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Use of top cowl for Plenum Layup
- Thread starter RV7Guy
- Start date
RV7Guy
Well Known Member
Thanks Paul
I reviewed your website. The plenum shots are helpful. My deal is a little complicated in that I'm using a 390 with front governor. Also, there is VERY little clearance between the top of the engine and top cowl.
Thanks again.
I reviewed your website. The plenum shots are helpful. My deal is a little complicated in that I'm using a 390 with front governor. Also, there is VERY little clearance between the top of the engine and top cowl.
Thanks again.
BillL
Well Known Member
Darwin,
I made one like this from a SJ cowl then made a mold from that after making it fit. Just remember (I didn't) the engine is twisted and lays oddly on the contours of the upper cowling. Also if it is made from the upper, just dropping 1/2" won't make 1/2" clearance on the sides - where it is closest. But - if you make it thin you can drape it over the baffles to get the contour adjusted and flanges marked. Imagine a semi circle with a 1/2" displaced center, it is close on the sides. Mikes comment about the "spacer" should negate any issue and make a smooth layup foundation. Definitely better than what I did.
You will have to add flanges after forming on engine or in cowl.
If you want to make it pretty, smooth, and evenly spaced from the cowling on sides, It might be easier to make on top of the engine like DanH and Pete Howell did. Having done it (myself) the within the cowl, and if you are only making one, I think this will yield less work overall and a more definitive process.
I like the way crabandy took off the baffles and turned them upside down over the plenum cover to make the flanges. Just be sure the twist is accounted for.
Just an opinion, though. Either way works. In cowl, more finishing work, on engine more contour sanding before layups. Maybe a toss up.
There is more experimentation both Andy, and I, tried if you want to know.
I made one like this from a SJ cowl then made a mold from that after making it fit. Just remember (I didn't) the engine is twisted and lays oddly on the contours of the upper cowling. Also if it is made from the upper, just dropping 1/2" won't make 1/2" clearance on the sides - where it is closest. But - if you make it thin you can drape it over the baffles to get the contour adjusted and flanges marked. Imagine a semi circle with a 1/2" displaced center, it is close on the sides. Mikes comment about the "spacer" should negate any issue and make a smooth layup foundation. Definitely better than what I did.
You will have to add flanges after forming on engine or in cowl.
If you want to make it pretty, smooth, and evenly spaced from the cowling on sides, It might be easier to make on top of the engine like DanH and Pete Howell did. Having done it (myself) the within the cowl, and if you are only making one, I think this will yield less work overall and a more definitive process.
I like the way crabandy took off the baffles and turned them upside down over the plenum cover to make the flanges. Just be sure the twist is accounted for.
Just an opinion, though. Either way works. In cowl, more finishing work, on engine more contour sanding before layups. Maybe a toss up.
There is more experimentation both Andy, and I, tried if you want to know.
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