MG Quiz

OK Bryan you are the winner ..

Some notes on the VVC

VVC (Variable Valve Control) is an automobile variable valve timing technology developed by Rover and applied to some high performance variants of the company's K Series 1800cc engine.

The VVC engine is also fitted into these non MG/Rover cars: Ariel Atom, Lotus Elise, Caterham 7, Caterham 21, GTM Libra


In order to improve the optimisation of the valve timing for differing engine speeds and loads, the system is able to vary the timing and duration of the inlet valve opening. It achieves this by using a complex and finely machined mechanism to drive the inlet camshafts. This mechanism can accelerate and decelerate the rotational speed of the camshaft during different parts of its cycle. e.g. to produce longer opening duration, it slows the rotation during the valve open part of the cycle and speeds it up during the valve closed period.

The system has the advantage that it is continuously variable rather than switching in at a set speed. Its disadvantage lies in its complexity. Other systems achieve similar results with less expense and better reliability.
In internal combustion engines, variable valve timing (VVT), also known as Variable valve actuation (VVA), is a generalized term used to describe any mechanism or method that can alter the shape or timing of a valve lift event within an internal combustion engine. VVT allows the lift, duration or timing (in various combinations) of the intake and/or exhaust valves to be changed while the engine is in 7operation. Two-stroke engines use a power valve system to get similar results to VVT. There are many ways in which this can be achieved, ranging from mechanical devices to electro-hydraulic and camless systems.

The valves within an internal combustion engine are used to control the flow of the intake and exhaust gases into and out of the combustion chamber. The timing, duration and lift of these valve events has a significant impact on engine performance. In a standard engine, the valve events are fixed, so performance at different loads and speeds is always a compromise between driveability (power and torque), fuel economy and emissions. An engine equipped with a variable valve actuation system is freed from this constraint, allowing performance to be improved over the engine operating range.

Strictly speaking, the history of the search for a method of variable valve opening duration goes back to the age of steam engines when the valve opening duration was referred to as “steam cut-off”. Almost all steam engines had some form of variable cut-off. That they are not in wide use is a reflection that they are all lacking in some aspect of variable valve actuation.

The desirability of being able to vary the valve opening duration to match an engine’s rotational speed first became apparent in the 1920s when maximum allowable RPM limits were generally starting to rise. Until about this time an engine’s idle RPM and its operating RPM were very similar, meaning that there was little need for variable valve duration.

It was in the 1920s that the first patents for variable duration valve opening started appearing – for example United States patent U.S. Patent 1,527,456. A surprising fact is that from these first patents until the appearance of the helical camshaft there has never been a really practical and useful variable duration camshaft..
The Mechanics of How it Works:
In its simplest form, what the VVC Mechanism does, is to speed up and slow down the camshaft so that the length of time the inlet valves are open can be varied without the profile of camshaft changing. Although the drive to the VVC Mechanism is at a constant half engine (or crankshaft) speed, the camshaft velocity varies within each revolution in such a way as to maintain an average of half engine speed.

The heart of the MGF VVC lies just underneath the cam cover.

The inlet camshaft is not a single casting as in most engines, but is in four sections. Inlet valves for cylinders 1 and 2 are controlled by lobes on a half cam-shaft driven by a VVC Mechanism (the most important components of which are two drive rings) at the front of the engine. Inlet valves for cylinders 3 and 4 are controlled by lobes on a half cam-shaft driven by a second VVC Mechanism (incorporating its own drive rings) at the rear of the engine, the drive for the latter is taken from the exhaust camshaft.

Each half camshaft is in two parts, an inner independent shaft and an external shaft on which the cam lobes are located. Each VVC Mechanism housing is machined to swiss watch standards and contains a pair of needle roller bearings.

The other thing one notices is a cast hydraulic control unit and next to it, two 1 square plastic coated solenoids. These are driven from the Engine Management System (EMS) and, through a spool valve, control shaft connected to the toothed control sleeve on the outside of each driving ring assembly.

The really ingenious bit is the design of the VVC Mechanism. the cross-sectional show, the outer control sleeve is machined such that it is much thinner on one side than the other, (i.e. it's bore is eccentric to it's outside diameter).

The sleeve can be adjusted through about a quarter-turn which causes the pair of drive rings within the sleeve to move outside the camshaft's centre of rotation.

