Sam James Cowl/Plenum Cooling

[rvbldr3170]

Well, I may have found my problem. I say may have because I am in the process of correcting it. I called Sam the other day while I was standing by the plane, and I asked him for some help with this problem. Seems you have to install the front baffle so that it hits the cylinder right at the "parting line" where the cylinders are cast. When I looked at mine they (both #1 & #2) were about hitting the cylinder cooling fins 3/4" higher than that line, so I was losing that fin area for cooling. I now have lowered those baffles to the parting line,(although it required additionnal fiberglass work) and hope to test fly it tomorrow.
I'll let you know how it turns out.

[rvbldr3170]

Well, I am still looking for answers to the cooling issue. The changes I made before my last post helped, but #3 & #4 are still running around 410-420 at cruise. I still can't run the engine above 2100-2200 RPM without getting those 2 cyl's above 400.
I am going to look at exit air issues next and see if I can optimize/augment that area of the equation.

[GusRV8]

Merle,

What did you finally end up doing or finding as the cause of the two cylinders running hot? Going through the same thing with a -4 right now and looking at options short of adding a cowl flap.

Thanks!

[Kenny Gene]

Guys,

I've been through the ringer with my 10 and the SJ cowl and plenum. This is my 2nd SJ cowl, the first was with 5" inlet rings, then I had Will James make another with 6",, still very warm on left side, #2, #4 and #6. I relocated my large SW oil cooler 10361S to directly behind #6 as Sam recommended,, oil runs to 210-218 and my #2 is the hotest at usually 408. I've had it up to over 425 when breaking my engine in, however I CANNOT lean as I need the fuel to cool, so I see 17 gph at best and if at lower allitudes, I'm closer to 20 GPH.

I've got 158 hrs on my 10 now and after this next trip, I'm opening the inlets to 8" rounds that I bought from Alan Bikle at OSH 2010, mod the cowl and plenum to see what happens. I've also got an A/C compressor on the left side, so I"m not going to split line the 8" inlets, I"m going to have them higher on top by a couple of inches to allow room for the A/C compressor and cut-reshape the plenum for now. I've also got Chri Frisella of Bonehead Composite on line for the 4" NACA scoop that I'm seriously considering installing on the lower left cowl and re-locating my oil cooler again with it's own seperate inlet and exit air.

I'm determined to get this thing cooled and working,, some of my building and flying buddies tell me why not just order a standard Van's 10 cowl,,, I like the looks of the round inlets and this 2nd cowl is nicely fitted on my plane now, so I'm going to start the old plow boy method of trial and error. I cannot do any worse than what I've got now!

Kenny Gene
Wichita KS area
RV 7a 294TC (AWC 9-07) 680 hrs sold 11-11
RV 10 484TC (AWC 10-10) 158 hrs

[DanH]

Originally Posted by Kenny Gene

Guys, I've been through the ringer with my 10 and the SJ cowl and plenum..(snip)...so I'm going to start the old plow boy method of trial and error.

Perhaps some diagnosis is in order before cutting the patient. Why not get upper and lower plenum pressure measurements, and an outlet temperature?

BTW, can you see any of the AC installation looking through the left inlet?