Header Ceramic Coating? Worth it?

[JohnH]

I believe that reducing heat transfer from an exhaust on a normally aspirated engine is counter productive. As a gas temperature reduces it also reduces in volume, aiding scavenging. This is not true for a turbocharged engine, where you would want maximum temperature reduction after the turbocharger, hence wrapping exhaust prior to the turbo.

 

I would paint the exhaust manifold matt black and concentrate on heat shielding vital components and promoting airflow through the engine compartment. You could think about creating an Unterbodenschutz similar to this homologated for the group 2 2002ti to aid in this endeavour

 

  

Edited December 10, 2016 by JohnH

[solo 2]

42 minutes ago, JohnH said:

I believe that reducing heat transfer from an exhaust on a normally aspirated engine is counter productive. As a gas temperature reduces it also reduces in volume, aiding scavenging. This is not true for a turbocharged engine, where you would want maximum temperature reduction after the turbocharger, hence wrapping exhaust prior to the turbo.

 

I would paint the exhaust manifold matt black and concentrate on heat shielding vital components and promoting airflow through the engine compartment. You could think about creating an Unterbodenschutz similar to this homologated for the group 2 2002ti to aid in this endeavour

 

  

I'm pretty sure keeping the charge hot maintains the velocity of the charge which in turn increases the scavenging effect. Turbos use blankets and coatings to keep the velocity of the charge from decreasing and also reducing under hood temps. For any exhaust to show maximum gains everything upstream must be working to their maximum. I'm wondering if he meant a 6hp gain which I think might be possible on a large well prepared motor but 6% seems high on 100hp motor.

Edited December 10, 2016 by solo 2

[jgerock]

Back in 2007, I had the stock (tii) manifold and downpipe ceramic coated (inside and out) by Jet-Hot in their silver configuration.  Other than some dulling, it still looks good (think I paid about $ 150). Their instructions say you can polish the exterior finish but I haven't touched mine.   Before that, I had them do the header for the VW in satin black. It looked brand new when I sold the car in 2012.  For the 69 BMW, I wanted the same thing in their "Sterling" (now called something else) high temperature finish but it was too expensive so I just used the brush on Eastwood exhaust paint.

 

https://www.jet-hot.com/ex-1300

 

http://www.eastwood.com/paints/hi-temp-engine-paints/exhaust-paints.html

 

 

['76mintgrün'02]

2 minutes ago, solo 2 said:

I don't doubt a 6hp gain on a well prepared larger motor, talking percentages might be more meaningful.

 

19 hours ago, jrhone said:

The claim was the temps under the hood could be reduced by 20% and that alone could result in a 6% hp increase.

 

Keeping temperatures down under the hood would be helpful, if your carburetor intake is not utilizing a snorkel to draw in cool outside air.  Other than that, I do not understand why this would increase horsepower.

[JohnH]

5 minutes ago, solo 2 said:

I'm pretty sure keeping the charge hot maintains the velocity of the charge which in turn increases the scavenging effect. Turbos use blankets and coatings to keep the velocity of the charge from decreasing and also reducing under hood temps. For any exhaust to show maximum gains everything upstream must be working to their maximum. I don't doubt a 6hp gain on a well prepared larger motor, talking percentages might be more meaningful.

 

The charge velocity is maintained on a normally aspirated engine, because the exhaust system typically uses smaller diameter pipework towards the end of the system. As you say, flow is everything.

[solo 2]

1 minute ago, JohnH said:

 

The charge velocity is maintained on a normally aspirated engine, because the exhaust system typically uses smaller diameter pipework towards the end of the system. As you say, flow is everything.

As you said previously the charge slows (cools) the instant it leaves the combustion chamber. Ceramic coating, internal and external, helps keep the velocity of the charge up. Keep in mind that scavenging is probably more dependent on exhaust header design and of course tube diameter also comes into play when you're talking velocity. 

[jgerock]

To me - longevity and no maintenance are the goals for coating any exhaust pieces.  I am willing to give up some performance for these things (although my tii goes pretty well).

