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Power Boosting Technology -------------------------------------------------------------------------------- Variable Valve Timing (VVT) Basic Theory After multi-valve technology became standard in engine design, Variable Valve Timing becomes the next step to enhance engine output, no matter power or torque. As you know, valves activate the breathing of engine. The timing of breathing, that is, the timing of air intake and exhaust, is controlled by the shape and phase angle of cams. To optimise the breathing, engine requires different valve timing at different speed. When the rev increases, the duration of intake and exhaust stroke decreases so that fresh air becomes not fast enough to enter the combustion chamber, while the exhaust becomes not fast enough to leave the combustion chamber. Therefore, the best solution is to open the inlet valves earlier and close the exhaust valves later. In other words, the Overlapping between intake period and exhaust period should be increased as rev increases. Without Variable Valve Timing technology, engineers used to choose the best compromise timing. For example, a van may adopt less overlapping for the benefits of low speed output. A racing engine may adopt considerable overlapping for high speed power. An ordinary sedan may adopt valve timing optimise for mid-rev so that both the low speed drivability and high speed output will not be sacrificed too much. No matter which one, the result is just optimised for a particular speed. With Variable Valve Timing, power and torque can be optimised across a wide rpm band. The most noticeable results are: - The engine can rev higher, thus raises peak power. For example, Nissan's 2-litre Neo VVL engine output 25% more peak power than its non-VVT version. - Low-speed torque increases, thus improves drivability. For example, Fiat Barchetta's 1.8 VVT engine provides 90% peak torque between 2,000 and 6,000 rpm. Moreover, all these benefits come without any drawback. Variable Lift In some designs, valve lift can also be varied according to engine speed. At high speed, higher lift quickens air intake and exhaust, thus further optimise the breathing. Of course, at lower speed such lift will generate counter effects like deteriorating the mixing process of fuel and air, thus decrease output or even leads to misfire. Therefore the lift should be variable according to engine speed. -------------------------------------------------------------------------------- Copyright

considering the following: - pay day: 20th every month - variable bonus accrual period end Dec 08 (i.e. 1 Jan 08 till 31 Dec 08) and payable on 20 Jan 09 - have been in the Company during the variable bonus accrual period (i.e. 1 Jan 08 till 31 Dec 08) - last day with Company: 10 Jan 09 Upon the last day, is the resignee entitled to receive variable bonus for the period 1 Jan 08 to 31 Dec 08? - assuming variable bonus is not contractual inside the employment contract.

Hi bros and sis who are working in a bank, Just doing a quick poll to see what's the climate like on the Variable this year for the banking and financial sector? Heard from market that this year will be a good year to expect a good bonus for the majority of the banks.

the statistics! people say: yes variable valve rocks (power and fuel wise). but any stats to prove it? Manufacturers we want answers!!!!

I stumbled upon this in the net, not sure its old news. Only on the AGN 1.8 engine , it says variable valve timing. By any chance its a Vtec equivalent? I welcome any info about this. Thanks. Pages from vw_g4_2.pdf

On NST today. Claim huge savings! However, what they didn't illustrate is that there is a 4% penalty for full early redemption. Go to DBS website and see what I mean. (I can not imagine what processing charge is equivalent to 2 % of o/s loan. It is purely labour costs I would think and it would be the same whether the loan amts are big or small) However, the website did not say whether there is penalty for partial redemption. If there is no penalty for partial redemption, then the early redemption penalty has no effect cos you could prepay 99% of the loan first and pay the last $ later ie full redemption. Yeah, charge me 4% of a $... Anyway, it is a good start for motorists as we have been screwed too long by the banks. Interesting to note that this product is offered when interest rates are going up. Wonder whether they will yank it off the mkt when interest rates start to decline???

Is this the future? http://www.canadiandriver.com/articles/jk/041014.htm Can big V6 and V8 monsters sip petrol like 4-bangers and still retain their monstrous torque without forced induction?

Since the 1.4L A14DMS engine that the new Aveo boasts have the VGIS, below is a link to Autozine's Technical School on VGI. Please note the technology is not new and lots of non-motorheads will think that it is VTEC but it is not. Have a good read. http://autozine.kyul.net/technical_school/...ch_engine_2.htm Read about the SAAB Variable Compression engine. I remembered about it and realized GM owns SAAB as well. The prototype is a 1.4L turbocharged inline-5. Fascinating! Prime candidate. Very exotic!

To all VAG owners driving 1.6 engines with the variable intake thingy: How do you chck that the system is actually working? On mine, I can only play around with the throttle when the bonnet is up but I don't see the variable intake linkage moving at all. And that linkage is not stuck or seized as I can move it about. Well do another check some other time but if anyone can point out the right way, much appreciated.

Recently, Mitsubishi and Nissan cars are coming with these kinda gearbox, it remind me of Subaru Justy J10. Can someone enlighten me?

