Heat-Wrapping Extractors Or Headers

[altezzaclub]

These have been running on the KE70 for several years, beautfully wrapped in the fibreglass cloth they sell for the purpose. The rowdy sound of a pipe cracked off the manifold means I pulled them off, and got quite a shock.

 

They have been red-hot and soft enough for long enough to flow into a new shape. While the obvious place for them to get hottest is right by the head, you can see that the paint is still fine at the ends, it is only where the pipes join together that is has over-heated.

 

I could wrap each pipe individually for the first part, but then had to wrap around all four at once, and that is where the metal got really hot. I assume the pipes were transmitting heat to each other, rather than passing it on.

 

The exhaust guy said the metal was OK where he welded the crack, even though it has re-crystallised several time.

 

I won't be wrapping them all this time, just the parts that are still blue with paint. I have a heatshield above them to keep the heat off the carbs and seeing is only a sheet of alloy I don't want to melt it.

 

I'll try to fit one below them to keep the heat off the starter motor. I thought of boxing them, but there is not enough room so I'll hook up a cold-air tube from the radiator panel to blow cold air on them generally.

 

I assume this is from running the carbs lean on cruise, I suppose the way to find out is a webcam under there again!

 

Anyone seen this before??

[Twinky]

It seems as though that inner tube has no airflow over it to cool it down like the outside ones would due to airflow from the front of the car.

With the heat wrap around it would have added to the over heating. All of the other tubes that are not over heated or warped have free air contact

whereas the warped runner is surrounded and barely any space for cool air to circulate.

[altezzaclub]

OK, the new ones are fitted and its all running. The webcam this morning showed no glow from the steel pipes so they must be getting the heat away. I'll get some video if we take the Rolla up to Armidale this weekend.

 

More here-

 

http://www.rollaclub.com/board/topic/42407-the-girls-ke70/page__st__105

[altezzaclub]

Just fell across this- video of Honda F1 motor on the dyno. There is a hotspot just outside the head, then the pipe is cooler until they all run together.

 

That makes sense, so the new system of just wrapping the individual pipes and leaving the junction free should work. 1000km trip coming up next week, Orange to Coolangatta to see little bro', then back to Walcha for a few weeks on the rally car....

[Trev]

Quite common for heat wrapping to hold in the heat and do stuff like this. ACL heat shield and/or ceramic coating is a better option.