View Full Version : Nikasil coatings for small engines?
02-18-2005, 11:14 PM
My current model engine project requires a steel cylinder but I am tempted to try an aluminum one and coat the inside of the bore. I thought about chrome, but the snowmobile crowd swears by Nikasil. Is this a nickel-silver alloy? I tried Caswell but they don't have any such thing. I was thinking of their electroless chrome coating for the bore of my cylinder. Anyone have any thoughts on this? Does a cast ring ride in a chrome cylinder okay, or do you have to hone the cylinder rougher to carry oil on the walls?
02-18-2005, 11:27 PM
Only thing I know bout Nikasil is it "was" expensive. I had a porsche carrera with a 3.2L engine and the barrels (cylinders) were lined with nikasil.
It made it expensive cause you could not bore or even hone the barrels and I had to buy special, very expensive rings, and the pistons were matched to the bores. What a pain. JRouche
Is that what they use in BMW motorcycle cylinders? I know they last forever and I have heard that they are replaced rather than rebored when "forever" arrives.
02-19-2005, 12:13 AM
I've wondered about PVD coatings for similar (flame resistant) coatings to resist flame checking of machinable steels. Machinable steels generally have a pretty high sulphur content which is burned out by the heat and flames, leaving a surface that is heat-checked which flakes off. Try a google search for PVD coatings. Sounds plausible, but I don't know how well they can control it dimensionally, or how deep they can throw it in a hole.
02-19-2005, 01:38 AM
I think nicasil coating is nickel plated on the cylinder wall with silicon carbide powder in a bubbled liquid suspension. Another way hard coating can be put on is with flame spraying. I do a lot of snowmobiling and the ni.cl. is used in almost all of the newer stuff. It is very durable but is a little on the brittle side when it comes to melt downs ( piston too big for the hole). I tried to find products and tecks on the net but couldn't find any let me know if you find a way to do this at home. I to have a .15 traxxas motor amazing little engines.
02-19-2005, 04:17 AM
Actually Nikasil is so hard it can be honed quite easily. Machinists that cater to the Porsche crowd do it all the time. There is quite a bit of missinformation out there about Nikasil. I've even seen guys bore them out and re-nikasil them! It's Alusil that is basically a use once and forget it coating. Although there are a ton of other coatings out there these days. EBS engines in NV has all kinds of interesting coatings.
02-19-2005, 07:22 AM
It's probably OK for model use but I don't think BMW or Jaguar would want to to admit how many millions & millions & millions of dollars they've spent replacing Nikasil equipped automobile engines, in & out of warranty due to premature failure. Aluminum cylinder walls ain't real happy when their thin little coating of miracle metal goes bye-bye! http://bbs.homeshopmachinist.net//wink.gif
In the real world, sometimes it's hard to beat the old school way of doing things. http://bbs.homeshopmachinist.net//smile.gif
Norvel (Russian) model airplane engines do extremely well with their "Revlite" cylinder technology. Not sure how it's appied or if it can be done in a homeshop environment but it sure makes a powerful, efficient engine and is extremely durable. I think it's a variation on an aluminum oxide coating process.
When new, they're so tight at TDC you can't turn them over by hand. The instructions say to take the head off, fill the cyl. with oil and let it soak (it must be somewhat porous) then turn the engine over 100 times by hand before attempting to start. Most guys just heat the cyl. up real hot with a heat gun and hit it with an electric starter.
Once broken in, they have marvelous compression and seem to be immune to lean runs. Dang Russians....must be the Vodka!
02-19-2005, 07:39 AM
The last model aero engine I did had a steel liner and a C.I. piston lapped to fit.
If you are not using rings the expansion ratio between piston and liner/cylinder need to be similar.
O.S. engines used to make ringed motors running in their own liner coating.If you go the home electoplating way be warned,any missing plating will give you problems,well it did in a Rossi motor I had with some plating missing at the top of the bore.
02-19-2005, 08:34 AM
You would not have a problem if you went with a steel cylinder and had it 'hard chromed'. Iron rings love it.
Also, I think there are companys that respray nikasil. Can't desribe the proccess. And I don't think it's in the realm of the HSM.
On the hard chrome you have to watch how thick it's allowed to get, the plater would be able to help with advice on that. And it does hone.
I'm sure you will get a better desciption/advice than I have given however.
02-19-2005, 08:38 AM
Nikasil will tend to flake off of aluiminum
just like chrome plating does.
02-19-2005, 09:09 AM
Man, I got a flyer in the mail from a company that rebores and rechromes liners and walls. They were redoing the nickleseal too.. And I just threw it away last week and cant remember who it was. I remember it was not to bad as far as cost. I wish I woulda had it years ago for dirtbike stuff. They could even weld up a gouge and rebor it then re-seal it...
02-19-2005, 09:23 AM
A little off topic, But the other day I was fortunate enough to see a guy who just had put a supercharger on his R/C truck,I just thought it was cool.
02-19-2005, 11:00 AM
Nikasil or electrofusion cylinder bores are used on most Japanese motorcycle engines, both 2 or 4 stroke, produced in the last 5 or 6 years. There are innumerable benefits over spun steel liners, not least of which being improved heat dissipation giving the ability to run much tighter piston / bore clearances, as with any process if the plating & honing is done properly it will far outlast any steel cylinder liner & will not flake or peel, here I suspect people are confusing Nikasil bores with the chrome plated bores used a long time ago which were very troublesome & prone to flaking.
I have used the company linked below for a number of years, who also have a plant in America, their work is absolutely excellent & they are great people to deal with.
02-19-2005, 04:47 PM
Mercedes, Porsche, and BSA? Yup, my 1966 Victor Grnd Prix 441 has chrome lined aluminium cylinder. Doug
02-19-2005, 06:27 PM
you can also try these sites;
02-19-2005, 06:28 PM
02-19-2005, 06:30 PM
02-20-2005, 02:20 PM
There is an extremely low friction Boron Nitride plating you can get from http://www.caswellplating.com/kits/bnen.html
It is used on Gattling guns and high speed firearems to reduce friction - helps prevent wear too - great for slides and frames...
[This message has been edited by Thrud (edited 02-20-2005).]
02-20-2005, 02:58 PM
With a nick like rsr911 I just had to chime in here. Yes nikasil is an excellent setup, it can be honed (EBS mentioned earlier does this). I've seen nikasil lined 911 engines go 300K miles without ever removing the heads. I would think on a model engine this would be a "set it and forget it" experience.
I seem to remember BMW's issue with nikasil was poor engineering and not the nikasil itself. Something about not leaving enough clearence for thermal expanision. On a air-cooled engine the pistons and cylinders expand at about the same rate compared to a water-cooled cylinder. Either way Porsche has enough success with endurance racing to suggest that nikasil is tough stuff.
-Christian D. Sokolowski
[This message has been edited by rsr911 (edited 02-20-2005).]
02-21-2005, 02:49 AM
Nikasil is an acronym for Nickel-Silicon, it has been used for the last twenty-five years at least on Stihl and Husqvarna chainsaw engines. If the air filter is cleaned and you don't lean it out the lining is bullet proof. I don't know of anyone who can redo it.