I have a 1990 model FZR250, 3LN that I'm going to make a speed machine out of - drag racing and speed record attempts. I think the bike isn't the best starting point in that it needs a new everything, but it needs pulling down before building up and trying make over a 100hp. I'm thinking to use a supercharger rather than turbo. I will have to consider which category I will be entering, whether I keep the bodywork as standard, or go an all-out class and extend swingarm with aerobody. There's a few things to learn, especially about riding on salt, so I'm open to advice.
Subscribed ! I agree with the supercharging part, it'll be a lot less hassle's with plumbing etc You could use something off a jet ski like the one used on the Kawasaki Ultra 300X It'd just be a matter of making up a suitable manifold for the conversion and setting up a throttle body and intercooler etc One of the harder part's to the conversion will be setting up a drive system off the flywheel Otherwise Elsberg Tuning make some small kit's that may be adaptable too http://www.elsberg-tuning.dk/supercharging.html
$$$$$ Rotrex Zeal cams or milder Carrillo rods (standard ones will snap like toothpicks) $$$$$$ clutch less compression and don't use a fat head gasket $$$$ Carb or EFI? AirFuel monitor Have a look at some of the work that A&A did http://www.aaperf.com/vfrkit-gen6.html
I've built both roadracing and speedway supercharged bike engines. Some of the above responses are right, some not... Question first - what fuel ? Petrol...difficult. Methanol...lovely. Cams - stock will do just fine. Blower - depends on budget but have a look at Subaru Justy. Don't know if you got them in Oz but it's a very nice small blower. Rods - the stumbling block. Cultivate someone with a 5 axis CNC who knows how to use it. Clutch - I believe the stock is a good basis, springs and an extra plate. Drive - use a polyvee belt about 25mm wide. It'll work fine and will slip on overrun - not breaking either the end off the crank or the blower shaft....Don't laugh I've seen it happen. The system must have some slippage. You WILL also need to make up oversize head studs. Std will NOT do. Plenty of room, actually, thinking about it, long capscrews rather than studs would be easier. Compression - they're small cylinders so you won't have to drop it much. I ran a 74mm bore twin at 9:1 static com on alky and 18lb boost. Fuel dependent of course. I can tell you that there's plenty of room in the valve springs to shim them for a bit more pressure. I'd shim the inlets around .020in to avoid them being blown open....A distinct possibilty at high boost. Carb - KISS principle. Small single choke Weber would be my choice as they're very tunable Head gasket - O ring the tops of the liners to take a 20G stainless wire. Used with a stock gasket it'll work fine. Shim the relief valve to get better oil pressure. Good luck.
SUBBED... good luck on your build. if you were to go an EFI route, take a loot at my thread. yeah its not that simple but with the system i'm using being a microsquirt it will run a flex fuel sensor so you can run ethanol e85 or any fuel you want to run. you can even use it to control your timing and fuel aswell. i'm just using the fuel only mode at the moment, but once i've done the engine swap i'll be converting it to timing and fuel.
That's for the encouraging responses, I better finish the term of uni, first. I can start in October. As for the supercharger, not sure on whether I go centrifugal, roots or other, yet. Positioning, plumbing and drive are likely to influence the decision. I'll run it N/A in an off the street drag meet in a couple of weeks and go from there. It's noisy in the motor, but deal with that first.
If you go Roots blower, a big blower run slowly has less heating losses as well as less churning loss. The last one I did we used a prototype Roots made locally which had dividing bars on the intake and output sides. It had been designed for high RPM use and had very low churning loss. We ran it to 13000rpm...with no drop in indicated pressure at all - 18lb from just off idle to max revs. Drive is certainly a problem as it depends on whether you need it to self start. Push start or rollers, just use the starter end of the crank. A possibilty is a gear drive off the bigger primary gear and blower placement above the gearbox.
Your requirements are at opposite ends of the boosting scale. To run at high revs for long periods on the salt a turbo would be my choice. For drags where you want torque off the line my choice would be supercharger. Suggested blower would be the one from a 660cc Suzuki cappachino car found in places that import Jap engines and half cuts. These are a two lobe roots blower with sealed bearings and oil chamber. I would drive it with the standard multi rib belt at about 1.5 to 1 ratio as a start. I have always used S.U. carbs on my blown engines, but I was wanting smooth power and a bit of economy. Good luck with your project, will watch with interest.
Agree totally with Murdo on that one. Turbo for the salt. @Murdo I imagine those SU's were running in a suck through configuration?
Suck through is the only way with a supercharger that will be any good. There will be manifold vacuum after the carb when the throttle is closed so the blower will be turning in vacuum and taking next to nothing to drive it. As soon as the throttle is open you start making boost and the load comes on the drive belt. This type of system will need to have a backfire valve to relieve large spikes of pressure in the manifold after the blower if the engine backfires, otherwise a broken belt or driveshaft will result. The systems I built were for hot road cars and racing/hill climb cars where I wanted instant response to the throttle and maximum torque. The S.U. carbs work extremely well with roots type blowers, particularly at low engine speed where the intake manifold 'pulses' at each turn of the rotors. The S.U. can react to those pulses and give good idle and instant response to throttle opening far better than a fixed jet type (eg Dellorto, Weber, etc) that will 'drop' the fuel from the jets at each negative pressure 'pulse'. My last racing car was powered by a 950cc Morris Minor engine using the two lobe Suzuki Cappachino blower and an 1.75" S.U. I never measured the power/torque output, but at 12 psi (above atmospheric, 26 absolute) it was a hell of a lot of fun in an open wheel car that weighed 400Kg.
Well, the drag race didn't happen, I was ready and the meet was cancelled due to rain. So we'll just have to wait until the budget and time is there before I do any more. I am doing a fluids subject and a thermal plant subject at uni this term, so that might help.
Lost my computer a 1yr ago and all contacts! I found a pic on line with a turbo and traced the pic to jap company that modifed and customized bikes in japan.I emailed them and was told they like to fit it in japan and I didn,t take it any further