How Honda's VTEC works:
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From: Overland Park
How Honda's VTEC works:
I would answer that question with, "good". But, if you want a more technical description visist this site:
http://www.howstuffworks.com/question229.htm
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http://www.howstuffworks.com/question229.htm
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>>>Anybody know *for sure* if production of a solenoid controlled valve engine has been planned? When? Specs?<<<
Presently the closest to this sort of thing is BMW. They are not using solenoids but mechanically vary the fulcrum point on a rocker actuating the intake valves. Valvetronic. Expect lots of interest and copies. It's a simple design!! No more throttle body. You simply open the valve as much and for as long as you need. So at idle the intakes barely crack open while at WOT and high revs they max out. Gains in MPG, emissions, power, torque, response, easy fuel requirements, you name it. Comes out on the controversially styled new 7 series this month. Soon to be on all or nearly all BMW motors. At least at first it's not good past about 7000 RPMs so the M engines may not use it. It provides stepless lift and duration changes rather than just cam A or cam B ala VTEC. The have it teamed up with intake and exhaust VANOS which Honda now does with i-vtec but only on the intake side. And continuously variable intake manifold length. That motor should pull everywhere. Actual solenoids on street cars might work even better but are likely to be pricier and perhaps not durable.
Stan
Presently the closest to this sort of thing is BMW. They are not using solenoids but mechanically vary the fulcrum point on a rocker actuating the intake valves. Valvetronic. Expect lots of interest and copies. It's a simple design!! No more throttle body. You simply open the valve as much and for as long as you need. So at idle the intakes barely crack open while at WOT and high revs they max out. Gains in MPG, emissions, power, torque, response, easy fuel requirements, you name it. Comes out on the controversially styled new 7 series this month. Soon to be on all or nearly all BMW motors. At least at first it's not good past about 7000 RPMs so the M engines may not use it. It provides stepless lift and duration changes rather than just cam A or cam B ala VTEC. The have it teamed up with intake and exhaust VANOS which Honda now does with i-vtec but only on the intake side. And continuously variable intake manifold length. That motor should pull everywhere. Actual solenoids on street cars might work even better but are likely to be pricier and perhaps not durable.
Stan
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From: Austin
tokyo_james, in theory the larger high-rpm cams could be used at lower RPMs. However you'd get very rough low-rpm performance from what I hear. It's kinda like why dragsters sputter at idle. Not sure what the specific behavior is, but apparantly the shorter valve open time doesn't cost you in terms of power and torque, but does allow for better running below the VTEC point.
Basically there are no "traditional" cam designs that don't either suffer at the low end or at the high end. VTEC essentially gives you two cam systems to give you the best of both worlds (lots of power via high RPM, yet still usable at low RPM)
Basically there are no "traditional" cam designs that don't either suffer at the low end or at the high end. VTEC essentially gives you two cam systems to give you the best of both worlds (lots of power via high RPM, yet still usable at low RPM)