Omega Owners Forum
Chat Area => General Car Chat => Topic started by: albitz on 19 December 2013, 20:57:39
-
Fancy doing the timing chains on an Audi RS4 ? :o
Back of the engine.
http://www.audizine.com/forum/showthread.php/425205-B7-S4-RS4-Timing-Chain-Layout-Picture
-
Proof, if any were needed, that VW couldn't give a rats testicle about long term ownership :-X
Lazy engineers who cba to design a proper solution...
-
what happens once the car is out of the immediate dealer servicing regime is not a feature of the design process.
why should it be - there's nothing in it for the manufacturer
-
I remember phaetons were not that different
-
True, but if the cars were more readily repairable then people might be more inclined to buy them. Afterall if you owned a nice easy to fix car on a budget, then should you be in a position to buy a new car you would be more likely to stick to that brand than if the cheap second hand car was a pig to fix...
How many people deliberately bought a nearly new Renault having previously owned an older second hand one? And how many of those people went on to buy a new one? Not many I suspect...
Dismissing the second hand market is short sighted imho :-\
My biggest issue with that particular VW brainwave is the fact that they are trying to sell those engines in the marine market, and they simply cannot be repaired in situ.
It has the added consequence of removing most of the Omega replacements from the short list as they are likely to become horrendous to repair/maintain as the mileages climb...
-
I remember phaetons were not that different
They're not... see my last paragraph :y
-
I remember phaetons were not that different
They're not... see my last paragraph :y
have a look at this
(http://i181.photobucket.com/albums/x80/mecdv6/30tdi_zps5c1ce8dc.jpg)
-
Four chains is definitely lazy engineering... and quite frankly taking the piss :-\
If you must put the timing gear at the back of the engine, at least make it gear driven ::)
-
I think the engineers who designed that sure have many concerns..
-
I think the engineers who designed that sure have many concerns..
Nothing a spot of sectioning wouldn't sort out :-X
-
Jag v lumps similar iirc.
And the width of it. :o poxy multi valve over head cam design. A nice push rod 8 valve is what you want. ;)
-
Absokinglutely, with a gear driven cam :y
Clearly far too obvious for some though ::)
-
Absokinglutely, with a gear driven cam :y
Clearly far too obvious for some though ::)
<cough> *chain* <cough cough>
but its a very short chain! about as short as its possible to get between two sprockets. The cam sitting directly above the crank. :-X ;)
-
Early Cologne V6 gear driven, with cam gear made of plastic (FFS ::)) pretty bomb proof apart from cam gear and 12k tappet adjustments :o
Later Cologne V6 chain driven, but still a pushrod lump :y
If the engineers wanted to be really clever, the could incorporate the cam lobes onto the crank with four pushrods, 2 inlet and 2 exhaust, with one of each either side of the conrods. Alternatively you could have two gear driven cams, one either side of the crank
Would make a nice easy modular engine, say 500cc for each cylinder, V layouts might be a bit longer than ideal, but hey ho, life is a mere compromise... ::)
-
Early Cologne V6 gear driven, with cam gear made of plastic (FFS ::)) ...
Fibre gear ..... ;) ;) For reduced noise IIRC & it worked ....... you can't get much quieter than an engine that's not running! ;D ;D ;D
-
If the engineers wanted to be really clever, the could incorporate the cam lobes onto the crank with four pushrods, 2 inlet and 2 exhaust, with one of each either side of the conrods. Alternatively you could have two gear driven cams, one either side of the crank
That would be a miracle on a four stroke
-
I seem to recall that the Honda VF 750 from the eighties came with gear driven cams. :)
.....so why are we still using belts and chains today?
-
If the engineers wanted to be really clever, the could incorporate the cam lobes onto the crank with four pushrods, 2 inlet and 2 exhaust, with one of each either side of the conrods. Alternatively you could have two gear driven cams, one either side of the crank
That would be a miracle on a four stroke
Ok do away with cam timing altogether...
A sensor either side of the crank for each cylinder, one exhaust and one intake, each sending a pulse to the ECU. In turn the ECU fires the appropriate solenoid to open or close the valves as required. Infinite valve timing based on fuel/air demands, four valves per cylinder - a solenoid for each one... if a solenoid fails engine can still run at a reduced level. If the engine is designed 'safe' then a total electrical melt down won't destroy it.
Exhaust sensor timing could act as a cross reference for the intake timing and vice versa, so again, if a sensor fails, the engine still runs...
