950 Supermoto Turbo Build Thread

Hey All. I decided to go nuts and turbo my 950 Supermoto. Some folks, even as far away as France, have asked for info on the build so here we go. This is the virgin prior to defiling.

Step one : Decide on objectives

I have in mind a low boost installation. Say under 6 psi. A couple of things are really important to me. One is that boost start early and enhance the already excellent midrange. Peak power does not need to be huge but if the turbo machinery can be sized for 150 hp with good midrange so much the better.

The bike should be quiet. This is important to me as I like to travel with the front tire ½ inch off the ground whenever possible and being quiet make it possible more. Turbos make nice mufflers but additional muffling will be needed for the level of stealth I’m after.

To make things interesting I’m shooting for a net weight reduction and significantly improved off road ability

standard 950 supermoto not enough?
increase off-road ability and add a turbo?

too awesome and really fucking crazy, good luck

Step Two : Select Turbo

Looks like a clone of a Borg Warner K03 will do fine. This trim should be good for 180 HP at a pressure ratio of 1.63, or 9.26 psi boost. Not that I’ll ever run it that hard. Peak boost is achieved at 4200 RPM.

There’s a lot of talk about how great ball bearing turbos are but I have no desire to spend $700. Final decision was for a Chinese journal bearing turbocharger. K03 turbos are used on untold thousands of VW Golfs and Beetles and there are a lot of these Chinese clones running around as replacements. I goggled around to see if anyone had bad experiences with them and came up empty. Sure, the quality is more spotty than the real thing but this sucker only cost $190. If it goes bad I’ll replace it for less than a change of tires.

Here's the efficiency map

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Holy crap. :eek1
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Step Three : Mounting Arrangement

The usual approach is to put the turbo in front of the motor, down low. A novel thing I want to try is to package the turbo where the right muffler was. This gives cleaner routing for the exhaust. Its all flowing backward. The air cleaner position makes more sense up high. Oil can probably drain from the turbo by gravity without need for an expensive and fragile scavenge pump.

I wish I could post more than one pic at a time.

Here’s another view with a temporary bracket and bailing wire holding the turbo. I’m trying to get it positioned in tight and keep the turbo within 18 degrees of level. That’s so oil won’t leak past the compressor seal and make embarrassing smoke.

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Are you making a pressure box for the carbs?

Good thinking! I'm in.

That's the plan

Saw your comment on the 990SM Turbo thread and had to join here.
I wondered when the convenience of the SM exhaust header outlet would be exploited with a whistle. The routing for pressure to plenum could all be contained within the bodywork, under the seat, with room left on the other side to pipe the exhaust outlet through a short can. Stealthy indeed.
Plus, with a rear mount, there's no messing with the oilbag or its plumbing.
Nice use of a Chirbo, too. My kind of budget.

along for the ride

Seriously interested in this! I wish you the best of luck.

In. This should be interesting.

Yes. We think alike. Stealth is an objective. This whole project got delayed a year while California debated mandatory motorcycle emissions testing. The bill was finally killed so the turbo is go, but I want to keep as low key as possible.

Here is the position I settled on

Honestly, a lot of hand ringing went into settling on this position. The Chinese turbo does not have real specifications on how much it can be tilted. I put the compressor end down as much as I dared. Too much and oil could leak into the compressor. On the other hand there's a good possibility that long wheelies will have oil leaking into the turbine and smoking.

That's a big risk for me. What good is a turbo bike you can't wheelie!

Anyway, this was a big step. Now that its located the plumbing work can begin.

If you rotated the turbo 90 degrees would that decrease the chance of oil getting into the compressor?

Yes, that's the usual orientation for a turbobike. It won't work for squeezing a muffler into the KTM's muffler space though.

My fallback plan is to use an electric scavenge pump. Lots of turbo Busas and GSXRs use electric pumps to move oil back up to the cranckcase from low mounted turbos. I REALLY want to avoid this. Simple and light is the objective here