Timing chain kit for 3.2 JTS V6

[Ascari32]

The drone, in my case came a a consequence of C.B.'s and Autodeltas in conjunction with the Alfa Twin Cat and post resonator. With the Man - cats gone, the extra fuel was burning in the twin cat and that excited the filter/resonator/silencer after it.

This has been resolved since the system is now wholly Supersprint with 100 cpi sports cat. But, although it no longer resonates, one can detect - quite loudly at times - a "Gas Burner - type Roar", as the excess fuels burns in the sports cat. It certainly turns peoples heads.

However, if you remove both the man - cat and have no further cats in the system, the emissions will be horrendous , not to mention excess unburnt fuel building up in the exhaust system.

It is wholly down to the NTC Sensor to moderate the excess fuel injected, which in turn is down to the temperature it sees at/around cylinder 2 exhaust port. I estimate the combination of the Colombo Bariani's and the Autodelta header, in conjunction with the free flow characteristics of the Supersprint cat and exhaust system, the engine temperature has dropped by somewhere close to 25deg.C.

The reduction is clearly great enough to cause the ECU to inject dosing quantities of fuel into the cylinders, in an attempt to restore it to "Light - Off" temperature, for the sake of destroying pollutants in the man - cats, which of course are not there.

If as I have done, I modify the "Effective" value the NTC Sensor presents to the ECU in an attempt to fool it into believing it is already up to working temperature, it strangles the fuel supply so much that what is injected is so small that the JTS Fuel Rail, remains almost full and when the JTS Pump restores the fuel used, the quantity is so small the excess is forced back through the bleed back valve to the tank. This causes the valve to clatter very loudly on tick - over and it sounds very metallic and loud, to the extent that one thinks there is something seriously wrong.

Back off the "Fake Value" and the clatter disappears, but the dosing resumes. Somewhere between the two, the engine is very quiet and the exhaust tips start to colour brown/grey. The problem is, the "Fake Value" appears to be effective over a very limited range of ambient air temperature - i.e., depending upon whether it is a fine day or cold.

It is true however, the massive PVO the C.B.'s create in conjunction with the headers and exhaust of my car, produce a velocity of gas that the Alfa secondary cats and back boxes could not handle and taken in conjunction with the "Dosing" quantities of fuel, the power within the exhaust gas provokes the post twin - cat silencer to resonate violently and only starts to subside; as I now realise, because beyond 2500rpm, the engine management system is now transiting over to "Maps" which are concerned with making power and with that comes sufficient heat for the man - cats to remain heated without intervention by the NTC Sensor.       

[Stu159]

AutoModa have already advised me that installing a sports cat to replace the twin cats was going to be necessary, with the headers, so I was ready for that. I don't want it louder than it is either, so that is another consideration in my planning. I'm not sure how to tag GTV6SA here, so if you know, pls do. His input would be timely for the reasons I outlined previously. I'll go back on another thread to see if I can get him on board

[Ascari32]

I pm - ed GTV6SA, so he may just pop up with his take on the issue.

The car will definitely be louder, particularly if the NTC Sensor raises its ugly head. Light throttle cruising is not the issue, it's when it is put under load.

It may be I am seeing the worst case scenario because of the massive Valve Overlap the C.B.'s introduce - intake air is already moving quickly across the piston crown at TDC, which cools the heads and the NTC Sensor. Plus the cylinder fill is from TDC to BDC + later closing, greatly increasing VE. So there is a lot of energy to get rid of after the power stroke.

To what extent this affects the sound level/gas burner-type roar the dosing creates with standard cams shafts, only testing can determine that.

But I wouldn't swap my CB's for all the "Tea in China", despite the NTC issue as both the sound on full chat and the way the engine pulls as the revs climb is mind blowing for such a heavy car.

A friend in the "States" posed the issue of duration and lift on one of the performance sites he contributes to which generated quite a debate about potential valve/piston interference.

One character contributed, saying; "One thing is certain, these ain't no Granny-cams, the angles and duration are very close to my Ferrari Racer"

I don't think anything other than the 2.9 Giulia can live with it above 4500rpm and the "G" one experiences on even modest bends in 3rd gear at those revs is startling. Which makes me absolutely marvel at the 159 chassis - it is colossal in every respect; taught and very predictable. Point the car at where you want her to go and she just tracks sublimely. It is such a great platform, it could handle the 2.9 engine under the bonnet.

