Alfa Romeo Forum banner

41 - 60 of 186 Posts

·
Registered
Joined
·
3,546 Posts
Discussion Starter #41
What’s more important is how the power is put down on the road. You don’t really feel horsepower, it’s the torque that you feel when you press on in real life situations.

A rolling road is a simulation, and the figures can change with every run

Sent from my iPhone using Tapatalk
I think a lot of people confuse "Drama with Performance". With the Q4, one does not get much Drama. But this, I think is due to the car being underpowered - the chassis is not tested. But what it does have, it puts cleanly down to the tarmac.

Not so with the front wheel drive versions. The "Drama" comes from the front wheels struggling not break away and adhesion is so poor, the chassis gets no chance to demonstrate just how good it is.

Lowering the suspension and changing the geometry of the car, only seeks to hide this, it does nothing to eradicate it.
 

·
Registered
Joined
·
3,546 Posts
Discussion Starter #42
Think you got me confused with someone else! I used to work for Audi....Im a 4WD fan....mainly on the road...rather than the track!...…

…..obviously rear wheel drive trumps both....but there you go!!
Many years ago, having a substantial fine wine cellar, I was offered the stock of a recently deceased, much loved local doctor. His wife wanted to keep a few cases of lesser wines as she was an occasional drinker, unlike her husband.

There were some recent vintages, notably '82's, '81's '78's Bordeaux' as well as some older ones. Also, he obviously new his Burgundies. So we agreed a sale, despite my relative ignorance of great wines and knowing nothing of Great Burgundies.

I was curious about one particular bottle of Burgundy. The level had fallen to about 3 inches below the underside of the cork. No wine could survive that kind of Ullage, I though. However, as we were having a dinner party, I decided, it would be worth seeing what it was like, after the wines I had chosen for dinner.

The Bottle was a Bouchard pere et fils 1953 Echezeaux Grand Cru. The cork came out gently, even though it was mostly decayed - it had shrunk a little so clearly the bottle was both weeping and prone to air getting in and oxidizing the wine.

I will not bore anyone with an inadequate description of the perfume that almost immediately began to fill the room, or the almost animal taste of truffles, and strawberry vanilla ice cream , or the hint of burnt sugar - damn now I have. I remarked, "I wish this were a magnum, or I had more bottles".

I have spent the rest of my life, trying to find another such bottle which, at the age of 72 still haunts me. None have matched it. Armand Rousseau's Mazy, Chambertin and Clos de Beze have come close, but could not match the sophistication of that '53.

I have been very fortunate in also owning a 2.5 GTV 6 Alfetta, although it was my young son's enthusiasm for it that persuaded me to buy it. I had the engine fully balanced with Colombo Bariani camshafts and fitted Koni shocks. As with that '53 Echezeaux, I continue to search for something which can match it.

As David Cironi says in the clip below - "no wonder older Alfa romeo Owners are angry".

My modified 159 cannot replace my GTV6. But I hope it ends up sufficiently different to make me feel less resentful towards Alfa Romeo.

 

·
Registered
Joined
·
1,007 Posts
I also had a GTV6 Alfetta that I rebuilt from a fire damaged insurance write off. Twas a most agreeable car. Never had any nice wine though :cheeky:
 

·
Registered
Joined
·
3,546 Posts
Discussion Starter #44 (Edited)
I also had a GTV6 Alfetta that I rebuilt from a fire damaged insurance write off. Twas a most agreeable car. Never had any nice wine though :cheeky:
Returning to the original purpose of this blog - Modified 3.2 JTS Brera engine - my search for supplementary oil pumps to enable full oil pressure start ups has led me to a particular seller on ebay.

I asked if the seller could provide me with more information regarding the Vanos Oil Pumps he was advertising. I gave him a brief idea of what I was trying to achieve and he more than happily supplied me with just what I wanted to know.

The oil pump(s) - two - come from a BMW M5/M6 V10. These 12 volt pumps and are used for the left hand and right hand banks of the engine to supplement oil pressure when lateral forces exceed 0.6 G. Anecdotally the V10 and the V12 suffered from oil starvation at high revs and it is known in BMW circles to run crankshaft / con rod bearings. Either way, their solution, to maintain oil pressure seem to be somewhat more sophisticated than Alfa's and therefore it makes sense to use it to my advantage.

So, after having such positive information and help from the seller, I have purchased a pair. these will feed oil into the engine before start up, to get the engine up to normal working pressure. They will be fed from a reservoir, separate from the engine. I am informed about 400 - 500 ml of oil is used when bringing the engine up to working pressure, my intention is to have a large capacity reservoir, possibly doubling the total quantity of oil in circulation to allow a decent "rest" period - extended recirculation time, to help air settle out of suspension. The reservoir will be continually replenished from oil "Bled" back from the engine at a low rate, so that all levels are correctly maintained and the rate of the bleed will be sufficiently low and only when oil pressure is above a figure I have yet to determine. When the reservoir is full, an overflow will simply feed back oil into the sump.

However, now knowing how BMW employed these pumps, opens up a whole new window of possibilities wrt protecting my engine. I have no intention of doing track days, but! The sump modifications and supplementary oil injection however, should reduce the risks of what happened at Bruntingthorpe, occurring again.
 

·
Registered
Joined
·
3,546 Posts
Discussion Starter #45
Returning to the original purpose of this blog - Modified 3.2 JTS Brera engine - my search for supplementary oil pumps to enable full oil pressure start ups has led me to a particular seller on ebay.

