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SIZEWELL "If the vvt’s are responsive, there should be as small a delay as possible between traces. There won’t be - time-wise they will be light years apart."

Lol...great phrase!....light years are a measure of distance...not time. Just sayin'!
 

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Discussion Starter #123
SIZEWELL "If the vvt’s are responsive, there should be as small a delay as possible between traces. There won’t be - time-wise they will be light years apart."

Lol...great phrase!....light years are a measure of distance...not time. Just sayin'!
True, but you get my drift.
 

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True, but you get my drift.
Arrrggh. I'm trying to learn by listening in to experts and I'm getting fking annoyed.

"1, Exhaust vvt timing is less important in determining real power gains" (Sizewell)

So it's about inlet, yes? But in has to go out, so how is "out" not important? I would have thought both equally important.

I make no excuse for my naive question. We all start stupid...
 

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Discussion Starter #125 (Edited)
Arrrggh. I'm trying to learn by listening in to experts and I'm getting fking annoyed.

"1, Exhaust vvt timing is less important in determining real power gains" (Sizewell)

So it's about inlet, yes? But in has to go out, so how is "out" not important? I would have thought both equally important.

I make no excuse for my naive question. We all start stupid...
The attached papers make good reading. They are only a start of course, but if you want to understand more, there are a multitude of papers SAE and MIT that take some wading through, but are very enlightening.

You will know that the Twin Spark has a variator on the inlet camshaft, whilst the exhaust is fixed.

A version of GM Based V6, also has fixed exhaust valve timing.

Colombo Bariani have said, changing only the inlet camshafts, can result in 85% of the power gains achieved when all for camshafts were replaced.

Quotes from attached papers:-

Effect of changes to Intake Valve Opening Timing – IVO

The opening of the intake valve allows air/fuel mixture to enter the cylinder from the
intake manifold. (In the case of direct injection engines, only air enters the cylinder
through the intake valve). The timing of IVO is the second parameter that defines the
valve overlap and this is normally the dominant factor when considering which timing
is appropriate for a given engine
. Overlap will be discussed in more detail later in this

Effect of changes to Intake Valve Closing Timing – IVC

The volumetric efficiency of any engine is heavily dependent on the timing of IVC at
any given speed. The amount of fresh charge trapped in the cylinder is largely dictated
by IVC and this will significantly affect engine performance and economy.
paper.
 

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Discussion Starter #126 (Edited)
Arrrggh. I'm trying to learn by listening in to experts and I'm getting fking annoyed.

"1, Exhaust vvt timing is less important in determining real power gains" (Sizewell)

So it's about inlet, yes? But in has to go out, so how is "out" not important? I would have thought both equally important.

I make no excuse for my naive question. We all start stupid...
Sorry for the double post. Forgot to attach below picture.

Also https://dspace.lboro.ac.uk/2134/15615
 

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Discussion Starter #127 (Edited)
Sorry for the double post. Forgot to attach below picture.

Also https://dspace.lboro.ac.uk/2134/15615
For those wishing to know/understand more about various grades of motor oil, the link below is extremely informative.

However, for those that just wish to understand the issues surrounding Oils, the following extract is from the same extremely good source:-

Viscosity index modifiers and how they work
mono-grade vs. multi-grade engine oil

Figure 2: Influence of viscosity index improvers: mono-grade vs. multi-grade engine oil

Formulated lube oils contain various additives. One of the most important groups comprises viscosity index improvers4 (= VII)/viscosity modifiers. These are mainly oil soluble polymers or copolymers. They can be used for both mineral and synthetic base oil types.

VI improvers work – expressed in a simplified way – via shape change. The polymer molecules are small and coil-shaped, or folded when cold. In that state, they do not increase the oil’s viscosity, as there is rather low friction on the wetted surfaces in the engine and in the liquid itself. With rising temperature, the molecules expand and unfold or uncoil. Consequently, they increase the friction in the liquid and compensate the decrease of viscosity that is caused by the higher temperatures. The impact of a VII on the overall system lube oil further depends on the molecular weight of the viscosity index improver5.

VI improving additives also have some drawbacks. They are sensitive to ageing caused by repeated mechanical shearing, which disrupts the molecule chains. Over time, additives lose their ability to act as thickener in the oil at high temperatures. Using polymers with higher molecular weight would improve the thickening properties, but they show less resistance to mechanical shearing. Polymers with lower molecular weight are more shear-resistant, but they do not increase the viscosity at high temperatures effectively enough. This is why they must be added in larger quantities. Without viscosity index improvers, it would not be possible to formulate today’s modern multi-grade lube oils. Figure 2 displays how VI improvers influence the oil’s temperature-dependent viscosity change.

