Thanks Chris, sounds like you have the tools to make the pattern. Get the shape you want and then unwrap it. If you can print it off you can glue the paper pattern to the steel and cut around it. If it's close enough you can panel beat the last bit.

I cut it by hand and marked the points out by hand, wish I'd taken some photos of the making to show you. Before cutting up the steel I made some paper models, printer paper's a fair bit cheaper than big sheets of galv steel.

I worked out a similar problem to make a front for my trailer. I marked up the profile to cut on the sheet so that it would bend up nicely into shape shown. The trick was to project the edge profile of the finished part onto a flat plane (the sheet). If you get the geometry right it's just a matter of cutting it out and welding it on, like I did.

How good is your maths? I imagine the flat piece of metal would look something like a smiley face. The trial and error method is to cut pieces of card out in the shape you think until you get a piece that forms the right shape when you stick it on the guard.

Do you use Solidworks? I don't know how to but I think it has a sheet metal function that might solve the problem for you.

If you're lucky my nerd gene will kick in and I'll solve it for you but I'm a bit short on time at the moment.

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I'd suspect something in the carbies making the noise but without fiddling around with it and a piece of diagnostic garden hose it's hard to guess. Having a dyno so you could run it up and then get around it with the hose to pin point the source would be very useful. I'm sure someone on this forum has come across it before...

My thinking is that there might be some kind of restriction or resonance going on there or something's not quite tight. COuld even be a piece of gasket partially obscuring a passage in the carb making the noise at a particular speed. You'll figure it out I'm sure.

Is it that higher pitched squeaky sound you're talking about? (The snarl.) Other than that it sounds really nice. Sounds a bit like a funny bearing but not quite. Not sure what that could be.

Check out Sikyne's turbo a series thread. He's done boost like you're talking on a stock bottom end with e85 so provided you prevent detonation and your turbo + piping etc. can cope you should be able to wind it up.

From memory, LPG tends to knock more when it's rich, opposite to petrol. Stick a knock sensor on it so you can monitor knock and start boosting. Better would be to boost it up on the dyno, there's a dyno day coming up soon, might even be a spare place left on the dyno that day.

Whoops, missed a zero.... I'm sure it wouldn't work as hard in a car as it does on a jet-ski so could probably go longer than 100 hrs.

I'm sure if you really wanted you could lock the washers and avoid rebuilds. 100hrs is roughly 40-60,000kms, for me that would be every 4 years for my road car which is the same interval for timing belt changes for my other car. 60,000kms or 4 years.

For some reason I can't upload a pic without crashing the browser but there's one here http://i.tfcdn.com/img2/hNBxSU4AY5r8z ... 6lvYlhp7JYU5O_p6qOXVZAOAA**/fyVMtP8A

Just a discussion piece really. I've thought for a while if you were going the supercharger route one of these would be a good match for an A-series, good flow (up to 185HP) and nice and compact.

http://www.ebay.com.au/itm/Seadoo-SUP ... ageName=ADME:B:SS:AU:1123

They have clutch washers between the drive and the compressor shaft, presumably to prevent broken shafts on over boost. When they talk about replacing ceramic washers with metal washers this is what's being discussed. The other challenge would be getting a big enough gear ratio. If I've found the right information I'd say you'd need a gear ratio of 86:17 or about 5:1 to 6:1.

As usual more ideas than time to action most of them.

Can you upload a vid? I want to hear it now..... I do love the sound of throaty ITBs without silencing. The air cleaners keep some of the noise in. I bet if you put some hose inside the air cleaner and listened to the other end you'd hear the snarl.