[toro1]

The bike pictured above is my bone stock K8. A friend gave me a fantastic deal on this bike last year, and it has just under 2000 miles on the clock. I love this bike for the same reasons everyone does -- incredibly smooth, extremely capable and controllable, great power, and fantastic ergonomics for a supersport machine. The local Dynojet 250i says it puts down 152whp (SAE corrected), which is actually more power than a full-exhaust, PCIII-tuned '04 ZX-10R produced on the same dyno.


Now, normally the next step would be to add an exhaust, change the gearing around, or add some braided lines, and while I'll eventually get to those mods, I have something different in mind right now...

It's a Rotrex C15-60 supercharger, right off the plane from Denmark. This little unit can support over 230whp, and that's the number I'll be shooting for with my little project here. Also, the impeller wheel used to be cast, but these new wheels are apparently machined out of billet.


Before you ask, yes, I am a power junkie. There's just no going back once you've ridden a boosted literbike...

You can see how small it actually is compared to the bike. Somehow, some way, it will fit in there...

After staring at this sight for a couple of days, I realized the only place to put this thing is in-between the engine and the radiator, just below the frame. I'd love to stick it up higher, but the frame would get in the way of the belt (which is a dealbreaker) and the radiator fan would also have to be relocated. Placing it lower eliminates these problems, but makes it much harder to hide the drive behind the fairings and also places the inlet of the Rotrex very close to the header. I also do not want cornering clearance to be compromised at all, so it will be in as far (and up as high) as possible.

If anyone is wondering how I plan on driving this thing, take a look at the picture above. The M10 bolt currently fastened into the end of the crank will be removed and a machined adapter will take its place (this adapter has to locate perfectly off the crankshaft for this to work). A pulley will sit on top of this adapter and then drive the supercharger via an 8mm synchronous belt. The supercharger bracket will either take the place of the stock cast cover or locate off of it -- I'm not exactly sure yet which way to go.



There's a lot of work left to be done, but I'm looking forward to it. I plan on tuning the ECU directly and, of course, it will run on pump gas. In the meantime, wish me luck, and stay tuned...

 

[toro1]

Man that's gunna be a tight fit...

Yeah it is. I don't think there's going to be any way to keep everything completely concealed behind the bodywork. Fitting the inlet tubing and filter is also going to be a major pain, but I think I have an idea on how to do it.

 

[toro1]

Subscribed, so nice to read a well thought out post; grammar, spelling, punctuation.

But still, this is a badass build!! unk

Thanks. No matter what it is that I do, I try to do it the right way.

I have some big plans for this bike...

Im sure you've probably seen this but TTS in the UK do a S/C kit for GSXR1000's as well..this PDF may or may not be of any interest!

http://www.tts-performance.com/catalog/content/english/download/gsxr1000k5-7.pdf

Yep, I've seen it. I'll be doing things a bit differently than TTS, though.

 

[toro1]

Mock-up time.

I had just finished making a set of custom pulleys for a guy (who owns a K5, coincidentally), so naturally I wanted to see how they'd look on my bike beforehand. I grabbed an old generic bracket that was laying around and proceeded to bolt it to the frame and the Rotrex; naturally the offset is all wrong, but at least I can grab some measurements off of it.

Clearly there are interference issues with the blower mounted in this position (primarily the inlet contacting the header tube and the compressor housing touching the engine case bosses), but as I said before, there's no other place to stick this thing. Now, if I was able to mount the blower closer to the engine, I could stick it further in and have more room for the inlet at the same time, but the bosses prevent that from happening.

You can actually see where the inlet was rubbing on the header -- that's no good. The only option here is for a little surgery.

Using a sawzall, a file, some sandpaper, and a little elbow grease, those bosses are now history. Much more room to play around now.

 

[toro1]

No, not boosting yet. There's still a ton of work to be done.


Removed the stock airbox from the TB...

All that clutter associated with the PAIR valve will have to go.

Much better. I pulled the reed valves out so that the block-off plates I'll be making will seal up flat against the rubber gasket of the base plate. I also took this opportunity to swap out the stock plugs for some colder NGKs. Eventually that black plastic panel attached to the front of the head will have to get yanked, too, to allow clearance for the intake tubing.


Now that all the crucial dimensions of the starter cover have been digitized, the next step will be to make a better mock-up bracket for the supercharger and see how everything fits.

 

[toro1]

Since I know the output of the stock pump cannot support 250-260 crank hp, some upgrading will need to be done. I yanked the stock assembly to see if it's possible to shoehorn in a Walbro, but there's just absolutely no way.

The new style Mitsubishi pump is just about half the size of a regular pump, and without a completely new housing design (including a built-in filter), an in-tank Walbro is out of the question. The K6 and older bikes would not have this problem as they use the larger style pumps.

