The 944 turbo heads were not coated. They had a ceramic liner cast into the head.
These block were not nikasil. They were alusil (aka Reynolds 390) a la Chevy Vega. Most of the German cars use alusil or a variation of this. Reread the speedtalk link.

 

These block were not nikasil. They were alusil (aka Reynolds 390) a la Chevy Vega. Most of the German cars use alusil or a variation of this. Reread the speedtalk link.[/QUOTE]

Thanks, but not only have I seen threads that contradict the Speedtalk claim, but I just got an email from a well-known 928 re-builder that referred to these finishes as Nikasil.

Could people be using these terms interchangeably?

 

http://www.autofieldguide.com/articles/110307.html

 

Engineguy on speedtalk knows his stuff. Nikasil is an applied coating. Alusil (Reynolds 390) is a high silicon casting that is machined/treated to leave the silicon crystals proud of the surface. On the aircooled engines, Porsche went back and forth between nikasil coated cylinders and alusil cylinders and back to nikasil coated cylinders AFAIK the watercooled 944/928 were always an alusil block.

Not if they know what they are talking about. There are aftermarket Porsche builders who put a nikasil coating on an alusil block for increased durability. http://www.928motorsports.com/services/uschrome.html

 

thanks, JCR

 

I've seen failure of the head gasket on a turbo M3 with a T-76, when both the combustion chamber and the tops of the pistons where coated. The problem we found was that the heat had no place to go and the head gasket became the wic. You can coat the tops of the pistons but just don't do the combustion chamber or vice versa. Also one thing to take into consideration is that the tops of the pistons will not always stay nice and shiny like when first installed. I would lean towards having the combustion chambers done with the intention of creating a "reflection" back towards the piston to achieve as much of a "complete" combustion as possible.

 

Expanding beyond just coating, are there any ongoing investigations by any manufacturer into cerametallic blocks? or have they deemed it too expensive to theorize about anymore?

edit: nikasil - patented thin layer of some Nickel silicon-carbidish product by Mahle... I think.

ceramic coating can be done, but mindful of the thermal expansion, nikasil/etc on an Al. block allows a bit tighter clearances.
I think that's right... ?
threadjack:
and thinkingGTM, that GTM is **** man...

 

A mid-engine, ~2500lbs vehicle that can handle over 800hp, with a big enough engine bay for all that power to come from an American-style V8, brought to market by one of the most respected builders around, at a fraction of the cost of a mainstream exotic.

Gotta love it!

I'd want one no matter what it looked like. (I started looking into this when it was far uglier.)

 

Hop,

In your experience, can an engine using readily available components be put together so that all surfaces exposed to the burn can/should be coated with a ceramic finish, or do the BTU #s simply not add up to making this possible?

Also, can one coat Nikasil and/or Alusil with these thermal ceramic coatings? (My context is a sleeveless aluminum block.)

 

This is an excellent thread. Kudos to those who have healthy skepticism sp? (is there a spell checker here?).

The practical engineering experience and advice offered has been good. Yet so has the polite and honest request for proof. I was saddened and disappointed with the Dart representative when he took offence to what looked like a fair and humble question and request for more proof and then started grouping all of us in LS1tech.com as bull headed and unreasonable. I'm sure that Dart has mechanical engineers on staff who were taught classical statistics and conventional science testing methods. They should come on-line here and give the thumbs up to the request for better testing proof. Mechanical engineers know exactly how and what bias can be introduced into experiments/tests. (or should know). Hey, I have heros too, like the late Smokey and recently the late Lennart Bergqvist who's testing and opinions were very valuable and many held onto all of their words and writings. If the motor seems to make more power then I'll stick with that tune up no matter what. But we remain curious as to why the motor made more power with that tune up. If we really learn the why, then we'll be even further ahead.

But it's neat.
The 2 independent tests performed, (by somewhat non-biased enthusiast), are very revealing. The results showed that a thin layer of Tec-line ceramic coating has no affect what-so-ever on heat transfer, (good-or-bad). That has me wondering why. Would the radiant heat be measured well by the test thermocouples and at a useful resolution? What is the heat that is showing up in the higher exhaust gas temperatures of the Dart Machinery testing? I wish I knew and this is very curious.

