Leonard:
I would like to hear you comments on coating both the inside and outside of exhaust headers, especially on turbocharged engines.
I understand the big issue of concern is proper prep for the interior coating and ensuring it adheres properly. Folks are concerned that flaking does not occur possibly causing damage to turbocharger turbine impellers.
Do you know of users that have successfully coated the interior of exhaust headers in turbocharged applications? Does it accomplish enough to justify what ever special prep is necessary? Are the current generation of high temp coatings up to the task of internal coating on headers and turbocharger hot side housings?
Larry
ENGINE COATINGS - A REFERENCE THREAD
Moderator: Team
I am interested both chamber/piston coating and exhaust valve coating for heavily turbocharged engines.
I'm not quite sure I understand your comments about not making the combustion temps hotter- if heat isn't being rejected into the head/piston then doesn;t it follow the combustion temp must be higher- and thus my question-
1.On detonation limited engines doesn't an increase in combustion temp increase the chance of detonation?
2. While ceramic coating an exhaust valve must keep heat out during some parts of the cycle, wouldn't it also keep it from cooling when the fresh charge enters? I guess what I'm asking what is the heat balance?
Thanks for any replies.
This is an awesome forum.
I'm not quite sure I understand your comments about not making the combustion temps hotter- if heat isn't being rejected into the head/piston then doesn;t it follow the combustion temp must be higher- and thus my question-
1.On detonation limited engines doesn't an increase in combustion temp increase the chance of detonation?
2. While ceramic coating an exhaust valve must keep heat out during some parts of the cycle, wouldn't it also keep it from cooling when the fresh charge enters? I guess what I'm asking what is the heat balance?
Thanks for any replies.
This is an awesome forum.
-
Torquemonster
Welcome Leonard, thanks for coming and being willing to address questions that have been clouding the issue for years. It seems Techline is one of the few companies willing to stand up and share their knowledge.
I also have a question:
Both Ray Barton and JE have complained of piston collapse in the past - which has turned them against piston crown and chamber thermal barriers... as you'll have seen in this thread - JE claimed the rockwell strength of the piston took a huge dump.... can you address how this can be reversed (if at all) so that a coated piston and chamber will be stronger - certainly not weaker... and if there is a weakness under certain conditions - what are they?
I also have a question:
Both Ray Barton and JE have complained of piston collapse in the past - which has turned them against piston crown and chamber thermal barriers... as you'll have seen in this thread - JE claimed the rockwell strength of the piston took a huge dump.... can you address how this can be reversed (if at all) so that a coated piston and chamber will be stronger - certainly not weaker... and if there is a weakness under certain conditions - what are they?
Coating
The issue has to do with the cure temp. Some pistons depending on the exact alloy will lose some hardness at 350f. However all of our thermal barrier coatings for piston tops will cure at 300f, if left in a little longer. Two of our dry films cure at 300f. In discussing this with a manufacturer who's pistons seem especially prone to this, we seemed to agree that 300f is not a problem. This is not a problem with all pistons, just certain ones.
We did one test that showed a 2 point drop in hardness, which was not desireable. But only on this one alloy. In speaking to another Piston mfg, they said their pistons have no problem at 350f. 1000's of pistons have been coated with no problem. My recommendation is to ask the mfg more questions and check with diferent mfgs.
My concern with a piston that loses hardness at 350f is what happens when it gets hotter than that in use?
We did one test that showed a 2 point drop in hardness, which was not desireable. But only on this one alloy. In speaking to another Piston mfg, they said their pistons have no problem at 350f. 1000's of pistons have been coated with no problem. My recommendation is to ask the mfg more questions and check with diferent mfgs.
My concern with a piston that loses hardness at 350f is what happens when it gets hotter than that in use?
Re: coating headers
<<I would like to hear you comments on coating both the inside and outside of exhaust headers, especially on turbocharged engines.
In my opinion, the exterior coating is the most important for a variety of reasons. However coating the ID can be beneficial in some instances.
Most companies coat to the first bend and up the collector. These are the two most critical areas. In some instances the unit is coated all the way through. You need to ask for tbis, if this is what you want. Preparing and coating the complete ID is difficult without the right equipment.
