VHT / Piston Crown

[cycle]

Hey everybody,I"m new here,so if this has been posted before bear with me.I build motorcycle drag race engines for a living. I recently read somewhere that a auto drag racer took his pistons , blasted the dome with aluminium oxide and painted them with white VHT header paint.Did the same to his aluminum heads. Now I do know why he did it,to cut heat loss , (energy). Here is what is hard to believe,he gained on the order of 25 H.P.!!! Has anyone heard of this or tried it?? I"m in the process of building a alky/turbo engine. Due to alky "cold nature" and low energy value I" giving this some serious thought. Craig

 

[MaxRaceSoftware]

VHT stuff was a very long time ago
you have to go back pretty long ago for some of those magazine articles....in the articles they said it was worth some HP ???

i did 2 personal experiments ..one was small block Chevy
350 cid with aluminum -VS- cast-iron heads
the other was a Hemi 426 cid engine with aluminum -VS-
cast-iron heads ...i tried the best of my ability in being able to duplicate flow, velocity, and port shape and bowl-shape by making a large number of horizontal and vertical aluminum templates ....the cast-iron heads made
more HP/Torque than the aluminum head replicas
the range was 8 to 15 hp from memory between the Hemi and SBC tests ..would have to look at data to be more exact

so i can easily see HP gains with coatings ..one other time
in a SS 305 coated pistons there seemed to be an honest 4 to 5 HP gain.

Another time we tried a 500 cid BBC aluminum block
vs cast -iron block ..the cast -iron block made a bunch more HP

Again we tried it on a aluminum small block -vs-
a cast-iron small block ..again a bunch more HP
with cast-iron

so since there can be that much differences..there should be HP gains in some coatings

we tried the header coatings ..but in those tests they were on highly optimized Super Stock engines we had dynoed
for 2 years + and tried everything as far as headers
over 2 years...when we tried the same exact headers coated =vs- uncoated there were no real HP gains that were
attributed beyond the repeatability of the dyno
we might have seen 1 HP one way or the other or less, at the track all 3 cars ran the same..these guys make a bunch of runs in a year and keep records of weather and track conditions, lanes, etc. we couldn't see any real gains or losses in actual track times with or without coated headers
,,,maybe some one has better and more car data ???

but i definetly recommend you coat headers inside and out..they will last a ton longer and a bunch prettier
to look at and handle..no rust coming off in your hands .



Larry Meaux (meauxrace2@aol.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

 

[cycle]

Thank You for the reply Larry. I could have sworn it was in a recent "hotrod" type magazine. I just can"t remember the right one. I have hundreds of them !! It would seem a professionally applied coating would be best, but it is hard to argue with a 6.00 dollar can of high heat paint. At the very least it would be a great experiment. I don"t think I would make it routine..I do have a dyno, I might just have to try a before and after,with NO other changes!! Craig

 

[MaxRaceSoftware]

Craig....on the SS 305 we were only allowed to coat the piston top ..the chamber has to remaim FACTORY stock OEM
..and that was a cast-iron head....so coating or doing the same experiment with an aluminum head and being able to coat the chamber also maybe worth more than the 4 or 5 hp we seen on the SS 305

additionally;

i did #041x SuperStock heads and intake manifold
for a NHRA SS/I stick 1967 Camaro with the 327 cid engine

he set the NHRA SS/I record the record was even faster ET than the 2 higher classes . NHRA "retired" this record after 2 years no one breaks it..they put back a few tenths higher to let some one else have a try

he ran this cloth=type wrap completely around his headers
..the car didn't run faster ...but he left it on there
to "psyc" the competition and make them spend money and time needlessly ...a really nice guy ,,but you didn't want to be in his same SS/I class ..no help from him Larry Meaux (meauxrace2@aol.com)
Meaux Racing Heads
MaxRace Software
ET_Analyst for DragRacers

 

[evelrod]

cycle---

I did what you anticipate with the cheapo approach to coating pistons and aluminum combustion chambers , still do occaisonally, and , although I found no hidden horsepower on the dyno, I did find the engine kept its edge a bit longer on the track. Went TWO seasons on one of them with little performance drop. When I refreshed the valves, it was a BUNCH easier to clean up!!!
Did it make more HP? Quien sabe! Looked pretty cool there on the bench, though.