Better than the GTV, the 156GTA and the Brera, in my opinion.

Even AutoItalia, in their latest magazine commented, belatedly about the 2.4 159SW, stating she is a fine handling car which takes roundabouts at startling speeds. Not before time, the platform is starting to get attention. Reputedly, it cost more to develop, than some motor companies were worth. Certainly, Fiat settled the divorce alimony question by accepting £2billion  + the chassis/platform from GM.

[Stu159]

another question Brian, assuming the Mace cams do deliver the x 30kw (approx) extra power, would I lose performance down low? They state "These cams provide power gains of approximately 30rwkw between 1500 and 6000rpm".

The other thing to take into account with the Mace claim is, when you consider the potential sales capacity of the cams they're selling Vs the amount of 159 V6's that actually exist, it wouldn't make commercial sense to make the statement anyway. They stand a lot more to lose than to gain.

Also in relation to some of your editorial I've read about your concerns about valve springs, they also state "If you intend on revving your vehicle beyond the factory rev-limiter or adding a little boost, then we'd at least recommend our high-performance valve-spring kit and aftermarket timing chain set."

As always, interested in your thoughts here, most notable on the power delivery

Cheers
Stu

[Stu159]

got a DM from GTV6SA, Brian. He said he had to go back a couple of times to the local custom exhaust fitter, before he was happy with the volume, but is now content, so all good there. He said initially the increased flow created too much extra noise so he went back for further adjustments

Cheers
Stu

[Ascari32]

another question Brian, assuming the Mace cams do deliver the x 30kw (approx) extra power, would I lose performance down low? They state "These cams provide power gains of approximately 30rwkw between 1500 and 6000rpm".

The other thing to take into account with the Mace claim is, when you consider the potential sales capacity of the cams they're selling Vs the amount of 159 V6's that actually exist, it wouldn't make commercial sense to make the statement anyway. They stand a lot more to lose than to gain.

Also in relation to some of your editorial I've read about your concerns about valve springs, they also state "If you intend on revving your vehicle beyond the factory rev-limiter or adding a little boost, then we'd at least recommend our high-performance valve-spring kit and aftermarket timing chain set."

As always, interested in your thoughts here, most notable on the power delivery

Cheers
Stu

Stu,
I am not going to subscribe to what any company claims without more tangible evidence to the effect that it is true. They do not give enough detail to make a judgement. On the basis of what they do say, I do not believe what they say.

The caveat to what they state is other changes needing to be made - so given so many go on about software modifications, are they making claims for cams when in conjunction they are fitted along with software modifications? The only way to properly test any improvements is by testing each change in isolation. So to me, they are being disingenuous. And how exactly is any of what they say relevant to a 3.2 JTS which is not boosted? There is no turbo!!!!

As far as cams are concerned, I have said before, their cams do not provide extra lift, therefore no extra air can get in. Their duration is even less than Alfas, so again, even less time for air to get it. However, with regard to valve springs, a more peaky cam - which theirs have given their shorter duration - and you are more likely to get valve bounce even if you don't over rev the engine. Even if stronger springs are not fitted, because of the profile, they will be more likely to clatter than Alfa's.

On the basis of a straight swap - out, nothing else changed, I personally believe the 3.2 JTS engine will be less powerful with MACE cams, than with Alfa's - based on the information they have given.

You pay your money and make your choice. C.B. are expensive for good reason. Bottom end torque Will Not improve unless lean burn at low rpm can be eliminated and scavenging improves dramatically. That can only come with increased duration; assuming lobe centres stay the same, and ridding the engine of "Negative Valve Overlap".



The are not giving us, me in particular; given I have asked them, relevant information to make an informed judgement. So I would not recommend fitting them on the premise of what performance gains will be made. As a cheap experiment, with everything else untouched, yes and I have said I would be willing to test them on my car, giving them sight of the results first and not disclose details to anyone. But that is not something they appear willing to do.

Although they are expensive, the simple fact is, only Colombo Bariani have proved their worth. They do not concede any failure in increasing power as the cams are designed around improved torque. No one wants to be permanently revving the nuts off an engine just to demonstrate "X" power gains. As Carrol Shelby said, "It is Torque that wins races".

