RE: [alfa] single-row timing chains

["Gwynne W. Spencer" <gwynnes1@xxxxxxxxxxx>]

Could you tell us what gain was had by removing the mechanical fan?

Gwynne Spencer


At 02:01 PM 11/8/2004 -0500, you wrote:
> > I'm not sure why one would want to go to a single-row timing
> > chain on a four-cylinder Alfa.  There might be a tiny
> > reduction in friction, but at a loss of reliability, and I
> > would guess at a huge cost in parts and labor.
> > There are two chains, and a total of six sprockets, if you
> > include the two on the idler.  I'd guess you'd need to change
> > all those.  Or can you get by putting a single-row chain on
> > the double-row sprockets?
> >
> > I believe when Mercedes went to single-row chains on the V8s
> > in the 70s/80s they had a lot of trouble, and eventually went
> > back to double-row.  I recall they even offered a conversion
> > to retrofit single-row chains on older engines to double-row.
> >  I believe one of the reasons BMW went to a single-row chain
> > was to save a bit of length in the design of the engine, not
> > something you could benefit from on an existing Alfa engine.
> >
> > What's the motivation?
>
>Well, given that it was I that started this thread a while back..
>
>The motivation is a not-insignificant gain in power, measurable on a dyno.
>I think it was in the range of 5-10 hp on a 1600 motor.  And the associated
>comment was that there was no drop in reliability.
>
>The source was a letter from Dr Tenney to Pat Braden, quoted in Pats last
>book.  Dr Tenney's comments were to the effect of looking for ways to reduce
>losses in the motor, as opposed to ways to increase HP.  He mentioned three
>things in particular, removal of the mechanical fan, single row timing
>chain, and removal or modifications to the alternator.
>
>Fwiw,
>
>bs
>
>bs
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