nikasil cylinders

[Mytonic]

Merry x-mas all, I'm looking for feed back on nikasil cylinders. I would like to hear from anybody who has been following nikasil cylinders around the sky for a few years, how are they holding up and what brand are they. Chucker, what brand are you purchasing? Thanks

 

[Chucker]

I am talking to Scott Casler at Hummel Engines. He turns the cylinders from 6061 T6 alloy then sends them to US Chrome for their NiCom coating. They are 1/2 the price of L&N nickies and three times the price of the Chinese models being sold by QSC on eBay.

One of my concerns is thermal expansion. The aluminum will grow twice as much as cast iron. It is this growth that can drive the cylinder into the head and cause a loss of head torque. This can eventually lead to blow by and loss of compression. Some our colleagues here have experienced the loss of torque issue recently....and they were using cast iron cylinders. The real culprit is excess head temperatures that soften the aluminum and allow it to deform. With twice the growth using aluminum cylinders the clamping force at operating temps will clearly be higher than it would be with cast iron cylinders. When I asked Scott about that issue he said that he uses stainless steel sealing rings between the heads and cylinders to avoid the deformation problem. He also said that head re-torquing is necessary, but no more frequently than engines with cast iron cylinders. Hmmmm?

 

[Mytonic]

Chucker, thanks for the info, Do you know if the Nikasil cyl require a specific piston and rings? Hummel price list has only nikasil cylinders.

 

[Chucker]

According to Scott, no. Head studs, Pistons, and rings are all stock. You might want to visit the US Chrome website. After they coat the cylinders they hone them to exacting specifications. They also have coatings for pistons to improve fit, performance, and longevity. I have not asked Scott yet but it may be worthwhile to send the pistons back with the cylinders to have them matched. But that may be overkill.

 

[Bil4381]

Here I thought only Jabiru engines had aluminum growth issues and needed retorqing at regular intervals. One of the reasons I went to the Jab 3300 engines is that growth or bolt pulling issues are not immediately flight threatening. Bill