The 1st bend is important because this is where the hottest exhaust gases impact. Consequently errosion is a problem. The joint where the tubes come together at the collector is the 2nd hottest point and is an area where condensation can form and rust occurs. I have never seen a header rust through from the inside except at this point. In an application where every erg of energy is important have it coated all the way through. In most normally aspirated applications that is not necessary
Turbo's are a different issue. Here we do not want the ID coating to delaminate. Prep and application is critical here, as a small hard particle hitting the turbine can cause damage.
Generally double coating the exterior gives you tremendous thermal advantage. Garrett approved our HHBK top coated with Black Satin for a special run of Turbo Charged Mazda's in Australia. it doesn''t get any hotter than that.
For coat-it-yourself applications use our Turbo X, either Black or Blue. These work extremely well and are to be applied to the exterior only.
In my opinion, the exterior coating is the most important for a variety of reasons. However coating the ID can be beneficial in some instances.
Most companies coat to the first bend and up the collector. These are the two most critical areas. In some instances the unit is coated all the way through. You need to ask for tbis, if this is what you want. Preparing and coating the complete ID is difficult without the right equipment.
The 1st bend is important because this is where the hottest exhaust gases impact. Consequently errosion is a problem. The joint where the tubes come together at the collector is the 2nd hottest point and is an area where condensation can form and rust occurs. I have never seen a header rust through from the inside except at this point. In an application where every erg of energy is important have it coated all the way through. In most normally aspirated applications that is not necessary
Turbo's are a different issue. Here we do not want the ID coating to delaminate. Prep and application is critical here, as a small hard particle hitting the turbine can cause damage.
Generally double coating the exterior gives you tremendous thermal advantage. Garrett approved our HHBK top coated with Black Satin for a special run of Turbo Charged Mazda's in Australia. it doesn''t get any hotter than that.
For coat-it-yourself applications use our Turbo X, either Black or Blue. These work extremely well and are to be applied to the exterior only.
<<I am interested both chamber/piston coating and exhaust valve coating for heavily turbocharged engines.
<<I'm not quite sure I understand your comments about not making the combustion temps hotter- if heat isn't being rejected into the head/piston then doesn;t it follow the combustion temp must be higher- and thus my question-
Heat is caused by the combustion of the fuel air mix. Maximum temp occurs from that process. All the coatings do is slow down the loss of heat. You cannot add heat to heat unless you have a hotter source than the combustion . There is no other source, except in detonation which is actually cooler than a proper combustion event. Yes the surfaces may be a little hottter but not as hot as the max temp they are exposed to. If coated they will not get hotter. IF the piston is coated and the head is not, theoretically the head may be a little hotter, but it is fractional. The combustion temp IS what is created by the ignition of the mix. The coatings just slow down the loss of heat from that point.
1.On detonation limited engines doesn't an increase in combustion temp increase the chance of detonation?
Most detonation is caused by the incoming fuel mix absorbing heat from the surfaces. Then while compressing that mix you are creating even more heat, as it is compressed. Under certain situations the mix will reach ignition point and you have pre ignition. Less often is a hot spot igniting the fuel. Generally this is from a sharp edge staying hot after combustion.
Ouyr coatings, but not coatings out there, will maintain a cooler surafce temp, thus less heat is absorbed by the mix.
With our coatings it is also common to run even leaner with no problems, as the fuel is better oxidized with our coatings, meaning you burn more molecules of the fuel present. This creates in effect a rich condition, so you pull fuel out creating a theoretically leaner condition, but actually a better ratio of combusted fuel to air. You make more power. Then you can run a little leaner and still not have a problem or run more compression without problems due to less heat absorbtion. Once in a while, particularly on 440's we see the engine actually want more fuel, and make more power.
2. While ceramic coating an exhaust valve must keep heat out during some parts of the cycle, wouldn't it also keep it from cooling when the fresh charge enters? I guess what I'm asking what is the heat balance?
