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View Full Version : dohc w/ sohc pistons. i searched, but still confused.

darknightMR2
10-07-2005, 01:22 AM
basically, i found a helpful thread on this subject, but one question wasn't answered. do they fit? i have an s13 dohc w/ a cracked piston, but i also have a spare sohc engine w/ good pistons. i wasn't sure if they fit or even if they're the same bore size, so i didn't know if they could swap. as i understand they raise compression when swapped. so, would it cost effective to swap them, or just buy new pistons and overhaul the engine. any advice fellas? thanks in advance.
orion::S14
10-07-2005, 08:07 AM
The answer is yes...but there are 3 grades of OEM piston (1, 2, 3)...so unless you're lucky enough to have 2 engines with the same grade in all 4 bores (like 2,2,2,2 in the DOHC and the same in the SOHC)...you need to buy new pistons.

How'd you crack the piston? If it was boost, then you shouldn't do this...+11:1 static compression is not-so-good for a KA-T.

- Brian
darknightMR2
10-07-2005, 06:23 PM
no, i didn't crack the piston. the previous owner said that it was, my impression was that its a blown ring or valve seal. thanks for answering my question. the car was never boosted, but the dohc ka has 200k on it. so i suppose its time for a rebuild huh?!! im very new to this silvia/240 world so anything helps.
thanks again,
Ian
RBS14
10-07-2005, 09:33 PM
I really wouldn't rebuild it with used pistons from another engine...
theicecreamdan
10-07-2005, 10:26 PM
http://img224.imageshack.us/img224/1749/bustedka9ht.jpg

you don't need boost to destroy pistons.
ryan hagen
10-08-2005, 01:20 AM
looks like alot of 4g63's ar ethose little vlave chunk dents in the pistons?

a couple blown timing belt 4g63's i tore down have large holes beat through them, one so bad as the wrist pin stayed with the rod and the rest was smashed to tiny bit, gotta love high rpms and interfernece valve trains
darknightMR2
10-08-2005, 11:51 AM
holy crap! i didn't know that the pistons look like that stock. there's no relief dishes on them at all? should i just order some oem pistons and rebuild it then?
RBS14
10-08-2005, 09:05 PM
get some pistons from www.hybridka.com Best OEM replacements (aside from OEM, duh), and CHEAP!

EDIT: fixed the link.
darknightMR2
10-09-2005, 01:17 AM
the link isn't working for me for some reason. what are the prices? do they come in a set w/ rings and stuff? thanks for posting that for me.