Coating pre cup (1 Viewer)

[baxter650]

Like the title says i am thinking of coating my soon to arrive precups with a high temp ceramic coating.
I do however have some reservations, if i do this should i coat the whole thing, injector side only, injector side / combustion side but not the interference area. I am not concered about coating flaking off cause they coat turbo housings with no issues. My thinking is leaning towards coating the whole cup.
I am interested in your insite and opinions.

 

[amaurer]

Given your concerns, what do you imagine the benefits to be? I can't think of any reason to do this.

 

[Radd Cruisers]

I don't see the point...

You press them into place and then you machine the head back to spec. Any coating will get machined off.

~john

 

[baxter650]

The idea is to keep the heat out of the precup itself and in the precombustion chamber.
The benfits should be evident, less heat in the cup insert helps prevent cracking, keeping heat in the chamber increases efficency.
There are engine rebuilders that have been coating precups as well as combustion chambers intake /exhaust ports, valve heads, piston tops, and other engine parts as well.
GM 6.5 precups have been done for a while now by builders to avoid cracking, they are similar to our 3Bs as far as heads go so if they remove them after the head is machined, coated, then reinstalled, i will find out.
It may be they install them caoted but slightly below the surface of the head.
To have the parts coated is cheap and it can only help so i figure WTF i may even coat the exhaust ports.

 

[Eric Winkworth]

run a pyro... I'm far from a 3B guru.... but from what I do know about these engines they get beat HARD without a pyro... and to me that's why precups crack... 1800F is what the aluminum furnace is set at to pour moulds... and it isn't hard to make those kind of temps!

 

[Big Blue 84BJ60]

are you gona port your pre cups? open them up to allow for a bigger explosion into the cylinder

 

[amaurer]

are you gona port your pre cups? open them up to allow for a bigger explosion into the cylinder

Don't do that. You want the stock size opening in the precups so the fuel-air mix blasts with high velocity into the mixing features on the top of the piston.

Opening up the precups slows the gas flow down (bad) and lets heat out of the cup (also bad).

 

[baxter650]

I am not going to port out the pre cups.
I will be coating the exhaust ports and the pre combustion chambers , have it surfaced, then have the combustion chambers and other side of the precups coated. The coating used isn't the same ceramic used on headers and has been used to coat piston tops for some time now.
A pyro is on the list already as well as a boost gauge.

 

[Eric Winkworth]

so there is absolutly 0 chance of this coating falling off and bouncing around in there? wrecking your clyniders and pistons? You do realize that people get 500 000km's on there trucks (or more) without ever pulling the head? In my mind head and precups aren't a 3B problem, it's how people drive these underpowered engines.... if you never went above 1500F you'd have an engine that would run longer then you'd wanna drive it.... running 10/15% canola oil will drop your exhaust gas temps a few hundred degrees... probably doing exactly what your coating will do for the precups....

If you do it, we want pics

 

[baxter650]

This really isn't anything new, pistons and combustion chambers have been coated for years now.
The coating is only .0015" thick so i wouldn't think bouncing around is a worry.
If i can keep the heat out of the cooling system and in the exhaust i can make more power with the same fuel.
How many engines are running fine with cracked precups at lower temps but fail quickly when the temps go up?
I may never know if this does anything but give a little peace of mind, for under $300.oo i think it's worth a try.
I will take pics for you all. but it wont be for a few weeks.

 

[dbryan]

Don't do that. You want the stock size opening in the precups so the fuel-air mix blasts with high velocity into the mixing features on the top of the piston.

Opening up the precups slows the gas flow down (bad) and lets heat out of the cup (also bad).

I completely disagree. I ported my precups about %10, polished them a bit too, just to remove all the sharp edges. The difference was unreal. (I have driven many 3bs, rebuilt and not.) For me it worked well, and I recommend it. (mind you, I also TIG welded them to the head.....)