The practical example in this figure shows two mono-grade oils for use in engines of road vehicles. SAE 10 has a lower viscosity at low temperatures than SAE 40. Roughly said, the first oil is for use in cold surroundings: it is the “winter” oil. SAE 40 is for use in warm surroundings: it is the “summer” oil. By adding VI improvers (and other additives) to SAE 10, it is possible to formulate a multi-grade oil that contains both properties: the SAE 10W-40. This oil has properties of both oils: the good pumpability at low temperatures of SAE 10, and a thicker, more stable, oil film at increased temperature of SAE 40. By using a multi-grade oil, there is no more need to change the engine oil with the season. For details regarding SAE (SAE International; former Society of Automotive Engineers) viscosity classification see SAE J300 and SAE J306 standards or our article on SAE viscosity grades for a specification of oils over a broad temperature range.


https://wiki.anton-paar.com/en/
 

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Discussion Starter #128 (Edited)
Sorry for the double post. Forgot to attach below picture.

Also https://dspace.lboro.ac.uk/2134/15615
Yippee, the 159 engine is now out. Ancillaries being transferred from it to Brera Engine. I will be going down to transfer the mod - Ed vvt’s and oil filter + cat - less manifolds, new water pump and new air con compressor.

Here’s hoping. The 159 was started yesterday by garage, so they knew everything worked beforehand. Except the engine rattled with the shot crank bearings.

159 engine now spare. Crank to be reground, straightened if necessary, new con rod, then maybe for sale.

Arrived at garage to see both the redundant engine and the rebuilt Brera engine on stands as parts were transferred over from one to the other.

took some pictures of the engine bay, which is devoid of engine and gearbox, sub - frame, steering rack, etc, etc. It looks pristine for an 11 year old car and the absence of corrosion is astonishing.

However, Cam covers came off the redundant engine and the amount of tar products was equally astonishing. Adam said he had never seen so much crud in a petrol engine - the only bright work was the cam lobes as the crud must be 3 - 4 mm thick in places on the covers, bearing caps and the cylinder head floor. Just amazing the thing still ran.

As he removed the Brera Engine when it failed in his brothers car, to be replaced by one bought on the internet, he remembered the mileage was only around forty thousand. Gareth - Scholar engineer said both the rings and pistons showed little signs of wear so that is good news.

The engine; being taken out, was run yesterday, before it was removed and the guys really put a spurt on to get things to where we are today. Anti - Knock devices and crankshaft sensor transferred from old engine and new Cat - Free Manifolds now fitted. He will ring me at the back end of the week when the Brera engine is in situ in the 159.

Christmas has come early for me, although I am extremely anxious for her to fire up cleanly. Everything has been done to the highest standard, but still it is worrying.

I am still banking on well in excess of 300 bhp - 315 -320 is my best guess.

Happy Days!
 

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Discussion Starter #130 (Edited)
Hope all goes well. Keep us posted.
Thanks Roop.

Below are two extrapolated plots from the previous document. I overlaid the figures that were given to make it easier to make direct comparisons between the various grades.

It is interesting, well something I previously did not know, that the second figure for viscosity is a function of the additives (VII - Viscosity Index Improvers).

I have also read, where serious racers/engine builders in the States, use an oil with a higher first figure. E.g, instead of say 5W40, use 15W40. The implication being the first figure is the natural viscosity of base oil and the second a function of the VII's used to achieve a higher viscosity @ 100 deg.C.

According to builders, a fair bit of time is spent cruising at low revs after a spell at WOT. So having an oil formulated from a higher viscosity base oil provides extra bearing protection when they come off the gas with very hot oil. It appears bearing bleed; crankshaft and journals, is greatest at low rpm, particularly when oil pump pressure has dropped off. Some also go to the extent of shutting off piston spray jets below 3500 rpm.

Anyhow, more can be gleaned from the excellent document and it may help people make more informed decisions about what oil they may wish to change to. Certainly, I will give it some thought, maybe going from 5W40 to 10W40 and see how the vvt's perform with a slightly thicker oil.
 

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Be interesting to see how you get on, I went for Millers CFS 5W40 Nano drive fully synthetic competition engine oil for mine on track and has performed perfect for me (at the moment!) however I did think about 10w60 after reading some forums but went back to 5w40.

Looking back at the 1 owner service history, sturgees Alfa had always used 10w50 at all previous services

And then I used Millers CRX 75W90 NT+ high race transmission gearbox oil

The only thing that I’ve noticed was that in the 8,000 mile road trip I did, plus the Nurburgring ring 10 times and an hour on the gp track the car used just over 2litres of engine oil top up! But since then it hasn’t really used any.

It’s cureently got 138k on it and I reckon the valve seals may be leaking but I have no technical knowledge on this part... the other thing is that the intake manifold was very very gunky/oily so I now have a catch can that I need to get round to fitting
 

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Discussion Starter #132
Hope all goes well. Keep us posted.
Coming on! Rear manifold and heat shield. Original cam covers fitted temporarily as metal ones could get scuffed as the engine goes back. Plus have to modify the PCV valves, as per Chrysler/GM instruction.
 

