High Compression Pistons

[Denis]

Not sure where this is going but might be of interest.

I'm having my engine rebuilt (it was using an oil well per run) by a well known bunch of engineers. Having found from this forum that High Compression Pistons are available in this country, I specified that these should be fitted. A set was ordered and arrived next day. My engineers weighed them - 671 grams each against 549 grams for low compression types. 122 grams difference or 22% - 978 grams per set. Thinking of all that extra weight being accelerated and decelerated each revolution my engineers suggested that I might reconsider and fit Low Compression. The HC were sent back to the supplier and LC will be fitted. Now I wonder just what is the difference in power output? Any thoughts?

Denis

[Andrew S]

imported post

Hi Denis. My conern would be nowadays is that unleaded is happier on the flat top pistons and HC coudl attract pinking. I had to make this decision when I build my engine and can assure you that there is no low in power and very pleased

Saved me a fortune as well

[Denis]

imported post

forgot to mention - a set of HC pistons including vat and delivery £590. A set of good used LC cost me £100.

Denis

[flying farmer]

imported post

The HC pistons might be heavy but they are bloody tough.

Just got my LH head off tonight to inspect the damage after the LH timing chain snapped at 4000rpm on the motorway. Five bent valves and four pistons with tiny scuffs on the piston crowns. The pistons are plus 20 thou HC and have obviously done less than half the indicated 107000 miles judging by their condition. Depending on how much damage has been caused by the shredded water pump gears and the jackshaft which seems reluctant to turn, I may not have to resort to my spare engine.Just need the time to remove the enginenow.

Neil

[Westfaling]

imported post

I had the jackshaft seize up when the guys who stole it were thrashing it down a dual carriagway. Sort of an anti theft device! Front bearing seized solid - took some removing! I ended up buying a new short engine.
Nick