Author Topic: bore to piston clearance k2 advise please  (Read 624 times)

Offline K2-K6

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Re: bore to piston clearance k2 advise please
« Reply #15 on: October 30, 2024, 12:28:32 PM »
A nice car and not often seen around much today.

My interest is from the new type  :) P6 onwards, a very interesting marque generally.

I seem to recall from watching an engineering workshop, clearance issues with bore on 90 type rover engine, they were guided by the owner as to the tolerance they were to use. They felt it was very large though, I'll have to go and watch again.

These Honda use (Japanese engine in general, I think its fair to say) raised silicone content aluminium alloy casting to better match expansion of piston to cylinder block over extended heat range. Effectively "travelling" in expansion as a pair and able to maintain their desired clearance in practical operation.  This as opposed to coping with significant piston expansion by leaving a larger space, then to arrive at correct clearance only while hot.

The Rover V8, similar but through slightly different route, with the skirt and crown designed with quite a large gap to avoid the skirt being distorted by crown expansion, has the gudgeon pin low in the skirt with fairly high crown but with the skirt accepting more side thrust from rod geometry. This needed a tight clearance on skirt to not clatter around when cold.

Different methods, but similar tolerance and outcome. Both are typically quiet either hot or cold. Most current engines use that Honda specification now though, in type that is.

 

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