Obviously not car specific but internal combustion 4 stroke engine technology can have cross over implications.
As the post title says 17,500rpm redline and 133hp from 600cc = 3.6hp/cid. This would be F1 levels not long ago and you can buy this technology at any Yamaha dealer for around $10k.
I personally like high torque street car engines but Good God... 17,500rpm. There has to be something we can learn from this engine.
SchmidtMotorWorks wrote:They seem to be getting bye with bucket followers, not finger followers.
You know, I'm not quite sure where bucket followers got a reputation as less than good....really, finger followers may have some small advantages, but they are minor until you really start getting the revs to stratospheric levels.
The box part looks in principle a lot like the expansion boxes we just built for a road race Corvette, to get the exhaust from Burns-style merge/meg/reverse collectors to the Series-mandated muffler. The idea was to end the 'tune' at the meg by decoupling the rest of the system from same with a big box volume.
The valve? Don't know. A couple of top end cars have such these days for sound tuning...
Could the valve at the output of the box actually serve like the old 'heat riser' valves, for cold starts, that we had in our 50's and 60's exhaust systems?
SchmidtMotorWorks wrote:Is the box on the collector with the valve in it a new thing or something common on street bikes?
They allrady have em now for quite some time (+10years), in order to rescue some bottomend. and also (not admittedly) to cut on noise restrictions in the government tests, where they are tested at specific rpm´s.
For the race bikes they are pulled out though.
Ape wrote:
For the race bikes they are pulled out though.
Not always...seen Yamaha Race Kit exhaust from just a couple years ago have the same EXUP-valve...
Well yes but i guess not the majority of the race exhausts, i guess its also track dependent, maybe the valve for the shorter tracks, as you know they´re also being (or where) used on suzukis.
Bike only makes 120bhp at crank (111bhp at wheels) and revs to 16k redline. Rev counter reads over 17k but then most bikes are at least 1krpm optimistic. Manufacturers claims are always way over reality.
The engine is also lacking midrange on the dyno but feels good on the track.
Be interesting to see how the engine life is as the honda's are not good when pushed to over 16k. Bore wear, piston wear and rock, and a whole bunch of other weaknesses. 2 year life on the block and crank and in the trash!
The exhaust valve is known as EXUP. Been on their bikes since mid 80's and now used by suzuki and others. They have similar valves in the intake too which suzuki are being clever with and controlling on a closed throttle to reduce engine braking.
Race bikes are very limited in rear tire contact area so factory race bike engine torque curves are managed to allow the maximum rear wheel torque that the tire can handle in each gear and RPM. This is accomplished by fixed design and variables in areas such as the intake/exhaust systems and the ECU. Some expert riders may choose to modify some of these limiters and instead rely more on throttle and bike control.