It depends on the ability of the coating to absorb heat. Certain ceramics are excellent thermal barriers but will retain a lot of heat, which is abosrbed by the mix. Other coatings, like ours use a thin conductive film on top of a barrier. The thin film cannot hold as much heat and thus less is transferred. In addition it spreads the heat more evenly over the surface reducing the focus of heat.
On valves the coating will insulate the valve from heat, so cooling it is less of an issue. Unless of course you do not coat the valve. It is a balance in this case. On intake valves it works well, as less heat is transferred to the incoming fuel mix, which is good.
Heat only flows from hot to cold. Just follow the heat.
<<I'm not quite sure I understand your comments about not making the combustion temps hotter- if heat isn't being rejected into the head/piston then doesn;t it follow the combustion temp must be higher- and thus my question-
Heat is caused by the combustion of the fuel air mix. Maximum temp occurs from that process. All the coatings do is slow down the loss of heat. You cannot add heat to heat unless you have a hotter source than the combustion . There is no other source, except in detonation which is actually cooler than a proper combustion event. Yes the surfaces may be a little hottter but not as hot as the max temp they are exposed to. If coated they will not get hotter. IF the piston is coated and the head is not, theoretically the head may be a little hotter, but it is fractional. The combustion temp IS what is created by the ignition of the mix. The coatings just slow down the loss of heat from that point.
1.On detonation limited engines doesn't an increase in combustion temp increase the chance of detonation?
Most detonation is caused by the incoming fuel mix absorbing heat from the surfaces. Then while compressing that mix you are creating even more heat, as it is compressed. Under certain situations the mix will reach ignition point and you have pre ignition. Less often is a hot spot igniting the fuel. Generally this is from a sharp edge staying hot after combustion.
Ouyr coatings, but not coatings out there, will maintain a cooler surafce temp, thus less heat is absorbed by the mix.
With our coatings it is also common to run even leaner with no problems, as the fuel is better oxidized with our coatings, meaning you burn more molecules of the fuel present. This creates in effect a rich condition, so you pull fuel out creating a theoretically leaner condition, but actually a better ratio of combusted fuel to air. You make more power. Then you can run a little leaner and still not have a problem or run more compression without problems due to less heat absorbtion. Once in a while, particularly on 440's we see the engine actually want more fuel, and make more power.
2. While ceramic coating an exhaust valve must keep heat out during some parts of the cycle, wouldn't it also keep it from cooling when the fresh charge enters? I guess what I'm asking what is the heat balance?
It depends on the ability of the coating to absorb heat. Certain ceramics are excellent thermal barriers but will retain a lot of heat, which is abosrbed by the mix. Other coatings, like ours use a thin conductive film on top of a barrier. The thin film cannot hold as much heat and thus less is transferred. In addition it spreads the heat more evenly over the surface reducing the focus of heat.
On valves the coating will insulate the valve from heat, so cooling it is less of an issue. Unless of course you do not coat the valve. It is a balance in this case. On intake valves it works well, as less heat is transferred to the incoming fuel mix, which is good.
Heat only flows from hot to cold. Just follow the heat.
Coatings
Aah nuts I just read some of my posts. Please forgive the poor spelling. fat fingers, a dozen phone calls interrupting my typing and a rush to get work done has led to sloppy typing. 
-
Torquemonster
That was great... thank you so much for your time.
I like the line: "My concern with a piston that loses hardness at 350f is what happens when it gets hotter than that in use?"
couldn't agree more... which is why I don't use the brand in question...
would you be willing to advise some of your dealers that you are confident spend considerable time and care in preparation for top dollar engines.... I know this is a double edged question and there's a risk of customers not named getting upset (if they read this) - but let's just say you must have a couple of star performers out there you'd like to especially show off...
cheers
I like the line: "My concern with a piston that loses hardness at 350f is what happens when it gets hotter than that in use?"
couldn't agree more... which is why I don't use the brand in question...
would you be willing to advise some of your dealers that you are confident spend considerable time and care in preparation for top dollar engines.... I know this is a double edged question and there's a risk of customers not named getting upset (if they read this) - but let's just say you must have a couple of star performers out there you'd like to especially show off...
cheers
[quote="Leonard"]<<I am interested both chamber/piston coating and exhaust valve coating for heavily turbocharged engines.
