High compression pistons

[Shietson]

I was told that you would have to run high octan fuel or racing fuel when your running high compresion pistons. When running these piston on octane 87 you will find your engine to have a knocking noise unless high octane fuel is used. Is this true?

[litkaj]

Yes, the higher the compression ratio (or more accurately, the greater the pressure, for those with cars with boost) the higher the octane rating on your gas will need to be.

[TurbyGT]

what u do is get the pistions out of a 1.8 beta and drop them in the 2.0 beta, use stock rings if you wish... then mill the head 0.08~1.0mm and then use the head gasket off of a elentra " the new one" they have 3 types 1ply 2ply and 3ply.... i am using the 2ply and so far no problems at all :

[i8acobra]

Originally posted by TurbyGT
[body]
what u do is get the pistions out of a 1.8 beta and drop them in the 2.0 beta, use stock rings if you wish... then mill the head 0.08~1.0mm and then use the head gasket off of a elentra " the new one" they have 3 types 1ply 2ply and 3ply.... i am using the 2ply and so far no problems at all :
[/body]

Any idea what your CR is with this setup? I'm installing cams and a P&P head and was thinking about bumping up the CR while I'm in there.

[Shietson]

Why is the reason for using 1.8L pistons ina 2.0L block? Is it because the 1.8 has a higher compression ratio than than the 2L pistons?

[TiGgEr]

what difference will the elantra head gaskets make? specifically what will be the differences between the different gasket plys 1, 2 and 3?

[dweet]

i am guessing 1 is thin, 2 is a little more thicker and 3 is the thickest

[TurbyGT]

the 1.8L pistion have a steep to them "a little higer dome to them" it is one of the first mods they did to the tibby here in korea... secound was the head gaskets "only use the one ply for drag only" it will only last you 6 months... the pistions will last you forever..when i ran with them they were great...i upgraded to 13.5:1 hicomp pistions "can i get a h$ll yeah" imo get an oil cooler it is a must with the heat that highcomp pistions make + the high rpms

[TiGgEr]

do you know what CR the 1.8l pistons will bring you to?
Also I have seen those 13.5:1 pistons and was wondering do you need an aftermarket piggyback computer or ecu to compensate for them? Taking into account you're in korea so you probably also have a different ECU than a US tibby. I assume you would need better cams, fuel delivery upgrades and have to run high octane all the time. But what are the absolute minimum requirements for the 13.5:1 pistons to run safe/reliable?

[Edited by TiGgEr on Oct 1, 2003 6:16 AM]

[OdessitPashka]

what power gain should be expected from high compression pistons?
thanx