Heard some rumors that they are not worth the trouble and that they tend to leak. Is there any truth to this? Comments from those that run these please.

 

No first hand experience, just some observations.

Geoff at Full-Race at one point said BW investigated using them on the EFR line and found they did not seal up properly. I have had most V-bands leak to some degree on exhausts. It's not significant, but I almost always find traces of exhaust gas on the outside of the joint. Could be just my welding though...

I could see the main reason for leaks being more due to the clamps are pretty weak to begin with than any other reason. The standard clamp doesn't have bellville washers or anything to take up tension during expansion to maintain a consistent tension in the clamp. It is also a 0.030" thick or so band doing all the clamping. I could see a machined clamp like Tial uses on their wastegates working out a lot better. Combine that with a method to take up thermal expansion and you could probably have a reliable setup. An inconel "fire ring" in the housing (similar to what was used in the older Mitsu open volute housings) creating a joint overlap would probably also be worthwhile for reliability.

I think the true benefit for the average user is that they are compact. You can package more in a smaller area. For the racers, it's less hardware to worry about.