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What pistons for 85.5mm bore?!

Number996

Well-known member
Joined
Feb 12, 2012
Messages
143
Location
Gaithersburg, MD
I need some help guys;

Some of you maybe following my build thread in General VR4 Discussions but this is an imperative and time sensitive enough subject to make a separate post in Technical Discussions.

I have given Jim of Justice Racing of Frederick, MD my newly purchased replacement stock rebuilt small block and to disassemble and inspect (stock pistons and rods with Nippon's and Clevite's). As well as the pistons and rods (Ross and Eagle) pulled from the bad bored out block that was originally in GVR4#996 when I purchased her.

The news is this: The crank (only in need of polishing) and Eagle rods are in excellent condition and re-usable for race use. All of the Ross rings are bad and one of the Ross pistons have sustained significant deterioration from long term detonation. The stock pistons are usable, but unfortunately the block cylinder walls (stock 85mm) are worn enough that stock pistons will not be efficient for race related use. The next bore size would be 85.5mm (+0.5mm bore/cylinder).

My questions for the forum are; What pistons and from where should I buy for 85.5mm bore (I have been told in person to go with Ross)? And what displacement (in Liters) does 85.5mm bore make?

Thanks Gentleman,
Robby
 

iceman69510

Turn Right Racing
Staff member
Joined
Mar 5, 2001
Messages
10,964
Location
Michigan
Almost any aftermarket make will have 0.5 oversize pistons available. It does not add any significant displacement.
 

citymunky

Well-known member
Joined
Sep 22, 2010
Messages
1,761
Location
Chesapeake, VA
I guess your name is Noobsauce for a reason. ^

996, don't listen to him, or else next time this happens your would need a new block since you will be unable to bore it out anymore if you get a 86mm bore piston. So if I was you I'll get some pistons to fit a 85.5mm bore. The difference is the diameter from 85mm to 85.5mm is about 0.020 of a inch, which is why it does not add any significant displacement. Wiseco, JE Pistons, CP Pistons are just a few brands out there.
 

Noobsauce

Well-known member
Joined
Apr 7, 2012
Messages
159
Location
Beaverton, Oregon
New block or have it sleeved. But a new block would be cheaper.
I picked the name Noobsause to weed out the douche bags. Hey guess what? Found you!!!
 

Noobsauce

Well-known member
Joined
Apr 7, 2012
Messages
159
Location
Beaverton, Oregon
If you want pistons for your bore. have the machine shop get you the exact dimensions and call up the manufacturer of your choice. They can make pistons to your exact size so the fitment will be optimal to your block.
 

toybreaker

iconoclast
Joined
Apr 30, 2006
Messages
3,581
now, now, kiddies /ubbthreads/images/graemlins/banghead.gif

... no reason to show your asses to the board.

... when kiddies start tossing around lame insults, nobody "wins"





Just present your views, back it up with your personal experience, and leave the petty sh*t/name calling out of your posts.

Nobody really gives a f*** if you;re the best damn google jockey that ever lived, on this board we value real world experience.

There are some really saavy folks on this board, but they won;t share their hard learned knowledge/experiences when they have to bandy words with asshats.

capische?
 

toybreaker

iconoclast
Joined
Apr 30, 2006
Messages
3,581
As someone who has been on the other side of the counter at a machine shop, I just gotta say I would toss half of the asshats posting bullshit and blather on this board on their ass within ten seconds of them walking in the door.



There's an art to doing machine work, and it's not something you get from readin posts on the internet.

If anything, all you gain is a little knowledge about the proccesses, but with no practical experience that's just enough to be dangerous.


Find a good guy, and let them do their job!

... and you know he ain;t the guy if he'll bore/hone the motor without the pistons right there in front of him.
 

Brianawd

Well-known member
Joined
Apr 18, 2005
Messages
2,117
Location
Portland OR,
Its really not that hard to figur out. You have a stock bore block. Take it to a machine shop and have them check it out. Let them tell you if you need .20over or .40 pistons. Then once you know pick what you want. Ross, Aris,wistco,JE. I have used Ross. Did not like them because of the valve pocket. Ended up with some Aris on the last build. From putting the Ross and Aris side by side the Aris was a much better piston. If I every build the motor on the evo it will be getting aris.
 
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