roundle on Aug/12/02 said:
BMW is working on a valvetrain that uses electronic magents. BMW's design will eliminate the need for camshafts and valvesprings, making VTEC/multiple stage camshafts obsolete. Just imagine how much friction would be eliminated.
Lotus already has a camless engine running now in prototype development as we speak. Electromagnetic valve lifters right now are not developed enough to control the speed of the valve when it closes at high rpms. They slam against the seat pretty hard. Even with advanced metallurgy to improve hardness and durability of the valve and the head seat, the amount of wear on the valve backface and seat is too high for passenger vehicles. Renault is currently running electromagnetic lifters in their 120 degree V10 F1 engine right now but are far from being refined or better than the pneumatic lifter engines like the Ferrari or BMW V10's.
Lotus has opted to use the tried and true method of pneumatic valve lifters seen in most F1 engines but they choose to apply it to passenger cars. Camless pneumatic valve lifters would be a huge step forward, since you are not fixed to one cam spec.
Imagine this: the ECU has a library for the Integra of ALL available aftermarket and stock cam specs in its memory. For a given rpm, throttle angle, vehicle speed, and air flow delivery (all these things measure something called "engine load"), the library can pick the best cam spec instantaneously out of the library and use it to direct the pneumatic valve lifter to lift the valve for a specific lift and duration at a specific geometry on the fly. The ECU could instantly, in a fraction of a second, at that particular rpm, choose the best cam spec. It could choose a different best spec for each and every rpm on the fly depending on the engine load input with the computer memory speeds we have now. So yes your future ECU would have all the Toda specs, Jun specs, Skunk2 specs, Honda specs, etc. in it's library and choose the best one at any given instant in time and engine loading!! Gee I wonder how much that chip will cost?
This way you would have the broadest flattest torque band across the whole of the rpm range. Seem far-fetched?
That's what they said about having intake cam timing being changed instantaneously on the fly. Instead of being stuck with one intake cam gear setting using your current adjustable cam gear , the ECU could guide a chain driven belt to alter cam gear position to optimise the cam overlap for any engine load on the fly at each rpm....far-fetched? this is what VTC of iVTEC is.
We already know the ECU can change already between 2 different cam specs for lift and duration in response to a change in engine load to get a better broader flatter torque curve ...this is what VTEC is. Now imagine expanding from 2 to 100's. Unreal? Lotus already has a mock up working camless engine. It actually uses the thrusters that are used on the NASA Space shuttle to precisely control the valve lift position with the pneumatic lifters. It is being developed as we speak for their next generation PASSENGER car...not race car. The goal is to cut NOx emissions to meet the Kyoto Accord standards without sacrificing fuel efficiency or performance. Current catalytic converters cannot filter out NOx products from the emissions...hydrocarbons and carbon monoxide? no problem...but the NOx gases are the troublemakers.
If you want to hear something that will bend your noodle:
The Japanese are already developing along with Lotus a way to use a controlled detonation...yes detonation: the thing we don't want...to add extra power.
Right now, in our engines, if unburnt gases are left in the cylinder, after combustion, they actually can help cause detonation on the next intake-combustion cycle. If there is too much unburnt gases left, it actually triggers pre-ignition by speeding up the rate of burn in the combustion process. This is why performance integras don't have an EGR (exhaust gas recycling) for better fuel economy...burnt gases don't burn well a second time to make power but they can assist completing the burn in the next cycle (unfortunately they help too much and the process runs away causing the out of control combustion at the wrong time in the engine cycle like on the compression stroke).
Well the Japanese found out, by accident one day, that when they turned off an EGR fuel efficient prototype engine, it kept on running on its own without the use of an ignition system...no spark to trigger the combustion!
What was igniting the mix at the right crank angle? If there is a consistent small amount of unburnt gases or EGR left over each time, at the right time, it would detonate the mix but not so fast as to cause full detonation. The engine would have kept on running had it not been for the loss of fuel and lack of coolant recirculation, electrically-driven by the pumps.
Lotus and some Japanese auto institutes are working on this CoNTROLLED DEToNATIoN or CoNTROLLED AUTO-IGNITIoN to power the out of synch pistons on every other power stroke rather than using a spark on every power stroke.
amazing...the future looks bright...less emissions, more power...better driveability....everything will become variable depending on engine load driven by the ECU: intake runner lengths, intake lengths, manifold plenum sizes, header lengths, compression ratios, valve timing....