I asked if the seller could provide me with more information regarding the Vanos Oil Pumps he was advertising. I gave him a brief idea of what I was trying to achieve and he more than happily supplied me with just what I wanted to know.


The oil pump(s) - two - come from a BMW M5/M6 V10. These 12 volt pumps and are used for the left hand and right hand banks of the engine to supplement oil pressure when lateral forces exceed 0.6 G. Anecdotally the V10 and the V12 suffered from oil starvation at high revs and it is known in BMW circles to run crankshaft / con rod bearings. Either way, their solution, to maintain oil pressure seem to be somewhat more sophisticated than Alfa's and therefore it makes sense to use it to my advantage.

So, after having such positive information and help from the seller, I have purchased a pair. these will feed oil into the engine before start up, to get the engine up to normal working pressure. They will be fed from a reservoir, separate from the engine. I am informed about 400 - 500 ml of oil is used when bringing the engine up to working pressure, my intention is to have a large capacity reservoir, possibly doubling the total quantity of oil in circulation to allow a decent "rest" period - extended recirculation time, to help air settle out of suspension. The reservoir will be continually replenished from oil "Bled" back from the engine at a low rate, so that all levels are correctly maintained and the rate of the bleed will be sufficiently low and only when oil pressure is above a figure I have yet to determine. When the reservoir is full, an overflow will simply feed back oil into the sump.

However, now knowing how BMW employed these pumps, opens up a whole new window of possibilities wrt protecting my engine. I have no intention of doing track days, but! The sump modifications and supplementary oil injection however, should reduce the risks of what happened at Bruntingthorpe, occurring again.

Arrived back home from a few days away to find a package on top of the dustbin. Inside was a pristine pair of BMW Vanos Oil Pumps, one of which is below. As can be seen, they are not very big, but damned substantial non the less. The quality is superb - not a FIAT sticker to be seen anywhere.

Also attached is picture of C.L.L.S. My current thinking is to inject the oil into the rear loop - leg, which will take the injected oil directly to the lower timing chain tensioner and the rear upper timing chain tensioner first.

A non return valve will be fitted to ensure it does not back - feed to the oil cooler/filter unit. An extra oil pressure switch and a gauge will be fitted into the "Horseshoe", so the start - up pump will cut out when the oil pressure reaches a point which has yet to be determined. The gauge will give me a continuous oil pressure reading and my thinking is to fit the extra instruments where currently the Radio/CD player is. Being almost as deaf as a post, it makes sense to get rid of it and utilize the space for the extra instruments.
 

Attachments

·
Registered
Joined
·
3,546 Posts
Discussion Starter #46
Hi Brian,

As you know all 4 of my solenoids are sitting on my garage floor at the moment. I'm keen to try your O ring mod out.
Question, Can you tell me what size Viton O rings I need to order, and are they for both banks exhaust solenoids only?

Cheers,








Roop.


roop,

For your information, and for anyone else who wishes to better understand the way the 3.2 JTS camshaft position sensors work.Or don't as the case may be.

The pulses derived from the camshaft magnetic front plate, which the Hall effect positional sensors detect and reconstitute (process electronically into an ideal waveform), are used by the ECU to determine the timing of the camshaft setting wrt other derived data which the ECU needs to set the engines performance.

The left hand diagram indicates the pulses derived by both tooth and slot profiles cut into the rotor plate.

If one looks at the rotor, one will see the shape will result in both tooth and slot signals.

"The signal induced into the Hall effect will be maximum when the field cuts the sensor at right angles - Bosch, quote +/-0.5 degree maximum alignment error - beyond which the output in the sensor falls away substantially."

So, it is clear the amplitude of the signal from the rear exhaust bank camshaft sensor "IS NOT MAXIMUM" as it is substantially out of alignment, whereas the other three are pretty precise.

This then is the crude data, from the sensor plate that the Hall effect device has to process: left hand picture.

When one now looks at the right hand picture, clearly one can see the effect of a low amplitude signal being induced into the sensor, due to the misalignment of the rear bank exhaust camshaft sensor.

Reduced amplitude will produce a shorter reconstituted pulse, upon which the ECU has to work. Any Chain stretch will further exacerbate the timing error.

Had this engine been a "Straight Six" or the camshaft timing derived by "Gear", then the amplitude of the pulse would be the only issue.

However, as valve timing is also effected by chain tension and so by definition oil pressure, if oil pressure is inadequate; as it most definitely is on the rear bank, not only are timing errors likely due to lack of tension, but also the response time of the VVT rotors, which is also derived from oil pressure.

Equal pressure from the oil feeds to the VVT solenoids and the only issue; again conditional upon chain tension, would be the misaligned rear exhaust positional sensor. Otherwise, the valve timing would be very accurate.

The internal spring bias of the exhaust camshaft VVT sprockets is massive, by comparison to the inlet camshaft sprockets. It therefore requires considerable oil pressure to rotate. It doesn't have that luxury, and therefore, the signal to the ECU is much delayed, wrt the front bank exhaust, which in its self is much slower than the inlet camshafts. However, the Front Bank Exhaust Camshaft VVT is the second device to be fed; after the oil enters the block. Only the Front Bank Intermediate Idler gets its oil before it, and that requires very little.

