Intake Manifold Coatings

[1989GTA]

Just wondering if anyone has any results on using a thermal barrier coating inside the runners of an intake manifold? It would seem to me that this would be a good way to keep the incomming air cooler and of course more horsepower.

I would be doing this on a fuel injected motor if it is worth the effort. I have read of a 1% power increase for every 10 degrees you can cool the incomming air. So if you can keep the air 20 degrees cooler that would be 10 horsepower on a 500HP motor.

[Pinhead]

It depends on how well your fuel is being atomized. If you're getting very well atomized fuel, the colder air will help. If your fuel system is spitting out globs of fuel, a heated intake is pretty much required to vaporize the fuel and keep it well homogenized.

Read David Vizard's In Cylinder Turbulence and Combustion Dynamics: Part Three.

[1989GTA]

Thanks Pinhead for the link to David's article. Now I'm going to have to wait to see the next article about the coatings. I have my highly modified TPI intake system off the car and was about to put it back on after a lot of further modifications for higher flow.

I will leave it off for awhile longer to read the article unless David chimes in for a little heads up. To late to coat the intake valves as the heads are on the car and I'm not going to take them off.

Edit: Got to thinking that my intake track is longer than most. I have the plenum, runners and the intake manifold itself to be coated. Won't be doing the heads. So the coating of the runners may have a bigger effect.

[Nick]

Hello to all who read this post as I recently joined the board

I'm curious,

Does the role of intake heat where atomization is concerned change any in this case? Or in the case of port fuel injection engines in general?

With a TPI intake (which aims the injector at the intake port), the fuel mainly travels through the cylinder head intake port as opposed to a carb where the fuel must travel through the entire manifold and the intake port. So I'd think the fuel wouldn't acquire heat from the intake manifold quite as much for that reason.

Also, with a 40+ psi fuel injector, is it safe to assume that the fuel is atomized well enough already?

[Stan Weiss]

Remember that in an EFI system for a good part of the duty cycle the fuel is being injected against the back of a closed intake valve.

[Pinhead]

Also, DV mentioned that atomization from a FI system isn't as good as a well-equipped carb until you get to abou 100psi.

[BMac]

Yea, what Pinhead said. I just bought two more Zenith-Strombergs so I'll be experimenting with adaptions to a 4bbl intake. I have designed and programmed the parts needed to build it. I just need a test vehicle now with a 5.2 Magnum or older 318. A friend from down the road offered up his Dakota for that since he'll be putting it away for the winter.
Those are the type of carbs DV was talking about better atomizing fuel than an injector below 100psi.

[1989GTA]

So with a fuel injection system maybe it is better to leave the intake valve uncoated to help with atomization. Especially if the fuel is being sprayed to the back of the hot intake valve. Thank you Stan for the reminder.

I was also thinking of the long intake track being coated on the inside of the runners. With the IAT sensor located in the plenum in my case it would be able to compensate better than a carb with the changes in air temperature.

Still would like to hear about the effects of coating the insides of the intake track. I just might go ahead and do it as it sounds from David's article that there is some gain to be had. I would hate to leave 5hp or more on the table.