Why hasn't VTEC been adapted to pushrod engines?
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From: Upstate NY
Solenoid operated valves (SOV) require a significant amount of electrical power to operate, perhaps equal to all the rest of the systems on your car. They aren't able to cycle fast enough for ultra fast engines like F1, and the extra weight is carried high and wide on the engine. They will be very costly to produce and generate significantly more heat under the hood than current engines (no pun intended 
)
I still fail to see the overwhelming advantage of SOV. Even if they could produce a "square wave" valve motion, which they cannot, that isn't at all ideal for breathing. Varying lift can eliminate the need for a throttle, as BMW has shown, but why bother? Variable phasing, especially with multicam engines, goes a long way toward optimising engine output.
I would rather see variable length intake runners to shape the torque curve (along with cam phasing). It worked well in F1 until it was outlawed for 2006. Renault, especially misses it this year.
If we are going to take something from F1, pneumatic valve springs sounds good to me.
We already produce OEM engines (gasoline, NA) with torque curves having 90% of max torque from converter stall(<2000) to WOT upshift point (>5500). We're headed toward an almost flat torque curve with current technology.
FWIW, flat lifter pushrod engines (NASCAR Cup, for example) have almost point contact between the slightly radiused lifter foot and the slightly tapered lobe. That point moves on the lifter, but the loads are very high, and they live, just as flat lifters lived in OEM engines. That's not really a hurdle lto 3D cams.
)I still fail to see the overwhelming advantage of SOV. Even if they could produce a "square wave" valve motion, which they cannot, that isn't at all ideal for breathing. Varying lift can eliminate the need for a throttle, as BMW has shown, but why bother? Variable phasing, especially with multicam engines, goes a long way toward optimising engine output.
I would rather see variable length intake runners to shape the torque curve (along with cam phasing). It worked well in F1 until it was outlawed for 2006. Renault, especially misses it this year.
If we are going to take something from F1, pneumatic valve springs sounds good to me.
We already produce OEM engines (gasoline, NA) with torque curves having 90% of max torque from converter stall(<2000) to WOT upshift point (>5500). We're headed toward an almost flat torque curve with current technology.
FWIW, flat lifter pushrod engines (NASCAR Cup, for example) have almost point contact between the slightly radiused lifter foot and the slightly tapered lobe. That point moves on the lifter, but the loads are very high, and they live, just as flat lifters lived in OEM engines. That's not really a hurdle lto 3D cams.
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Actually, you probably wouldn't operate the valves electrically. You would operate a valve that would change hydraulic pressure that would move the valve. You're control over the valve may use valve displacement as an input. A 1-1.5 in² disk mounted on the valve with a 600psi pressure should get the desired valve movement. The valve would be adjusting the pressure differential across the disk.
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From: Upstate NY
Originally Posted by DavidNJ
Actually, you probably wouldn't operate the valves electrically. You would operate a valve that would change hydraulic pressure that would move the valve. You're control over the valve may use valve displacement as an input. A 1-1.5 in² disk mounted on the valve with a 600psi pressure should get the desired valve movement. The valve would be adjusting the pressure differential across the disk.
A 1.0 sq.in. disk moving .650 in. @ 7200 rpm with a 300 degree (seat-seat timing) duration needs to move the hydraulic oil at a rate of about 48 gallons per minute with no restriction and with a control making changes every 10-40 microseconds (not milleseconds). This is for each valve. That might be a fairly large challenge. Perhaps I missed something.
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Think brake system in contrast with lubrication system. Since there is less mass and no extra energy stored in the spring or disapated in valve spring heat, the power should be lower than current cam driven open, spring driven close valvetrains.
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From: Upstate NY
Originally Posted by DavidNJ
Think brake system in contrast with lubrication system. Since there is less mass and no extra energy stored in the spring or disapated in valve spring heat, the power should be lower than current cam driven open, spring driven close valvetrains.
Dig a little deeper into hydraulics and their controls.
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From: Upstate NY
Originally Posted by joecar
I agree, I think low power solenoids controlling high pressure hydraulics is probably the good way to go.
Perhaps we could use tiny CNC ball screws.
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From: So.Cal.
Originally Posted by Cop Car
BMW already has a camless V10. its in the M5 and M6. valves are actuated by solenoids. its the future, and i cant wait till all the kinks are worked out.
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From: Upstate NY
Originally Posted by DavidNJ
Maybe my pressures are off...this is roughly analogous to the time fuel is injected. Also a non-compressible fluid system.
I'll leave it to others to figure the pump power, oil tank capacity and cooling system needed to make such a system work. Note that we don't see a lot of hydrauliclly actuated valve on high speed IC engines.
Shoot, high-revving F1 engines couldn't make electrical solenoids work fast enough, and the weight (high up) and electrical power required made the systems impractical even before they were ruled out.
Another big problem there would be with a SOV (solenoid operated valve) is the need for a soft landing of the valve in the seat. If you just slammed the valve shut against the valve seat you would destroy it quickly. Without showing any numbers and proof I don't think anyone can dismiss either an electrical or hydralic system.
UofMn
UofMn
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From: Anna, OH
Originally Posted by Cop Car
BMW already has a camless V10. its in the M5 and M6. valves are actuated by solenoids. its the future, and i cant wait till all the kinks are worked out.
They have a camshaft. It's very much like VTEC, with a couple of very expensive actuator gimmicks thrown in... 
On The Tree
Joined: Apr 2006
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From: Boring Ohio
I didnt read the whole post so I'm not sure if this was already mentioned, but GM does have a variable cam timing in-block cam motor about to be released. Its The 6.2L vortec coming out in the yukon denali. It has an actuator on the cam that can advance or retard like 60 degrees or so. It also has displacement on demand so its rated in the low 20's on gas mileage and makes like 430 HP or something like that. So they are one step ahead of the game, I cant wait to drive one.
BMWs system uses their Valvetronic system on the E65/66 V8/V12 cars. Also the E53 X5s w/V8s, and E60/63/64 5 and 6 series V8 cars.
Valvetronic = intake valve variable lift adjustment
Intake air flow is set with the throttle body fully open, and by adjusting the valves on the fly.
Intake/Exhaust cam for each head (4), with an added eccentric shaft higher above and off to the side of the intake camshaft. Two DC motors adjust these shafts.
The throttle body isn't even used 99% of the time. At start up, the throttle body controls air flow. Air flow is also controlled by the throttle body if any faults are to occur in the system.
Ex.
In the event of a motor failing, the motor on the opposite bank will match the failed motors position.
Pretty bad *** setup. Sounds like a lot to go wrong, but so far this has been pretty reliable.
Valvetronic = intake valve variable lift adjustment
Intake air flow is set with the throttle body fully open, and by adjusting the valves on the fly.
Intake/Exhaust cam for each head (4), with an added eccentric shaft higher above and off to the side of the intake camshaft. Two DC motors adjust these shafts.
The throttle body isn't even used 99% of the time. At start up, the throttle body controls air flow. Air flow is also controlled by the throttle body if any faults are to occur in the system.
Ex.
In the event of a motor failing, the motor on the opposite bank will match the failed motors position.
Pretty bad *** setup. Sounds like a lot to go wrong, but so far this has been pretty reliable.