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Engine basics => Engine set up tips => Topic started by: Air Ministry . on December 17, 2019, 05:45:35 PM
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As per thus . Drilling oiling tracts to wrist pin in piston . Any downsides to this ? .
(https://www.mgccyregister.co.uk/wp-content/uploads/2013/07/XPAGD9pistonb.jpg)
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As per thus . Drilling oiling tracts to wrist pin in piston . Any downsides to this ? .
(https://www.mgccyregister.co.uk/wp-content/uploads/2013/07/XPAGD9pistonb.jpg)
You would most likely do much better to make the piston, perforated ported, that is cut holes in the skirt that lines up ONLY with the intake ports, and only the intake ports, the fuel charge will then pass under the piston, thru the sides, and in doing so will lubricate the wrist pin much better than it would normally
Randy
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Like this, Randy? ..but I thought the 2 small holes won't do any harm.
L
😋
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Like this, Randy? ..but I thought the 2 small holes won't do any harm.
L
😋
Lauri; I always enjoy looking at the results of your awesome machining skills.
As for oil holes for wrist pin, almost all modern high Performance glow engines have them, as well as, oil holes in top of rod and in strategic locations at bottom of rod to lube crank pin/rod bushing.
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Looks like the picture in first post is of something slightly bigger than our stuff. That makes it a completely differend story as with small 2-strokes.
In our use, where stability is everything, I would try to avoid any bigger cutouts to improve lubrication/cooling of piston like Randy suggested. That is especially so in ringless ABC's or AAC's.
Seeing lubrication holes for wristpin smells like an attempt to improve something when the problem is actually elsewhere, like in bad materials.
In my case, I use 100% piston scavenging, that's the reason for those big cutouts. But then, I rely on the ring in sealing stability. Even though materials are right, I doubt it would work well without the ring.
L
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Like this, Randy? ..but I thought the 2 small holes won't do any harm.
L
😋
Hi Lauri
Yes nice work, the piston holes in the side that let the charge come thru the bottom of piston really lubes the pin area very well, anyone that can do the excellent precision machining you have done, will have no problem, I just wanted to make sure they were being careful, You can ruin a piston if the holes open into the exhaust port
Good work !
Randy
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Thanks Randy.
My point was, that a healthy engine should not really need holes in piston, better to look other cures first, like materials and finishing quality.
We have learned with T/R engines that holes make quite big heat & strenght gradients. So the negative effects may well counteract the positive ones :)
But there is no universal truth.
L