This being the advanced tech forum, we could possibly discuss that. I have no idea as to why ceramic coated piston tops seem to reject heat and allow more to enter into the exhaust during the Dart testing yet the independent torch testing was not able to measure an ability of a ceramic coated piston top to reject more heat than a non-coated piston top. Is infrared heat energy produced or some product of internal combustion? Dart stated (paraphrased) they needed to add more fuel and fuel is power but was that extra fuel actually making power? (I just assumed "yes") but I don't think it was stated. The extra fuel added my not have resulted in more cylinder pressure or power or whatever.

Well, it's fun to read all this and please keep it up gang.

Karl Ellwein

 

FWIW, they use ceramic based thermal barrier coatings (TBC) on hot parts of after-burning engines. Some of those parts test the upper limits high term Inco and it doesn't flake off; I'm sure it will be fine on a piston. They definitely make a huge difference, otherwise they wouldn't be there when tenths of a pound are accounted for. How well they work- I can just say "well." Beyond that, my lips are sealed.

However, these coatings are different. They have a bond coat and a TBC on top of that.
I'm also seeing indications that people are confusing wear coating with TBC. They are definitely not the same. wear coatings are silicide based stuff. TBCs are ceramic based stuff.

 

I highly doubt that was the case; I think that was just a case of coincidence. I had a professor who did R&D with full ceramic motors to eliminate coolant back in the day. Apparently, all the extra heat just went into the exhaust
Anyway, no reports of blown head gaskets. I mean, how much additional heat is it going to create? Road race cars run WOT with high specific output (read: hot!) all day without blowing head gaskets. I cant see a coated chamber doing that.

 

shh, dont tell anyone, but I heard higher compression can give you more power.

In all seriousness, they's probably coat them for the thermal resistance alone.

I also saw a post talking about the coating only being 1 thousandth thick? if that's the case simple heat transfer will tell you it wont provide much thermal resistance.

 

In all seriousness, they's probably coat them for the thermal resistance alone.

I also saw a post talking about the coating only being 1 thousandth thick? if that's the case simple heat transfer will tell you it wont provide much thermal resistance.

Very good point by TreyZ28. The TBC has shown by all the tests spoken about in this thread to help with longevity of the piston.

There is another thread somewhere in here that simply links to a Chevy High Performance magazine interview with Darin Morgan of Reher-Morrison and Morgan gives some general engine building tips. One very interesting comment was concerning TBC.. . . . . The link to full artical

Two things here. 1) He has seen some power gain when coating the piston crowns and combustion chambers.....(I'll take 6 hp if it only cost $200).....
2) He has seen a LOT of power gain if the motor is lacking in things such as chamber design....

There could be a testing tool here. A tell-tale of how well your engine or my pile is designed. If I put one of my piles on the dyno and test with and without TBC and there is no measurable difference in power then I may have hit upon a good design and I'll probably stick to that combo for a while.

This whole thread has been a very good read and one of the main reasons to be a member of LS1Tech.com.

Karl Ellwein
Ellwein Engines

 

Good points.

Personally I haven't used the coating(CBX by Techline in my case) to hold the heat in the combustion chamber, but to help protect the pistons in nitrous applications.

Since Ive switched to turbocharged alcohol , both Methanol and then E85, treyZ28's statement brings up an interesting point about pumping more heat in the exhaust. With the alcohol running as cool as it does I'm sure the turbos could use the additional heat going into the exhaust to spool up faster. This would hold true for turbocharged gas applications as well, even though the parts reliability would become a issue sooner due to the higher combution temperatures of gasoline. On tear down it may be time to coat the new pistons, Chambers and Valves.

Being this statement is coming from Reher-Morrison I take it they would most likely coat their engines since 6-8 HP to a Pro-Stock team is much harder to come by than a turbo or nitrous car. If it's worth any power and they are allowed to use it you know a competitive Pro-Stock team will be using it .

 

I can't believe I just read all of this. It was interesting up to the arguing point, but got better towards the end.

 

"What can be asserted without evidence can be dismissed without evidence."
- Hitchens

 

And here you are,14 years late to the party. Slow morning??

 

Nice G, way to make friends and influence people. Did they make you the head of the snarky comment department? I guess I had better things to do with my time than sit there at a computer and troll comments on these boards, so who's having the slow morning?

BTW- the reason I found this thread was research into ceramic coatings, and after reading nine pages of arguments back and forth, the question of scientific independent verification was a valid-and unanswered- question posed by some of the members.

 

...which really added nothing but a bit of useless philosophizing. Nobody in the thread will ever see it after all this time. Hence my comment. But maybe it made you feel better...
You are way too easily offended. I was not offensive at all. Grow a thicker skin.