<<I'm not quite sure I understand your comments about not making the combustion temps hotter- if heat isn't being rejected into the head/piston then doesn;t it follow the combustion temp must be higher- and thus my question-
An example of the efficiency in this regard is found in an example provided by one of our applicators. I will give you his somments about a drag engine they did the coating for. You can contact him at his shop, though i am at home and do not have hios number. The company is:
JCM Machine
Housesprings, MO
His comments are as follows:
" ... the combustion chamber coatings were so efficient at keeping heat in the chamber and out of the parts that they were concerned when the engine temp gauge showed a very low reading. They thought it might be broke. It wasn’t. They literally drove the car back and forth in the pits in an attempt to get what they felt were normal engine temps."
The same situation was found to be true, by an new applicator:
Anson Powder and Performance Coatings
Lancaster Texas.
"Jason wanted to pass on his personal experience with our coatings. Jason races a Camaro, running a small block Chevy, in the Street Stock class at the local ½ mile dirt track. He coated the Pistons, Combustion Chambers, Cyl walls and the Intake Manifold. In two weekends of racing he won his Heat and the Feature Race on BOTH weekends.
He observed that his throttle response was so good that he would “jump” 2 to 3 car lengths ahead of the competition when the green flag was dropped to start the race. In addition his water temperature, which normally ran 210 to 220F, never went above 160F."
These quotes are from the April edition of our Newsletter, that is posted to our web site.
<<I'm not quite sure I understand your comments about not making the combustion temps hotter- if heat isn't being rejected into the head/piston then doesn;t it follow the combustion temp must be higher- and thus my question-
An example of the efficiency in this regard is found in an example provided by one of our applicators. I will give you his somments about a drag engine they did the coating for. You can contact him at his shop, though i am at home and do not have hios number. The company is:
JCM Machine
Housesprings, MO
His comments are as follows:
" ... the combustion chamber coatings were so efficient at keeping heat in the chamber and out of the parts that they were concerned when the engine temp gauge showed a very low reading. They thought it might be broke. It wasn’t. They literally drove the car back and forth in the pits in an attempt to get what they felt were normal engine temps."
The same situation was found to be true, by an new applicator:
Anson Powder and Performance Coatings
Lancaster Texas.
"Jason wanted to pass on his personal experience with our coatings. Jason races a Camaro, running a small block Chevy, in the Street Stock class at the local ½ mile dirt track. He coated the Pistons, Combustion Chambers, Cyl walls and the Intake Manifold. In two weekends of racing he won his Heat and the Feature Race on BOTH weekends.
He observed that his throttle response was so good that he would “jump” 2 to 3 car lengths ahead of the competition when the green flag was dropped to start the race. In addition his water temperature, which normally ran 210 to 220F, never went above 160F."
These quotes are from the April edition of our Newsletter, that is posted to our web site.
<<would you be willing to advise some of your dealers that you are confident spend considerable time and care in preparation for top dollar engines.... I know this is a double edged question and there's a risk of customers not named getting upset (if they read this) - but let's just say you must have a couple of star performers out there you'd like to especially show off...
On our web site we have a section that lists our Approved Applicators. Each has submitted samples of their work for our evaluation. This is a good starting point.
Anyone can email me at leonard@techlinecoatings.com and I can give specific information on an Applicator near them and in some cases the names of shops that may have a specific expertise. Note only until Tuesday then I am off to Europe to business until may 31.
On our web site we have a section that lists our Approved Applicators. Each has submitted samples of their work for our evaluation. This is a good starting point.
Anyone can email me at leonard@techlinecoatings.com and I can give specific information on an Applicator near them and in some cases the names of shops that may have a specific expertise. Note only until Tuesday then I am off to Europe to business until may 31.
[quote="Gary 540"]Leonard, I have asked this before, but can you give me your thoughts on
"thermal" barrier coating the intake ports on an aluminium cyl. head. ?
The advantage comes in isolating the incoming air fuel mix from heat in the head. This is of far more importance on a carburated engine than on an injected engine. Coating the head of the Intake Valve, both sides with a barrier coating also helps.
