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+--- Thread: Liner protrusion (/showthread.php?tid=2786)
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RE: Liner protrusion - schISM - 02-23-2018
Now I know it's taboo to speak against shimming liners around here so I'm just asking for real world experience on the matter. Has anyone measured a seated liner I.D. for out of roundness with some sorta torque plate and 15 thousandths crush?
It seams everybody's favorite height has risen a thousandth a year since big h.p. has become more easily obtained. Just a theory I had but I'm thinking you might end up with an oblong liner even with a midstop in the middle.
It's been years since I've done any kinda engine work like this but I found out the hard way how accumulating tolerances can distort even the biggest chunk of iron.
If I were rebuilding an engine knowing it wasn't intended for more than 600hp I'd concentrate more on all six pots being .0095
+/- .0005 on any one hole.
Just saying ;-).
RE: Liner protrusion - Wiseman - 02-23-2018
Theoretically you have valid point. But only theoretically!
Real world results are more then eye opener. As long are interpreted right.
Now think for a second what consequences will have a simple statement from engine manufacturers,
meaning something like that : - Uhm , ok guys, our liner protrusion and head gasket crush calculations just fail short off just about 3-4 thousands . So that’s why so many of your engines have liner fretting issues leading to combustion gases in coolant sistem , hydro lock and extra ventilation/inspection holes in the block.
Oh ... and we should of install an bypass oil filter at the factory, so you have a million miles engine and keep your money in your pocket.
Disclaimer:
I’m not looking to start anything with what I wrote.
It’s my way off thinking and understanding the world in between the lines.
RE: Liner protrusion - Rawze - 02-24-2018
(02-23-2018 )schISM Wrote: Now I know it's taboo to speak against shimming liners around here so I'm just asking for real world experience on the matter. Has anyone measured a seated liner I.D. for out of roundness with some sorta torque plate and 15 thousandths crush?
It seams everybody's favorite height has risen a thousandth a year since big h.p. has become more easily obtained. Just a theory I had but I'm thinking you might end up with an oblong liner even with a midstop in the middle.
It's been years since I've done any kinda engine work like this but I found out the hard way how accumulating tolerances can distort even the biggest chunk of iron.
If I were rebuilding an engine knowing it wasn't intended for more than 600hp I'd concentrate more on all six pots being .0095
+/- .0005 on any one hole.
Just saying ;-).
It is the block mid-stop that deflects during crush, not so much the liner itself. I have seen guys use too much protrusion (more than 0.017") and distort or crack the mid-stop in the block.
The optimum seems to be 0.014" - 0.015" on anything 600hp or less to yield a sort of maximum holding pressure while still in the safe zone of deflection tolerance.
it is also not typically the "Bang" of a piston that makes them fret liners. It is internal wall friction in the opposite direction of the rod as the piston drives the rod downward. That is why they always fret to the exhaust side, opposite of rod deflection during the compression stroke.
The red engine maker themselves have had issues with this since the birth of the ISX and the mid-stop liner. they have had countless tweaks over the least several years because they know is it a weak point. - I doubt it ever gets fully solved actually. I don't see them offsetting bores, increasing rod length, or doing any of the other things to relieve it like other engine makers have done in the past.
The problem of this kind of internal friction is in ALL engines that have a crank and pistons. Many engine companies relieve this problem with things like offset wrist pins, offset bores, offset heads and valve seats, longer rod length, and other tricks to reduce internal friction of this type. The red engine maker does it by a lower then normal recess in the top of the piston on the exhaust side, but obviously it seems that it is not quite enough at higher HP levels on its own due to the mid-stop liner designs?.
Because it is an issue that will likely never be solved, precise control of combustion burn length is needed as a supplement to any sort of liner height modifications as a prevention.
(reference)
http://rawze.com/forums/showthread.php?tid=2227&pid=19318#pid19318
RE: Liner protrusion - Joesixpack - 03-02-2018
Just thought I'd mention we used an IPD kit and the liner's are sitting 12.5 thou proud on the factory cut ledge. The Cummins liners came out at 9 thou.
Not worried in the slightest about it lasting.
RE: Liner protrusion - Unilevers - 03-03-2018
(03-02-2018 )Joesixpack Wrote: Just thought I'd mention we used an IPD kit and the liner's are sitting 12.5 thou proud on the factory cut ledge. The Cummins liners came out at 9 thou.
Not worried in the slightest about it lasting.
it will last at 12.5 as long its not pushed hard. thats a decent number if they are not fretted.