Piston thermal coating

[4vpc]

The new Dynomation package has piston and chamber coatings as an option, I'm still getting to grips with it, but initially it shows quite noticeable gains. It doesn't have a head material choice, so I wonder how much that matters....

[digger]

I wouldn't rely on a elcheapo 1d sim for this kind of stuff. The combustion model accuracy and heat transfer calculation is not going to be accurate enough. Unless you've done correlation testing I'd take it with a grain of salt.

[4vpc]

Yes i'm inclined to agree, I did wonder how they'd managed to calculate that with some reasonable accuracy. Then I got to thinking if it's so inaccurate why did they put it in?!

[MadBill]

I wouldn't rely on a elcheapo 1d sim for this kind of stuff.

So, if five hundred bucks is 'elcheapo', how much would you be willing to pay for an adequate program?

[4vpc]

I wouldn't rely on a elcheapo 1d sim for this kind of stuff.

So, if five hundred bucks is 'elcheapo', how much would you be willing to pay for an adequate program?

Contact Ricardo, I think theirs is reassuringly expensive
Or to put it another way, no prices on their website mean if you need to ask, you can't afford.

https://software.ricardo.com/

[Mark O'Neal]

One thing I've always like about "baked on" coating is, if you do it just right, you can suck the heat treat right out of the pistons.

[In-Tech]

One thing I've always like about "baked on" coating is, if you do it just right, you can suck the heat treat right out of the pistons.

[4vpc]

One thing I've always like about "baked on" coating is, if you do it just right, you can suck the heat treat right out of the pistons.

What temp would that be?

[MadBill]

Well according to the literature I've read, the operating temperature at the center of the crown can reach 300°C.(572° F.), well above any likely coating bake temperature, but skirts could be as low as 300° F.
A practice by some is to check Rockwell hardness at various locations on the crown of a used piston, to determine loss of heat treat and thus maximum temperature reached.

[Mark O'Neal]

One thing I've always like about "baked on" coating is, if you do it just right, you can suck the heat treat right out of the pistons.

What temp would that be?

Beats me. I only got to deal with the aftermath.

[In-Tech]

Disaster, but it is humorous when someone shows me their great thermal coating and they have cut through it for valve pocket depth after the fact. It's the same as indifference of coating depth. It WILL find the heat relief AND concentrate on that. I don't understand why this isn't common knowledge of heat dissipation regardless of the material. I "painted" pistons many years ago, use a torch and learn something about pin clearance and dome thickness, not in an even temp oven.

[David Redszus]

A practice by some is to check Rockwell hardness at various locations on the crown of a used piston, to determine loss of heat treat and thus maximum temperature reached.

Aluminum can be alloyed with a variety of elements to modify its strength.
Depending on the alloys, it can then be work hardened or heat treated to
further increase its yield strength.

But aluminum yield strength is quite sensitive to elevations in temperature.
As the metal gets hotter, it loses its strength. Not all alloys will loose their
strength by the same amount or at the same temperature.

In addition, under tensile loading, aluminum will change its length as a
function of temperature.

This worksheet shows the yield strength and elongation of aluminum at a
range of temperatures. The upper limit of any aluminum is very close to about
450 oF. Beyond that point, it will become considerably weaker.

By knowing strength of aluminum before exposure to heat, and measuring
its strength after exposure, it is possible to determine how high a temperature
the metal was exposed to.

Brinell hardness can be used to measure aluminum hardness. Hardness
correlates very well to tensile strength.

[dwilliams]

That's one reason 2618 used to be popular for racing pistons. Unlike the fancier alloys, 2618 was still reasonably strong after "stronger" alloys had given up. It gave a wider margin for tuning errors or other problems.

2618 was on the expensive side, which is probably the most important reason why it's not very common nowadays.

[4vpc]

The Techline Powerkote is baked on at 350'f/177'c, that's nowhere near the temp needed to take the heat treatment out of aluminium.
That's a fact, not some unsubstantiated (half baked?) comment.

[Mark O'Neal]

That's one reason 2618 used to be popular for racing pistons. Unlike the fancier alloys, 2618 was still reasonably strong after "stronger" alloys had given up. It gave a wider margin for tuning errors or other problems.

2618 was on the expensive side, which is probably the most important reason why it's not very common nowadays.

2618 and 4032 forgings are exactly the same price.