Good reading here:
http://www.crxsi.com/articles/read/what-s-best-timing-belt-or-timing-chain-february-2009.htm
"In 2009 model year we see a new trend of car manufacturers moving back to
timing chain engine design.
Many of them rely on a service data and price/performance evaluation for the
size of the vehicle.
It is unlikely that general public will know exact figures on timing belt/chain
price/performance
comparison but we all have our own preferences and that may become a driving
force for the future engine models."
and here:
http://newsgroups.derkeiler.com/Archive/Alt/alt.autos.toyota/2008-02/msg02133.html
Personally, I prefer a timing chain. Over the years I have dropped some
serious change to replace timing belts.
Changing a chain has never been an issue on the cars I owned that had them,
namely, Ford's Cologne based V-6s
and of course the A-series.
And contrary to what people say, timing is not compromised with a worn chain,
assuming the tensioner is in order.
----- Original Message -----
From: "Kirk Hargreaves" <khargreaves2@gmail.com>
To: <spridgets@autox.team.net>
Sent: Wednesday, January 20, 2010 4:36 PM
Subject: [Spridgets] Question
>A Porsche has it's cams driven by an internal chain. . the same as I think
> about it as the straight 6 Jaguar engines hailing from the 1950's (and
> possibly earlier).
>
> Many high end cars have their cams driven by an internal chain with a
> tensioner which needs very little maintenance, if any, compared to an
> outside belt drive.
>
> The Ferrari, and I am guessing the Lambo and other super high end cars have
> their cams driven by outboard belts . . which need to be changed out at
> around 30k miles.
>
> With the Ferrari, I understand that it is a big process in that the engine
> has to be pulled to change out the belts. I have read that it can cost up
> to 10k to have the dealer change out the belts in a Ferrari.
>
> So why would Ferrari, as well as others, go with an outboard belt drive on
> their cams?
>
> Is it because the system is lighter, gives a better response, or? I am
> guessing that the thought is that outboard belt driven cams enhance
> performance?
>
> Just a question that has been in my head for a while. . I never have heard
> anyone explain the theory behind the out board belt as opposed to the
> internal timing chain for driving cam shafts?
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