Brera 3.2 JTS Q4 SV 48,000 miles Timing Chain - Page 8 - Alfa Romeo Forum
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Originally Posted by sprint_veloce View Post
Interested to know what the benefit would be of varying chain tension with oil pressure. A spring seems like a much more reliable device for this sort of application.
If you're interested, you're welcome to find out for yourself. Then you will realize how wrong you are.
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- Insert the piston in the hydraulic tensioner body.

- Compress the piston in the hydraulic tensioner body rotating it and locking it in the end of travel position.
What the manual omits to say is that you are compressing the piston against the spring pressure before locking it off and inserting the temporary lock wire. Having done this procedure a few times I can confirm it's a right royal PITA to push the piston against the spring pressure and to lock it off, but once you manage it it's actually quite rewarding.
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Er, well I was trying to find out for myself, by asking someone who knew. I usually find that's the best way to understand these sorts of things.

So again, any idea what the benefit is of varying chain tension by engine oil pressure?

The early Busso V6 did have an oil pressure actuated tension reduction device but Alfa removed that in favour of a simple sprung tensioner for the 24v version of the engine so assume they also questioned the benefits?

In the GM application, does the hydraulic pressure act to decrease the chain tension like early Busso or increase it?
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Originally Posted by sprint_veloce View Post
Er, well I was trying to find out for myself, by asking someone who knew. I usually find that's the best way to understand these sorts of things.

So again, any idea what the benefit is of varying chain tension by engine oil pressure?

The early Busso V6 did have an oil pressure actuated tension reduction device but Alfa removed that in favour of a simple sprung tensioner for the 24v version of the engine so assume they also questioned the benefits?

