Drop in pistons?
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I've seen videos of factories where engines are being assembled (not the Mitsubishi engine plant) and I notice racks with preselected pistons on it, one for each hole. Now maybe if the same tool bored every cylinder this wouldn't be necessary but they bore them all at the same time.
To point out the obvious, a cylinder that wears doesn't get smaller. On top of that you are going from a cast piston to a forged piston and forged pistons require more clearance. So there's some reasons a forged standard sized piston just dropped in may cause problems. At least on a nearly new engine you have more of a chance of it being satisfactory.
Anyway, the OP asked for a consensus not a technical answer. A consensus is a group of opinions.
To point out the obvious, a cylinder that wears doesn't get smaller. On top of that you are going from a cast piston to a forged piston and forged pistons require more clearance. So there's some reasons a forged standard sized piston just dropped in may cause problems. At least on a nearly new engine you have more of a chance of it being satisfactory.
Anyway, the OP asked for a consensus not a technical answer. A consensus is a group of opinions.
pistons, as well as cranks, blocks, bearings.. etc, are always measured in the factory and grouped according to their size... you can find such markings stamped on evo blocks, and when you order new stock pistons and bearings you can always choose their size group.. Give some credit to the factory, even though in the videos you always just see guys throwing the engine togeather, there is always someone in the back doing the measurements..
as for drop in forged pistons... forged pistons are sized for bore size, and sold as such.. so a 85 mm bore piston will allready be undersize enough to have the right PTW clearence that that forged pison requires when installed in 85 mm bore..
a couple of points...
pistons, as well as cranks, blocks, bearings.. etc, are always measured in the factory and grouped according to their size... you can find such markings stamped on evo blocks, and when you order new stock pistons and bearings you can always choose their size group.. Give some credit to the factory, even though in the videos you always just see guys throwing the engine togeather, there is always someone in the back doing the measurements..
as for drop in forged pistons... forged pistons are sized for bore size, and sold as such.. so a 85 mm bore piston will allready be undersize enough to have the right PTW clearence that that forged pison requires when installed in 85 mm bore..
pistons, as well as cranks, blocks, bearings.. etc, are always measured in the factory and grouped according to their size... you can find such markings stamped on evo blocks, and when you order new stock pistons and bearings you can always choose their size group.. Give some credit to the factory, even though in the videos you always just see guys throwing the engine togeather, there is always someone in the back doing the measurements..
as for drop in forged pistons... forged pistons are sized for bore size, and sold as such.. so a 85 mm bore piston will allready be undersize enough to have the right PTW clearence that that forged pison requires when installed in 85 mm bore..
a couple of points...
pistons, as well as cranks, blocks, bearings.. etc, are always measured in the factory and grouped according to their size... you can find such markings stamped on evo blocks, and when you order new stock pistons and bearings you can always choose their size group.. Give some credit to the factory, even though in the videos you always just see guys throwing the engine togeather, there is always someone in the back doing the measurements..
as for drop in forged pistons... forged pistons are sized for bore size, and sold as such.. so a 85 mm bore piston will allready be undersize enough to have the right PTW clearence that that forged pison requires when installed in 85 mm bore..
pistons, as well as cranks, blocks, bearings.. etc, are always measured in the factory and grouped according to their size... you can find such markings stamped on evo blocks, and when you order new stock pistons and bearings you can always choose their size group.. Give some credit to the factory, even though in the videos you always just see guys throwing the engine togeather, there is always someone in the back doing the measurements..
as for drop in forged pistons... forged pistons are sized for bore size, and sold as such.. so a 85 mm bore piston will allready be undersize enough to have the right PTW clearence that that forged pison requires when installed in 85 mm bore..
I know Hyundai ranks pistons/bores but Honda doesn't (at least the V6's don't).
Also, just some added (irrelevant?) insight. The supplier would usually be the one to measure and assign a sizing grade. The factory would do the same for parts they make or machine in house. Bearings and pistons are usually from an outside supplier in many cases.
Last edited by XSivPSI; Jun 30, 2016 at 03:14 PM.
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From: Croatia
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