Throttle body heat.

[John Courte]

Hi all,

Have a look at this picture:



I've got about 3/4" of clearance between the exhaust pipe on the left side to the housing of the throttle body. I'm not too sure of what heat mitigation options I've got here, other than maybe sliding the heat muff down so it's between the TB and the pipe. I figure with the cool air blowing through it, that'll be enough to keep the worst of the heat from the pipe from soaking my throttle body and giving me vapor lock issues.

My only other options are either to move the heat muff back to the tailpipe and clamp a heat shield or two on the pipe in its place, or send the crossover exhaust back to Van's and get a 4-pipe version from Larry Vetterman, since Van's doesn't offer the 4-pipe for the -7.

What do you all think?

[elippse]

What a lot of people think is the worst source of heat from an exhaust is warm air, but it is radiant energy that will get you every time. In this case I would suggest a thin piece of shiny sheet metal between the throttle body and exhaust pipe. If you saw those pipes at night you would see that they glow bright red at higher power. Looking at the throttle body finish it is hard to determine its reflectance or absorbtion to IR. I had a bright yellow VW that I thought would refect the sun's heat, but to the sun's IR it was almost the same as being flat black; it got really hot in the sun!

[billgill]

in 850 hours...very similar to your installation.










Best regards,

Bill
RV-7 N151WP
Barrett IO-390
Lees Summit, MO

[John Courte]

Bill, I'm assuming the cable in your 3rd picture goes up to the governor? I have a very similar situation, the O-360-F1A6 has a front-mounted governor, but it's a parallel-valve engine.

[billgill]

it is the governor cable.

More info on this installation on Marc's site:

http://www.io-390.com/IO-390.com/Prop_Gov_-_Bill.html

Bill