Oil Cooler Duct - Velocity stack worth it?

Hi All,

I'm in the process of putting a larger oil cooler on my -7, remote mounted on the engine mount. I plan to duct it with 4" SCEET from the baffle to a fiberglas plenum on the cooler.

Question is, would something like this velocity stack from Amazon Aircraft Supply do anything worthwhile to smooth the air going into the duct from the engine side of the baffle? It's designed for a turbocharger or intercooler inlet, but I'm wondering if it would work with the relatively low-velocity air going through the cowl into the duct.

Thanks and Happy New Year!

https://www.amazon.com/4-0-Aluminum-Velocity-Stack-Black/dp/B00ME67EAW/ref=sr_1_3?ie=UTF8&qid=1514517737&sr=8-3&keywords=4%22+velocity+stack

Yes, but how much would probably depend on how slow and disorganized the air is before it enters. The SKEET tubing adds a lot of drag, too. And most of the plenums you see on oil coolers violate just about all the accepted best practices for a diffuser.

It looks promising and is inexpensive. Skeet tubing should have less resistance to flow than scat tubing, although 4 inch diameter of either should be plenty big enough to get good airflow, so not sure there is really a problem to be solved here. The velocity duct is relatively large too; is there room for that on your baffle? Also make sure to allow enough room for any bending of the skeet tubing necessary to direct it downward to the cooler intake plenum. It takes a fair amount of space.

Here is what I did on my -7A
http://www.vansairforce.com/community/showthread.php?t=155188&highlight=Erich

although it has a differnet engine mount than your -7. Might give you some ideas though.

Erich

I found some old charts that showed a 1/2" radius was enough for that velocity. It was surprisingly small, but some radius is definitely needed. Sorry can not remember the reference.

Thanks for the advice!

Erich, I would love to set mine up like yours, but I have some extra tubing in the way due to the taildragger engine mount.

If I move the 4? inlet toward center I have enough room, but then I have to move the plug wires. That crosses the threshold of time/complexity vs tangible gain, in an unscientific, bar napkin kind of test.