Obviously only as good as the person programming it... but should be alot lighter and alot more efficient :-\
-
My teacher was ex Audi and VW so in our lessons we get a lot of Audi material including this stuff. As peeps have pointed out..... all the way at the back of the engine with 3 or 4 chains. I have no idea, from an engineering point of view whether it's good or bad, but I know I wouldn't like to be the technician having to replace them :o :o :o :o :o
-
Or the person paying for it :-\
-
Its this issue currently causing issues with the 4 pot beemer diesels.
As for the electronic actuated valve train, its not so far off, already being done by Sulzer on large marine diesels.
Only needs a crank sensor to do this (remember that cam runs at half crank speed on a 4 stroke :y)
-
A pair of sensors for each cylinder might complicate things but will give more precise control and add in a degree of redundancy just in case :y
-
A pair of sensors for each cylinder might complicate things but will give more precise control and add in a degree of redundancy just in case :y
The GM crank sensor has 60 teeth, so the ECU gets an update every 6 degrees of rotation as it is ( potentially 3 degrees if it triggers on both edges). You can happily do a linear interpolation between crank sensor events because the speed won't change much in 6 degrees of rotation, so I'd say there's no need for more sensors.
-
Its this issue currently causing issues with the 4 pot beemer diesels.
As for the electronic actuated valve train, its not so far off, already being done by Sulzer on large marine diesels.
Only needs a crank sensor to do this (remember that cam runs at half crank speed on a 4 stroke :y)
I was amazed how slow the cams actually turned, when we where struggling with TB's gravel chomping rusty bullit engine. Cranking the engine with the cam covers off I was expecting oil to be flung everywhere. But no, they turn surprisingly slowly.
-
A pair of sensors for each cylinder might complicate things but will give more precise control and add in a degree of redundancy just in case :y
The GM crank sensor has 60 teeth, so the ECU gets an update every 6 degrees of rotation as it is ( potentially 3 degrees if it triggers on both edges). You can happily do a linear interpolation between crank sensor events because the speed won't change much in 6 degrees of rotation, so I'd say there's no need for more sensors.
Well that's the bottom end sorted :y Would a 3mm headgasket be enough to ensure top end clearance? I know this would drop the compression ratio, but that rather conveniently opens up the avenue of forced induction...
-
Engine out jobby, no problemo . Now how would you like to pay for that sir :D
-
I seem to recall that the Honda VF 750 from the eighties came with gear driven cams. :)
.....so why are we still using belts and chains today?
The Honda VF750 had a cam chain, was moderately unreliable (it used to eat cams) and had a reputation for being a bit of a slug. Honda were so embarrassed that they went all out to rebuild their reputation by developing (at great expense) the VF750R racer and VFR750 road bike.
I had a VFR750, I used to commute 18,000 miles a year on it. Almost indestructible (a lorry reversed over mine ::)).
The gears were an engineering marvel and reputably cost a fortune to make. They made a very distinctive whine which I found quite adictive :y
-
What make me laugh is in the V8 Supercars you now have Merc & Nissan who have spent thousands on quad cam, multi valve all singing all dancing engines and the old pushrod motors from Ford & GM are still beating them
Had i better no say that the new engines from GM are also rear chained
Andy
-
What is wrong with using hi-vo chains like many motorbikes do and that are designed to last the life of the engine. They are much, much stronger than conventional chains. :y :y :y :y
-
I seem to recall that the Honda VF 750 from the eighties came with gear driven cams. :)
.....so why are we still using belts and chains today?
The Honda VF750 had a cam chain, was moderately unreliable (it used to eat cams) and had a reputation for being a bit of a slug. Honda were so embarrassed that they went all out to rebuild their reputation by developing (at great expense) the VF750R racer and VFR750 road bike.
I had a VFR750, I used to commute 18,000 miles a year on it. Almost indestructible (a lorry reversed over mine ::)).
The gears were an engineering marvel and reputably cost a fortune to make. They made a very distinctive whine which I found quite adictive :y
The rc45. Very expensive.
http://en.wikipedia.org/wiki/Honda_RVF750_RC45
-
Gear driven cams drawing. :)
http://force-v4.com/forum/viewtopic.php?p=2261&sid=91ca8e47fb5562fb810063ebf57ed0ff
-
Cem,
That picture you posted above; is it a still from the latest Transformers" movie? ::)
-
Might as well be ;D but actually VWs finest effort :D