RE: [alfa] single-row timing chains

[hagen_jason@xxxxxxxxxxx]

I want to be careful with my words, but I would bet my left ... that their is no 5 - 10 HP gain by going to a single-row chain on an Alfa engine.  That is impossible.  I am not buying it at all.  

As a mechanical engineer in my previous career at Ford, and from a practical perspective, that is just not possible.  I have an 8HP riding mower that can carry me around my yard, cut 10" grass, etc. or a 8 HP snowblower that can throw 24inches of snow twenty feet...  there is no way it takes this much power to bend and mesh an additional row on a chain in the Alfa engine.

I don't mean to offend anyone, I am just not even close to buying that argument.  Whatever dyno test was done was not done properly or was "goal seeking" (for those familiar with the Excel function...).

--
Jason Hagen 
Chicago, IL 
'73 Spider 
'95 164Q 
'91 164S

-------------- Original message -------------- 

> > 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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