Van's Air Force
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Sam James Cowl / Plenum??
- Thread starter Daniel S.
- Start date
I have the long cowl with plenum ...
... and the cooling is excellent. Just yesterday, for the first time ever, I had one cylinder sneak to 401F during a long hot climb to 7500'. Flattening the climb rate got it quickly back under 400.
Unlike some others, my plenum had a generally good fit, which I improved by adding silicon rubber soft seals in strategic locations. My concern during the build was the oil cooler, tucked low on the back of #4. That has not been a problem; yesterday's hot climb I saw 192 oil temp, the first time it's ever gone over 190. In the winter, I have to block off 80% of my oil cooler.
I'm a happy Sam James customer.
... and the cooling is excellent. Just yesterday, for the first time ever, I had one cylinder sneak to 401F during a long hot climb to 7500'. Flattening the climb rate got it quickly back under 400.
Unlike some others, my plenum had a generally good fit, which I improved by adding silicon rubber soft seals in strategic locations. My concern during the build was the oil cooler, tucked low on the back of #4. That has not been a problem; yesterday's hot climb I saw 192 oil temp, the first time it's ever gone over 190. In the winter, I have to block off 80% of my oil cooler.
I'm a happy Sam James customer.
mrblob
Well Known Member
I have a Sam James Shorty with standard baffles. I had a SJ plenum lid, but didn't like the way it fit when I started playing with it. Also, after asking lots of people, the consensus was that it would be a lot more work to fit, more work to access the engine, and not really a substantial benefit. I cut it up and used the inlets on the front of my baffles. Can't tell you too much about how good the cooling is... my new IO-370 only has 3 hours on it, so I'm still dealing with break-in temps. That said, I'm running 380/390 so far for break in, so I expect it will cool as effectively as a standard Van's cowl.
I have the James Holy Cowl & plenum. It works fine & is pretty. Will James is wonderful to work with.
I would not do it again. I don't think it is worth all the effort and it complicates inspections. But, sure looks sexy all buttoned up.
That's my honest answer.
Cheers & best whatever you choose,
I would not do it again. I don't think it is worth all the effort and it complicates inspections. But, sure looks sexy all buttoned up.
That's my honest answer.
Cheers & best whatever you choose,
bullojm1
Well Known Member
I have the Sam James shorty cowl with the plenum on my RV-7 and I would absolutely do it again. Personally I like the way the SJ cowl looms over the stock cowl. Also, the cooling performance is great. My typical cruise CHT's are around 330 degrees (75% power) in the peak of summer, and in the winter I am running under 300 degrees. My peak CHT's are never above 380 on the climb out. Oil temps are also favorable - I have a tough time keeping them up to 180 degrees.
The downside as mentioned above is there is a good amount of work involved getting the SJ cowl installed. I'd estimate it adding a extra 50-100 hours over the vans cowl.
My setup is an 180hp superior io360, whirlwind cs prop, and a stewart Warner aftermarket oil cooler.
The downside as mentioned above is there is a good amount of work involved getting the SJ cowl installed. I'd estimate it adding a extra 50-100 hours over the vans cowl.
My setup is an 180hp superior io360, whirlwind cs prop, and a stewart Warner aftermarket oil cooler.
LIke Mike said ...
...my cooling performance numbers are very similar, and I concur with his additional build-hours estimate. Another point: the fiberglass quality in my SJ cowl is some of the best I've seen. I have almost no pinholes in the cowl ... far less than the Vans cowls I've looked at.
It was interesting to see Mike's comments ... I used his website extensively during the cowl & plenum phase of my build. Thanks, Mike !!!!!
...my cooling performance numbers are very similar, and I concur with his additional build-hours estimate. Another point: the fiberglass quality in my SJ cowl is some of the best I've seen. I have almost no pinholes in the cowl ... far less than the Vans cowls I've looked at.
It was interesting to see Mike's comments ... I used his website extensively during the cowl & plenum phase of my build.
Thanks, Mike !!!!!Reading Mike & Terry's comments
makes me think back about all this.
First, my temp numbers now are all good bc of particular attention to sealing details. But, I had no cooling problems with the standard cowl.
The big thing I really DO like about the plenum is not watching the cowl flex in flight. It is rock solid now. I've sat behind flexing standard cowls for some 1,700 hours. Somehow, at 10,500' looking out at that beautiful solid snout is more reassuring. For sure, I'm not changing back to the standard.
It certainly IS a quality cowl. Will James is a craftsman & gives excellent support too.
Hmmmm.....
makes me think back about all this.
First, my temp numbers now are all good bc of particular attention to sealing details. But, I had no cooling problems with the standard cowl.
The big thing I really DO like about the plenum is not watching the cowl flex in flight. It is rock solid now. I've sat behind flexing standard cowls for some 1,700 hours. Somehow, at 10,500' looking out at that beautiful solid snout is more reassuring.
For sure, I'm not changing back to the standard.It certainly IS a quality cowl. Will James is a craftsman & gives excellent support too.
Hmmmm.....
Sam James Cowl
Installed on a RV-9A.
Based in Hillsboro OR. Gets plenty hot in the summer. Rarely see 350 degrees on CHT. Mostly down in the 315 to 325 degree range. Plenum and baffle design keeps temps down and cylinder to cylinder variations low.
That said, the additional work to fit the cowling and plenum is significant. It looks great though and the plenum keeps the cowling pressure and working low.
Keith Southard
N355RV
Installed on a RV-9A.
Based in Hillsboro OR. Gets plenty hot in the summer. Rarely see 350 degrees on CHT. Mostly down in the 315 to 325 degree range. Plenum and baffle design keeps temps down and cylinder to cylinder variations low.
That said, the additional work to fit the cowling and plenum is significant. It looks great though and the plenum keeps the cowling pressure and working low.
Keith Southard
N355RV
Platenuts get riveted into the sides and back of the plenum; #8 screws go thru the baffles into the platenuts. Works great; no complaints. I don't think the camlocks would be much improvement, unless you're going to mount/demount the plenum an awful lot. Also, for my installation camlocks would interfere with the FI lines near the nozzles (or maybe spark plug wires) ...not much room under the plenum.
