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Coating Air cooled pistons

General engine tech -- Drag Racing to Circle Track

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ptuomov
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Re: Coating Air cooled pistons

Post by ptuomov » Mon Oct 07, 2019 11:10 am

Kevin Johnson wrote:
Mon Oct 07, 2019 10:36 am
If you have not already done so, the factory GKN sinter-forged rods can be modified with slots to direct ejected oil from the rod bearings towards the pistons. This will not increase the demand on the oil pump.
We've though about that, especially since modern pistons will require different length rods anyway. The issue is that it's difficult to get a narrow enough spray pattern from that sort of slot. The engine has too much oil on the bore walls anyway, so anything that has a wide spray cone is not ideal. Because of this, the jets from the main are likely to best piston cooling solution.

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Re: Coating Air cooled pistons

Post by Truckedup » Mon Oct 07, 2019 1:48 pm

JodyB wrote:
Sun Oct 06, 2019 6:31 pm
Back to the original poster's GS1100. Being air cooled, piston to bore clearance at your average riding or racing conditions/temp will be #1 priority for making hp and having the mill live. Magic coatings, oil squirters, water injection are distant 2nds if you have sufficient octane.
Stock piston to wall clearance on these engines is .002", fairly tight for an air cooled engine, likely cast pistons...These engines do have a repuation for reliability even when abused...An increase in power of let's say 30% may require no special treatment
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Re: Coating Air cooled pistons

Post by ptuomov » Mon Oct 07, 2019 4:05 pm

lewy-d wrote:
Wed Oct 02, 2019 1:45 pm
I've got a bit of analysis paralysis on this one. The engine is a 1980's Suzuki GS1100, mild performance build. Will hard anodizing, coating piston tops and or skirts reduce the effective heat transfer from piston to block to air? Will it matter?
thanks, Lewy
Here's a question/comment. For air cooled application like that, would there be any downside from thermal barrier coating the exhaust port and the back of the exhaust valve? It seems to me that insulating those components should reduce cylinder head temperatures and shouldn't increase detonation tendencies. Any thoughts?

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Re: Coating Air cooled pistons

Post by Kevin Johnson » Mon Oct 07, 2019 4:45 pm

lewy-d wrote:
Wed Oct 02, 2019 1:45 pm
I've got a bit of analysis paralysis on this one. The engine is a 1980's Suzuki GS1100, mild performance build. Will hard anodizing, coating piston tops and or skirts reduce the effective heat transfer from piston to block to air? Will it matter?
thanks,
Lewy
I rode a GS back and forth to school for several years. Got tired of arriving drenched and bought a Metro.

You ARE already using an oil cooler, correct? Reject the mild performance build heat from the oil, i.e, the interior of the pistons and bores. Tons of aftermarket kits.

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Re: Coating Air cooled pistons

Post by David Redszus » Mon Oct 07, 2019 5:19 pm

lewy-d wrote:
Wed Oct 02, 2019 1:45 pm
I've got a bit of analysis paralysis on this one. The engine is a 1980's Suzuki GS1100, mild performance build. Will hard anodizing, coating piston tops and or skirts reduce the effective heat transfer from piston to block to air? Will it matter?
thanks, Lewy
Hard coat anodizing is, de facto, a ceramic coating called alumina. It has a thermal conductivity one tenth that of aluminum. It will reduce the heat transfer from the surface to the interior of the metal surface, leaving the surface in a higher temperature state.

An examination of the thermal transfer path and the insulation properties of each layer will provide an insight to the issue of heat transfer.

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Re: Coating Air cooled pistons

Post by JodyB » Fri Oct 11, 2019 12:15 am

To the original poster: What approximate wheel hp range are you shooting for with the air cooled suzuki?

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Re: Coating Air cooled pistons

Post by Truckedup » Fri Oct 11, 2019 7:02 am

JodyB wrote:
Fri Oct 11, 2019 12:15 am
To the original poster: What approximate wheel hp range are you shooting for with the air cooled suzuki?
What is the stock RWHP? Maybe about 80?
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Re: Coating Air cooled pistons

Post by lewy-d » Fri Oct 11, 2019 8:49 am

thank you for all the help.
I'm not sure about the original HP. 80 sounds right. Vance and Hines sold a video about degreeing cams on the 16valve GS (I bought it can't find it now!) and they showed 149 at the sprocket. Same size engine but I don't know the rest of the specs.
Diamondyze is the anodizing I'm thinking of using. It's interesting to me that the coater will anodize pistons then coat the tops and skirts. I've had some parts WPC processed lately and I like it. so maybe anodize the piston and coat the top and WPC the skirts and pins.
I hadn't thought about doing the exhaust ports but they're short and it might not be a bad idea.
I agree the clearance is important I had the block bored and honed by a shop I trust but I will check. Other than Wiseco's recommendation I'm not sure what I should do. Any help here is appreciated.

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