required the engine mount to be removed to change the timing belt - how can you end with such a poor design that the mount goes through the centre of the time belt?

With Mini's, I think the latest ones are now a UK built shared BMW/Mini engine made about 10 miles from where I live at Coleshill just east of Birmingham. These engines, I am sure, will be a lot better than the French sourced product.

Edd W

Also very high inertia and a requirement for a lot more finely machined components with no means of coping with changing tolerances due to wear.

MP4.2+6.0

I think Mister Bally is talking VW boxer engines--as in uprights and pancakes, air cooled and all. Juxtaposed w/ the non contact [non-interference] OHC reference though.

Not F1 and the antithesis of high power, but about as durable as they come given the simplicity.

Meanwhile Audi (and most all) pushing the valves out the the edge of the cylinder walls and a desire to get to a shaped chamber generally seem destined to have valves and pistons crash when all goes wrong. Having owned a C1 pushrod/OHV with a simple oval chain path, I can confirm even then they were interference, with no fancy head, belt or anything. Known more as a "tractor motor" derogatorily--pistons weighed in the pounds--even though the basic block ended up in the 924...and the Pacer and Gremlin.

Mister Bally

<<< Ummm...think VW old school

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I think Mister Bally is talking VW boxer engines--as in uprights and pancakes, air cooled and all. Juxtaposed w/ the non contact [non-interference] OHC reference though. >>>

Yes, Volkswagen Type I Beetle engine. Dr. Porsche would be proud. Never lost a valve due to a pison hitting it. Now, burnt away, that's another story.

Also Type II's and III's and even IV's. On the rare occasion I see one on the road, I roll down the window to hear the valve clatter. A sound like no other.