Decompression

Newt Wolfsburg Wizard

478 posts · joined Mar 2008 · 26 Feb 2013, 6:04 pm

#945435

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

It is as it is - If you didnt enjoy today, you've missed the opportunity.

SuperOwen Fahrvergnugen

868 posts · joined Jan 2009 · 26 Feb 2013, 6:32 pm

#945440

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 Moderator Go hard or go home

8,114 posts · joined Mar 2006 · 26 Feb 2013, 6:43 pm

#945445

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

Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
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