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Coating Air cooled pistons

General engine tech -- Drag Racing to Circle Track

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lewy-d
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Coating Air cooled pistons

Post by lewy-d » 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

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Re: Coating Air cooled pistons

Post by Racer71 » Wed Oct 02, 2019 2:04 pm

I coated tops of pistons on many cb750 sohc motors i built for tq midgets. It did bring oil temps down compared to uncoated domes. These were alky dry sump motors, high load in the those cars especially on the dirt tracks.

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Re: Coating Air cooled pistons

Post by RCJ » Wed Oct 02, 2019 3:14 pm

If the coating are reducing heat transfer to the pistons, where is that heat going?Is the chamber staying hotter and heating the income fuel and air?I've been working with small air cooled motors and am see a reduction it hp as the motor gains temp ,trying to figure out which direction to go.

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Re: Coating Air cooled pistons

Post by hoodeng » Wed Oct 02, 2019 3:50 pm

Internal engine coatings will not change the heat released by the combustion process, they will only change the paths of conductance. Piston crown ceramic coatings reduce the heat path to the under crown so reducing the heat path to the crankcase, ceramic coatings to the combustion chamber will reduce the conductance path to the cylinder head, same goes for the inlet valve.

Any heat/energy not converted into work will be rejected in the exhaust.

Ceramic coated pistons in a high continuous load application will help lower case temps and oil temp.

If the heat generated in the combustion process can not be controlled power loss is inevitable.

Cheers.

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Re: Coating Air cooled pistons

Post by peejay » Wed Oct 02, 2019 5:35 pm

As a corollary, the less heat is lost to the piston or chamber, the more is available to do work.

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Re: Coating Air cooled pistons

Post by 4vpc » Wed Oct 02, 2019 6:55 pm

The work of heating up the combustion chamber until detonation occurs.
There is no S on the end of RPM.

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Re: Coating Air cooled pistons

Post by MadBill » Wed Oct 02, 2019 9:15 pm

And how do you know it will do that rather than increasing the cylinder pressure and so transmitting more force to the piston?
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Re: Coating Air cooled pistons

Post by hoffman900 » Wed Oct 02, 2019 9:21 pm

MadBill wrote:
Wed Oct 02, 2019 9:15 pm
And how do you know it will do that rather than increasing the cylinder pressure and so transmitting more force to the piston?
Paging Nitro2...

Regardless, some of the Porsche aircooled racers report that heads are consumables. Coating pistons, chambers, and exhaust ports increases their life some, but overheating is overheating.
-Bob

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Re: Coating Air cooled pistons

Post by Circlotron » Wed Oct 02, 2019 9:50 pm

peejay wrote:
Wed Oct 02, 2019 5:35 pm
As a corollary, the less heat is lost to the piston or chamber, the more is available to do work.
But the expansion ratio on the power stroke remains the same so I'd expect higher gas temp at the top of the stroke and higher at the bottom, leading to higher exhaust temp but no real increase in efficiency or power simply because of less heat lost to coated surfaces. Maybe increased efficiency or power as a secondary effect because of other stuff not getting so hot.

Edit -> Maybe higher exhaust temps would help in a turboed setup. There would be more heat available to do work there.
Edit 2 -> I suppose if the temp was higher all the way down the stroke, the pressure would be higher too. Okay...

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Re: Coating Air cooled pistons

Post by digger » Wed Oct 02, 2019 11:10 pm

MadBill wrote:
Wed Oct 02, 2019 9:15 pm
And how do you know it will do that rather than increasing the cylinder pressure and so transmitting more force to the piston?
that's what detonation does?

logic suggests that if you're knock limited then there's not much benefit to coated other than reducing exposure of parts to some heat but cylinder pressure and heat rise due to any insulation affects is going to be more prone to knock. i've heard this from well respected members on here before. in which case just run higher CR and save the cost of expensive coatings?

if not knock limited then sure could be something to gain as you get the similar effect of higher CR with less compromise on the combustion space from large dome or what not that would be needed to get the CR up

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Re: Coating Air cooled pistons