Personally, I think the biggest single improvement comes from fitting Colombo Bariani Camshafts and their gross cost will seem cheap compared to the accrued cost of changing so many other things, with little by way of tangible improvement. One can gas - flow an exhaust system, but it doesn't make a jot of difference, if the cams won't let the engine breath properly.

     

[Stu159]

not trying to have the last say or anything or prod you in anyway, but my marketing brain (as adapt as your engineering one ) suggests that Mace shooting their mouth off in writing about the potential gains, for as noted, minimal returns, when.........as noted, they have a solid reputation, makes little sense. I'm sure they know the engines well.....also

My headers installation will be months away yet, owing to work commitments and they've only just been ordered. Additionally I have other significant spends that will take priority, that include a 2nd car, to take the load off my 159 and keep my k's down to preserve it.

Suffice to say that out of interest I'll get it dyno'ed once the headers are done to see where it's at. So considering I'll already have the add ons that Mace suggest would be necessary to achieve the performance gains, fitted, if after discussion with them pre-purchase and further consultation with others, I decide to go ahead, then we'll all know!

Cheers
Stu

[Ascari32]

With all due respect, we won't all know, at all! Not least because you appear to be willing to conflate issues by changing a whole load of things, without recording what has been gained; or lost, in making individual changes.

I am not saying MACE are shooting their mouths off, just what they say is ambiguous, given the 3.2 JTS is only one variant of many in the Holden Catalogue, all of which; to a substantial degree, share many parts. But JTS technology is very different from PFI technology and High Volumetric Efficiency is relatively easy with Turbo charged cars. And it is disingenuous to introduce that aspect into advertising touting virtues of gains to be had with vehicles which are Naturally Aspirated. 

I asked for details about MACE cams and they were unwilling to give any actual figures for them as fitted to the 3.2 JTS.

However, they say the lift remains the same as Alfa's, but duration is only 210deg. So whilst every other cam producer either goes for increased lift or duration, or a combination of both, MACE seem to run counter to even Alfa!!!!

You appear to be unwilling to accept that to achieve more torque, one has to get more energy into the cylinders. And to do that the relevant components must be present, fuel and air. And if you want greater gains, you need more of both. If the engine is naturally aspirated, then better breathing is essential and that equates to allowing more air into the cylinders.

Now. given the same lift, the length of time the inlet valve is open is a crucial factor and a valve that is open for 254deg. (Alfa) is better than one which only opens for 210deg.(MACE) And one that is open for 278deg.(C.B.) is better than one that is open for 254deg.

Somehow, you seem to be intent in adding headers and exhaust systems into the debate, without making the distinction about what their role is in all of this. Removing the Manifold Cats and fitting a good free flow exhaust system is not actually increasing the power of the engine. It is simply reducing the losses that suppress it's true power.

To get more power, you need more energy in. However Alfa's criteria was low emissions and as a consequence camshafts and timing that assist in achieving that goal were fitted.  However, they certainly can't be called performance cams in a conventional sense.

And, on the basis of what information MACE have given, their figures indicate they will perform less well than Alfa's.

That I am afraid is as much as I have to say on this subject. I am not going to be revisiting old ground given the work I have already done. My priorities are in solving the issues surrounding my NTC Sensor. Good luck with your project. I have posted sufficient on both this forum and the UK forum for people to make use of, or otherwise.     

[Stu159]

I'm more than happy to let it go. All I've been saying is I'd like to look into it further, before I make the decision. For the record, I've never stated, or thought, that exhaust mods were going to increase power. I completely understand they simply make more available and those are the results I've enjoyed so far. Hence me wanting to go further.....

I appreciate all of the info and love the sound or your build. I'm just not one to write things off without further research, in this case, for some of the reasons I've outlined. Automoda also know these engines inside out, so when I'm next there, I'll discuss this with them too. Then, if it's cost effective and Mace will back their claim, I'll give it a go, as I've stated. Nothing to lose. I can always put the originals back in as I would keep them either way, for a future owner to maintain the originality of the car

If I was going to go to the expense of the CB cams, I'd prefer to find another few grand and just supercharge it. Can't see me doing either though. I'd prefer a trip to Europe for a couple of weeks.....

All the best
Stu