20.11.2002, 15:29
Hallo, hier noch mal ein paar Extrakte aus meiner Internet-Recherve zu dem Thema. Zwei Firmen, zwei Meinungen....
Hier die Infos...
Should I use exhaust wrap on my Hooker Headers?
If your vehicle is being run on the street or for extended periods of time, you should never wrap headers. Exhaust wraps insulate the exhaust too much and the exhaust temperature is raised to a level that fatigues the header material causing cracks.
If under hood temperatures are an issue, we recommend using Hooker's Metallic Ceramic Thermal Barrier Coating. Our coating is applied inside and out. It is corrosion and heat resistant up to 1600°F. It also reduces underhood temperatures and has a polished high luster finish. Holding exhaust temperatures inside the header increases the exhaust gas velocity producing more horsepower.
Aber Teegarden Motorsports sieht das alles anders:
How Does Thermo Tec Work ?
Think of exhaust gases as a piston moving down through the tubular system. As each pulse travels down the system, it creates a vacuum behind itself. The negative pressure behind each is the scavenging effect. As the velocity of the pulse increase, the negative pressures also increase. As you have an increase in velocity, the length of time that you have a negative pressure in the system is increased. The net result of high velocity to assist in scavenging is increased performance of the intake and exhaust system.
Maintaining higher exhaust temperatures throughout the system increases performance in many ways. Think of exhaust gases as a heavy liquid such as an oil additive. If the liquid were traveling down a tubular system in a cold state, it would move very slowly. If you heat the liquid, the density of the fluid changes. The liquid responds to the heat increasing its velocity. Exhaust gases respond in the same manner. Higher temperatures in a system increase the flow of the system. If the liquid is allowed to cool in the system, it slows the flow of the liquid. By this illustration, you can now see the importance of maintaining higher temperatures in an
exhaust system.
How does wrapping headers increase horsepower?
Wrapping the headers maintains exhaust gas heat within the header. This translates into more exhaust flow due to maintaining exhaust temperatures as it flows out of the engine. By improving the scavenging of spent gases, the engine breathes more efficiently. This reduces contamination of gases, thus allowing the engine to develop more power.
How much wrap is required to do a set of headers?
Guidelines recommend: (1) 2 inch x 50 ft.roll for a 4 cyl., (2) 2 inch x 50 ft. rolls for a V6 or V8, and (3) 2 inch x 50 ft. rolls for a big block or 180 degree set of headers.
Why do you use only a 1/4 inch overlap and nothing more?
Using only 1/4 inch overlap draws the heat from the motor but still allows the heat to evenly dissipate through out the system. If you use more than 1/4 inch overlap you may cause fatiguing due to hot spots in your tubes.
Does the wrap overheat exhaust components?
This area is not a problem due to the added flow of the exhaust. Increasing flow also increases the amount of heat extracted from the engine and manifold
When is it not recommended to use header wrap on cast iron
exhaust manifolds on a turbo engine?
Cracking on stock exhaust manifolds and housing has never been a problem. Manifolds to the turbo can be a problem only if extensive modifications have been made to the castings. These types of castings have a high failure rate even without the wrap being applied to them. This is due to the uneven wall thickness of the castings from the machine work performed to improve flow of the manifold. The heat
cycle generated could cause the cast iron to become brittle eventually causing cracking to occur.
Can the header wrap be used on a catalytic converter?
YES!
What temperature will the wrap withstand?
2,000 degrees Fahrenheit
Does the header wrap contain asbestos?
NO!
What kind of material is the header wrap made of?
Highly textured silica based fabric with a patented inorganic coating applied by a proprietary process. A heat conducting coating is applied with a binder to the surface to provide a equal amount of heat distribution. Limit 2,000 degrees Fahrenheit.
Does the header wrap retain heat better than ceramic coatings?
Yes. Ceramic coatings are made from inorganic compounds made of aluminum oxide or of zirconium oxide or coating of an intermetallic compound. These coatings are all very good conductors of heat and only provide corrosion protection..
Does header wrap increase power and improve fuel mileage?
Yes. By wrapping headers, exhaust gas heat within the header is maintained. This translates into better exhaust flow because the hotter the exhaust gasses stay, the faster they flow out of the engine. By improving the scavenging of spent gases, the engine breathes more efficiently. This reduces contamination of the intake fuel air charge with exhaust gases. Thus allowing the engine to develop more power
with less throttle.
Why is it necessary to lean the motor down in most applications with the wrap?
Air/fuel mixture is enriched due to cooler intake and increased exhaust velocity. Increased scavenging of the exhaust has an effect on the induction side of any motor. Clearing the combustion chamber more efficiently means more efficient flow of the incoming air fuel mixture.
__________________________________________
Teegarden Motorsports Specialties
11383 Pyrites Way
Rancho Cordova, CA 95670
916.638.RACE(7223)
Fax: 916.638.2885
Hier die Infos...
