\'Interesting\' (for some) discussion on the Norton Rotary forum today (unusual!!)...
Thought i\'d share it with you...
1. Hi, my name is Mark I have recently bought an F1 sport and would like to do some tuning to make more power. I have had the bike dyno\'d and have 85 bhp at rear wheel. I would like to get 100bhp+. Does anyone know where I can get performance parts from and what power increases I will get. I don\'t really want the ejector exhaust system as they are probably too loud to use on track or road. I would be grateful for any advice. Thanks.
2. Hi Mark. An F1 Sport !! you lucky man !! As i understand it you cannot get much more power due to the high air intake temperature. For more power you need cold air feed into the carbs. The only proven way to do this so far is by using the noisy ejector exhaust. If you do find another way to get more power please let me know.
3. Hi Mark, Well I think it is fair to say there are no performance parts for the F1, with only around 200 being made there isn\'t much of a market really. They can be ported in much the same way as a 2 stroke, someone on here might have one of the templates they used to open up the ports. Apart from that the ejector exhaust is really the only way to get big increases in power. The problem is that they breath hot air and that isn\'t conducive to making power.
4. You could do worse than to talk with Richard at Norton, Rugeley; mention the \'curly wurly\' exhaust system.... he reports a power increase with this.
5. I imagine that the Norton Motors \'curly wurly\' exhaust system is less restrictive than the standard system. Rotaries seem to respond quite well to a free flowing exhaust, the first mod\' Mazda rotary owners always go for is a \'de-cat\' pipe (replaces the Catalytic converter section). I’m convinced that the loud exhaust on my Interpol has increased the power a bit.
Having said that ive either heard or read somewhere that no matter what else you do, without lowering the intake temperature you hit a power ceiling at around the 100bhp mark. Ah! ive remembered where it was...i quote John Robinson (Performance Bikes magazine, August 1990) -
\'More power could be available but not with the present system of rotor cooling. At about 100bhp, this becomes the restricting factor. Intake air is taken through the eccentric shaft; oil is injected into it and centrifuged out through the shaft bearings to lubricate the rotor seals. The air is then fed into a plenum chamber before going to the downdraught Mikuni (F1) carburettors. This preheats the air to between 70 and 150 degrees C, and pressurizes it to some 20 inches of water. The extra pressure is good for power, but the increasing temperature isn\'t and around 100bhp is where the temperature has more influence than the pressure. The \'exhaust ejector\' method of forcing air through the shaft (as on the racer) is too noisy for use on a road bike. One possible way to get more power would be to use a separate fan to cool the shaft and rotors, and let the intakes breathe fresh air\'. (end quote).
The claimed power output for your bike is something like 90-95bhp which ties in with your dyno rear wheel figures. If the above info is true then i fear that the best you can hope for by tuning is a gain of 5-10bhp. Sorry!
6. ‘One possible way to get more power would be to use a separate fan to cool the shaft and rotors, and let the intakes breathe fresh air\'. Hasn\'t this been done already? Somewhere in the darker back regions of my mind something says that Crighton or whoever tried this once just before the last Rotaries where build. Shouldn\'t be too difficult as the rotation of the fan could be used for some kind of centrifuge or the oil mist might be routed through a cyclone separator.
7. I believe you may be right, i have heard rumours that Brian Crighton was experimenting with fan cooling when Norton went under. All we need now is for someone to finish off the work Brian started.
If only Norton had survived maybe we would now be riding highly developed 150bhp rotary road bikes.... maybe.
8. At least the engines have survived, somehow. The Diamond Air-rotaries (used to be Mid-West) still feature the same displacement numbers, however they are similar in performance figures, 105Hp for the FI\'ed 588 twin rotor.
9. Also UAV at Shenstone still make the 588cc Norton engine. They quote 120bhp using fuel injection. I believe they use the exhaust ejector system though.
10. Hi Mark, I have recently bought a Norton Commander (in bits and no fairing) with the express object of achieving your aim - to increase the power without using the ejector exhaust (which is ok for racing but not really acceptable for road use). What I am planning to do is to use an electric fan and an oil-air separator to suck cooling air through the engine, and to allow the carbs to breathe cool air in the normal fashion. Unfortunately I haven\'t even put my bike back together yet. I have a couple of things to get out of the way before I can start playing with the Norton so I don\'t think I will get round to this for a few months.
Another option would be to convert the engine to oil cooling, and use an electric scavenge pump to suck the oil out. However as the engine was designed as air cooled I am not sure how practical this would be as it would certainly need internal engine changes to prevent any problems with puddling and the oil may change the effective mass of the rotors which could have other effects. Also the bearings may need to be changed, but it may be worth investigating. I will keep the group informed as and when I make any progress.
WATCH THIS SPACE !! as they say.
Any suggestions? / bright ideas?