Can you paint the CIS plenums?

[mack6820]

Hey guys. I got the CIS off my 3.0 and I sandblasted the plenums. Now I want to paint them. Has anyone ever painted these?

[Oh Haha]

You can use a high temp paint but I wouldn't paint them anything but a light color. Dark colors can keep the heat in the plenums which will reduce the effectiveness of the fuel mixture.

Cool fuel=more power

[turbobrat930]

Originally Posted by Oh Haha

You can use a high temp paint but I wouldn't paint them anything but a light color. Dark colors can keep the heat in the plenums which will reduce the effectiveness of the fuel mixture.

I am going to have to disagree with you on this one. If we were talking about which car kept cooler on a hot sunny day (black or white), then I think you would be on the right track. However, it is not so in this case.

First off, the intake and runners are NOT in the sunlight. Second of all, the intake does not aid in cooling as it sees no airflow(over the outside of the intake). If it did, Porsche and almost every other car manufacture in the world would have fins on the intake to aid in cooling, as well as routing air to the cool the intake. This is not so.

If one wanted to get the most benefit from trying to keep the intake as cool as possible, there are several ways to accomplish this.

One, get the intake ceramic coated as that will insulate the airflow inside the intake from radiant heat.
Two, use reflective film (such as the gold reflective film used on racecars) to shield the intake from radiant heat.
Paint, regardless of color wil not effect the heat soak of the intake.

Now if we were talking about someone painting or powdercoating their cylinders or cylinder heads, this would be a different story. Those parts are made to shed heat.

[kach22i]

I thought it was best to keep the air cool and the fuel warm to get best results.

Mack, can you post a photo of the part for me? I'm a bit confused about which part is the plenum and want to follow the discussion.

[mack6820]

They look nice when I sand blasted them, but just as soon as I touched them with my hands, they got dirty again because of the material their made of. SO I want to apply silver caliper paint, 500 degree heat paint.

[Vmarch]

Why not just leave them alone or have them clear powder coated?

[calling911]

Oh please paint them red or something so you look like a ricer.. maybe it will start flaking off too.. perfection!

[GaryR]

I bead blasted mine and painted them with Eastwood "Spray Grey", which is close (a little darker, but that's what I wanted) to the freshly blasted aluminum but MUCH easier to keep clean. I would have used Eastwood diamond clear as I did on the cam boxes/valve covers but I was out..

Has held up perfectly in a hard driven car..

[Craig_D]

Originally Posted by kach22i

I thought it was best to keep the air cool and the fuel warm to get best results.

Cold fuel makes power over warm fuel. Superbike teams cool the fuel on the racebikes for two reasons; 1. it makes more power (denser molecules and denser/cooler air mean more air/fuel mixture in the combustion chamber), and 2. cooler fuel take up less space and you can get more fuel in the same tank than when using warm fuel.

So I'd say cool air and cool fuel are the best combination, but for the sake of this conversation cool air is the only variable.

Dark paint will not keep in heat to any measurable degree if at all.

Oh, and Gary, engine looks gorgeous! Nicely done!

[GaryR]

Thanks Craig, it's good to have a big media blast cabinet in the shop. Was just making the point that coatings don't have to be ricer to be nicer..

[mack6820]

{Oh please paint them red or something so you look like a ricer.. maybe it will start flaking off too.. perfection!}
Come on, everyone knows it has to be yellow to gain true ricer horsepower!
But yes, I like the silver paint. The freshly sandblasted pipes attract way too much oil and dirt too fast and I feel the paint will be easier to keep clean.
Thanks Gary, thats a nice looking engine!

[GaryR]

Originally Posted by mack6820

{Oh please paint them red or something so you look like a ricer.. maybe it will start flaking off too.. perfection!}
Come on, everyone knows it has to be yellow to gain true ricer horsepower!
But yes, I like the silver paint. The freshly sandblasted pipes attract way too much oil and dirt too fast and I feel the paint will be easier to keep clean.
Thanks Gary, thats a nice looking engine!

Nah, this is my good looking engine...

[mack6820]

sigh... must be nice!

[cnielsen]

Powder coated silver runners...

[ischmitz]

you can paint anything.... - as long as it is YELLOW

[Geronimo '74]

Originally Posted by mack6820

They look nice when I sand blasted them, but just as soon as I touched them with my hands, they got dirty again because of the material their made of. SO I want to apply silver caliper paint, 500 degree heat paint.

Silver heat resistant paint will be just fine, go for it.

Originally Posted by calling911

Oh please paint them red or something so you look like a ricer.. maybe it will start flaking off too.. perfection!

Thank you for your constructive advise, very helpful...

[kach22i]

Originally Posted by calling911

signature: '76 911s Ice Green Metallic bone stock

So Macks car will not be "bone stock", his car, his choice.

I think all the car engines posted look great, bone stock or not.

[kach22i]

Originally Posted by Craig_D

Cold fuel makes power over warm fuel.

Not to hi-jack the tread, but you might be interested in this.

Transonic Combustion fuel-injection system
CARNUTS.US • View topic - Ladies & Gentlemen, I Give You The 200 MPG Carburetor!

[Oh Haha]

I didn't mean to mislead you on my suggestion.

When I ran SBC drag cars we always painted the intake a light color as well as any carb spacers, if not plastic or aluminum already.

Headers/exhaust/mufflers were painted black for heat retention which was suppose to help with the exhaust gas or so the old school theory goes.

I forget sometimes that typical "hot rod" tricks don't always apply to our air-cooled engines.

That said, I'd still clearcoat them or paint them silver.

[kidrock]

IIRC, there are a few contributors with painted or powdercoated intakes. On some, it looks pretty good. On others...meh.

I think polished runners would look awesome...but you'd probably never be able to keep 'em in good condition.

A couple people have mentioned having the inners done with ceramic coating. I might recommend against this. Porsche has done an excellent job engineering these motors, to the point where there is truly not much one can do to inexpensively modify and realize significant horsepower. Chances are, the intakes were engineered to pretty exacting specifications.

For a short time, Harley Davidson enthusiasts were polishing the heads of their Evolution motors...thinking they were getting more bang for their buck. In reality, they weren't realizing any true gains...because the rough texture of the heads near the intake were specifically engineered to "break up" or atomize the incoming fuel more efficiently. Smooth, polished heads defeated that purpose.

I know these aren't Harleys, I am only drawing a feasible analogy.