SJ plenum inlet tubing improvement

[Raymo]

After replacing the standard neoprene tubes twice in a year, I decided to upgrade them to something that will last. I'd purchased the liquid rubber that Dan H used for his but wanted an easier solution. CHTs seem to be more even than before (+1 to -1 F vs +10 to -10).

These only took about 30 minutes to cut with a razor knife.

Purchased from Amazon.

Planning the same for the intake tubes to sump and filter inlet next time the lower cowl is off.

[Carl Froehlich]

Interesting. The neoprene I made mine out of are just like the day I installed them six years ago.

Is this product as flexible as the neoprene?

Carl

[Toobuilder]

This is the same product I use as induction tube boots - its pretty stiff. Depending on how much the engine moves around Id be concerned about cracking the glass inlets. Maybe leave the hose clamps off the plenum side to allow more translation (in and out), rotation and angular displacement.

[DanH]

Probably too stiff.

[BillL]

Yeah the rocking means a lot of movement, flexibility is a real asset.

I was talking the Sam James a couple days ago and he said the neoprene he is using is getting hard to source. It is a specific high temperature material, not the standard wetsuit spec. He said the standard material will only last months, maybe less than a year before requiring replacement. Shut down temps under my cowl are in the 190F range.

I do not know what spec material it is, does anyone? Please sound off.

[Raymo]

I considered the stiffness, which is why I didn't shorten the distance between the ring and plenum. Will monitor for issues here. I have the liquid rubber for plan B.

I purchased the neoprene material from Sam after talking to him about other sources. It would likely last longer if I lengthened the plenum tubes.

[Toobuilder]

If the tube is long enough to stay trapped between the plunum and ring, then maybe start with both hose clamps removed. This might effectively double your range of articulation. The most critical mode is probably going to be the "wet dog shake" on shutdown where the plenum inlets are going to move +- 3/4 inch (WAG) relative to the cowl.

[BillL]

Originally Posted by Raymo

I considered the stiffness, which is why I didn't shorten the distance between the ring and plenum. Will monitor for issues here. I have the liquid rubber for plan B.

I purchased the neoprene material from Sam after talking to him about other sources. It would likely last longer if I lengthened the plenum tubes.

I figured you probably did consider stiffness, it is hard to get a perfect material. Keep us informed as more experience is gained. I only have a 1/4" gap to the ring and the screw clamps did not hold the neo-boot. It is urethane glued to the ring. I just roll it back to remove it, and do the same for the inlet boot. The small clearance is hard on the + 1/2" shear from rocking, but it does not touch.

edit: or 3/4" :-)

[Raymo]

Originally Posted by Toobuilder

If the tube is long enough to stay trapped between the plunum and ring, then maybe start with both hose clamps removed. This might effectively double your range of articulation. The most critical mode is probably going to be the "wet dog shake" on shutdown where the plenum inlets are going to move +- 3/4 inch (WAG) relative to the cowl.

I was just thinking of removing the aft clamp to allow for more "jiggle." The transition from tube to fiberglass is not a completely straight path so there will likely be a gap at the bottom leading edge of the fiberglass when the clamp is removed.

I've flown 1.2 with the setup. I'll pull the top cowl tomorrow before flying and ponder some more.

[Charles in SC]

Has anyone thought about some silicone mat like the red stuff kitchen muffin pans are made of. It will stand a lot of heat and it is very flexible.