hombre
Nitrous
- Joined
- Dec 31, 2006
- Messages
- 1,021
Everything I've read on supercharged engines advises a practical limit of 2 RWHP per cubic inch of engine displacement. They say that beyond that limit (280 RWHP for the R3) things begin to break, and reliability greatly diminishes. Well I've tipped the 280 HP mark on the dyno, and experienced my first failure... so I beginning to think that sage advice. Brembo tipped 280 HP some time ago, and asked the same question.
I had just finished a pull on the dyno, and after letting bike and dyno cool, started her up for another pull. An knocking sound was immediately evident... sounding to everyone's ears like a rod in the middle of the engine!
In heart attack mode, I shut her down and started to check over the bike... oil, temps, coolant. All seemed normal. Fired her again... same knocking noise, same instant shutdown. Dylan ran for the stethoscope.
We fired her again to listen for the problem... the noise had vanished! I pulled off the chin fairing to get a better look at the SC drive pulley. As other SC R3 owners will know, there's an eccentric seal that gets placed in the front cover to seal the crankshaft extension for the SC drive. The front of this alloy seal was "chewed"... and the set screws that held the eccentric were laying in the chin fairing. The screws had backed out until they contacted the steel pulley... which promptly ripped them out of the alloy threads, destroying the seal in the process. The noise stopped because the last screw left the scene.
I neglected to freshen the loctite on these screws when I adjusted the cam timing, and the extreme stress of dyno step testing caused them to back out into the SC pulley. My fault, but it goes to show that things start to go wrong pushing the engine above the practical limit. Additional power comes with additional vibration and stress. Believe me when I tell you that she rattles things off the wall when held at 7000 RPM. If you're standing in the dyno room, your legs will shake.
So SC R3 owners take note... be sure and locktite those seal screws when you take the front cover on and off. I'm inspecting all torques and have begun drilling some critical caps for lockwire treatment, before she goes back on the dyno.
I thinking to cease my HP quest right about here... **** tired of finding all the weak points.
I had just finished a pull on the dyno, and after letting bike and dyno cool, started her up for another pull. An knocking sound was immediately evident... sounding to everyone's ears like a rod in the middle of the engine!
In heart attack mode, I shut her down and started to check over the bike... oil, temps, coolant. All seemed normal. Fired her again... same knocking noise, same instant shutdown. Dylan ran for the stethoscope.We fired her again to listen for the problem... the noise had vanished!
I pulled off the chin fairing to get a better look at the SC drive pulley. As other SC R3 owners will know, there's an eccentric seal that gets placed in the front cover to seal the crankshaft extension for the SC drive. The front of this alloy seal was "chewed"... and the set screws that held the eccentric were laying in the chin fairing. The screws had backed out until they contacted the steel pulley... which promptly ripped them out of the alloy threads, destroying the seal in the process. The noise stopped because the last screw left the scene.I neglected to freshen the loctite on these screws when I adjusted the cam timing, and the extreme stress of dyno step testing caused them to back out into the SC pulley. My fault, but it goes to show that things start to go wrong pushing the engine above the practical limit. Additional power comes with additional vibration and stress. Believe me when I tell you that she rattles things off the wall when held at 7000 RPM. If you're standing in the dyno room, your legs will shake.
So SC R3 owners take note... be sure and locktite those seal screws when you take the front cover on and off. I'm inspecting all torques and have begun drilling some critical caps for lockwire treatment, before she goes back on the dyno.
I thinking to cease my HP quest right about here... **** tired of finding all the weak points.
