2 replies to this topic

[VAR1016]

Perhaps some of the very clever chaps who visit hereabouts could help?

I am interested in the mechanical effects of variations in piston crown height; i.e. the distance between the gudgeon ("wrist") pin and the top of the piston.

For my scheming, I am envisaging a rod to stroke ratio of about 2.2. I presume that the greater the rod/stroke ratio, then the less impact (!) variations in piston crown height should have.

As always, I would be most grateful for all opinions expressed.

PdeRL

[Halfwitt]

I'd imagine this is kept to a minimum to keep mass / weight down. Looking at that picture of the Ferrari piston, the pin is as close to the bottom ring as possible without actually breaking into the ring groove.

What is it that you are scheming then?

[VAR1016]

Originally posted by Halfwitt
I'd imagine this is kept to a minimum to keep mass / weight down. Looking at that picture of the Ferrari piston, the pin is as close to the bottom ring as possible without actually breaking into the ring groove.

What is it that you are scheming then?

More effing about with Fulvias. The plan involves larger bore and shorter stroke, so I will have too much "cylinder". I can lose some from the block (at both ends - separate block) I was wondering if I can get the final (guess) 5 - 6mm by increasing the piston crown height. The pistons will have to be made light (because of the different crankshaft) so they will possibly be slipper types without full skirts.

What interests me is what mechanical effect if any, an increased distance above the gudgeon pin has in terms of engine wear or other mechanical effects.

Also interesting is where the money for this scheme is going to come from!

PdeRL