The V8 Owners Forum -

has anyone herd of getting liners coated with a low friction coating?

my friend who just done a motor sport eng course was sayign it would be worth lookign in to, and reconed that it could give power gaines, if it did then it would also give economy gains as would be free power.

tho i dont know if this is somethign which is available to road cars but he recons it is a done thing.


Ralph

My personal view of all of this sort of stuff is that it's just "snake oil"

(In other words, a load of cack!)

double edged sword that one if it can be done.. If you have no friction your rings wont bed in giving poor sealing and low power. Coated pistons with teflon or whatever is fairly common though.

Dry film coatings are definately not a load of old cack!, but unless used in conjuction with many other detail mods then they would certainly not be the most effective use of your £'s with regard to horsepower gained. If you have an expensive racing engine with a strong lightweight rotating assembley and enough air/fuel to satisfy the demands of your engine then then next logical step in the search for hp/rpm is to reduce the internal friction within the engine. Use of carefully selected clearances and appropriate oils together with some of the coating technology now available can achieve this. Used on it's own as a mod in a mildy tuned engine coated pistons are unlikely to show an appreciable gain. The reasoning behind coating pistons rather than bores is, I suspect, that coating would innevitably become damaged by being in contact with the rings (remember the nikosil debacle with the early jag v8's..). On coated pistons the areas most exposed to high thrust loads are coated for reduced friction, it is not really neccessary to coat the whole bore. The crowns are often coated with a thermal barrier coating too. It's all Nth degree stuff really to eek the last few % out of already well built engines.

Various dry film and related coatings can be successfully applied by the diy enthusiast, but as has been stated the gains from their use to reduce friction are questionable without very careful attention to clearances. However, thermal barrier coatings seem to give real gains when used sensibly - many people report satisfaction with coatings on exhaust headers if only for their cosmetic performance, do some reading then the maths and you find that coating the inside of headers gives more performance than coating the outside. Personally I've seen pistons with a thermal coating survive failures that had previously damaged uncoated pistons.

If you are realistic in you expectations then they work - don't look for a twenty percent increase in power

Dave

I guess in my rather short post I should have been a bit clearer.

I was referring to the type of stuff that you pour into the engine oil which then claims to carry out all sorts of miricles.

I agree with other posts in that there maybe some benefit in an "applied" coating but in the real world you'd be much better off in terms of BHP by spending your money on other areas of improvement with these "old world" V8 lumps.


Pete

You need to be a little carefull what you put into what engine, the molibdimum disulphide ones especially, they can have benifit on an engine that has flat tappets, and no roller or ball bearings fed by the engine oil, but anything with a roller bearing surface will be dammaged by the stuff. Graphite based ones are good until they start to "clump" with the breakdown products of combustion, then they will tend to bung up your oilways. Teflon based ones are pretty safe and by some accounts do reduce friction but it is ridiculace to claim they form a low friction "surface" with continued use, you have to add a new bottle every time you change the oil.
Good synthetic oil of the correct viscosity at the right temperature is best IMHO.
Mike

I was reading that the teflon based snake oils can slowly choke the oil filters with the build up of Teflon particles....this in turn reduces the efficiency of the filter.

That makes sense....but I wonder how long it would take. My train of thought says that I would have changed the filter long before it became clogged with teflon....

Just quoting what I read.

Have to say I have never thought much of oil additives. Oil company's have never been one to miss making money and none of them do any of these additives or include them in oil. Also interesting to note Castrol don't sell Magnatec in the states or any brand with similar claims. Me thinks they know they would get sued over there like all the other companies, remember Duralube?

I'm sceptical of these 'additives' aswell. Not just additives for oil, but these fuel additives you can buy in garages nowadays.

Personally, I just stick a reasonable oil in, and don't take much notice of brand names such as castrol which cost 30/35 odd quid a carton. I mean I'd go to the local automate and buy a can for 10 or 15 quid, just for gneral road use, but wouldn't get oil from Wilkos for £2:50. I wouldn't put additives in though, because I think it's just a waste of moular.

I did quite abit of testing on this sort of thing when I worked at Cosworth, liner coatings on the whole weren't very effective and the ones which did give power were scraped off by the rings fairly quickly.
Piston coatings on the running faces does work tho' we used a DLC / Balinite C coating all over the piston with the exception of the crown which was polished.
This gave about 2HP / piston at 18,000Rpm

So don't expect night and day differences on 6000Rpm V8, if you really wnat to drop the friction thin piston rings and dry sump it that should net about 10-15 Bhp

Matt