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Discussion Starter #134
25% increase seems very optimistic but good luck
My modifications to the engine, did not increase the power output, just recovered losses.

A non too spectacular standard engine can expect to be improved by 8% in terms of power, if camshafts are changed out for something a little more performance related. It a reasonable assumption that this engine is a little better than basic, particularly with VVT's. And I estimate it was doing about 286HP Din after modification.

To go from 286 to 320 is only an increase of 11.8%. And this does not include the saving by removing the Manifold Cats.

The precise figure will not be known until I get the car back to Clive Atthowe. But, for certain, I shall be North of 300 by a fair margin.

I am desperately trying not to make a cross to be nailed to, as the real purpose of the cats is to get cylinder head/engine oil temperatures down. The free flow manifold should improve that, I hope by at least the same order as a 147 GTA, when a similar exercise was done - 20 deg. C. lower. Actually, I am hoping for better, given the JTS has VVT's.

But the camshafts should also contribute to better breathing as the engine now has a PVO of 23.5 deg. overlap, where hitherto, the figure was 2.5 deg. NVO. This should improve upper cylinder cooling considerably.
 

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Coming on! Rear manifold and heat shield. Original cam covers fitted temporarily as metal ones could get scuffed as the engine goes back. Plus have to modify the PCV valves, as per Chrysler/GM instruction.
Coming on indeed! :)

I really believe that the simplest first thing anyone should do to the 3.2 JTS to liberate power is to fit free flowing manifold down pipes - i.e. delete the cats. The engine will still pass emission inspections with remaining center cats.
 

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Discussion Starter #136 (Edited)
Coming on indeed! :)

I really believe that the simplest first thing anyone should do to the 3.2 JTS to liberate power is to fit free flowing manifold down pipes - i.e. delete the cats. The engine will still pass emission inspections with remaining center cats.
"The free flow manifold should improve that, I hope by at least the same order as a 147 GTA, when a similar exercise was done - 20 deg. C."

Actually, I should have made it clearer! It was a 20 deg. C. drop in oil temperature that was observed with the 147 GTA. But by the same token, for that to have happened, cylinder head temperatures must have dropped.

Again these notes are as much for me as to be of any help to anyone reading them.

Logically; I think, reducing back pressure from the manifolds will shift hot gases away from the heads more effectively. And in doing so, the incoming air will suffer less temperature elevation, thus remaining more dense. So if the charge air remains more dense, the mixture should be nearer the correct Stoichiometric figure.(1)

This is aside from the increased duration: up from 254 deg. to 278 deg. on the inlet and 250 deg. to 278 on the exhaust.(2)

Whilst PVO [Positive Valve Overlap] must exist during normal driving, because of vvt action, it is at lower revs, where there should be real benefits to cooling. If one has just come off the throttle after a spirited drive, the cylinder head temperatures will be elevated, because one was making more power.

So when being forced, by traffic/road conditions to slow down, a NVO [Negative Valve Overlap] is not going to help reduce cylinder head temperatures as there is no air flow across the cylinder heads, inlet to exhaust, which would facilitate cooling. But effectively by going from 2.5 deg. NVO to 23.5 deg. PVO, essentially a change of 26 deg., there will be a considerable increase in "Cross Flow" within the upper cylinders.(3)

The overall change to the dynamic valve timing is something the Camshaft Manufacturers must have taken into consideration and thus it is pointless for me to try to rationalize that aspect. Other than to accept, the primary consideration is to get more air into the cylinders to enhance the power output of the engine.(4)

But I am convinced engine/oil temperatures are going to drop considerably as a function of the combined effects of the Camshafts and the Catless Manifolds.(5)

It will be bloody marvelous if this reflected in a dramatic improvement in the condition of the oil over say, five thousand miles. Less carbon/tar products under the cam covers and less oil being drawn into the inlet track would be really welcome.
 

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Discussion Starter #137
Be interesting to see how you get on, I went for Millers CFS 5W40 Nano drive fully synthetic competition engine oil for mine on track and has performed perfect for me (at the moment!) however I did think about 10w60 after reading some forums but went back to 5w40.

Looking back at the 1 owner service history, sturgees Alfa had always used 10w50 at all previous services

And then I used Millers CRX 75W90 NT+ high race transmission gearbox oil

The only thing that I’ve noticed was that in the 8,000 mile road trip I did, plus the Nurburgring ring 10 times and an hour on the gp track the car used just over 2litres of engine oil top up! But since then it hasn’t really used any.

