Drivetrain Supertech forged piston ring gaps
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1st Gear
Joined: Mar 2019
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Supertech forged piston ring gaps
Hi I am installing new supertech forged pistons and preparing by measuring the ring gaps. The top ring is .35mm and 2nd ring in exactly the same location and bore is .7mm. The 2nd ring is meant to have a gap 25% more than the 1st. My rings are 100% different. This suggests the rings are incorrectly supplied by supertech, anyone else had this issue?! I have attached a pic with the rings installed together to demonstrate the gap difference
6th Gear
Joined: Mar 2011
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From: Northern NV
Here's a link to the applicable NewTIS engine specs, for my '07MCS --- https://www.newtis.info/tisv2/a/en/r...-pins/2SGSapgG I suggest you use the last 7 characters of your own VIN to get specs for your engine. If you do your own repairs, this is a great site for repair help. Also RealOEM.com for illustrated parts lists.
You probably didn't get any response 'cause there's not a lot of info about your engine --- OEM bore or oversize, and did Supertech offer any help with your problem or did you even contact them about it?
You probably didn't get any response 'cause there's not a lot of info about your engine --- OEM bore or oversize, and did Supertech offer any help with your problem or did you even contact them about it?
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1st Gear
Joined: Mar 2019
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My engine is standard 77mm bore, however this issue is related to the product supplied by supertech, not my bore. I have raised the issue with supertech and they acknowledged (via distributor) that they supply 2nd rings with a gap over 25% bigger than the 1st ring gap. In fact their 2nd ring gap is 60% bigger than the 1st ring. I have 15 thou top ring and 25 thou 2nd ring. Supertech have confirmed that this is ok. In the instructions from supertech they state the 2nd ring should have a gap 25% larger than the 1st. Supertech say they don’t specify a max gap size for the 2nd ring, therefore my gap is ok (according to them). There isn’t much I can do about this, I will have to install the pistons as they are as they certainly dont need the gaps enlarging.
6th Gear
Joined: Mar 2011
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From: Northern NV
Without a rebore, your rings are bound to have a larger than normal gap. Chances are the cylinders aren't as round as they should be either. Hopefully, you at least did a thorough hone and ridge removal. Don't expect to stop oil consumption with this level of repair, it's gonna take a long time for the rings to seat and the gaps will probably get worse. Hope you changed the valve stem seals too.
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1st Gear
Joined: Mar 2019
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The company I bought the pistons from installed the same ring set in new 77mm sleeves, they had exactly the same result. 2nd ring 60% bigger gap than the 1st ring.
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1st Gear
Joined: Oct 2019
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Without a rebore, your rings are bound to have a larger than normal gap. Chances are the cylinders aren't as round as they should be either. Hopefully, you at least did a thorough hone and ridge removal. Don't expect to stop oil consumption with this level of repair, it's gonna take a long time for the rings to seat and the gaps will probably get worse. Hope you changed the valve stem seals too.
You miss the point. He's not complaining that his gaps aernt to the tightest tolerance he's referring to the difference. IE his top ring is 0.35mm so his second ring should be around 0.4375mm This indicates that the second rings are being produced a little too short. They should really produce them in a way where if anything the second gap comes in tighter than 1st gap * 0.25. This way you can file the gaps to perfection. As you can always remove material but you can't add it.
1st Gear
Joined: Oct 2019
Posts: 42
Likes: 4
Hi I am installing new supertech forged pistons and preparing by measuring the ring gaps. The top ring is .35mm and 2nd ring in exactly the same location and bore is .7mm. The 2nd ring is meant to have a gap 25% more than the 1st. My rings are 100% different. This suggests the rings are incorrectly supplied by supertech, anyone else had this issue?! I have attached a pic with the rings installed together to demonstrate the gap difference
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