As the drive ring rotates within the sleeve, the camshaft drive pin moves from the inside of the radia slot to the outside, depending on whether the drive ring is at the thin side or the thick side.

A pin at the end of the external shaft slots into a hole in the face of the drive ring thus transferring the desired amount of movement to the external shaft and hence to the cam lobes.
What is the effect?:

The software in the EMS ensures that the VVC Mechanism allows the length of time during which each inlet camshaft lobe permits each inlet valve to stay open, to be varied as the camshaft rotates. The amount of variation is huge - 75 degrees between 220 to 295 degrees, or about 40 degrees either side of the basic camshaft profile of 260 degrees if you prefer.

The amount of precision control is incredible. The EMS can map and if necessary alter, the degree of valve opening required within each single camshaft revolution.

To quote Laurence Pomeroy: Increased valve overlap (either side of top-dead-centre) and the extension of the total period of inlet valve opening contribute to increased effectiveness for a given valve area .

A Musical Analogy:

If you take 1 bar of music, the underlying rhythm and hence the overall speed at which it is played can remain the same as hundreds of bars either side of that one. However a good instrumentalist (whether a string or wind player) can vary each note within one bar, and give clearly audible differences in phrasing.

This in its way, is what VVC does. It listens through the EMS sensors to the way you drive the car. The crankshaft rotates at a constant speed (i.e. constant rhythm), yet the inlet camshaft's rotate at variable speeds depending on the instructions given to it by EMS.

VVC's Benefits:

The system increases the power output from 120 PS to 145 PS. This additional 25 PS, is available over much more of the rpm range, giving more torque than the standard car. It also increases the maximum safe limit by 8% from 6750 to 7300 rpm.

The driveability of the car is drastically improved because the increased power is available between 4000 and 7000 rpm, which is what you need when accelerating hard to overtake that lorry.

Because the system enables the cam profile (and hence volumetric efficiency) to be accurately matched to the amount of welly you give the accelerator pedal, you use less fuel, probably by as much as 5% to 10% depending on your driving style and the journeys you take.

Finally, how can one measure increased fun. Getting from A to B today is an absolute chore. Anything that contributes to Safety Fast is a big plus. Through the VVC system, Rover have achieved this in quite a remarkable way. What a pity that Pom is no longer around to write about it...

Dumb blonde !! ?? :omg: :omg: :omg: :bang: :bang: :bang: :bang: :rant: :rant: :coat:

Right a quickie:- - - -

What was the VIN number of the first MG TF off the production line that was sold? (be careful with this one) and the date on which this car was made.
:broon: :bust:

what a good question,

Think I've found an answer but no question ready to go , so I'll try to develop one after dinner.

bryan young wrote: Right a quickie:- - - -

What was the VIN number of the first MG TF off the production line that was sold? (be careful with this one) and the date on which this car was made.
:broon: :bust:

Two earlier TF prototypes built using TD frames were numbered TF/0250 and TF/0251. One of these prototypes has survived and has been featured in British car magazines during the 1980s and 1990s. TF/0250 was the first hand built prototype car shown to MG's board of directors on January 8,1953 painted blue with 26 wide louvers rivited to the bonnet top panels. TF/0251 was completed in August from the TF (EX177/15) drawings dated May 7,1953 based on TF/0250 were completed. Hence, the comment made by Henry Stone that it took "6 months" for the Morris drawing office to complete the TF drawings for a car designed and built in Abingdon in a fortnight. For the first time, the last preproduction vehicle was not given the number 0251 but now 0501. TF/0501 was completed on the new TF assembly line on September 16, 1953. The very last TF made, April 1955, carried chassis number HDE23/10100

Here are the car numbers of vehicles with the first color on the TF production line; The first Black car is: HDA13/0501; first Birch Grey is HDB46/0570; first MG Red is HDC46/0513; first Almond Green is HDE43/0518; first Ivory is HDP43/0502. Therefore the VIN number of our example ( HDA13/0501) tells us that it is a MG two seater, black in color, RHD for the home market finished in cellulose and has the first car number assigned for a TF model, actually the last preproduction model. The TF has two engine codes or types; XPAG/TF for the 1250 models (1953 and 54) and XPEG/ ( 1954 and 55) for the 1500 models. The engine number is stamped on an octagonal tag located on the right hand side of the engine below the number 1 exhaust manifold branch as well as on the manufacturer's number plate on the firewall. If the octagonal tag is missing from the engine, for the XPAG/TF engines, the number is stamped just above location of the octagonal tag and for the XPEG engines, it's located on the engine-transmission bellhousing face at the 12 o'clock position - only the last three numbers. Engine numbers for the XPAG/TF engines would begin around 30,000, immediately following the end of the numbers the TD engines