It is quite obvious to me, Alfa recognized there was a problem as they modified the VVT timing between the two exhaust VVT's. It didn't solve it, but it sure as hell makes it clear, they knew there was something amiss.

A further problem the low oil pressure causes is:-

As the exhaust camshafts are biased in the maximum advance position - intentional to get the cats up to working temperature quickly, the late setting of the rear bank exhaust camshaft, although still within the operating range for timing, causes the ECU; as it functions predictively, to choose a "Set Angle" for the next power stroke, which is on the front bank. But this angle is false as the engine speed and power could be much greater than the rear bank exhaust camshaft sensor signal is indicating.

The consequence of this is, the front Bank Exhaust Camshaft has been falsely given an angle which is too far advanced. So The camshaft opens early in the power stroke, when the engine is making more power than the ECU dictated angle suggests. Hot gases therefore exhaust early in the power stroke and overheat the Front Bank Manifold Cat.

It is difficult, beyond prediction, to assess the degree of heat from the Cat which is reflected back to the cylinder head. But, with the evidence of extreme heat burning on three front cats I have examined and the fact that one of the front bank coil packs - centre, no 4 - has a penchant for melting and the lack of any such excess heat on the rear cats, it seems to me the most likely explanation.

Unfortunately, I am still laid - up, so I felt I would get a few more notes down, not least for my self and anyone else that is interested.

And for those that are unwilling to undertake a full reworking of the oil feeds, then I think, there will still be substantial gains if just the "Horseshoe Pipe" were fitted, along with the re-aligned rear bank exhaust camshaft sensor and the VVT "O - Rings".
 

·
Registered
Joined
·
3,546 Posts
Discussion Starter #47
roop,

For your information, and for anyone else who wishes to better understand the way the 3.2 JTS camshaft position sensors work.Or don't as the case may be.

The pulses derived from the camshaft magnetic front plate, which the Hall effect positional sensors detect and reconstitute (process electronically into an ideal waveform), are used by the ECU to determine the timing of the camshaft setting wrt other derived data which the ECU needs to set the engines performance.

The left hand diagram indicates the pulses derived by both tooth and slot profiles cut into the rotor plate.

If one looks at the rotor, one will see the shape will result in both tooth and slot signals.

"The signal induced into the Hall effect will be maximum when the field cuts the sensor at right angles - Bosch, quote +/-0.5 degree maximum alignment error - beyond which the output in the sensor falls away substantially."

So, it is clear the amplitude of the signal from the rear exhaust bank camshaft sensor "IS NOT MAXIMUM" as it is substantially out of alignment, whereas the other three are pretty precise.

This then is the crude data, from the sensor plate that the Hall effect device has to process: left hand picture.

When one now looks at the right hand picture, clearly one can see the effect of a low amplitude signal being induced into the sensor, due to the misalignment of the rear bank exhaust camshaft sensor.

Reduced amplitude will produce a shorter reconstituted pulse, upon which the ECU has to work. Any Chain stretch will further exacerbate the timing error.

Had this engine been a "Straight Six" or the camshaft timing derived by "Gear", then the amplitude of the pulse would be the only issue.

However, as valve timing is also effected by chain tension and so by definition oil pressure, if oil pressure is inadequate; as it most definitely is on the rear bank, not only are timing errors likely due to lack of tension, but also the response time of the VVT rotors, which is also derived from oil pressure.

Equal pressure from the oil feeds to the VVT solenoids and the only issue; again conditional upon chain tension, would be the misaligned rear exhaust positional sensor. Otherwise, the valve timing would be very accurate.

The internal spring bias of the exhaust camshaft VVT sprockets is massive, by comparison to the inlet camshaft sprockets. It therefore requires considerable oil pressure to rotate. It doesn't have that luxury, and therefore, the signal to the ECU is much delayed, wrt the front bank exhaust, which in its self is much slower than the inlet camshafts. However, the Front Bank Exhaust Camshaft VVT is the second device to be fed; after the oil enters the block. Only the Front Bank Intermediate Idler gets its oil before it, and that requires very little.

It is quite obvious to me, Alfa recognized there was a problem as they modified the VVT timing between the two exhaust VVT's. It didn't solve it, but it sure as hell makes it clear, they knew there was something amiss.

A further problem the low oil pressure causes is:-

As the exhaust camshafts are biased in the maximum advance position - intentional to get the cats up to working temperature quickly, the late setting of the rear bank exhaust camshaft, although still within the operating range for timing, causes the ECU; as it functions predictively, to choose a "Set Angle" for the next power stroke, which is on the front bank. But this angle is false as the engine speed and power could be much greater than the rear bank exhaust camshaft sensor signal is indicating.

The consequence of this is, the front Bank Exhaust Camshaft has been falsely given an angle which is too far advanced. So The camshaft opens early in the power stroke, when the engine is making more power than the ECU dictated angle suggests. Hot gases therefore exhaust early in the power stroke and overheat the Front Bank Manifold Cat.

It is difficult, beyond prediction, to assess the degree of heat from the Cat which is reflected back to the cylinder head. But, with the evidence of extreme heat burning on three front cats I have examined and the fact that one of the front bank coil packs - centre, no 4 - has a penchant for melting and the lack of any such excess heat on the rear cats, it seems to me the most likely explanation.

Unfortunately, I am still laid - up, so I felt I would get a few more notes down, not least for my self and anyone else that is interested.

