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Piston skirt coatings?

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Piston skirt coatings?

Posted by robert_tuck at October 09. 2017

My 99 was rebored and fitted with 650 SS short skirt pistons, 41/2 thou clearance. It is now nicely bedded in and has really good compression and goes very well.  It is a little noisy  with  cold slap just like many other 99's I have heard. I am considering to get the skirts coated at my next stripdown to O/h the crank, Has anyone tried this? ,used a lot in modern race engines.

Re: Piston skirt coatings?

Posted by Charles Bovington at October 09. 2017

A good proportion of friction losses in an engine come from piston skirt/ liner contact. Coatings used in race engines are to reduce this friction loss. Not really worth the trouble in a 99 dommie.

Re: Piston skirt coatings?

Posted by robert_tuck at October 09. 2017

Don't want to go faster,just to run quieter.

Re: Piston skirt coatings?

Posted by john_hall1 at October 09. 2017

Remember STP!

Re: Piston skirt coatings?

Posted by Charles Bovington at October 09. 2017

Previously robert_tuck wrote:

Don't want to go faster,just to run quieter.


Don't think coatings will help you. just love your dommie and accept the noise.

Re: Piston skirt coatings?

Posted by Gordon Johnston at October 09. 2017

You could always just buy ear plugs. Much cheaper!

Re: Piston skirt coatings?

Posted by anna jeannette Dixon at October 11. 2017

silicon-based firecoat  VHT 400g spraycan witch has been tested to  650F temperatures witch you can by off E-bay.co.uk  yours  anna j

Re: Piston skirt coatings?

Posted by Charles Bovington at October 11. 2017

It is a car spray paint for High Temperature applications. I really would n't try this on your pistons.

Re: Piston skirt coatings?

Posted by robert_tuck at October 12. 2017

Previously Charles Bovington wrote:

It is a car spray paint for High Temperature applications. I really would n't try this on your pistons.

I was thinking of a slippy coating of about 1 to 11/2 thou , these are now routinely used in automotve applications.

Re: Piston skirt coatings?

Posted by anna jeannette Dixon at October 12. 2017
Previously Charles Bovington wrote:

It is a car spray paint for High Temperature applications. I really would n't try this on your pistons.

hello it's not an external car spray   but made for internal engine parts as its high-temperature silicone based or ceramic coating like extreme coating others like camcoat and others  use your computer for more information    has used in Nascar   yours  anna j   
 

Re: Piston skirt coatings?

Posted by david_evans at October 12. 2017

I would have thought that 0.0045" was a good clearance for an air cooled engine, reducing it further may end in tears, Check that the slap isn't the carb slides rattling or something else.

Re: Piston skirt coatings?

Posted by Fritz Wettstein at October 13. 2017

Why coating the pistons? They shouldn't get in contact with the barrel, because there has to be oil.

Fritz

Re: Piston skirt coatings?

Posted by Charles Bovington at October 13. 2017

Previously anna jeannette Dixon wrote:

Previously Charles Bovington wrote:

It is a car spray paint for High Temperature applications. I really would n't try this on your pistons.

hello it's not an external car spray   but made for internal engine parts as its high-temperature silicone based or ceramic coating like extreme coating others like camcoat and others  use your computer for more information    has used in Nascar   yours  anna j   
 


It is used for insulation of high temperature exhaust systems and has been used on piston crowns. But use on the skirts at your peril! Other expensive coatings may be applied to skirts (piston) but I fail to see the point on a 99 dommie. Will not cure piston slap. 40-60 % of engine friction losses are from piston / piston skirt  contact with the liner. There is an oil film formed between rings and liners because of the wedge or barrel shape of the ring profile but little between the skirt and the liner.

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