In the GM application, does the hydraulic pressure act to decrease the chain tension like early Busso or increase it?
Hi,
The Busso is different.The mechanical belt tensioner has passed into legend as the static pressure is greater than the hydraulic, as I understand it. When the engine oil pressure is up to working value, it effectively "Backs - Off" the mechanical tension. So when oil pressure drops, as revs com off the engine, the mechanical (spring) tensioner re-applies it it to maintain the tension. The belt slack is on the back face in such circumstances, so the mechanical (spring) tensioner, re-applies the static tension to the belt. Perhaps this why Alfa initially said 72,000 mile belt change; I think. But that did not take into account belt wear or deterioration of pulleys. "Busso gave them an inch and Alfa took a mile". There are so many brilliant aspects to Busso's design and historically most failures are not attributable to the "Great" Snr. Busso. Every modern V6 engine owes so much to this man's engineering talent. It has also to be said, he had considerable concern when the 24 valve version, quad cam was introduced as he did not think there was sufficient contact area between the belt and pulleys. And if one looks at his original design with a single cam per bank, it would have been very easy to adapt to the new heads of the, "Twin Air", where a single exhaust cam is used and the inlets are operated by rod with variable hydraulic valve advance/retard. The bore and stroke would have suited this turbo method and V.V,T would have taken care of emissions for the regulators. I think it is Twin Air, but I have lost touch with modern Fiat inspired Alfa's.
The Gm engine springs back up the chain tension when the oil pressure drops and when the engine is switched off. Operational pressures for the oil pump is given as 4 - 6 Bar. but at low revs/tick-over, the mechanical pump cannot cope with the low speed bleed through the crank and journal shells, so without the springs, there would be slack. It should work well when pressures are adequate. When they are not, they are having to do work that they were not intended to do. And the more work they do, the weaker they become. If you have a Brera, your intentions are clear. With inadequate oil pressure, the springs will suffer fatigue and the consequences of that are well known. Where as boring old f---s like me, have never hit the rev limit. But poor gallery balance also exacerbates the G.M. engines ability to maintain tension.
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The galleries etc of the VVT are down to Suzuki - who I think know a thing or two about performance engines.
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The galleries etc of the VVT are down to Suzuki - who I think know a thing or two about performance engines.
Semantics, semantics, always semantics. I don't care who they are down to. I am beyond debate, the work is going ahead. However, I have just returned from a meeting with a Specialist Engineering Company, and I think I will go with their view on this issue. If one want's to sit on one's hands and procrastinate, then that's fine. But if the Engineering World took a similar view, we would never move forward. It is results that matter and we shall see what we shall see. Permanent points scoring are like Pyhrric Victories. No victory at all.
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Semantics, semantics, always semantics. I don't care who they are down to. I am beyond debate, the work is going ahead. However, I have just returned from a meeting with a Specialist Engineering Company, and I think I will go with their view on this issue. If one want's to sit on one's hands and procrastinate, then that's fine. But if the Engineering World took a similar view, we would never move forward. It is results that matter and we shall see what we shall see. Permanent points scoring are like Pyhrric Victories. No victory at all.
Your choice - but it's an incredible amount of work to have done to save 150 every 100k.
I'll just ignore the attempts at petty insults.
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Your choice - but it's an incredible amount of work to have done to save 150 every 100k.
I'll just ignore the attempts at petty insults.
It's an engineering exercise, plain and simple. The money is irrelevant although you are someway off what the real cost/benefit figure is. I am new to the 159, but not so Alfa Romeo. However, some of the topics regarding the 159 and it's supposed failings are just fanciful. Or do people just like to promulgate myths about this model, without getting to the bottom of issues? I enjoy debate, on a technical level. But this isn't debate, it's gainsay. It would have been nice to have had all the information on the Q4 at my finger tips, but hey, thats life. I do however now feel confident in what I am trying to achieve and the benefits it will bring in doing it. And if it helps others, then great. But I'm not one who suffers negativity for too long. I have been in some S----y places around the World in charge of prototype projects that never worked on leaving the factory. I was responsible for contracts worth millions of pounds. But working thousands of miles away and trying to make things work, does not make one predisposed to suffer fools gladly. Whilst I do not see you as a fool, you do tend to oscillate from tepid support to just plain contrary. I'm sorry for that. With regard to the incredible amount of work, well genuine success, no matter how small, is a joy. There are gains to be had in failing also, as it brings a fresh understanding, broadens one's experience. But to do nothing, not to challenge one's own capacity, that's too depressing, even for me at almost 69.
