Comments on: Helical Camshafts – Variable Valve Actuation with a Mechanical Twist

By: Danny Williams

Danny Williams — Wed, 28 Jul 2010 04:54:23 +0000

Bart – THe Wiki article below has some graphs at the end of it which were measured directly off the cam in the photos and videos – so you can see for yourself what +45 degrees would be.
http://en.wikipedia.org/wiki/Helical_camshaft
The engine as tested was (apart from the cam) exactly as Mr. Suzuki made it. I had originally thought (before it ran) that I would need big-volume plenum chambers etc. to stop the backflow caused by the LIVC upsetting the carbs. Despite many hours of running I have no idea why there is no sign of backflow. Even at +85 degrees nothing is obvious. At +85 (zero on the compression gauge) the engine turns over on the starter as freely as if the sparkplugs were not fitted – so it could be handy for starting a high CR engine (a diesel maybe?)- as somebody commented.
Speaking of diesels – modified long-duration cams can’t be used in diesels because they then won’t have enough cylinder pressure to ignite the fuel for starting or at low RPM. Using this cam would allow the use of longer duration cams in diesels – just how much this would help power output remains to be seen.
The measurements are in crankshaft degrees.

By: Bob Nedoma

Bob Nedoma — Wed, 28 Jul 2010 04:08:13 +0000

When it breaks down, can I fix it myself (and/or) can I afford to get it fixed, that’s what matters, as far as [this one] invention is concerned. There is enough of throw away stuff out there already.

By: OMMAG

OMMAG — Wed, 28 Jul 2010 00:19:30 +0000

The big advantage of the mechanical solution (helical cut cam) is that it is simple.

Simple ….. the first rule of engineering design … KISS.

Williams follows the rule … I predict success.

By: Bart

Bart — Tue, 27 Jul 2010 22:39:00 +0000

todd – I have same assumption as you, talk’in crankshaft degrees here.

mike – my baseline assumption is that a typical high perf motor like Danny used here will have intake closure around 40 deg ABDC. Adding 45 deg to that gets 85 deg ABDC. It could work because the double pumping would be at low manifold vacuum (there wouldn’t be much work being done by an idling piston to shove air out a big open hole) and then at valve closure there would be only minimal compression done, just enough to meet idling load. I think its just a motorhead communication gap here.

Also, I think the motor he used has fuel injection, but I’m not sure; I don’t keep up with all the motocross stuff. You’re right if it were carbed, it might double pump fuel with a carb at such long durations. But timed fuel injection can beat that problem down.

By: Mike

Mike — Tue, 27 Jul 2010 21:59:18 +0000

Bart makes a good point about double pumping. Is this system going to create an ultra-rich mixture, creating emissions issues as presented with the CV Carbs installed? Obviously if this was incorporated with a direct injection system, I can see some interesting economy and HP gains.