Variable Valve Actuation

[Manolis]

deltaf said: Very elegant concept Manolis. I like the fact that it would seem possible to transplant it onto most engines. Have you approached any manufacturers yet? Surely theyd bite your hand off to be a part of this idea?
Once again, well done mate! I like it!

Thank you for your good words.
Have you ever tried to approach any manufacturer?
Do you know after how many months (or years) they use to reply?
Do you know how they reply?
We have currently a good collection of replies.
But we have not one straight answer, mentioning disadvantages regarding the proposed system, yet!
Not to mention Universities and Magazines.

[deltaf]

The more i hear about this design, the more i like it.
Do you get much sleep Manolis??
Well done again.

[bogbeast]

ultimasimon said: Wow! This new technology is definately radical. If they are available for a SBC then I am seriously interested.

The only thing I didn't like about the chevy engine is its inability to rev without iminent destruction being a likely contender. This changes things.

Thanks for the interesting facts Manolis.

I would be very intrested too.

but looking at the animations would it would be very much more difficult to apply to OHV design ?

[Manolis]

bogbeast said:

ultimasimon said: Wow! ... but looking at the animations would it would be very much more difficult to apply to OHV design ?

It depends on the specific design of the OHV engine. If there is space, the VVA system could be interposed between cam followers and cam lobes.
The system suits better to OHC design, as it has the camshaft closer to the valves, achieving more accurate control of the valve’s motion.
It is more difficult to reliably achieve the same accuracy with OHV design (for instance 0.15 mm lift for the intake valves at idling) due to the interfering long pushrods and rocker arms. The less joints the more accuracy.

[rev-erend]

Manolis - congratulation. Great work.

Looks very impressive. Very like the BMW
valvetronic system that uses the valves to control
the intake mixture amount and recover the loses that
the carburetor or injection throttle bodies add.

Only your design is much simplier.

Good luck getting in to the real world of production.

One point - OHV engines typically have the push rods
and control mechanish in a single line - your system
would really need the inlet & exhaust valves to
be spaces apart for the two control shafts.

So bad news for owners of Small block chevys and Rover
V8 cars.

[Manolis]

rev-erend said: Manolis - congratulation. Great work.

.... So bad news for owners of Small block chevys and Rover
V8 cars.

Actually the system works also with a single camshaft and the valves at a row. A common control shaft (in order to be the system simple) can control both, intake and exhaust valves, not necessarily having common lift. For instance, with proper design of the control shaft, you can have at idling 0.15 mm lift for intake valves and 1.0 mm for the exhaust. Rotating the control shaft you can increase both lifts, not necessarily equally. The engine becomes even simpler in this way: just a camshaft and a control shaft, but you have to decide – by lab tests – for the best relation of the intake and exhaust valve lifts and then to approach it.
Even so, the system is more suitable for OHC systems (e.g. single overhead camshaft without rocker arms) than OHV systems.