And for those that are unwilling to undertake a full reworking of the oil feeds, then I think, there will still be substantial gains if just the "Horseshoe Pipe" were fitted, along with the re-aligned rear bank exhaust camshaft sensor and the VVT "O - Rings".
Omitted the attachments to go with previous post - sorry.
 

Attachments

·
Registered
Joined
·
1,724 Posts
When are you going to put your money where your mouth is and show us this car that you talk so highly of Brian? It’s all good quoting your own posts, but if you want to impress YouTube Vlog it and share the links on here..


Sent from my iPhone using Tapatalk
 

·
Registered
Joined
·
3,546 Posts
Discussion Starter #49
When are you going to put your money where your mouth is and show us this car that you talk so highly of Brian? It’s all good quoting your own posts, but if you want to impress YouTube Vlog it and share the links on here..


Sent from my iPhone using Tapatalk
I am simply detailing the work I am doing to my engine. It may be of use to others who do not share your mindset.

The work is suspended for the moment due to ill health, but will resume at the earliest. It is not intended for the banal amusement of those that would not willingly risk their own vehicles. Understanding the 3.2 JTS engine has been an engineering exercise, which has given me countless hours of enjoyment.

As for wanting to impress anyone, if that were really the case, you certainly don't fall into that category.

If you have nothing positive to contribute, I can't think why you would need to comment.
 

·
Registered
Joined
·
106 Posts
I am simply detailing the work I am doing to my engine. It may be of use to others who do not share your mindset.

The work is suspended for the moment due to ill health, but will resume at the earliest. It is not intended for the banal amusement of those that would not willingly risk their own vehicles. Understanding the 3.2 JTS engine has been an engineering exercise, which has given me countless hours of enjoyment.

As for wanting to impress anyone, if that were really the case, you certainly don't fall into that category.

If you have nothing positive to contribute, I can't think why you would need to comment.
Hi Brian,

Your knowledge sharing is very appreciated and for me highly interesting. I hope you return to good health promptly.

Cheers,

Roop.
 

·
Registered
Joined
·
3,546 Posts
Discussion Starter #52
Arrived back home from a few days away to find a package on top of the dustbin. Inside was a pristine pair of BMW Vanos Oil Pumps, one of which is below. As can be seen, they are not very big, but damned substantial non the less. The quality is superb - not a FIAT sticker to be seen anywhere.

Also attached is picture of C.L.L.S. My current thinking is to inject the oil into the rear loop - leg, which will take the injected oil directly to the lower timing chain tensioner and the rear upper timing chain tensioner first.

A non return valve will be fitted to ensure it does not back - feed to the oil cooler/filter unit. An extra oil pressure switch and a gauge will be fitted into the "Horseshoe", so the start - up pump will cut out when the oil pressure reaches a point which has yet to be determined. The gauge will give me a continuous oil pressure reading and my thinking is to fit the extra instruments where currently the Radio/CD player is. Being almost as deaf as a post, it makes sense to get rid of it and utilize the space for the extra instruments.

Front of 3.2 JTS showing Oil ways.
 

·
Registered
Joined
·
3,546 Posts
Discussion Starter #53 (Edited)
Front of 3.2 JTS showing Oil ways.
Only just started driving again. So took time out to check on where we are with my engine re - build. Dropped off a couple of bags of bits and discussed what is out standing. I never lose things, just put them safely away, where I cant remember. So (lost) six camshaft bearing cap bolts somewhere, so I need to buy some new ones - will find the originals the day the new ones arrive.

Still I am happy with progress - discussed full pressure start up mod and agreed the best way is to remove the sump plug, drill and tap for a 12 mm. i/d compression fitting, feed that to filter, then the vanos pump I bought and then via a NRV into the "horse Shoe" of my CLLS.

To much going on at the moment, both children buying new houses, plus my problems. So no real rush to get things finished. Important to get it right.

Further thoughts on my full pressure start up system, It makes sense to keep any plumbing work as simple as possible. To take my feed into the "Horseshoe Pipe" requires a fair bit of plumbing and I am still at a loss as to where it will all be routed.

So, yet again, I have revised the plan as follows:-

1). 12 mm I/D fitting replaces the sump plug - sump plug hole tapped out.

2). Braided hose to a locally mounted Oil Filter housing.

3). output of filter housing - clean side connected to BMW M5 (V10) Electric Oil Pump.

4). Oil Pump connected to a Legris FKM D10 NRV.

5). NRV connected, via "Tee", to the C.L.L.S. Bypass Line feeding into the rear block plug, near
the Lower Timing Chain Tensioner.

6). Pump will be started by a oil pressure transducer/switch, when the ignition key is inserted into the dash.
 

Attachments

·
Registered
Joined
·
3,546 Posts
Discussion Starter #54
Only just started driving again. So took time out to check on where we are with my engine re - build. Dropped off a couple of bags of bits and discussed what is out standing. I never lose things, just put them safely away, where I cant remember. So (lost) six camshaft bearing cap bolts somewhere, so I need to buy some new ones - will find the originals the day the new ones arrive.

Still I am happy with progress - discussed full pressure start up mod and agreed the best way is to remove the sump plug, drill and tap for a 12 mm. i/d compression fitting, feed that to filter, then the vanos pump I bought and then via a NRV into the "horse Shoe" of my CLLS.

To much going on at the moment, both children buying new houses, plus my problems. So no real rush to get things finished. Important to get it right.

