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Decompression
Newt - February 26th, 2013 at 06:04 PM

Hi Guys,

Im putting together a 1955cc engine.

Heads have been heavily fly cut to (from memory) 35cc.

This brings the static compression (with a 1.5mm deck) arround 11.5 (and dynamic around 10).

2 questions.

1) On a VW is there much difference between forged and cast pistons.

2) Is there much difference between running dished pistons and a wider deck height?

2B) Any thoughts on dished pistons. I did see on the net Toyota 1AR-FE pistons are about right (-27cc) (90mm with 22mm pin) which could come in a 0.50 oversize. Any other options.

Just pondering at then moment as I am in Perth for a month (away from my shed).

Newt


SuperOwen - February 26th, 2013 at 06:32 PM

If it were me.....I would hemi cut the chambers and blend the left over chamber into the hemi by hand. Be prepared to run a bit more advance.


matberry - February 26th, 2013 at 06:43 PM

^ me too, Don't go more than 1.5mm deck IMO. Converting pistons can be a pita, and not always successful.