variable valves

1fastredsc · 05-13-2003, 05:28 AM

Someone else on this bb posted this website. After reading through the site, studing the function of the valves, i got the thinking. 911S cams, stock or ported cis system, then i realized that i wouldn't be able to stand without knocking over my drink in front of me

. I'd like some opinions from the tuners on this board. I talked to a gentleman from aatap and he told me that he puts cars on the to do list based on the demand from people who e-mail him. So if you got 30mins to spare, read through, and then let's see what you think.
www.aatap.com

thabaer · thabaer's Garage

I suppose you'd be less likely to spill if you gazed a little less vigorously at the chopper pilot

Only two years of limited real-world data, fatigue and hi revs concern me too. I'd need a lot more empirical data from independent sources before I'd consider using these puppies.

Other systems may cost more but I prefer the idea of precise active controls vs calibrated springs and hope.

s_wilwerding · s_wilwerding's Garage

One thing I don't understand about the system is that if the valve profile changes (because of the movable collar), how does the valve seat? Does the collar collapse back as the valve seats? I can't imagine the movable collar would last long if that were the case. It would also mean that the collar has to move only when the valve leaves the seat, which doesn't give it much time to open and close, and, consequently, to do much good.

1fastredsc · 05-13-2003, 10:21 AM

The collar can collapse, but only collapse. In a set state, it's no different than a normal valve. When open, the collar will only move if the cylinder pressure is still higher than that of the port. Therefore if the cam opens it early, but the exhaust is still pressurizing to leave out, the it continues to seat against the head even though the valve is attempting to open. When it's still open but attempting to close, if the air is traveling at a slow pace, and assuming there's enough duration to create blow back, then the positive pressure in the cylinder during the beginning of compression will cause the collar to collapse and seat early eliminating blow back. This is why in theory this is amazing, but the practice is still limited which sucks. I guess we'll all have to wait a couple of years before this becomes fully reliable and available.