There was an article on VHT coatings in Hot Rod mag last year, but I don't save them anymore, besides I think it was intended for the "looks" crowd. Book on advanced engine building and tuning techniques from about 30 years ago, maybe Smoky Yunick or Carrol Smith, can't remember, sorry. Larry might know of it.

Give it a try and get back to us, we are always open to new data, good or bad.


Rod

 

[cycle]

Thanks for the info Rod. Wish I could find that article. I'M starting to think it was a bad dream. It would seem seem piston top coating still has mixed results. I liked to spend my ,and my customers dollar wisely. Craig

 

[evelrod]

I'm not sure it matters, but I used 'white'.


Rod

 

[GregLocock]

Well it might improve the heat rejected into the piston, so colour could be important.

The paint could be doing (at least)

(1) insulating
(2) reflecting radiant heat
(3) different surface texture
(4) WAG - different wetting properties

Paint colour would only affect (2), but if so you'd expect white or silver to be optimum (I don't know what these colours are like for absorption in the IR spectrum)

Cheers

Greg Locock

 

[Darkman270]

Please check out this web site. It seems to offer some solutions to these questions. This page is a dyno test with some amazing claims.

http://www.hpcoatings.com/engine_coatings.htm

I would be interested in your comments. They seem to make logical claims but..... Your thoughts on this would be greatly appreciated.

 

[cycle]

Darkman, I looked at the HPC website. Interesting. I suppose there are some merits to different types of coatings,however I find fault in there test.To start, they used two different dyno facilities on two different days.Would the same engine with no changes make 5% more power just through a dyno and/or day change?? Very possible. The next parameter I see fault with is using many different coatings in the same engine. This does not reflect ONE coatings ability to do a paticular job.Had they coated,for instance, ONLY the piston dome then maybe it would have been a more viable test.(regardless of outcome). So,One of two things will have to happen. Either some hard,hard facts will have to reach me from a very reputable source or in the future I will have to dyno test different engines for myself. I believe the latter to be the best bet. Craig

 

[evelrod]

Craig, a whole lot of this 'speed tuneing' thing is "monkey see, monkey do". I have used the VHT paint and found that it actually stayed on the pistons. This led me to believe that, for no good reason I can come up with, it worked.
How well it worked, and in which direction it changed the power output---weeeeeellllll?????? I did not use it on the last several engines I built, including my 1275 Mini Cooper.
I built the engine in Sept. but have yet to turn it over. Maybe I'll pull the head off and try some coatings. I'll let you know what happens if I do, but it may be next summer before I get the car finished, still have the inst. panel to build and the TOTAL wireing to do.

As to the hpcoatings.com site,' been there, none that'! I learned the 'scientific method' in high school, and after 50 years, I am still totally amazed at the number of so called 'miracle cures' end up being the result of poor or faulty method. Caveat emptor---

Rod

 

[Darkman270]

Valid points!!

They should not have used different dynos. The logic is valid on the friction reduction and heat reflectivity. I have requested pricing but no response so far. I do know that NASCAR and top NHRA people use the coatings so there must be something to them.

Charles Buzbee

 

[cycle]

Yes,I know. An old thread. Well I had to tell everybody I just found that old magazine article.Finally!! It was a 406 cu.in. Chevrolet built by Joe Sherman. A pretty well known engine builder & well respected. Anyway,I rechecked the article and the claim was 40 h.p. gain by just spraying the piston crown with white VHT!!! Remember,This is in an engine that had already been flogged pretty well on the dyno.Pre piston spraying max h.p. was 770 h.p... After spraying the crowns max was 808 h.p.!! Again remember this is a (seems to me)pretty well thought out piece to begin with,,at 770h.p.out of 406 cubic inches.. To gain another 40 h.p. would ordinarily take some doing. I know it is quite a claim ,but?? This was in the November 2000 issue of Car Craft magazine..... Craig