Quote:
|
Originally Posted by s2ook
what sort of weight would this setup add to the valvetrain? Assuming there is a weight deficit (more spinning mass) wouldn't this inhibit maximum engine speed and longevity? Finally, any dynos?
|
Hello.
Talking for the quickly moving parts, the new system can actually reduce the weight.
For instance, the rocker arms instead of three per pair of valves can be just one, and only one roller cam follower is used in new VVA per pair of valves.
The camshafts also can be a little lighter and a lot cheaper, as it is needed just one cam lobe per pair of valves, so totally 8 cam lobes in the engine instead of 24 in S2000.
The control levers replace the pivot shafts, and they are heavier. But they are slowly moving parts, so they do not add inertia loads.
At idling, at low revs and at partial loads (that is at very low valve lifts) the new VVA operates with very light loads, which in turn improve reliability and longevity. For instance, removing the timing belt and keeping the control shafts at idling position, you can rotate the camshafts easily by your small finger. This means very smooth and free from friction operation. Try the same in any other system (conventional or VTEC) to see the difference, especially in ?racing? engines where the strong valve springs load the valve train system with friction and wear even from idling.
The engine is the first and unique prototype, its construction accuracy is not the proper one, its carburetor cannot feed the engine correctly and the spark is not advanced according the new operational conditions. Nevertheless, the behavior of the engine is remarkably good, as well as the reliability of the mechanism.
As you understand it is meaningless to get dyno graphs in this case.
The next project with fuel injection, correct spark timing and proper construction accuracy will be measured in dynamometer and the graphs will be published in the web site.
By the way, do you know the
1. valve lift used in S2000?
2. the timing of the crankshafts at low and high lift operation?
3. the differences between S2000 and Civic TypeR 2000 cc cylinder heads? (forget the driving of the camshafts)
4. where can be found more technical info (like valve lift to crank angle curves)?
Thank you
Manolis Pattakos