Should I use exhaust wrap on my Hooker Headers?
If your vehicle is being run on the street or for extended periods of time, you should never wrap headers. Exhaust wraps insulate the exhaust too much and the exhaust temperature is raised to a level that fatigues the header material causing cracks.
If under hood temperatures are an issue, we recommend using Hooker's Metallic Ceramic Thermal Barrier Coating. Our coating is applied inside and out. It is corrosion and heat resistant up to 1600°F. It also reduces underhood temperatures and has a polished high luster finish. Holding exhaust temperatures inside the header increases the exhaust gas velocity producing more horsepower.
Aber Teegarden Motorsports sieht das alles anders:
How Does Thermo Tec Work ?
Think of exhaust gases as a piston moving down through the tubular system. As each pulse travels down the system, it creates a vacuum behind itself. The negative pressure behind each is the scavenging effect. As the velocity of the pulse increase, the negative pressures also increase. As you have an increase in velocity, the length of time that you have a negative pressure in the system is increased. The net result of high velocity to assist in scavenging is increased performance of the intake and exhaust system.
Maintaining higher exhaust temperatures throughout the system increases performance in many ways. Think of exhaust gases as a heavy liquid such as an oil additive. If the liquid were traveling down a tubular system in a cold state, it would move very slowly. If you heat the liquid, the density of the fluid changes. The liquid responds to the heat increasing its velocity. Exhaust gases respond in the same manner. Higher temperatures in a system increase the flow of the system. If the liquid is allowed to cool in the system, it slows the flow of the liquid. By this illustration, you can now see the importance of maintaining higher temperatures in an
exhaust system.
How does wrapping headers increase horsepower?
Wrapping the headers maintains exhaust gas heat within the header. This translates into more exhaust flow due to maintaining exhaust temperatures as it flows out of the engine. By improving the scavenging of spent gases, the engine breathes more efficiently. This reduces contamination of gases, thus allowing the engine to develop more power.
How much wrap is required to do a set of headers?
Guidelines recommend: (1) 2 inch x 50 ft.roll for a 4 cyl., (2) 2 inch x 50 ft. rolls for a V6 or V8, and (3) 2 inch x 50 ft. rolls for a big block or 180 degree set of headers.
Why do you use only a 1/4 inch overlap and nothing more?
Using only 1/4 inch overlap draws the heat from the motor but still allows the heat to evenly dissipate through out the system. If you use more than 1/4 inch overlap you may cause fatiguing due to hot spots in your tubes.
Does the wrap overheat exhaust components?
This area is not a problem due to the added flow of the exhaust. Increasing flow also increases the amount of heat extracted from the engine and manifold
When is it not recommended to use header wrap on cast iron
exhaust manifolds on a turbo engine?
Cracking on stock exhaust manifolds and housing has never been a problem. Manifolds to the turbo can be a problem only if extensive modifications have been made to the castings. These types of castings have a high failure rate even without the wrap being applied to them. This is due to the uneven wall thickness of the castings from the machine work performed to improve flow of the manifold. The heat
cycle generated could cause the cast iron to become brittle eventually causing cracking to occur.
Can the header wrap be used on a catalytic converter?
YES!
What temperature will the wrap withstand?
2,000 degrees Fahrenheit
Does the header wrap contain asbestos?
NO!
What kind of material is the header wrap made of?
Highly textured silica based fabric with a patented inorganic coating applied by a proprietary process. A heat conducting coating is applied with a binder to the surface to provide a equal amount of heat distribution. Limit 2,000 degrees Fahrenheit.
Does the header wrap retain heat better than ceramic coatings?
Yes. Ceramic coatings are made from inorganic compounds made of aluminum oxide or of zirconium oxide or coating of an intermetallic compound. These coatings are all very good conductors of heat and only provide corrosion protection..
Does header wrap increase power and improve fuel mileage?
Yes. By wrapping headers, exhaust gas heat within the header is maintained. This translates into better exhaust flow because the hotter the exhaust gasses stay, the faster they flow out of the engine. By improving the scavenging of spent gases, the engine breathes more efficiently. This reduces contamination of the intake fuel air charge with exhaust gases. Thus allowing the engine to develop more power
with less throttle.
Why is it necessary to lean the motor down in most applications with the wrap?
Air/fuel mixture is enriched due to cooler intake and increased exhaust velocity. Increased scavenging of the exhaust has an effect on the induction side of any motor. Clearing the combustion chamber more efficiently means more efficient flow of the incoming air fuel mixture.
__________________________________________
Teegarden Motorsports Specialties
11383 Pyrites Way
Rancho Cordova, CA 95670
916.638.RACE(7223)
Fax: 916.638.2885
Cheers
Peter
Peter