Don't be offended. But just let me get on with what I intend. You will be the first to know if it is a failure. Sadly, it won't be.
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Do we know what the OP did?
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Got bored reading the post?
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With regard to the incredible amount of work, well genuine success, no matter how small, is a joy
As an engineer myself I always need to understand what success looks like - I don't see how you can with this project until you understand the problem. You have set off with a preconception of the problem and a very blinkered approach to solving it. From my first hand experience of having changed the chains on my 159 3.2 Q4 myself I have tried to provide the facts to help you understand the problem, I'm also fully aware of the costs involved. You will probably improve the chain life by a small amount but your solution (from what I can understand of it) seems very complex and may cause damage elsewhere - but as you say your choice.
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I'm looking forward to see what you discover and can improve sizewell, be it power, response, economy, chain life, or even if no improovement can be made at all, I still admire your project!
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I'm looking forward to see what you discover and can improve sizewell, be it power, response, economy, chain life, or even if no improovement can be made at all, I still admire your project!
Thank you for that.
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As an engineer myself I always need to understand what success looks like - I don't see how you can with this project until you understand the problem. You have set off with a preconception of the problem and a very blinkered approach to solving it. From my first hand experience of having changed the chains on my 159 3.2 Q4 myself I have tried to provide the facts to help you understand the problem, I'm also fully aware of the costs involved. You will probably improve the chain life by a small amount but your solution (from what I can understand of it) seems very complex and may cause damage elsewhere - but as you say your choice.
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I am trying to think of what you may have derived from your experience and how it could perhaps have benefited others who suffer the problem of timing chain failure. Perhaps you can elucidate on any specific area which you may have concluded as being attributable to such failures? I don't recall any positive technical contribution, only matter of fact statements, without any technical substance to support your opinion. For in reality, that is all it is. But is probably sounds impressive to sycophants. As to offensive comments about what "OP's" background may be, it matters not. It is simply a matter of having the capacity to understand complex issues. and that is not based on the ability to replace chains and tensioners with the aid of a Hand Book and a spanner.
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I've provided you with a lot of information and experienced based facts. I think you now have a much better understanding of how this engine works and can make better judgments on your modifications. Hopefully, this has also gone some way to correct some of the earlier incorrect information you have been purporting as fact.
If you could step away from your keyboard a little bit, take off your Busso tinted glasses and explain what you're doing and why you're doing it people may be able to benefit. I've never had the stamina to read all your posts so a brief description would be really helpful.
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Sizewell wants to take measurements of oil pressures in the engine, and see if redirecting oil from the bypass valve to the vvt supply helps, and then add an external pump and accumulator just like Ferrari used with the same vvt system to see how that changes things, chain and engine lubrication will be improved but it's not the only aim.
I think vvt operation and vvt improvements are the main challenge, sizewell has explained many times how there would be a serious oil pressure problem in the vvt system everytime it engages, which would cause an oil pressure drop across the whole engine. It's not just engine wear that can be improved, but vvt improvements can help economy, response, maybe power as well, this is very interesting r&d!
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But won't this require access to hardware, software and testing to change the ECU mapping to compensate for the out of range solenoid pulsing voltage signals generated by the abnormal pressures v cam phasing?
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I think what sizewell is trying to do is provide a reliable supply of oil pressure to the cam phasers so the vvt actually does what the standard map is trying to do. When the engine is running at a constant rpm for more than a second or so, there is plenty of time for the standard pump to provide the required oil pressure, so the standard cam phasing map could be tuned very well, but during rpm changes, sizewell believes the standard pump isn't adequate, which could be affecting economy, power, response, and oil pressures, which is what his research and proposed tests are all about.