[AceAndrew]

3 hours ago, JohnH said:

I believe that reducing heat transfer from an exhaust on a normally aspirated engine is counter productive. As a gas temperature reduces it also reduces in volume, aiding scavenging. This is not true for a turbocharged engine, where you would want maximum temperature reduction after the turbocharger, hence wrapping haust prior to the turbo.

 

I would paint the exhaust manifold matt black and concentrate on heat shielding vital components and promoting airflow through the engine compartment. You could think about creating an Unterbodenschutz similar to this homologated for the group 2 2002ti to aid in this endeavour

 

 

  

 

You are looking at this from only one angle, this is not a theoretical exercize. 

 

Heat management via ceramic coating is very productive in keeping underhood temperatures down to promote healthy engine operation.  The 2002 has decent-ish airflow through the engine and to "promote airflow through the engine" any more would mean chopping out a fair amount of sheet metal or drilling extra mounting points, etc.  In short, ceramic coating is a viable method for heat management underhood.

 

As I stated earlier, even on the 991 GT3R we are strategically ceramic coating certain sections of the exhaust to prevent heat-related damage to the bodywork and other components.  Performance loss even at that high ouput was negligible.

Edited December 10, 2016 by AceAndrew

[jrhone]

4 hours ago, JohnH said:

I believe that reducing heat transfer from an exhaust on a normally aspirated engine is counter productive. As a gas temperature reduces it also reduces in volume, aiding scavenging. This is not true for a turbocharged engine, where you would want maximum temperature reduction after the turbocharger, hence wrapping exhaust prior to the turbo.

 

I would paint the exhaust manifold matt black and concentrate on heat shielding vital components and promoting airflow through the engine compartment. You could think about creating an Unterbodenschutz similar to this homologated for the group 2 2002ti to aid in this endeavour

 

 

  

 

 

The idea is it doesn't reduce the heat INSIDE the exhaust header it actually retains it INSIDE.  It just reduces the radiant heat from the exhaust so OUTSIDE exhaust manifold temps are lower while the internal exhaust temps remain higher for better burning and flowing.  

[jrhone]

4 hours ago, '76Mintgrun'02 said:

 

 

Keeping temperatures down under the hood would be helpful, if your carburetor intake is not utilizing a snorkel to draw in cool outside air.  Other than that, I do not understand why this would increase horsepower.

 

Yes that is what the idea is...the performance gains are because the temps under hood are lower so the intake temps are lower giving more HP.  Thats what was stated in the show, and it was on a Sunbeam Alpine that probably was pushing 80-90 HP.  

[jrkoupe]

just forget 6% was ever mentioned.....

[JohnH]

12 hours ago, jrhone said:

 

 

The idea is it doesn't reduce the heat INSIDE the exhaust header it actually retains it INSIDE.  It just reduces the radiant heat from the exhaust so OUTSIDE exhaust manifold temps are lower while the internal exhaust temps remain higher for better burning and flowing.  

 

Yes, but that is the exact opposite of what you want! Anyway coat it up, it looks nice.

[downhillwolf]

What do you think about heat wrap on ss headers?


Sent from my iPhone using Tapatalk

[bpatrol]

I wouldn't use heat wrap on anything.it hold moisture looks  crappy after awhile and is not cleanable. Ceramic coating is the best way.

I think John is confused. Most people understand the value of under hood temperatures being lower. Is there a performance increase? Only if your sucking intake air from under the hood.  And it has been correctly stated that hot exhaust improves scavenging. The idea is to keep all the heat inside the exhaust.

Now last point

Ceramic coating is delicate until it's been burned in by the engine Temps. 

I coat my friends headers all the time and only go to 450f and it needs about 800 to set.

I have even used high temperature powder coating with success.

Jet hot does an awesome job and has the capability to get them that hot to cure.

But holy crap expensive. 

[Conserv]

10 hours ago, bpatrol said:

 

...I have even used high temperature powder coating with success.

Jet hot does an awesome job and has the capability to get them that hot to cure.

But holy crap expensive. 

 

Ahhh, so that explains why $150 for a complete header sounds really inexpensive to me.  And Jet Hot strongly promotes its internal coating process -- at additional cost.

 

I've employed high-temperature powdercoating on the tii's exhaust heat shield -- not it's manifold -- with good success.  

 

Regards,

 

Steve