Ceramic coating pistons, exhaust ports, valves, combustion

[1975 Kombi]

I just spoke with my powder coat guy and he quoted me a price of $250 to ceramic coat the top of the pistons and apply a moly based lubricant coating to the skirts, ceramic coat the combustion chambers and exhaust ports along with the valve faces and partial stem and coat the rest of the stem with the moly coat. Also treat the outside of the head with a heatsink coating and the outside of the barrels. Coat the valve springs and retainers.

Has anyone ever done this and is it worth the $250.

Picture from Jake's web site.

He also mentioned that the heads might be able to be re heat treated to bring them up to a T6 aircraft quality. If the seats and studs are removed they may be able to be strengthened back to better then factory. Not sure if that is possible but I thought I would throw that out there.

Any thoughts. I am seriously thinking about having it done.

Here is his web site: http://www.fireballcoatings.com/index.php?option=com_frontpage&Itemid=1
_________________
Brett

“He’s decieving you boy! Reach into his pocket and take what he’s got.” Mr. Crabbs.

75 Westy auto
03 Jetta TDI
71 SB
74 Westy
Licensed pilot (single engine land VFR)
--
Rust In Pieces: 72 Bug, 73 Bug, 81 Rabbit LS D 2D, 83 Rabbit D 2D, 84 Jetta TD GL, 85 Jetta D, 68 Z28 RS 302, 91 Passat 16v

[aeromech]

I have no knowledge on this but would love to see what happens if you try it.
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[1975 Kombi]

He said the heat reduction would be substantial. Which I think is the number one issue with the older air cooled stuff. He has constant business for the pistons and heads on all makes.
_________________
Brett

“He’s decieving you boy! Reach into his pocket and take what he’s got.” Mr. Crabbs.

75 Westy auto
03 Jetta TDI
71 SB
74 Westy
Licensed pilot (single engine land VFR)
--
Rust In Pieces: 72 Bug, 73 Bug, 81 Rabbit LS D 2D, 83 Rabbit D 2D, 84 Jetta TD GL, 85 Jetta D, 68 Z28 RS 302, 91 Passat 16v

[pkrboo]

$250 seems like a good price to me, worth a try i say.
_________________
1979 Sage Green Westfalia P22

[1975 Kombi]

I wish I had new AMC heads but $250 is not bad. I might pick up new valves that could be transferable to another head in case the seat drops.

Just a couple of questions:

1. Should I balance the pistons before the coating. My powder coat guy says the addition of weight is negligible.

2. Should I also lap the barrels into the head after the coating.
_________________
Brett

“He’s decieving you boy! Reach into his pocket and take what he’s got.” Mr. Crabbs.

75 Westy auto
03 Jetta TDI
71 SB
74 Westy
Licensed pilot (single engine land VFR)
--
Rust In Pieces: 72 Bug, 73 Bug, 81 Rabbit LS D 2D, 83 Rabbit D 2D, 84 Jetta TD GL, 85 Jetta D, 68 Z28 RS 302, 91 Passat 16v

[raygreenwood]

Yes, youshould lap the pistons into the barrels.

You can always rebalance the pistons again later...as the removal of material is done inside under the dome...and the ceramic coating is on the outside.

There are some fantastic heat "shedding" coatings out there....but just be absolutely sure they have been tried and used successfully on the outside of a VW head....not an aircraft head...a VW aircooled head and make sure you talk to someone actually using it....not selling it...before you have the head coated on the outside.
There are some definate advantages to this....but there are also some potential issues. Do a lot of reserach.

The wrong coating on the outside of the head (or even just the wrong application method)can actually decrease heat shedding because of the airflow characteristics. The ACVW does not have the same constant speed airflow as an aero engine.

The moly coat is excellent. The Kolbenschmidt pistons always used to come with a moly coating on the piston skirts.

Other than that, the prices seem reasonable. I would go for it. Ray

[WestyPop]

[SGKent]

the supervee folks were doing this 35 years ago. Just make sure the guy has done this type work for well known racers in the area who are winning.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Hoody]

Without new amc castings and Len's magic, you are pissing in the wind.

[1975 Kombi]

[raygreenwood]

Yes, re-hardening the heads works great, but you will need to then check virtually every machined surface for flatness and remachine....which is not too far off what is needed anyway.

Heat cyling does not destroy every centimeter of the head. What it does do is change the elasticity of areas that have been machined into the grain of the casting.
More accurately put...in places where you have an interefrence fit...the part that is fitted is under tension....i.e....valve seats.
With repeated heating and cooling the aluminum around that valve seat reepatedly expands and contracts until it fatigues and loses some of its ability to re-expand properly. In general...simply replacing your valve seats with slightly oversized ones with a proper interefrence fit will restore new metal contact around the seats.

I would only worry about heat treating if the heads have been cracked and welded or seriosuly overheated and alot of warpage is present.

"Aircraft Quality"...is an often overused or misproperly used word. T-6 is a hardening standard used in far more places than the aircraft industry...and not all aluminums used in aircraft are hardened to this standard. In fact...only a few aluminum types are actually what could be described as something directly aircraft quality....and it has "0" to do with teh ardening....its the alloy.

be really careful about what you are being told by yoru machinist...unless he has LONG experience with many ACVW's...and not just occasional performance with somone building a racing engine or aircraft engine. It is not the same. Ray

[Hoody]

Good luck with it.Let us know how it turns out.

[SGKent]

you said one thing that concerned me - that the seats and guides looked Ok. That is not how you decide whether they need to be done. You can't turn them into good heads just by coating them. The guides, seats, valves etc all need to be co-ordinated with the machinist. You also need to look for cracks and possible bad studs. The cylincer mating area needs to be flat also.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[1975 Kombi]

Ya I hear you. I need to be there when the machine shop guys checks the heads. I hate taking the guys word when I don't know if he checked everything possible. He isn't a Len Hoffman.
_________________
Brett

“He’s decieving you boy! Reach into his pocket and take what he’s got.” Mr. Crabbs.

75 Westy auto
03 Jetta TDI
71 SB
74 Westy
Licensed pilot (single engine land VFR)
--
Rust In Pieces: 72 Bug, 73 Bug, 81 Rabbit LS D 2D, 83 Rabbit D 2D, 84 Jetta TD GL, 85 Jetta D, 68 Z28 RS 302, 91 Passat 16v

[Hoody]

Put the 250 towards new amc castings.Those valve guides and seats are spent.

[1975 Kombi]

[raygreenwood]

[1975 Kombi]

Well I got the word from the "Hoff" himself on the coatings. He wouldn't coat the combustion chamber or the top of the pistons. Reason being the heat tends to build greater then normal on the section of the piston just under the top and above the top ring and causes severe heat issues and possibly welding the top ring to the ring land. Instead of the heat being absorbed into the head casting it just bounces around until it finds something to transfer into. He recommends exterior heatsink coatings on the head and cylinder fins only.
_________________
Brett

“He’s decieving you boy! Reach into his pocket and take what he’s got.” Mr. Crabbs.

75 Westy auto
03 Jetta TDI
71 SB
74 Westy
Licensed pilot (single engine land VFR)
--
Rust In Pieces: 72 Bug, 73 Bug, 81 Rabbit LS D 2D, 83 Rabbit D 2D, 84 Jetta TD GL, 85 Jetta D, 68 Z28 RS 302, 91 Passat 16v

[raygreenwood]

[markd89]