Further thoughts on my full pressure start up system, It makes sense to keep any plumbing work as simple as possible. To take my feed into the "Horseshoe Pipe" requires a fair bit of plumbing and I am still at a loss as to where it will all be routed.

So, yet again, I have revised the plan as follows:-

1). 12 mm I/D fitting replaces the sump plug - sump plug hole tapped out.

2). Braided hose to a locally mounted Oil Filter housing.

3). output of filter housing - clean side connected to BMW M5 (V10) Electric Oil Pump.

4). Oil Pump connected to a Legris FKM D10 NRV.

5). NRV connected, via "Tee", to the C.L.L.S. Bypass Line feeding into the rear block plug, near
the Lower Timing Chain Tensioner.

6). Pump will be started by a oil pressure transducer/switch, when the ignition key is inserted into the dash.
Copied from "Melting Coil Packs".

“Not saying I agree with it all but that's the rules...and it's up the the individual if they want to risk the consequences for what will be a fairly minor performance increase by removing them.”

The problem I have with the above, perfectly reasonable statement is, no one appears to provide definitive evidence on what “minor”, or otherwise improvements can be gained by removing the cats.

I contend the improvements will not be minor, because they have such an overarching effect on so many issues surrounding this engine.

And just to be clear, These are not manifold cats in the strictest sense, they are pre - cats. The main cats are, the devices - Siamese - Ed, under the car.

The Lambdas inserted into the pre - cats are before the elements, so they are actually monitoring the exhaust gases - from the engine. The valve timing of this engine can vary over 50 degrees on both inlet and exhaust camshafts. With the standard Alfa camshafts, there is no overlap in the static condition, the exhaust being closed before the inlet opens.

It is known valve timing of this engine is specifically designed to create an element of “EGR”, and I assume this is achieved by the manifold pre - lambdas, working in conjunction with the ECU, to modify the valve timing appropriately.

But this function, can only really be effective if the VVT Phasors can reposition themselves quickly enough to the Impetus of the ECU.

In other words, have “Excellent Dynamic Response”. I.e., to be really dynamic, have a really fast “setting time”, to ensure the camshaft positioning sensor does not “Time - out” and the ECU display a camshaft error - particularly the rear bank exhaust camshaft.

The engines valve timing , on start - up, is set with the inlet camshaft fully retarded and the exhaust camshaft fully advanced. As a consequence, the exhaust camshaft is closing 9.0 degree after TDC. The camshaft having a duration of 250 degrees, that means, on a power stroke, the exhaust valve is opening at 61.0 degrees before BDC.

If my logic is correct, the power stroke ends effectively 119 degrees after TDC, i.e., when the exhaust valve opens. But at that angle there is still considerable unburnt fuel/air mixture in the cylinder. However, as this is a JTS engine, the ECU will meter the fuel such that at tick - over, the mixture is lean, with any mixture still burning used to raise and maintain the pre - cat manifolds at “light - off” temperature.

I have no issue with the exhaust camshaft timing settling out at an angle predicted by the ECU at tick - over, or at constant speed, but dynamically, when it is rotating - particularly on the rear bank exhaust - the oil pressure is not high enough to move and retard the timing swiftly enough.

Thus, not only is power lost, but a full - charge petrol/air mixture, on accelerating will have considerable unburnt fuel discharging into the manifold. This will raise the pre - cat temperatures beyond their light - of temperature, and because they restrict exhaust gas flow, heat is reflected back into the cylinder head.

Oil temperature is monitored in the sump and is thus not a true reflection of how hot it is in the cylinder heads. Were this statement not true, Oil lacquer, evidence of burnt oil, would not be so obvious under the cam covers.

Water temperature equally, is not measured at a point which would be most indicative of the engine running over hot - a point made to me very early on during my Dynamometer runs.

Consequences of high engine temperatures; I contend, a function of these manifold pre - cats would be.

1. Over - hot heads leading to early degradation of valve stem seals.

2. Oil vaporising and being drawn out through the Crankcase pressure relief valve - evidence of oil in the inlet tract after the MAF.

3. Vaporised oil, burning under the cam cover - extensive lacquering of both camshaft bearing caps, cylinder head floors and underside of cam covers. The design of these heads is such that little oil is retained in the heads and thus - my belief - thin film coating the heads is prone to burning on the over - hot surfaces.

4. Mis - fires due to elevated upper cylinder temperatures.

5. Excessive temperatures leading to coil pack melt - down.

6. Inaccuracies in valve timing resulting in poor economy.

In conclusion, perhaps the manifold pre - cats would not be so detrimental to the performance of this engine had the VVT system been more dynamic in the way it responds to the impetus of the ECU.

Ultimately, this comes down entirely to poor oil flow/pressure across the entire engine and VVT solenoids which, are unable to hold the camshaft in the position dictated by the ECU.

Some sources suggest about 8 bhp is recovered by removing the pre - cats. I believe, dynamically, it will be more. But I am talking about in conjunction with my mods, which because of faster VVT response times, the exhaust camshafts will retard away from the pre - light of temperature angles much more swiftly, which will result in higher motive force being extracted from the charge due to the timing being more willing to assume any angle the ECU dictates between 61 degrees and 11 degrees BBDC!
 

·
Registered
Joined
·
110 Posts
Copied from "Melting Coil Packs".

“Not saying I agree with it all but that's the rules...and it's up the the individual if they want to risk the consequences for what will be a fairly minor performance increase by removing them.”