I do not want to go to an external pump, though, so for the moment I'm kinda stumped. I do have one idea that I'm going to try out, but it's going to take some careful experimentation; if it works, it will be a very elegant solution to this problem.

 

[toro1]

Here in dominican rep. for some reason of the universe the K7 pumps have failed miserabily and my mechanic uses the K5 ones, since they are easy to find car pumps that fit. I think that mitsubishi lancer evo is the same or hondas.

If I where you I would use a external pump with a external presure regulator.

There is no other pump that fits like the K7 one.... they are small maybe that is the reason they are failing like that.

I wasn't aware of K7 pump failures. I have read of a few cases where the pickup filter became clogged over time and lead to poor performance, but nothing in particular was about the pumps themselves. What kind of failures were seen? Were the actual causes of failure ever determined?

 

[toro1]

Gotcha. Thanks for the input. I want to run some tests on the stock pump to check on things like the temperature at various pressures and voltages, and then compare it to a Walbro. The older style pump housing always kept part of the pump submerged, but the newer style housing has a flat bottom and, as you said, could lead to much higher operating temps (and premature wear) if the gas is run down all the way.

 

[toro1]

Steddy, this is not my first Rotrex-equipped bike. I've been personally running my stock-internal, non-intercooled, pump-gas powered VFR on 10.5psi since '07 without a single issue to speak of. As you said, tuning is key, but the boost curve of a centrifugal supercharger is just about as good as you can get for running safely on pump gas. This bike won't be pushing that amount of boost, but I do plan on it maxing out the C15-60.

I will be utilizing a vacuum operated Bosch bypass valve to limit surge. To tame the exhaust heat, I plan on wrapping the entire unit with Thermotec shielding, and also plan on running a separate oil cooler for the Rotrex itself.

You just cannot beat the tuning benefits and controllability that a supercharger provides, and though it can be tricky to implement, I love the challenge (and, of course, the end result).

 

[toro1]

Simply crimp the pressure regulator and you will be surprised at just what a stock pump is capable of.

I very well might end up doing just that. I still want to thoroughly test it, though, before deciding which way to go.

 

[toro1]

Thanks for the info Maj. That Bosch pump is still the size of the older design, though -- the K7 & K8 pump is an entirely different animal. I realize I can replace the housing with one from an earlier bike, but my goal is to use as many of the original parts as possible.

 

[toro1]

Hi Toro,now that you mentioned it,are you are going to use ecueditor to flash the stock ECU since it can control fuel vs boost,retard the timing etc etc?

Yep. Actually, while I have downloaded and played with the ecueditor software, I'm going to be working with Guhl Motors for the tuning. I've spoken to Don and he really knows his stuff, so I think I'll be able to do exactly what I want with the stock ECU.

I'm thinking about generating a couple different maps (that can hopefully be assigned to the stock ABC power switch); one which will allow me full power for hooligan antics and general around town riding, and one which will allow full throttle while keeping the front end on the ground (the best that it can, anyway). The timing and secondary throttle plate control on a per gear basis should be the key to making it work...

 

[toro1]

I was able to mill the pulleys for the bike this past weekend. First, I had blanks CNC turned by a local shop to my specs. Then, I made a fixture to perfectly locate the blank and mounted that into my CNC mill:

Finally, I created a program to machine the pockets, set the tool height, and presto:

The machining process for the the supercharger pulley is the same, and once I get the teeth cut in both pulleys (for a Gates PowerGrip GT2 belt), I'll send them both down for hard-coat anodizing. This hard-coat will keep the relatively soft aluminum surface from wearing over time as it is basically as hard as diamond.

More good stuff still to come once I find some time...

 

[toro1]

I'll post some more pics once I get the teeth cut -- it looks like jewelry afterwards.

 

[toro1]

For a real hi tech configuration it may be possible to modify the starter assembly and gears to provide the drive and run the blower in behind the engine near the throttle body. A lot of work cutting gears and doing starter modifications.

First off, sorry for the lack of updates -- work has been crazy and this whole project got pushed back by quite a few months. All I've wanted to do is work on this bike, and now I'm finally able to do so again...

Kwaka, you said it right - a whole lot of work. It might be possible to do that (I've seen 1098s set up that way), but the position I have the Rotrex right now really is quite good.


Ok, onto some new stuff. I tested the fuel pump at various voltages and found out that despite being small, that little sucker can really pump some fuel -- in standard configuration it can easily handle 230whp, and with a boost in voltage, 400+ is possible, so no more worrying about fitting a Walbro or different pump housing.

After cutting the teeth, I sent the pulleys out to get hard anodized...

