25 replies to this topic

[ACDodd]

Hmmmmm old school thinking. Good job they don't think like that anymore. Bore and stroke need to be matched to the application. Long stroke for low down lugging and short stroke for higher rpm work.

[ACDodd]

Compression height, can't remember. I remember fitting a set in a stock 850 block with an 1100 crank and it was about 0.015 to 0.020" down the block. The piston Sare flat top and have a stock 998/1100 pin size of 0.6245".

Ac

[DeadSquare]

Hmmmmm old school thinking. Good job they don't think like that anymore. Bore and stroke need to be matched to the application. Long stroke for low down lugging and short stroke for higher rpm work.

 

So how do you reduce the stroke when pulling away from the traffic light and lengthen it with 3 fat passengers when going up hills?

[mini13]

http://www.patentsen.../20090095262_02

[DeadSquare]

http://www.patentsen.../20090095262_02

 

That is quite something, to celebrate your 3,000th post !

[DeadSquare]

 

Hmmmmm old school thinking. Good job they don't think like that anymore. Bore and stroke need to be matched to the application. Long stroke for low down lugging and short stroke for higher rpm work.

 

So how do you reduce the stroke when pulling away from the traffic light and lengthen it with 3 fat passengers when going up hills?

 

 

 

I was thinking something along the lines of how the stroke of the valve gear in the steam-chest of The Flying Scotsman works.

[mini13]

 

http://www.patentsen.../20090095262_02

 

That is quite something, to celebrate your 3,000th post !

 

 

 

oh wow! i woulndt have spotted that!

[Retroman]

The adjustable stroke is an interesting and potentially really good concept

 

Not sure how well it would actually work, there is a lot of weight and engineering involved looking at the one above

 

Its also odd the make such an 'advanced' design with pushrods

 

https://arstechnica....e-in-september/

 

Don't know what has happened since 2016

 

But Porsche look like they are trying to do it with a variable length conrod

 

https://www.enginela...connecting-rod/

[mini13]

dont confuse variable compression with variable stroke,

[Retroman]

Variable stroke will alter the compression too, so in essence its already confused 

 

Strictly speaking the porsche variable compression method also changes the rod / stroke ratio, but it's not variable stroke

 

Variable stroke ( thus compression) will have more potential output but much more mechanical weight and engineering to acheive it.

 

Would the gains from the variable stroke be out weighed by all the extra parts needed to control and work it when compared to the variable conrod method ?

[nicklouse]

remember the SVC?

https://www.saabplan...hp-out-of-1-6l/