The problem I have with the above, perfectly reasonable statement is, no one appears to provide definitive evidence on what “minor”, or otherwise improvements can be gained by removing the cats.

I contend the improvements will not be minor, because they have such an overarching effect on so many issues surrounding this engine.

And just to be clear, These are not manifold cats in the strictest sense, they are pre - cats. The main cats are, the devices - Siamese - Ed, under the car.

The Lambdas inserted into the pre - cats are before the elements, so they are actually monitoring the exhaust gases - from the engine. The valve timing of this engine can vary over 50 degrees on both inlet and exhaust camshafts. With the standard Alfa camshafts, there is no overlap in the static condition, the exhaust being closed before the inlet opens.

It is known valve timing of this engine is specifically designed to create an element of “EGR”, and I assume this is achieved by the manifold pre - lambdas, working in conjunction with the ECU, to modify the valve timing appropriately.

But this function, can only really be effective if the VVT Phasors can reposition themselves quickly enough to the Impetus of the ECU.

In other words, have “Excellent Dynamic Response”. I.e., to be really dynamic, have a really fast “setting time”, to ensure the camshaft positioning sensor does not “Time - out” and the ECU display a camshaft error - particularly the rear bank exhaust camshaft.

The engines valve timing , on start - up, is set with the inlet camshaft fully retarded and the exhaust camshaft fully advanced. As a consequence, the exhaust camshaft is closing 9.0 degree after TDC. The camshaft having a duration of 250 degrees, that means, on a power stroke, the exhaust valve is opening at 61.0 degrees before BDC.

If my logic is correct, the power stroke ends effectively 119 degrees after TDC, i.e., when the exhaust valve opens. But at that angle there is still considerable unburnt fuel/air mixture in the cylinder. However, as this is a JTS engine, the ECU will meter the fuel such that at tick - over, the mixture is lean, with any mixture still burning used to raise and maintain the pre - cat manifolds at “light - off” temperature.

I have no issue with the exhaust camshaft timing settling out at an angle predicted by the ECU at tick - over, or at constant speed, but dynamically, when it is rotating - particularly on the rear bank exhaust - the oil pressure is not high enough to move and retard the timing swiftly enough.

Thus, not only is power lost, but a full - charge petrol/air mixture, on accelerating will have considerable unburnt fuel discharging into the manifold. This will raise the pre - cat temperatures beyond their light - of temperature, and because they restrict exhaust gas flow, heat is reflected back into the cylinder head.

Oil temperature is monitored in the sump and is thus not a true reflection of how hot it is in the cylinder heads. Were this statement not true, Oil lacquer, evidence of burnt oil, would not be so obvious under the cam covers.

Water temperature equally, is not measured at a point which would be most indicative of the engine running over hot - a point made to me very early on during my Dynamometer runs.

Consequences of high engine temperatures; I contend, a function of these manifold pre - cats would be.

1. Over - hot heads leading to early degradation of valve stem seals.

2. Oil vaporising and being drawn out through the Crankcase pressure relief valve - evidence of oil in the inlet tract after the MAF.

3. Vaporised oil, burning under the cam cover - extensive lacquering of both camshaft bearing caps, cylinder head floors and underside of cam covers. The design of these heads is such that little oil is retained in the heads and thus - my belief - thin film coating the heads is prone to burning on the over - hot surfaces.

4. Mis - fires due to elevated upper cylinder temperatures.

5. Excessive temperatures leading to coil pack melt - down.

6. Inaccuracies in valve timing resulting in poor economy.

In conclusion, perhaps the manifold pre - cats would not be so detrimental to the performance of this engine had the VVT system been more dynamic in the way it responds to the impetus of the ECU.

Ultimately, this comes down entirely to poor oil flow/pressure across the entire engine and VVT solenoids which, are unable to hold the camshaft in the position dictated by the ECU.

Some sources suggest about 8 bhp is recovered by removing the pre - cats. I believe, dynamically, it will be more. But I am talking about in conjunction with my mods, which because of faster VVT response times, the exhaust camshafts will retard away from the pre - light of temperature angles much more swiftly, which will result in higher motive force being extracted from the charge due to the timing being more willing to assume any angle the ECU dictates between 61 degrees and 11 degrees BBDC!
Hi, Brian,
If I have understood you correctly, you are expecting 2 more liters of oil to be in circulation after your modifications. Are you going put 2 more liters of oil in the engine? Do you plan on expanding the sump pan to fit more oil?Will it have time to settle down?
Cheers!
 

·
Registered
Joined
·
3,546 Posts
Discussion Starter #56
Hi, Brian,
If I have understood you correctly, you are expecting 2 more liters of oil to be in circulation after your modifications. Are you going put 2 more liters of oil in the engine? Do you plan on expanding the sump pan to fit more oil?Will it have time to settle down?
Cheers!
I posted a more detailed reply, but it disappeared into the ether. So I posted this in brief. even the above quote vanished, only to re - appear five minutes ago. So, I hope you get the gist of the below.

"Are you going put 2 more liters of oil in the engine?" In circulation -Yes!

Alfa Oil filter History - Housing in circuit, but with no element fitted.

Monster filter housing replaces it - Huge element - lower pressure drop across it - greater capacity to strip detritus out of oil, and still maintain oil flow rate.

Capacity of housing 1 litre + adding to the total capacity in circulation - increased capacity, increased oil recirculation time - increased capacity - oil resting time increased - oil temperature lower.

