Spark Plug Heat ranges, what gains have you made?

[Jeff Stout]

Originally Posted by Stan Weiss

When you add wrist pin offset a number of thinks happen. The piston and the crank rod journal are not ATDC and BBDC at the same time. Now based on which way you have the offset decides if piston TDC is before or after crank rod journal TDC. Another thing that happens is all 4 cycle are not long 90 degrees each. 2 become less and 2 become more. Again which 2 do what is based on where the offset was placed.The is also a very very small change in stroke and displacement. (For inline engines where you can move / offset the crank center line these can be larger).


Stan

Did not think of this. Could you run just 4 pistons with offset? Don't know if it is worth anything as I understood using offset helps with side thrust on bore.

[MoJo Risen]

Originally Posted by Stan Weiss

Within a normal range of piston pin offset the piston travel curve does not change very much from centered. So if you are using piston TDC there should be almost no difference in VTP clearance because of wrist pin offset.

I believe it slows the piston down more at top of cylinder helping capture more usefule cylinder pressure. There are many different functional aspects of using offset Piston pins.

Stan


PS Above I am talking about if you degree the cam. If someone just installs the cam dot to dot (crank rod journal TDC?) There will be more of a change in VTP clearance from the offset over centered pin.


Stan

I believe it slows the piston down more at top of cylinder helping capture more usefule cylinder pressure. There are many different functional aspects of using offset Piston pins. Maybe this is a competition eliminator question since anything goes just as like STOCK Eliminator Piston pin offsets.