Ferrari used an external pump and accumulator with the same vvt system, but I suspect Alfa had to keep costs down, the vvt still makes a nice improvement to the gm engine using the standard pump, and the engine lasts long enough without an external pump. The Alfa intake manifold seems to have longer intake tracks than the gm units i've seen, and a popular mod for the gm v6 is to add a one inch thick manifold spacer which gives a very noticeable boost to low rpm performance.
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I think what sizewell is trying to do is provide a reliable supply of oil pressure to the cam phasers so the vvt actually does what the standard map is trying to do. When the engine is running at a constant rpm for more than a second or so, there is plenty of time for the standard pump to provide the required oil pressure, so the standard cam phasing map could be tuned very well, but during rpm changes, sizewell believes the standard pump isn't adequate, which could be affecting economy, power, response, and oil pressures, which is what his research and proposed tests are all about.

Ferrari used an external pump and accumulator with the same vvt system, but I suspect Alfa had to keep costs down, the vvt still makes a nice improvement to the gm engine using the standard pump, and the engine lasts long enough without an external pump. The Alfa intake manifold seems to have longer intake tracks than the gm units i've seen, and a popular mod for the gm v6 is to add a one inch thick manifold spacer which gives a very noticeable boost to low rpm performance.
This and Previous post by alfafanboy. Glad someone was listening (metaphorically speaking). End of!
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Hey sizewell, on top of comparing before and after fuel consumption, if you get a dyno app for your phone, you will have some figures to compare performance differences as well!
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Hey sizewell, on top of comparing before and after fuel consumption, if you get a dyno app for your phone, you will have some figures to compare performance differences as well!
Good thinking Batman. I am some way off that yet. Presently buying-up unused Swagelok stainless valves and connectors. Cheaper on e-bay than brass stuff currently available from the likes of Demon Tweeks, but you have to take what is available. So its all 12 mm. stainless. Which is fine as I don't want any modifications to interfere with the figures I get. So the pluming inertia should be negligible. Still waiting for a lull in Paul's work load to get things started. I also have to get some bits engineered up with a local specialist. It's giving me plenty of time to review, review and review again. However, from the only picture I have it does not look like the V.V.T.'s are Siamese-ed, which is going to provide a challenge. I am reliably informed that the mechanical oil pump is capable of 140%~ more than the oil pressure relief valve quoted operating threshold so that would be useful. However, not budgeting for it and won't really know until the oil ways are opened up and tapped off.
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[QUOTE=alfafanboy;14217785]Hey sizewell, on top of comparing before and after fuel consumption, if you get a dyno app for your phone, you will have some figures to compare performance differences as well![/QUOTE
Hi. Project not shelved, just taking longer than expected. However the situation is thus. I managed to pick up a brand new oil filter/cooler assembly from Germany. I think the V6 designer may have intended to fit an oil pressure gauge as just up stream of the oil pressure switch is a blank boss. It is cast over the oil way from the filter housing to the block. I have as a consequence of this had this blank boss drilled and threaded to accommodate the oil pressure switch proper. The existing threaded boss for the original oil pressure switch has been drilled and tapped to take a 3/8th's B.S.P. to 12 mm. compression adapter (Stainless Steel). This now enables me to get a oil feed out to facilitate oil pressure supplementation on the other side of the block. I am also considering feeding this line via a further oil cooler, mounted in front, just behind the front grill.
Anyway, this feed will give me a 10 mm. I.D. cross section pipe to the block plug, which is just behind the alternator mounting bracket. In line with this 12 mm. pipe, there is to be a none return valve. This I hope will sustain the oil pressure on the rear bank; left hand bank on the e-disc diagram, during gear changes and accelerating. The diameter of this pipe is such as to give to give virtually the same flow rate available to the rear/left bank as the one which goes directly into the block from the oil filter/cooler assembly.
It may be possible to almost balance it, it the Block Plug can be drilled out and tapped to a greater size. i managed to pick up a 46,000 mile engine complete very cheaply to use as a R & D mule. needless to say it was cheap as the chains had failed. So I will see for myself first hand what is going on. There are other areas which have spun of from this and will get to them in due course. however, currently achieving 28 mpg on a long run. Hope to see further improvements when I get the oil pressure supplementation connected up.
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As it happens my 115,000 mile V6 runs on Mobil1 0W-40 for this very reason.
That 0W ensures that from cold starts and short journeys oil is quickly moving.
I avoid long oil interval changes too - 8000 max
very good tip

will start using this oil from my next change
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Any updates sizewell?
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Any updates sizewell?
Hi, yes. Car currently with Paul and work is being fitted in around his other "Duties" Meaning he is a one man outfit, albeit a very good one but he has probably more work than he can cope with. It is going to work out fine though - can't believe I said that given work is going to be made more accessible because my steering rack has to be replaced. At the same time he is going to get my sub - frame powder coated. My new Oil Filter/cooler has been modified and all associated fitting have been bought - oil pressure transducers and N.R.V./Check - valves). Got my test equipment ready and raring to go. But I'm not pressing him and want to take photos as well as record measurements as we go. Hoping to fit an extra Oil Cooler in behind the front grill but that is not a must do at the moment as before and after figures need to be taken first. Also bought some snazzy little temperature probes/electronic display boards with programmable relay outputs which I hope can be utilized. Relays can be programed normally open or normally closed. And got my hands on a very tasty programmable pressure switch where both the pressure and the hysteresis can be set and range more than covers the 3.2 oil pressure range easily.
I'm sorry it has taken this long to get this far and will re-iterate, we have plenty of first class small engineering outfits. But they will never amount to anything really as long as they continue to see themselves as hobbyists. They take too much on for the time scales involved. You are always their priority until the next customer walks through the door and progressively you go to the bottom of the pile. Otherwise, had loads of time to revise and still convinced about these issues. Coupled to all this however is, we are in the middle of trying to sell the house.
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