Post by Truckedup » Thu Oct 03, 2019 9:16 am

Smokey Yunick claimed that on the dyno,a SBC continued to make more power up to about 230F if detonation was under control...
I hold/held several land speed racing records vintage detonation prone air cooled bikes....My bike runs faster with a warmed up engine.. Of course running wide open 1-1/2 miles may make the warm up unecessary and it might be be coincidence..I use less less compression and a flatter piston dome than the competion and I believe this resuts in less heat lost to the piston than the high boy domes.Thermal coating the pistons on the junk I run may melt the heads... :D
Motorcycle land speed racing... wearing animal hides and clinging to vibrating oily machines propelled by fire

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Re: Coating Air cooled pistons

Post by tt 383 » Thu Oct 03, 2019 11:24 am

hoffman900 wrote:
Wed Oct 02, 2019 9:21 pm
MadBill wrote:
Wed Oct 02, 2019 9:15 pm
And how do you know it will do that rather than increasing the cylinder pressure and so transmitting more force to the piston?
Paging Nitro2...

Regardless, some of the Porsche aircooled racers report that heads are consumables. Coating pistons, chambers, and exhaust ports increases their life some, but overheating is overheating.
Funny I was looking at Porches the other day and always wanted an earlier aircooled deal but prices have apparently climbed since i last looked so thats not happening. Still though, I have wondered with the availability of E85 why this isnt more widely used/converted in the aircooled engines? Temps should be reduced and the mid range torque should be greater if NA, thats not even jacking up the compression like you could.... but I also thought this could possibly be the solution for performance turbo applications in the aircooled engines. Sorry not to ramble about Porche, but it would seem to apply here as well if the OP is open to it, if its available to him.

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Re: Coating Air cooled pistons

Post by hoffman900 » Thu Oct 03, 2019 12:52 pm

It could work sure. A lot of air cooled motorcycle race engines are built for methanol. The only issue is installing a bigger tank in the nose on a Porsche, which ultimately screws with the weight distribution. Also, most racing classes prohibit methanol - has to be gas, even in the lawless vintage racing world.

Pretty sure the VW drag race guys run alcohol, where allowed.
-Bob

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Re: Coating Air cooled pistons

Post by tt 383 » Thu Oct 03, 2019 1:40 pm

hoffman900 wrote:
Thu Oct 03, 2019 12:52 pm
It could work sure. A lot of air cooled motorcycle race engines are built for methanol. The only issue is installing a bigger tank in the nose on a Porsche, which ultimately screws with the weight distribution. Also, most racing classes prohibit methanol - has to be gas, even in the lawless vintage racing world.

Pretty sure the VW drag race guys run alcohol, where allowed.
Gotcha, ok makes sense. I guess in general those types of guys are about the experience more so than all out performance too? I thought in the context of the engine here for a motorcycle? 3 "5gal" jugs would fill a tank a few times for little hassle even if its not local to him. Also I thought hoodeng had a great explanation of what would happen if coated.

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Re: Coating Air cooled pistons

Post by 4vpc » Thu Oct 03, 2019 7:22 pm

tt 383 wrote:
Thu Oct 03, 2019 11:24 am
hoffman900 wrote:
Wed Oct 02, 2019 9:21 pm
MadBill wrote:
Wed Oct 02, 2019 9:15 pm
And how do you know it will do that rather than increasing the cylinder pressure and so transmitting more force to the piston?
Paging Nitro2...

Regardless, some of the Porsche aircooled racers report that heads are consumables. Coating pistons, chambers, and exhaust ports increases their life some, but overheating is overheating.
Funny I was looking at Porches the other day and always wanted an earlier aircooled deal but prices have apparently climbed since i last looked so thats not happening. Still though, I have wondered with the availability of E85 why this isnt more widely used/converted in the aircooled engines? Temps should be reduced and the mid range torque should be greater if NA, thats not even jacking up the compression like you could.... but I also thought this could possibly be the solution for performance turbo applications in the aircooled engines. Sorry not to ramble about Porche, but it would seem to apply here as well if the OP is open to it, if its available to him.
They can add quite a bit of value to your house if done properly.
There is no S on the end of RPM.

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