Aftermarket upgraded pistons?!?!

Dark Knight 56

The Dark Knight
Jan 12, 2010
40
0
0
New York
I purchased my 7mgte with a bhg. When I took the head off these pistons were in the block. They are definately aftermarket because I haven't seen these in any other 7m & I've seen 3.
There is also "020" stamped on the pistons. What's does this mean? Is anybody familiar with these pistons?
 

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BrandonW

New Member
Jun 25, 2007
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N.J.
020 would = .020 over (larger piston)
that one looks like a oem type replacement just dirty
 

Dark Knight 56

The Dark Knight
Jan 12, 2010
40
0
0
New York
I'm not too sure about pistions but would "020" dramatically change my compression. I've done a Hks MHG 1.2 with arp studs & The head has work.
 

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Dark Knight 56

The Dark Knight
Jan 12, 2010
40
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0
New York
Well the head was definately machiened but the block wasn't. I spent about an 1/2 hour checking to make sure the block was straight & then an hour sanding down the surface with WD/40 & 400grit sand paper. The block is smooth as glass, I know it shoulda been Machiened to
Be safe but we will see.
 

Dark Knight 56

The Dark Knight
Jan 12, 2010
40
0
0
New York
Unfortunately I can't since the head is on. But with help from this forum & more research these seem to be wiseco 020 pistons 9.0 compression -16cc dish & 83.5mm bore
 

supraguy@aol

Well-Known Member
Dec 30, 2005
4,241
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Atlanta
I'm going to guess that they're not stock, but oem replacements. You said you bought it with a blown head gasket. If it had a BHG, then it almost certainly didn't have a MHG.
ANYONE who is going to use forged pistons, is going to use a metal head gasket and arp's.
They wouldn't spend $500 on pistons, and use a $30 composite head gasket.
 

IwantMKIII

WVU MAEngineering
Jun 12, 2007
2,477
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Perkasie, PA
Dark Knight 56;1528368 said:
Well the head was definately machiened but the block wasn't. I spent about an 1/2 hour checking to make sure the block was straight & then an hour sanding down the surface with WD/40 & 400grit sand paper. The block is smooth as glass, I know it shoulda been Machiened to
Be safe but we will see.


I guess ill see a thread in a few weeks, "Why is my HG still leaking?!?" or something along those lines. Just because its smooth, doesn't make it straight. Get it done right.
 

kneedragger85

New Member
Sep 9, 2008
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Boulder, CO
Dark Knight 56;1528677 said:
Would stock oem replacments have 020 stamped on them? I'm not sure.
Yes, you can buy stock replacements in 020 and 040 over and the respective size will be stamped on the dish. The person who asked for an under picture asked you because most aftermarket pistons stamp the manufacturer on the bottom side of the dish which would end the guessing game.
 

VooDoo

Draggin ass on his build
Mar 20, 2008
342
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Valdosta ,Ga
supraguy@aol;1528577 said:
I'm going to guess that they're not stock, but oem replacements. You said you bought it with a blown head gasket. If it had a BHG, then it almost certainly didn't have a MHG.
ANYONE who is going to use forged pistons, is going to use a metal head gasket and arp's.
They wouldn't spend $500 on pistons, and use a $30 composite head gasket.

This is very true. I wouldn't even consider putting this thing together without have the block checked and machined so insure smoothness. As well as the head. A shortcut now will just get you back to square one. Consider if the block isn't smooth enough and then you have an epic failure and have to buy a new head or block or HELL a whole other motor. You said you spend time with some sandpaper? 400Grit? :nono: Do a search for the RA spec required for your HG. I am sure you didn't get it there with sandpaper. These cars DO NOT LIKE shortcuts. just check before you go to far. Would hate to see your work go to waste.
 

hvyman

Dang Dude! No Way Man.
Staff member
Apr 17, 2007
12,568
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Fullerton,CA
Dark Knight 56;1528550 said:
Unfortunately I can't since the head is on. But with help from this forum & more research these seem to be wiseco 020 pistons 9.0 compression -16cc dish & 83.5mm bore

Head can be on. Just need the pan off. Is it still in the car?

kneedragger85;1528686 said:
Yes, you can buy stock replacements in 020 and 040 over and the respective size will be stamped on the dish. The person who asked for an under picture asked you because most aftermarket pistons stamp the manufacturer on the bottom side of the dish which would end the guessing game.

Yes.