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N/A, .004 - .0045" per bore inch, on the top ring; .0005" more than that on the 2nd. So for a 5.3, .019 - .022" or so on the top, .022 - .025 or thereabouts on the 2nd.
Boost/nitrous, add about .001" per bore inch to that.
Always better to have slightly too much (heavy emphasis on "slightly") than ANY too little. A bit too much, you get some unnoticeable extra blowby; too little, ANY too little, even .0001", you get INSTANT CATASTROPHIC DESTRUCTION. Since nothing about that sort of thing is ever "perfect", pretty obvious which side you want to tilt your errors toward.
N/A, .004 - .0045" per bore inch, on the top ring; .0005" more than that on the 2nd. So for a 5.3, .019 - .022" or so on the top, .022 - .025 or thereabouts on the 2nd.
Boost/nitrous, add about .001" per bore inch to that.
Always better to have slightly too much (heavy emphasis on "slightly") than ANY too little. A bit too much, you get some unnoticeable extra blowby; too little, ANY too little, even .0001", you get INSTANT CATASTROPHIC DESTRUCTION. Since nothing about that sort of thing is ever "perfect", pretty obvious which side you want to tilt your errors toward.
thank you, for taking the time to reply. It’s much appreciated
For Example UEM Silv-O-Lite have specific recommendations. I forget what the Speed Pro say...
Very interesting. I’ve never seen this info before, and never had any of my builder friends talk about this ether. I’ll admit that I do mostly forged or billet piston builds but still…
Very interesting. I’ve never seen this info before, and never had any of my builder friends talk about this ether. I’ll admit that I do mostly forged or billet piston builds but still…
I have used a few set's so I thought I would mention it.
I used the Speed Pro's too But I will have to look for the sheet that comes with them as I can't recall if they had any thing like this. I also was unable to find anything specific on line for them.
I’m not sure why they are asking this to be done. In all of our testing, we found that a smaller second ring gap caused the second ring to flutter, and the engine lost power. All of that testing involved forged pistons, which have more piston to wall clearance than a hypereutectic piston. This means that the forged pistons top ring will see more heat than the hypereutectic pistons top ring, at least until the assembly gets up to operating temp. I could see opening up the top ring gap in a setup where the top ring was higher than normal, toward the crown, which will see more heat, but I’d still want the second ring gap larger than the top ring. I’m absolutely not opposed to learning something here, that’s for sure. I’ve built 4 hypereutectic builds in the past few years and I set them up .018/.020 top rings, with larger second ring gap. I did one turbo build this year that was hypereutectic and was way out at almost .030, with larger second ring gap. I always make sure I’ve got enough oil pump in a build to keep oil temps in check, which keeps piston crowns and cylinder walls cooler…which keeps rings cooler as well.
1FastBrick, what’s your take on this deal? Anyone else got pertinent info or data on this subject?
I’m not sure why they are asking this to be done. In all of our testing, we found that a smaller second ring gap caused the second ring to flutter, and the engine lost power. All of that testing involved forged pistons, which have more piston to wall clearance than a hypereutectic piston. This means that the forged pistons top ring will see more heat than the hypereutectic pistons top ring, at least until the assembly gets up to operating temp. I could see opening up the top ring gap in a setup where the top ring was higher than normal, toward the crown, which will see more heat, but I’d still want the second ring gap larger than the top ring. I’m absolutely not opposed to learning something here, that’s for sure. I’ve built 4 hypereutectic builds in the past few years and I set them up .018/.020 top rings, with larger second ring gap. I did one turbo build this year that was hypereutectic and was way out at almost .030, with larger second ring gap. I always make sure I’ve got enough oil pump in a build to keep oil temps in check, which keeps piston crowns and cylinder walls cooler…which keeps rings cooler as well. 1FastBrick, what’s your take on this deal? Anyone else got pertinent info or data on this subject?
So It could be that there is more expansion in the aftermarket Hypereutectic piston or that the top of the piston is either exposing more of the ring to heat or that the ring land is higher than factory. I am not 100% sure for there exact reasoning for the additional gap but they did put the disclaimer in there for a reason!!!
FYI, I am building a Diesel engine right now with Mahle Motorsports Race cast pistons and Mahle call's for Bore X 0.006 for Top Ring and Bore X 0.0055 Second Ring...
So It could be that there is more expansion in the aftermarket Hypereutectic piston or that the top of the piston is either exposing more of the ring to heat or that the ring land is higher than factory. I am not 100% sure for there exact reasoning for the additional gap but they did put the disclaimer in there for a reason!!!
FYI, I am building a Diesel engine right now with Mahle Motorsports Race cast pistons and Mahle call's for Bore X 0.006 for Top Ring and Bore X 0.0055 Second Ring...
I totally get opening the top ring up if the top ring has been moved up toward the crown. I just haven’t came across any eutectics that have the top ring moved up…not yet. The Mahle info you posted is stating that it’s current tech to open the second ring up larger than the top…but I’ve been doing that since I started cutting rings over 30 years ago.
I think I’ll call my machinist Monday and chat about this. He works for Gibbs as a consultant now. They spend over a million a year with JE. He will get me up to speed on this larger top gap.
I totally get opening the top ring up if the top ring has been moved up toward the crown. I just haven’t came across any eutectics that have the top ring moved up…not yet. The Mahle info you posted is stating that it’s current tech to open the second ring up larger than the top…but I’ve been doing that since I started cutting rings over 30 years ago.
I think I’ll call my machinist Monday and chat about this. He works for Gibbs as a consultant now. They spend over a million a year with JE. He will get me up to speed on this larger top gap.
Right On! I know it goes against what we were all taught but they must have a reason. I am still trying to figure it out myself.
What has my thought process wondering here, is that eutectic (high silicone content) material doesn’t grow nearly as much as a non-eutectic aluminum piston. Therefore it allows you to set the eutectic and especially hypereutectic pistons up with a tighter wall clearance. A tighter clearance shields the top ring more, keeping the top ring temp lower than with a forged piston setup…at least until the assembly gets up to full temp. Ok, I’m rambling…I’m looking forward to learning here.
What has my thought process wondering here, is that eutectic (high silicone content) material doesn’t grow nearly as much as a non-eutectic aluminum piston. Therefore it allows you to set the eutectic and especially hypereutectic pistons up with a tighter wall clearance. A tighter clearance shields the top ring more, keeping the top ring temp lower than with a forged piston setup…at least until the assembly gets up to full temp. Ok, I’m rambling…I’m looking forward to learning here.
I totally understand what your saying. But I know they have changed the formulations a little bit too. I am curious to see what your contacts have to say about it as well.
I know I have the box some where for the speed pro, but not sure if it has the paperwork in it. I am curious if they have the same recommendation.
Here is the Mahle kit that comes with the pistons for the diesel I am working on.
Hello people I know that when I was building a 5.3L about 15 years ago that the Speed-Pros had right around 17% silicon and the Mahles had in the 12% silicon range . I imagine this would also make some difference not sure what but maybe this info will help . Good luck
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5.3 piston ring help 
