Don Terrill’s Speed-Talk

Looking for thoughts /experiences on trying the application of PPG's 707-b Hi Temp thermal barrier coating to the underside of a sbc intake manifold to prevent heat from getting to the intake plenum area of a bowtie cast-iron dual plane intake that i want to use on a "somewhat" stock appearing build.

The only personal experience i have is on our auxiliary boilers at work. The exterior doors approach 330 degrees with regular paint. With the PPG-707 you can place your hand on them as they are then about 127 degrees. The coating is marine grade and durable, can be brushed or sprayed on etc. Became popular around 2015,

Short video below,Thoughts???

https://www.youtube.com/watch?v=8_6HY-7D3fE

Hello all,

I'm still thinking about applying this thermal barrier coating to the underside of a cast iron intake manifold.

Question: What is an estimated temperature of the underside of a running small block with a cast iron intake? Hot oil, heat soak and all???

Thanks.

I was thinking 250 to 275 degrees tops.... the product is good to 350 to 375 degrees.

Anyone have actual experience with underside cast iron intake temps?

IIRC, David Vizard did a write up on a method he used to drop underside intake temps using insulating foam or something. I'll have to see if I can find it.

Edit: not finding anything. It may have been someone else. Though I did find a pic of one manifold he did using other materials.

Vizard had a page in one of his books re extensively insulating an SBF manifold (and I think there was a S/T thread on it too); I'll see if I can find it. As well as several other steps, he used an aluminum valley plate foamed and bolted to its underside, to isolate the manifold from hot oil and vapors (which can reach ~ 300° F.).

the 2101 edelbrock has fuel distribution problems because 4 of the runners are exposed to the hot oil. heat shield i installed

The PPG coating caught my interest some time back.

In the end, I went with a lifter valley tray and an aluminum tray above it. Made a nice difference in intake temp.

Isolated the intake from hot oil and the exhaust crossover not blocked?

Okay, I'm gonna experiment with the ppg 707. I think I am gonna run the stock splash pan under the coated plenum area as well.

The product is good to 350 to 375 degrees.
I can get it done for free.

Question: will extra cool runners along with a blocked heat crossover negatively or positively affect tuning?

For short duration stuff, like drag racing, there could be some benefit. But once it heat soaks, it won't matter much.

Frankshaft wrote: ↑Tue May 08, 2018 9:14 am For short duration stuff, like drag racing, there could be some benefit. But once it heat soaks, it won't matter much.

The heat soak only becomes a temporary issue during long idles and longer very low throttle angle driving. Once you get the fuel flowing at higher rates all that higher soak temp quickly goes away.

Short of maybe a full race alcohol or nitrous motor, you'd be hard pressed to ever get a cast iron manifold too cold on the street.

Do your tuning only when the engine is up to operating temp and then see if you can live with it while engine is cold. You might think a about ducting some air flow into the intake/carb as under hood temps have a lot to do with intake temps.

Some ceramic header coatings will work if you can get someone that will coat the inside and out correctly

DrillDawg wrote: ↑Tue May 08, 2018 8:38 am Isolated the intake from hot oil and the exhaust crossover not blocked?

Crossover is filled.

I see, said the blind man, I could not see it on my tablet, it shows up well on my desktop, that's why I had the ? mark.