Hi! Read somewhere that the MIVEC engine in the new Colt does not come with variable valve timing technology like the VVT-i. Is it true?

Check this out ! http://www.autonews.com.tw/cgi-bin/as/as_show.cgi?qry=M4

I still want to see SVC in the 9-5, but I reckon GM have canned it Undoubtedly, a small but powerful 4-pot engine goes against the American car building philosophy doesn't it? Let's just hope that the engine will see the light of day in the end. Well there is a cutaway sitting in the saab museum.. wonder if that says something?

Saab engineers have developed an engine technology that improves fuel efficiency by up to 30 percent, reduces tailpipe emissions, and doesn't negatively impact overall performance. Saab calls its new engine technology Saab Variable Compression (SVC). Interestingly, Saab engineers have been thinking about variable compression since 1981, and prototype engines with SVC technology have existed since 1990. At the 2000 Geneva Auto Show, Saab finally felt its SVC technology had advanced enough to show it to the world. The SVC engine shown at Geneva was a supercharged, 1.6-liter, inline five-cylinder engine. With dual-overhead camshafts and four valves-per-cylinder, it looks pretty much like your average internal combustion engine. In fact, an objective in the development work on the SVC concept was to retain as many of the basic components of a conventional engine as possible. The crankshaft, connecting rods, pistons and valves are all of the same type as those of today's engines. What distinguishes the SVC engine is the way it is split into upper and lower parts. Instead of having the cylinders located in the block like all modern vehicle engines, the SVC engine's cylinders are located in the upper section. This upper part is known as the monohead. You heard us right -- the cylinders are built into the head. For those of you who may not know it, this is a very unconventional design. Traditional engine architecture places the cylinders below the head (or heads if the engine is of a V or flat configuration), between the valves and the block. Everything else is pretty "normal" inside the Saab engine. The lower portion of the SVC engine -- the block -- contains the crankshaft, camshaft and pistons. But here's the trick. Since the cylinders are built into the heads, the monohead can be adjusted (moved) relative to the block without affecting engine or valve timing. On the SVC engine, the monohead tilts at up to a 4-degree angle. Rubber bellows seal the monohead to the block. By adjusting the "slope" of the upper part of the engine in relation to the lower part by the use of hydraulic actuators, the Saab engine can vary the volume of the combustion chambers. This, in turn, changes the compression ratio. Compression ratio refers to the ratio between the combined volume of a cylinder and a combustion chamber when the piston is at the bottom of its stroke, and the volume when the piston is at the top of its stroke. The higher the compression ratio, the more mechanical energy an engine can squeeze from its air-fuel mixture. Higher compression ratios, however, also make detonation more likely. In all modern engines, the compression ratio is fixed and cannot be altered unless different engine components are installed. Saab's SVC technology allows a variable compression ratio from a low of 8:1 to a maximum of 14:1. Although variable compression is what makes the SVC engine unique, Saab says the fuel efficiency of a conventional, normally aspirated engine would only improve by 4 percent if it were equipped solely with SVC. The potential of variable compression is most effective when combined with a smaller engine design (for better efficiency) and high supercharging pressure. It's hard to argue with that given the impressive results. Saab says its 1.6-liter SVC concept engine generates 225 horsepower and 224 foot-pounds of torque. Maximum boost pressure from the supercharger is 40 psi. These horsepower and torque figures are comparable to a normally aspirated engine of similar displacement (like a 3.0-liter V6 from a Nissan Maxima, for instance). Additionally, Saab says the SVC engine is more fuel efficient at light loads than a standard 1.6-liter normally aspirated engine. Due to its variable compression ratio, the SVC engine can run at an optimum compression ratio of 14:1 at low engine loads to maximize fuel efficiency and lower harmful tailpipe emissions. Increased supercharger pressure at such a high compression ratio would cause detonation, so the compression ratio is lowered to 8:1 at high engine loads to enable maximum engine performance. The SVC engine continuously varies the compression ratio according to driving conditions. This would not be possible, however, without an advanced engine management system. Saab engineers credit their Trionic engine management system with making the whole thing work. The current system, which Saab has been using since 1991 to manage their turbocharged engines, served as the basis for the specially designed SVC system. The Saab Variable Compression technology illustrates yet another innovative success story in the search for more fuel-efficient cars. While manufacturers such as Honda and Toyota have gone the hybrid route, other automakers such as Saab have taken a more traditional route, exploring variations on the theme of the internal combustion engine. The results so far look encouraging. Saab hasn't announced official production plans for SVC technology. The engine is still in the concept stage. However, Saab does say that extensive testing has been performed, including 200,000-kilometer durability tests. Additionally, Saab wouldn't have gone to such marketing lengths at the Geneva Auto Show if it didn't think there was a future to variable compression. Stay tuned, though, as Saab is now owned by GM. Never know what might happen with this technology if it gets perfected.