I fabbed up a bracket out of some plexiglass I had laying around and turned up some standoffs to get everything properly spaced and positioned into place. At this point I have the main bracket design pretty much figured out, but I want to make sure everything fits before I start writing any CNC programs. Plexiglass is great for mock-up as it's easy to work with and allows you to see potential issues lurking behind the bracket.

This is about as low profile as I can get make it. An idler will eventually reside between the pulleys on the top belt span.

Definitely going to need some clearance here. I don't know how much of the pulley will end up poking outside the fairing, but one way or another, most of the drive will fit behind the bodywork.

There shouldn't be any issue with ground clearance here. I actually think there's less clearance with the stock cover on the LH side than there is with the supercharger positioned there.



Lots more to come, so stay tuned...

 

[toro1]

I had an extra airbox laying around from my 10R project, so I popped it on the GSXR to check fitment...

Everything easily fits under the tank, and there is loads of room under the airbox itself (so much, in fact, that I plan on mounting the BOV under there rather than welding a nipple in the intake tubing). I can also fit the Rotrex oil reservoir right next to the airbox.

Obviously a new throttle body plate will have to be made to match the GSXR's runners, but I'm glad that everything else fits so well. The tubing going from the Rotrex outlet to the airbox inlet should also be a piece of cake to fab up, needing only a few simple bends.


Next up, I can't believe how quickly this part came in, but here's the inlet for the Rotrex:

It's made out of Alumide using a process called Selective Laser Sintering. It has a very high temp resistance and is quite strong. This part only existed on my computer before it was literally printed into this form. Amazing. I could actually get it made out of stainless or titamium, but the cost is ridiculous.

Anyway, this inlet will allow an oval tube to run right behind the header to the other side of the bike, where cool fresh air will be drawn in. I plan on removing the ram air tube and sticking a filter up in that empty pocket as I hate filters that stick out the side. Everything will be heat wrapped to keep the temps as cool as possible.



Lots of machining still to come.

 

[toro1]

Before I get to the CNC machining, it's time for some good old fashioned lathe work. I needed to make an idler pulley and an adapter for the BOV to interface with the airbox.

First up is the idler. I started with a 2.5" bar of 6061...

An hour later....

Next up is the BOV adapter. Another hour (or more) later...

After parting each blank, I faced the backsides and did a secondary drilling op on the adapter. The idler was designed with hard anodize in mind, so the bore was left .002" larger to properly fit the bearing. Precision pays dividends in the end.

 

[toro1]

Here's a little guide on CNC machining parts. Most people probably think that all it takes to machine a billet part is a drawing and the push of a button. Ha, I wish. Unless you have access to some expensive CAM software and a 5-axis machine, it's nowhere near that easy.

First you create a drawing. In my case, a 2D drawing of the front and back of the part is required. Then, using those drawings, you create a program that the CNC mill runs on. With the software we have, this means manually creating toolpaths, figuring out cutting depths, and generating code for each individual tool to be used. For this supercharger bracket, a total of 4 programs (front, back, fixture, facing) will have to be created to get to the finished part.

We're not done yet. After ordering material, the blanks have to be cut to the proper length. Then, each blank is squared up and faced (front and back) to the final thickness. The first op is the front side...

Before the back can be machined, the fixture has to be created. This fixture locates the blanks via 3 pinned locations and will allow the final part to be cut out of the larger material.

The fixture is clamped in the vises and the blank is bolted to it. After loading up a different set of tools, the backside program is run...

The part is then unbolted from the fixture, cleaned off, deburred, and voilà:

The only thing to check now is fitment on the bike. Think it fits?

Woohoo! All is good. The only thing left to do now is send out the bracket and idler pulley for anodize.

 

[toro1]

Thanks for the compliments, guys. I've got a lot more coming, too (wait until you see my little exhaust project).

Anyway, some more updates. I rocked out the PAIR block-off plates:

So much cleaner. These were the easiest parts to create yet, just needed a fixture, blank prep, and final cutout stage. I plan on having these anodized as well.


Next up is the throttle body runner plate...

 

[toro1]

Here we go again...


In order to maximize the efficiency of the intake, a custom throttle body adapter plate will be made to exactly match the runner geometry. I start with a blank, then cut it to length and face both sides so it ends up at the final thickness:

After lots of chips and with the help of some special endmills, we end up with tapered runners and fully radiused inlets:

Back when I made the Kawi parts, I designed the TB adapter fixture to accept any adapter plates I could possibly come up with, regardless of bore size & spacing. Thus, after clamping the fixture and mounting the part, I'm able to machine the bottom side. BTW, I actually had a custom endmill made to put the little ring around the runners (which gives the silicone connectors something to bite onto).

I'd say it's a pretty good match. The bores are much bigger than the 10R.

One more part done. I'm quickly running out of stuff to machine...