interesting. im liking the cam actuated idea. a cam so to speak could have lobes under the pivot point of the rockers and be rotated by a linear actuator controlled by rpm activated switches. the cam would in effect rotate and raise and change the pivot point on the rocker arm to increase the ratio for a higher lift. now, can anyone make this setup work?
Well, it looks like I screwed up on this subject big time and jumped the gun just a little. The 5M head design doesn't vary the rocker ratio by shifting the pivot point of the rockers or the cam towers. The variable rocker ratio on the 5M/6M is fixed by design and doesn't vary with changes in RPM. Sorry for the misleading link!! My bad!
Still, a neat article. Reminds me of an original (I thought at the time) idea i got as a freshman for a continuously variable transmission. It envolved two christmas tree shaped rollers lined up so that the small end of one lined up across from the large end of the other. In between would be a thick disk or sphere on a shaft that could be moved from one end to the other thus continuously varying the rpm ratio between the rollers. This would allow for easy engine tuning as there would be no need for a broad the torque curve. Little did I know that technique had already been used in jet engines and some prototype cars. That tranny would be fun at the strip though:
cvt guy: so what do you launch at?
5spd guy: 2800. you?
cvt guy: 6k
5spd guy: :shock:
Electronically controlled CVT's are very efficient in transferring engine torque to the drivetrain!! Just ask William! LOL!!! Snowmobile manufacturers have been using the variable diameter pulley technique for quite some time. They are highly tunable and easy to tweak. I had a lot of fun with "Comet" snowmobile racing clutches back in the 70's. The drive belt takes one heck of a beating though and usually ends up being the weakest link. It's a weird feeling when the seat of the pants meter is telling you that continuous, uninterrupted force is keeping you planted in the seat and then all of a sudden the belt breaks with a very loud bang, and without warning. The whole speed thrill takes a very sudden dive as the engine over revs and the sled slows to a freewheeling halt. Unfortunately, rev limiters weren't very popular for magneto type ignition systems on 2-stroke engines back then, so most of the bad words were focused on the busted belt that was left lying flat in the snow about 100 feet or so behind. Lots of walking in a heavy snowmobile suit, glove tossing, and helmet throwing happened more than once on the long path back to the shredded belt(s). Engine survived the 10,000 RPM spikes (thanks to Amsoil synthetic 2-cycle racing oil and a good balance job). I kept trying different brands of replacement belts and ended up sticking with a "Dayco Max". Everything stayed in one piece from that point on.
Now, back to the thread: :lol: What about using a "slightly" thicker or thinner cam tower gasket on the 5M, 6M cylinder head to vary the rocker arm ratio curve from stock spec.? Keeping the lash adjuters in check might be difficult though. :roll: Any other ideas?
saturn uses the variable transmission too. too bad it's only available in their 4 banger model. i could just imagine flooring my car and having it hover above the redline and staying there till you let off the gas. then there also wouldn't be any abrupt gear changes.