With a carb, you want to also consider our dry film on top of the insulator to create boundry layer turbulence which helps keep fuel in suspension and does not hurt air flow.
<<What sort of coating is the red stuff used on some of the engine masters engines ?
I haven't seen the red coating. However in general any color is either a lubricant, such as Moly (gray/black), or an additive to make a unique color. The pigment additives offer no value except to the manufacturer to identify his product. We do not normally pigment our coatings as it reduces the amount of lubricant that you can add. To overpower a strongly colored lubricant, takes LOTS of pigment.
By the way an interesting fact.
Graphite is only a lubricant in the presence of water, except at very very high temps.
"thermal" barrier coating the intake ports on an aluminium cyl. head. ?
The advantage comes in isolating the incoming air fuel mix from heat in the head. This is of far more importance on a carburated engine than on an injected engine. Coating the head of the Intake Valve, both sides with a barrier coating also helps.
With a carb, you want to also consider our dry film on top of the insulator to create boundry layer turbulence which helps keep fuel in suspension and does not hurt air flow.
<<What sort of coating is the red stuff used on some of the engine masters engines ?
I haven't seen the red coating. However in general any color is either a lubricant, such as Moly (gray/black), or an additive to make a unique color. The pigment additives offer no value except to the manufacturer to identify his product. We do not normally pigment our coatings as it reduces the amount of lubricant that you can add. To overpower a strongly colored lubricant, takes LOTS of pigment.
By the way an interesting fact.
Graphite is only a lubricant in the presence of water, except at very very high temps.
thermal coatings and header wrap
I was wondering if you could use both header wrap and thermal coatings.
For example-- I found that at the drag strip I get best spoolup and harder launches if I sacrifice a bit of engine temperature to preheat the exhaust manifold and turbo hot side prior to staging. I work hard to keep the car cool but start the engine about one minute before I stage to bring the temperature up in the exhaust headers and turbo. I currently have header wrap on the headers and it makes a big difference.
Can you put header wrap tape on top of a thermal coated header without causing overheating and damage?
Thinking of using one of the 2000 deg thermal coats, with an over wrap of header wrap tape.
Larry
For example-- I found that at the drag strip I get best spoolup and harder launches if I sacrifice a bit of engine temperature to preheat the exhaust manifold and turbo hot side prior to staging. I work hard to keep the car cool but start the engine about one minute before I stage to bring the temperature up in the exhaust headers and turbo. I currently have header wrap on the headers and it makes a big difference.
Can you put header wrap tape on top of a thermal coated header without causing overheating and damage?
Thinking of using one of the 2000 deg thermal coats, with an over wrap of header wrap tape.
Larry
Thanks Leonard, is the solid dry film you speak of that goes over the thermal barrier coated intake port the same stuff you use on piston skirts ?With a carb, you want to also consider our dry film on top of the insulator to create boundary layer turbulence which helps keep fuel in suspension and does not hurt air flow.
So best bet would also be to thermal coat intake runner ports, then coat over the top with solid dry film as well, Yes this is a carb application.
thanks
Gary.
Re: thermal coatings and header wrap
<<Can you put header wrap tape on top of a thermal coated header without causing overheating and damage?
In theory you can. However we have foud that header wrap has a couple of problems.
First it traps moisture at the surface and can lead to severe corrosion problems. The coating will help, but it needs some air flow to work fully. The Turbo X system is designed to not simply be a thermal barrier but to also shed heat off the surface keeping the surface cooler and radiating less heat to the nearby components,etc. A Wrap will stop that.
Also if too much heat is retained it can lead to weld and metal fatigue problems. SS is not as susceptable but steel definitely is.
In theory you can. However we have foud that header wrap has a couple of problems.
First it traps moisture at the surface and can lead to severe corrosion problems. The coating will help, but it needs some air flow to work fully. The Turbo X system is designed to not simply be a thermal barrier but to also shed heat off the surface keeping the surface cooler and radiating less heat to the nearby components,etc. A Wrap will stop that.
Also if too much heat is retained it can lead to weld and metal fatigue problems. SS is not as susceptable but steel definitely is.