Re: Where's everyone playing tonight?
- From: "Ian Hayward" <ianm.hayward@xxxxxxxxxxxxxxxxxxxxx>
- Date: Sat, 31 Dec 2005 22:01:28 GMT
>P.S. Why don't all cars use timing chains (instead of belts)? Seems
like a swindle to me.
OK, for once I can be techy and professional, because this is my day job...
The biggest single advantage of a belt driven camshaft is less weight. The
consequent lower inertia in the valve train allows the component parts to be
accelerated and decelerated more quickly, satisfying the modern requirement
for high-revving and responsive engines. Using a conventional chain drive
would be the equivalent of installing an excessively heavy crankshaft and
flywheel, limiting the ability of the engine to change rotational speed
quickly. A belt drive system could be designed to last the life of the
engine, principally by increasing the diameter of the pulleys, but mass
would rise and the advantage would be lost. Many engineers (mostly Italian)
consider that a gear-driven valve train is the best combination of weight
and durability, but gears require precision machining that increases the
cost of the engine. Thus this option is not likely to be used on production
"cooking" engines where cost considerations are paramount. The real killer
for cambelts in the late 1990's was the increase in injection pressures
demanded by diesel engines to meet emission control legislation. Using the
then current "jerk pump" technology imposed a massive tensional load on the
cambelt twice every revolution on a four cylinder four stroke, leading to
cambelt failure in as little as 30000 miles. The latest high pressure
common rail injection engines require only that the belt should drive a
constant pressure circulation pump, thus removing the jerk load. My latest
project, a VM 2.5l/120PS diesel in a 2.8 - 3.5T light commercial (similar to
the Chrysler Voyager, I believe) is working fine on a scheduled cambelt
change at 100000 miles. The manufacturers would have you believe that the
increased mechanical efficiency of a belt-driven cam engine would have saved
you at least the replacement cost in fuel during the belt's life, but it
probably doesn't seem like it when you get the bill.
Nobody would be dumb enough to pay me to play at any time, so I am enjoying
a bottle of Paul Jaboulet La Chapelle Hermitage 1972 with my son, from whom
it was a Christmas present. Smart kid.
Happy New Year,
Ian
"Mike" <tetrickm@xxxxxxxxxxx> wrote in message
news:1136042857.774873.191960@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> >So, how about you?
>
> I'm filling in with a band tonight. The guitarist in my regular band
> is out of town, so I found a sub job. It's about 18 miles from home,
> but it's all interstate. Should be a few sobriety checkpoints up
> tonight around Atlanta. Gotta limit my intake to 2 beers (or so).
> Anyhow, the pay is not bad which is good as I need to replace the
> timing belt on my Honda and that's gonna run about $400. On the plus
> side, playing as a sub means I don't have to drive the band van nor
> worry about setting up/breaking down the PA. Less singing, too.
>
> Happy New Year all....
>
> Mike
>
> P.S. Why don't all cars use timing chains (instead of belts)? Seems
> like a swindle to me.
>
.
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- Where's everyone playing tonight?
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- Re: Where's everyone playing tonight?
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- Where's everyone playing tonight?
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