SonexBuilders.net

Hello all,

I'm the recent (part) owner of an Aerovee-powered Sonex, and the couplers between the intake runner and the manifold are splitting and needs replacing. The existing ones are some sort of wound rubber, but I noted that the ones sold on the Sonex web site are silicone. i know that standard silicone hoses as typically used for air intakes and radiator hose is not compatible with fuel or oil unless it has a teflon lining or something similar to protect it. Does anyone know if the couplers sold by Sonex are of the fuel-compatible type? (I'd assume since they sell them for this purpose they would be, but I wanted to double check.)

Cheers,

/Patrik J.

The new ones seem fine to me. I've got a few years and a couple hundred or more hours on mine and they seem fine. I've had them off recently and can see that they have been exposed to fuel (blue dye), but don't seem to have been affected by it. I suspect the new stuff is much better than what you have now.

The old stuff you are seeing is fuel filler hose (the type that goes from your fuel door to gas tank on your car). It can be bought by the foot from Napa and other auto part stores. The silicone ones from sonex are a more elegant solution but will cost more to buy and ship. They both work fine. The one thing I don't recommend is buying the rubber ones that many of the vw shops sell. They look similar to the ones sonex sells but are a different material and will tend to crack over time from the heat and vibration. They physically will fit but are designed to connect a solidly mounted carb to a solidly mounted intake on a car application. The intake on the sonex only has the one solid mounting point and moves around and shakes too much for the rubber ones designed for cars.

Keith
#554

Look for Aeroflex Silicone hoses.
Here in Australia we have a local distributor:
http://www.mscn.com.au/aeroflex-products

It's a UK company so I'm sure they will have a distributor in the US as well?

A few people on the RV forum have used this stuff with good results. Use a constant tension spring clamp instead of worm drive.
https://www.summitracing.com/parts/vpe-27051/overview/

When trying something out as a replacement for what Sonex offers, please consider what the effect will be if it fails. If you get a rip or tear in these couplers while in-flight it will cause your engine to go very lean due to the extra air induced and could lead it to stop running. The original fuel hose couplers may not look the best but are inexpensive, light, and most importantly durable. Personally I would have liked to see Sonex offer a flared intake tube that matches the size of the intake manifold so the couplers don't get squished down on one side. Either that or an intake tube that slid into the manifold and had a hard positive connection. It's experimental aircraft so feel free to try new things out, just please think through the consequences have a contingency plan if things don't work out.

Keith
#554

9GT wrote:A few people on the RV forum have used this stuff with good results. Use a constant tension spring clamp instead of worm drive.
https://www.summitracing.com/parts/vpe-27051/overview/

Thanks for all the replies, I ordered the silicone ones from Sonex.

I believe the Vibrant hose is unprotected silicone, which I would not use in contact with fuel/oil. I didn't do an exhaustive search, but I had no luck finding a reducer out of fluorosilicone, only straight sections.

I have the Sonex reducer silicone on one side and the original fuel hose on the other. I don't see a difference. Except it is easier to clamp the silicone reducer with hose clamps. The fuel hose needs a lot of force to reduce it to the intake diameter.

Just to wrap this up, the silicone reducers are mounted and seem like they will work well. The other thing I did was to improve the alignment with the Y intake runners since they were about 1/4" too far apart compared to the intake manifolds. I just used a big-ass clamp to bend it a bit and now the alignment is good, too.

I'd like to see the big-ass clamp setup. Mine were imperfectly aligned also.