Second Monster filter housing fitted in - line with oil feed from sump plug to BMW V10, M5 oil pump. Feeds NRV and then "T" - ed into bypass line to the rear block plug, adjacent the lower timing chain tensioner.

Total extra oil in circuit ~ 2 litres +. Second Filter protects the M5 oil pump during full pressure start ups.

Full pressure start up pump can run intermittently to recirculate oil more frequently - oil should be in better condition at time of oil changes. Pump could be used to support oil pressure at high revs.

Over all oil temperature should reduce.

External oil cooler to be fitted - Alfa's is history. Exploring extra water radiator, fed from hoses which hitherto went to the Oil Cooler/Filter Unit.
 

Attachments

·
Registered
Joined
·
3,546 Posts
Discussion Starter #57
Hi, Brian,
If I have understood you correctly, you are expecting 2 more liters of oil to be in circulation after your modifications. Are you going put 2 more liters of oil in the engine? Do you plan on expanding the sump pan to fit more oil?Will it have time to settle down?
Cheers!
Not teaching Granny to suck eggs or anyone how to change an oil filter. Just, the attached video clip shows the type of oil filter housings I have bought.

Hopefully, I can fit them somewhere equally accessible.

 

·
Registered
Joined
·
3,546 Posts
Discussion Starter #58
Hi, Brian,
If I have understood you correctly, you are expecting 2 more liters of oil to be in circulation after your modifications. Are you going put 2 more liters of oil in the engine? Do you plan on expanding the sump pan to fit more oil?Will it have time to settle down?
Cheers!

Internal EGR Function within the 3.2 JTS Engine.

Section 1.

I continue to struggle understand this engine. No matter how many engineering articles I read, it is difficult to pull more than two together, such that their theory overlaps in the context of this engine. Adopting JTS Technology, in pursuit of better economy and lower emissions, whilst applying it to a normally aspirated engine, meant that Internal EGR had to be adopted - unlike Turbo/Supercharged S.I. Engines. But to achieve this, it is critical that exhaust valve timing is not just accurate; to ensure the right degree of exhaust gas, but it must be agile to adapt very quickly to the changing load conditions of the engine.

For instance, I have searched to find where NVO - Negative Valve Overlap is applied to S.I. injection engines, let alone JTS GDI - Gasoline Direct Injection Engines such as Alfas 3.2 JTS. Yet Alfa do employ NVO. The principle I understand for Compression - Ignition engines ; Diesels, but not wholly the JTS S.I. One of reasons for using it in diesel technology is, NVO, after TDC creates a vacuum and when the inlet "Lightly Opens" [initially a small opening], the velocity of air creates a more uniform mix of residuals which results in a better burn when diesel is injected, lowering soot and emissions.

This is principle, I assume to be behind Alfa's use of Negative Valve Overlap in the design of their 3.2 JTS Engine. Charge Stratification appears to be used and the link to this; I believe to be in the design of the Piston Crown, used for implementing JTS Techniques, which a "lightly Opening Exhaust Valve would assist".
The Article, on which my research and conclusions are drawn; in this first section, is given below:-

https://www.researchgate.net/publication/27155974_Gasoline_engine_exhaust_gas_recirculation_-_A_review?enrichId=rgreq-7b92ae45b4a873224d4179ff4e884f54-XXX&enrichSource=Y292ZXJQYWdlOzI3MTU1OTc0MDtBUzo2OTU1NDI2OTA2MzE2ODJAMTU0Mjg0MTcwODM2Mw==&el=1_x_2&_esc=publicationCoverPdf


1. Extract from 2.

"Internal EGR" is achieved by increasing NVO during exhaust stroke, which requires an improved cam that can rapidly switch cam profiles to achieve any variable valve timing, otherwise it’s impossible to independently and effectively control EGR ratio. This greatly limits the application of internal EGR. As a result, external EGR has become widely used on today’s automobile engines." However Alfa Romeo chose to use Internal EGR for their 3.2 JTS engine, when they introduced Variable Valve timing on both Inlet and Exhaust valves.


"Alfa Employ NVO."


2. Unlike diesel engines, "Air Excess Ratio" can be actually used in gasoline engines to reduce NOX emission effectively. Therefore, recirculating exhaust gas on gasoline engines is used primarily to reduce throttling.loss at part load range, thus reduce fuel consumption, and secondarily, to reduce NOX emission levels. In order to keep the same torque and power output after introducing EGR in gasoline engine, further opening of engine throttle is necessary to increase the trapped charge density, which can reduce pumping loss and to increase fuel economy compared with that when no EGR is used. On the other hand, gasoline engine works with a stoichiometric air - fuel mixture in order to meet the need of TWC, so the O2 concentration in the exhaust is very low, which will cause a corresponding lower NOX emission.

For a GDI engine that is designed to work with lean or even ultra-lean mixtures, it is unfortunately true that a conventional TWC cannot be used to remove NOX, therefore other techniques for incylinder NOX reduction or exhaust after-treatment must be employed. EGR is an effective measure. Compared with PFI engine, EGR rates as high as possible are required by GDI engine to reduce overall NOX emission levels. EGR is considered as a principle method to reduce NOX emission of GDI engine. The application of EGR in GDI engine and in PFI engine is discussed in detail in this paper.