Is that OK? :nonod: :whistle: :pinch: :bust:

PPS Sorry but been golfing alllllllllllllllllllllllllllll day so was late to this :slapme:

Ooooo developing a question, that sounds interesting Gary, just make sure Mr Forgetful doesn't pip you to the post

:bust: Mr Forgetful did :bust: well done Ted and commiserations Gary, that is all assuming that Bryan was after the 1950's TF and not the 2002 TF or indeed the :lol: :lol: :lol: :lol: too many TF's

PQD44 wrote: :bust: Mr Forgetful did :bust: well done Ted and commiserations Gary, that is all assuming that Bryan was after the 1950's TF and not the 2002 TF or indeed the :lol: :lol: :lol: :lol: too many TF's

As it was BRYAN I assumed he wanted it "over egged", over the top, not what you would expect and, of course SIMPLE :woohoo:

PQD44 wrote: :bust: Mr Forgetful did :bust: well done Ted and commiserations Gary, that is all assuming that Bryan was after the 1950's TF and not the 2002 TF or indeed the :lol: :lol: :lol: :lol: too many TF's

Ted found the same web site I did, although I was also looking to close the loop and give the full Vin of the First TF's in 2002 and 2007....not that it matters much now........

It was a great question Bryan, were do you get them from......

Gadget2466 wrote:

PQD44 wrote: :bust: Mr Forgetful did :bust: well done Ted and commiserations Gary, that is all assuming that Bryan was after the 1950's TF and not the 2002 TF or indeed the :lol: :lol: :lol: :lol: too many TF's

Ted found the same web site I did, although I was also looking to close the loop and give the full Vin of the First TF's in 2002 and 2007....not that it matters much now........

It was a great question Bryan, were do you get them from......

Garry - I originally thought as you but then decided if we give Bryan the whole answer straight away he'll go off in a huff OR require additional information, not on the "Internettie" contained in a book, of which he has the only edition left, and which we cannot possibly guess!! :nonod:

I'll try the 2002 TF - 2D600101 First MGTF in January 2002 (154 cars pre-production, not sold to customers) so2D600155 :whistle: :pinch: and you can give him the "chinese" ones. Then, he has a conundrum :evil: :evil: :woohoo: :bust:

Mr Forgetful wrote:

Gadget2466 wrote:

PQD44 wrote: :bust: Mr Forgetful did :bust: well done Ted and commiserations Gary, that is all assuming that Bryan was after the 1950's TF and not the 2002 TF or indeed the :lol: :lol: :lol: :lol: too many TF's

Ted found the same web site I did, although I was also looking to close the loop and give the full Vin of the First TF's in 2002 and 2007....not that it matters much now........

It was a great question Bryan, were do you get them from......

Garry - I originally thought as you but then decided if we give Bryan the whole answer straight away he'll go off in a huff OR require additional information, not on the "Internettie" contained in a book, of which he has the only edition left, and which we cannot possibly guess!! :nonod:

I'll try the 2002 TF - 2D600101 First MGTF in January 2002 (154 cars pre-production, not sold to customers) so2D600155 :whistle: :pinch: and you can give him the "chinese" ones. Then, he has a conundrum :evil: :evil: :woohoo: :bust:

:woohoo: :omg: :woohoo: :omg: :woohoo: :omg: :woohoo: :omg: :woohoo: :omg: :woohoo: :omg:

Your first answer was perfect and quite correct VERY WELL DONE full marks and quite up to the expected Bryan "nit picking" answer. Then came the second part which was really the one i wanted but forgot to be specific :nonod: But if you add 154 to 101 you get 255 not 155 i think there is a mistake on this publication Then of course there was the chinese take away which was 251 and sold to Mr Newey now being raffled. Correct on all three counts. your turn for an easy question. :hugs:

I'm confused.com when it comes to complicated arithmatec sur! :oops: Oh - and I cheated :omg: yes I copied and pasted without checking Sorry, sorry :nonod:

Easy one coming up

What is the link between Cecil, Matilda, and Albemarle, why and the result