Honda Technology Definitions
Haydz
Moderator
The following was taken from the Honda New Zealand website...
Real-Time 4WD (CRV Only)
Honda's Real-Time four wheel drive system is designed to provide the benefit of all wheel drive in slippery conditions, without the penalties of extra drag, higher fuel consumption, greater tyre wear and increased noise which accompany conventional four wheel drive systems in conditions when the extra traction is not needed.
The other benefit of Real Time 4WD is that its engagement is completely automatic - there are no extra levers or buttons, the system automatically engages drive to the rear wheels when it senses that the front tyres have started to slip.
The Real-Time 4WD system incorporates a compact transfer case which distributes drive to a propeller shaft which runs to the rear differential. There are also two hydraulic pumps, one driven by the front wheels, the other by the rear wheels. When the CR-V is operating on dry pavement, the front and rear wheels are turning at the same speed, and so are the two pumps. If the front wheels start to turn faster than the rear wheels (due to loss of traction), the pumps turn at different speeds. The resultant hydraulic pressure opens a valve body and feeds pressure to a multi-plate clutch, which engages the propeller shaft to the rear differential, thus feeding drive torque to the rear wheels. The amount of drive going to the rear wheels is proportional to the amount of front wheel slippage.
There is no INTRAC specific information available as yet, but the following is what i have managed to put together so far...
INTRAC
JDM EF5 Shuttles have the option of INTRAC which adds rear L.S.D. and A.L.B enabled brakes. The INTRAC system also disengages the 4WD system while braking, allowing the A.L.B to function correctly. INTRAC RTi's also have an optional front LSD. Other features are uknown as yet.
Real-Time 4WD (CRV Only)
Honda's Real-Time four wheel drive system is designed to provide the benefit of all wheel drive in slippery conditions, without the penalties of extra drag, higher fuel consumption, greater tyre wear and increased noise which accompany conventional four wheel drive systems in conditions when the extra traction is not needed.
The other benefit of Real Time 4WD is that its engagement is completely automatic - there are no extra levers or buttons, the system automatically engages drive to the rear wheels when it senses that the front tyres have started to slip.
The Real-Time 4WD system incorporates a compact transfer case which distributes drive to a propeller shaft which runs to the rear differential. There are also two hydraulic pumps, one driven by the front wheels, the other by the rear wheels. When the CR-V is operating on dry pavement, the front and rear wheels are turning at the same speed, and so are the two pumps. If the front wheels start to turn faster than the rear wheels (due to loss of traction), the pumps turn at different speeds. The resultant hydraulic pressure opens a valve body and feeds pressure to a multi-plate clutch, which engages the propeller shaft to the rear differential, thus feeding drive torque to the rear wheels. The amount of drive going to the rear wheels is proportional to the amount of front wheel slippage.
There is no INTRAC specific information available as yet, but the following is what i have managed to put together so far...
INTRAC
JDM EF5 Shuttles have the option of INTRAC which adds rear L.S.D. and A.L.B enabled brakes. The INTRAC system also disengages the 4WD system while braking, allowing the A.L.B to function correctly. INTRAC RTi's also have an optional front LSD. Other features are uknown as yet.
Comments
"i-VTEC is the technology used in the latest family of Honda engines. The engines incorporate a host of innovative features designed to deliver a cutting-edge combination of performance, efficiency and low emissions. The technology combines VTC (variable Timing Control) - which continually adjusts camshaft timing - with Variable Valve Timing and Lift Electronic Control (VTEC), which changes valve lift, timing and duration. The result is impressive horsepower and high torque with outstanding fuel economy and low emissions. In addition, the new engines are rotated 180 degrees from the traditional Honda layout, bringing the exhaust manifold closer to the catalyst for improved light-off and reduced emissions at start-up.
Honda has designed a multitude of engine variations dependant on engine requirements, for example a high-performance version of i-VTEC, which operates on both camshafts.
i-VTEC valve control system
The 'intelligent' i-VTEC system adds new VTC (Variable Timing Control) to VTEC to provide continuously variable camshaft timing - taking the concept of variable valve timing to new heights. In short, VTEC + VTC. Not only does i-VTEC provide a substantial performance increase across a broad power band, it boosts fuel economy while also reducing exhaust emissions.
VTEC (Variable Valve Timing and Lift Electronic Control)
The innovative VTEC system is able to adjust the lift and opening duration of the valves to help the engine produce both abundant low-rpm torque and excellent high-rpm power. At low rpm, VTEC adjusts valve timing and lift for optimum cylinder filling and fuel efficiency. In addition, the timing of the intake valves is staggered and their lift asymmetric - creating a swirl effect within the combustion chamber. The result is increasing burn speed with improved combustion stability. As engine rpm builds, VTEC transitions to a high-lift, long-duration cam profile for improved high-rpm engine output.
There are different versions of VTEC used in the many i-VTEC engines."
VTC
"The new i-VTEC system adds a new camshaft VTC (Variable Timing Control) system to VTEC for continuously variable camshaft phasing across the engine's entire power band. As engine rpm builds, a VTC actuator - controlled by an engine-control unit that monitors cam position, ignition timing, exhaust emission and throttle position - advances or retards the intake cam throughout a 50 degree range, optimizing engine output and reducing emissions.
During typical operation, the intake camshaft timing is almost fully retarded at idle to help provide more stable idling while reducing the exhaust emissions (Nox). As rpm increases, the intake camshaft is advanced, opening the intake valve sooner and providing additional valve overlap. This results in increasing fuel economy (by reducing pumping losses) and a further reduction in exhaust emissions (by creating a large internal exhaust gas re-circulation effect).
Also, to generate additional power throughout the rev range, the intake camshaft is continuously varying the amount of advance or retard, instantly adjusting to provide additional power as required by the driver."
"It was Honda's own engineers who developed the genius of 'two engines in one' ... the revolutionary Variable Valve Timing and Lift Electronic Control (VTEC) system. Inspired by the challenges of Formula One, these revolutionary engines achieve the perfect balance between racing power and environmental responsibility, always breathing with the utmost efficiency from idle to red line and everywhere in between.
For city driving, the VTEC system rewards you with efficient fuel consumption and thus lower emissions and pollution. But when you head for the open road, the engine cleverly reinvents itself... giving you all the power you want, when you want it.
How
All vehicles in the Honda VTEC range start with the advantage of having 4 valves per cylinder. But it is the timing and lift of these valves that largely determine how each engine performs. VTEC combines these two characters by intelligently varying the valves' timing and lift according to the engine's revs.
So at low rpm, two small cam lobes are pushing the valves open quickly and narrowly for a lean burning mixture that results in economical driving, low pollution and plenty of low-down torque.
As the rpm rises, a hydraulic pin within the rocker arms locks in a high rpm cam lobe that forces the valves to open higher and for longer. With more fuel and air flowing into the combustion chamber, the engine can generate more power to move the car faster.
What
The Single Overhead Cam (SOHC) VTEC engine provides a selection of Honda's with a unique and satisfying balance of power and economy.
For example the 2.2 litre SOHC VTEC engine will, at low revs, provide an economy similar to that of a 1.8 litre engine, whilst at high revs the power available is similar to that of a 2.5 litre engine.
A direct descendant of our Formula One power plant is the Double Overhead Cam (DOHC) VTEC engine, which in varying sizes is the source of Honda's sports car performance.
The DOHC VTEC engine produces one of the highest outputs per litre of any normally aspirated production engine in the world.
Honda's DOHC VTEC engine unquestionably stands at the pinnacle of technological achievement, not only for its prodigious power, but also its ability to manage this whilst still offering low fuel consumption."