When hot EGR is used in engine, the exhaust can be used to heat the intake, so combustion quality and thermal efficiency are improved. However, cooled EGR increases inlet density and thus increases volumetric efficiency of the engine. At the same time, the reduced temperature can further reduce NOX emission, but the cycle-by-cycle variations will be increased compared with hot EGR.

Cooled EGR is a key technology enabling downsized SI engines and providing a means to meet the market requirement of ‘‘doing more with less’’. The comparison of the advantages and disadvantages between hot EGR and cooled EGR is given in this paper. As it is well known, the crucial point of gasoline engine behavior is the dramatic fall of energy conversion efficiency in part load operation. So, much effort has been made to decrease pumping loss and to optimize engine thermodynamic efficiency. However, knock risks impose strong limitations to the performance and efficiency of gasoline engine. So, in full load operation, fuel enrichment was usually adopted to suppress knock. EGR can reduce the combustion pressure and inhibit knock as well, and additional benefit is fuel economy as well as the decrease of HC and CO emission.

Turbocharged gasoline engine is a typical representative of downsized engines. EGR technique combining with supercharged direct injection engine is the trend of today’s gasoline engine.

Using EGR in turbocharged gasoline engine may involve compatibility issue, thus two implementation methods are reviewed in this paper, and both the advantages and disadvantages of these methods are compared. Furthermore, the problem of turbo matching when introducing EGR is described briefly.

Cylinder charge dilution with exhaust gas can be classified into internal EGR and external EGR. With external EGR, exhaust gas is taken from the exhaust port and supplied into the inlet port. Internal EGR is achieved by increasing NVO during exhaust stroke, which requires an improved cam that can rapidly switch cam profiles to achieve any variable valve timing, otherwise it’s impossible to independently and effectively control EGR ratio.

This greatly limits the application of internal EGR. As a result, external EGR has become widely used on today’s automobile engines. External EGR has a relatively low cost. It only needs to use dedicated EGR control valve, which can control EGR rate effectively under all work conditions of engine. Only external EGR is discussed in this paper.

From the above it is clear to this researcher, Alfa attempted internal EGR, which would have brought the kind of benefits detailed for a GDI Engine. However, as indicated in the text, to function properly it requires a "Dynamic Variable Valve Timing System". Modern systems, to achieve the required dynamics are electro - mechanically operated valves, but are very sophisticated and expensive. By definition; if oil pressure is used, to be effective it must be sufficiently high in pressure and the flow rate must be sustained during periods when the engines oil demand is greatest.

In it's current form, it is the opinion of this researcher, the Alfa 3.2 JTS engine does not fulfill these criteria. But it is clear, because of the improvements gained, wrt a modified 3.2 JTS, they could well have done. Other issues with regard to this engine are not insurmountable, but oil - way restrictions are the greatest problems.

Had it not been for this, this engine may well have been held in very high regard. But Alfa Romeo however, deserve credit for at least trying. The Vauxhall 2.8 and the Saab do not have variable valve timing on their exhaust valves, relying upon Turbo Inter-cooling to provide their EGR function, which is easier and cheaper to achieve. See below, or read full research paper attached.

External EGR system consists of EGR pipe, EGR valve and EGR cooler (cooled EGR). Exhaust goes through EGR valve and EGR cooler, and then enters intake manifold. Constant coolant goes through EGR cooler. EGR valve can be adjusted to get various EGR rates. Pipe material is stainless steel to avoid transfer of engine vibration to exhaust system and then to measuring instruments.

Internal combustion engine valve control system for improving automotive cold-starts.

A “negative” valve-overlap (NVO) time period is created during a first part of each piston's intake stroke wherein, with the intake and exhaust valves closed, a high vacuum is produced in its associated cylinder. As the intake valve starts to open at the end of the period an initial small low-lift valve gap creates a high-pressure differential across the gap increasing the velocity of the air charge being injected through the gap [JTS - only air].

The added velocity elevates turbulent mixing intensity of the internally injected fuel in the cylinder, enhancing atomization and vaporization of the charge, improving distribution in the combustion chamber for charge stability. This allows additional spark retard and a leaner air/fuel ratio, achieving rapid catalyst warm-up, while promoting converter efficiency and reducing exhaust-gas emissions.

With the 3.2 JTS engine, on Start - up, the VVT Lock Pins maintain the Rotors; Inlet maximum retard, Exhaust; maximum advance, in their static positions.

The static timing for the valves under these conditions are EVC - 9 degrees ATDC, IVO - 11.5 degrees ATDC, giving a NVO of 2.5 degrees ATDC. The valve timing on the 3.2 JTS is asymmetrical and as NVO occurs after top dead centre, an element of vacuum is created within the cylinder, before the inlet valve opens. This is believed to be the principle behind the paragraph I now repeat from above:-


[This is principle, I assume to be behind Alfa's use of Negative Valve Overlap in the design of their 3.2 JTS Engine. Charge Stratification appears to be used and the link to this; I believe, to be in the design of the Piston Crown, used for implementing JTS Techniques, which a "lightly Opening Exhaust Valve would assist"].
 

·
Premium Member
Joined
·
45,187 Posts
What do C&B think of this? Presumably their cams ensure Internal EGR otherwise your catless pipes will have zero chance at MOT.
Main cats will do enough even without the manifold cats and modified cams, assuming the mixture is controlled correctly by lambda sensors & air mass meter.
 
41 - 60 of 186 Posts
Top