It’s cureently got 138k on it and I reckon the valve seals may be leaking but I have no technical knowledge on this part... the other thing is that the intake manifold was very very gunky/oily so I now have a catch can that I need to get round to fitting

Below are pictures of the cats removed from my 159. Yet more evidence of my supposition about valve timing/Oil flow/Pressure issues.

With the best will in the world, if a V engine is balanced in terms of power strokes between front bank and rear, the thermal losses should be pretty much equal and would result in similar temperature "Treatment" on both cats. Clearly they are not! The discrepancy will be very much dependent upon the way the car is driven. But this should not be the case.

The evidence of excess heat is only half the story. What is seen on the front cat is indicative of the restrictive nature of the cats; even the pipes from the heads to the collector are extremely restrictive - "pinched in " even further where they enter the Catalytic element.

All other considerations aside, there should not be such an obvious difference in operating temperature between the two half's/banks of this engine. The reflected heat/hot gases from the front cat, into the exhaust ports of the front bank cylinder heads is in my opinion, one of the major factors in the low specific output power of this engine and, what I would term from my Broadcast Days, "Exacerbated thermal decay".

And if the power strokes of both half's of this engine are not balanced, a continual "Yo-yo" effect will exacerbate tensioning and relaxing of timing chains promoting stretch and tensioner/guide wear.

On a more positive note, the engine is now installed and has been turned over. On a negative note, sadly the oil pump was not primed and thus we are struggling to get the oil pressure up on the engine. The way the pump and oil Cooler/Filter are mounted, it seems there is too much air in the feed way to overcome and to draw oil up. Once oil is "lifted", it seems to be configured for zero siphoning effect. But until that is achieved, oil is quite content to stay in the sump. Thus, I may well need the oil filter housing to be removed and filled and the outlet of the Oil pump primed.

Disappointing, but we will get there!
 

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hi,mate.Nice to see that you are advancing,albeit slowly! You will get there! What is your guess? Insufficient oil pressure impeding vvt to operate efficiently and causing the yo yo effect?
 

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Discussion Starter #140 (Edited)
hi,mate.Nice to see that you are advancing,albeit slowly! You will get there! What is your guess? Insufficient oil pressure impeding vvt to operate efficiently and causing the yo yo effect?
Yes!

Oil pressure cannot be sustained, if the flow rate is below demand! Restrictions create the problem.

To reiterate, the ECU is predictive. The speed at which the camshafts rotate dictates what angle the ECU sets for the next cylinder’s power stroke; and importantly, exhaust valve opening.

We know the rear bank exhaust camshaft position sender is always late and progressively fails, throwing a code.

The exhaust camshafts are heavily biased in the advance position, by both the internal spring AND the hydraulic configuration, dictated by the ECU [control of the solenoid valves].

However, the speed of operation of the front bank exhaust camshaft, given it is the first major device after the oil cooler/filter is; should we say, normal. So the tell - back from its position sensor, to the ECU is within the standard timing parameters embedded within the ECU.

The ECU will, as a function of this set a predicted angle for the rear bank exhaust camshaft, at an angle which the camshaft cannot assume in the time the ECU predicts.

The exhaust camshaft timing is such that at idle, it is fully advanced, causing hot exhaust gases to heat the cats to light - off temperature quickly and thus quickly cause the reduction of pollutants by catalytic conversion. This occurs on start up. But light off temperatures have to be maintained throughout its duty cycle.

So, if the rear bank exhaust sensor is late, the ECU will interpret this as being “lower revs”. Lower power and hence to maintain light - off, will set an angle for the front bank exhaust camshaft, which is too far advanced for the power the engine is making.

Camshaft too far advanced - exhaust valves open too soon in power stroke - elevated exhaust gases cook the cat and, as the exhaust valve has opened early, an extended period during which these gases are reflected; due to cat restriction and re - ingested at a much higher temperature than normal. Evidence being the difference between the two pictures of the cats.

Further evidence was given by poster on this forum which indicated, by inspection of front bank spark plug, lean to very lean burn. The poster was investigating misfires, a function of unstable flame front of very lean mixtures.

This, I believe is also connected to “Coil Pack” breakdown/melting, which is seen predominantly on the front bank.

Lean burn in this instance can only be a function of retained hot gases, restricting the intake of fresh air charge.

The relevance of the last paragraph is, as hot gases reduce the inflow of the fresh air charge, the M.A.F. will sense a lower flow rate and the ECU will adjust the fuel injected to achieve the appropriate fuel/air ratio for the air flow the M.A.F. has just sampled.

This can only result in an extremely lean mixture, which will cause unstable fuel combustion, extremely high upper cylinder temperatures and potential breakdown of coil packs and melting.

The current drawn by a coil pack, under normal operation, is not sufficient to generate the heat required to melt the coil pack. Were this to be the case, there would be evidence of ECU failures, of which none have been reported to date.
 
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