Best heat box for RV-6 or RV-7?

[rvator51]

Vans shoes three heat boxes on its website. Any suggestions on which one might work the best or is there a third party one that works better?

[rzbill]

When I built mine, the RV-7 and 7A were designed to use the TG-10 box. I imagine one could use any of the 3 as desired.

In my opinion, the box is less important than the selection of exhaust manifold and its related heat muff. As a result of my own informal survey, I believe there are performance differences between the vertical induction manifolds and the horizontal manifolds with the horizontal manifold heat muff being less effective. It is simply a matter of available surface area. The exhaust manifold for the IO-360-M1B available circa 2010 for a 7A (mine) has limited surface area available for the muff. It is on one cylinder only (#1) vs after the collector or encompassing 2 ex pipes or surrounding a muffler on other units. All of the alternates provide more surface area and/or more exhaust mass flow vs only one cylinders pipe.

My memory of VAF posts says that there have been changes to the M1B manifold/heat muff design since I built but I am not positive on that.

[tgmillso]

Spruce sells a stainless one (PN 08-01311) that weighs only .7 oz more than the TG-10. In my mind there didn't seem to be any point in having some fancy stainless firewall if you were going to have a gaping 2" hole right in the middle with just a thin aluminum flap covering it. A chain is only as strong as its weakest link. Best 0.7oz and $100 I've spent yet.
Tom.

[rzbill]

Agreed. I simply replaced the TG-10 door with a free piece of stainless. No need to make the whole box stainless.