low compression pistons

MMamdouh · Post by **MMamdouh** » Fri Apr 27, 2007 11:11 pm

can one shave some material off the top of an OEM piston to reduce compression? the reason for that is a turbo project and the lack of custom low compression pistons in the country

any other suggestions on lowering compression?

MMamdouh

gse_turbo · Post by **gse_turbo** » Fri Apr 27, 2007 11:19 pm

DOT DO IT! it's way to hard for a machine shop to get it right, then you can get uneven compression. What motor are you building? if its the 2.0/2.2 SOHC or DOHC Wiseco offers a set for a good price.

garrett

gse_turbo · Post by **gse_turbo** » Fri Apr 27, 2007 11:19 pm

correction... DON'T DO IT!...

jidasas · Post by **jidasas** » Fri Apr 27, 2007 11:26 pm

I agree...grinding on the top of pistons is a cheap fix at best. The stock pistons are not good for much boost and with even less metal to hold the boost in I assume they would break even sooner because of the amount of strength that would be lost...If I'm correct you have a 1.5 liter...could you not bore it to fit the 1.6 liter pistons and use the low comp forged piston made for it. Or run a thick head gasket...to lower the comp a little.

Just my opinion.

Jimmy
I'll pm you another method...

gse_turbo · Post by **gse_turbo** » Fri Apr 27, 2007 11:32 pm

weel put.

gse_turbo · Post by **gse_turbo** » Fri Apr 27, 2007 11:32 pm

well put.

GsiTurbo · Post by **GsiTurbo** » Sat Apr 28, 2007 4:59 am

Why not use thicker headgasket? For lower boost level it would work just fine. What is the current compression?

MMamdouh · Post by **MMamdouh** » Sat Apr 28, 2007 11:55 am

gse_turbo wrote:DOT DO IT! it's way to hard for a machine shop to get it right, then you can get uneven compression. What motor are you building? if its the 2.0/2.2 SOHC or DOHC Wiseco offers a set for a good price.

garrett

it is the 1.5 SOHC

MMamdouh

MMamdouh · Post by **MMamdouh** » Sat Apr 28, 2007 12:00 pm

this is just an idea that i and a friend of mine that happens to be a proud owner of a turbo 1.5 SOHC lanos came up with.

the thing is he has got an extra set of used pistons for his engine and he thought he could shave some material off the top of the piston to lower compression as we didn't find any thick gaskets here and the experiance with double head gaskets was not so good. surly enough we found no custom made low compression pistons here.

the current compression ratio is 9.5:1 and the boost is set to 6 PSI... as you all know boost is an addiction so we want more boost.

MMamdouh

wolfhound · Post by **wolfhound** » Wed May 02, 2007 5:42 am

The problem with moving the pistons further away from the head, either with the thicker gasket, skimmed pistons or (In my case) shortening the con rods is that the rim of the piston actually cools itself as it get close to the head, the further away from the head the hotter the piston will run and hence the more likely you are to have detonation.

The piston cooling effect is called "Quench" by the way.

The std Woo piston is only 5mm thick in the middle of the dish and to get the compression down to 8.5-1 you hav to add amost 8cc into the dish. There really isnt enough meat there for you to play with.

check out the diff in the dish on ubuyau's Ross pistons compared to std Woo one.

Buy the Wiseco pistons from Dwayne direct.

dsnyder@wiseco.com

Séan

MMamdouh · Post by **MMamdouh** » Wed May 02, 2007 9:16 am

thanks for the advice guys.

MMamdouh