Timing chain kit for 3.2 JTS V6

[milospinkfloyd]

@ascari32

You are running 291hp with CB cams + autodelta headers + ss exhaust and with remap or without remap?

[Ascari32]

Yes! My Dynamometer plot has been posted, registering 287 BHP, which is 291 PS, or DIN. Alfa quote 260 hp for the 3.2 JTS, which is actually 256 BHP. So either way it is 31 ps/bhp above standard.

Forty one above the Busso GTA.

But it is the improvement in the torque response that is most impressive, which I believe is being restricted at the top end due to air flow inertia created by the "Slatted Screen".

Now that it has been removed, once we get into the New Year and I get my final mods surrounding the NTC sensor in place, I will return to the Dyno Station for another run. I fully expect it to be over 300 PS as the removal of the slatted screen and trimming of the Petrol - Chip had made a tangible difference to performance since the last Dynamometer plot was done.

I have maintained my view, throughout this process - too much store is placed in Software, particularly the way it is employed with this "Jewel" of an engine - substantially for the sake of emissions.

[Ascari32]

@ascari32

You are running 291hp with CB cams + autodelta headers + ss exhaust and with remap or without remap?

To reiterate - "NO REMAP, NO SOFTWARE MODIFICATIONS"

All down to mechanical realignment and performance hardware additions!!!!

[Ascari32]

@ascari32

You are running 291hp with CB cams + autodelta headers + ss exhaust and with remap or without remap?

Great football team by the way,

[Ascari32]

Not wanting to claim any credit for the improvement to the 3.2JTS's performance as I have seen it all before, given I am 75. So, I have plenty of history on my side. With this in mind, it is now accurate to say, the improvements I have achieved are a function of that history. In essence, it is more accurate to say, Alfa Romeo squandered 31 PS for the sake of meeting EU emissions.

I have long held the view, that; specifically, one would never see the best from this wonderful car, unless it was a Q4: a system the Audi R8 uses, and the power output was in excess of 280 BHP. As a sports saloon, it is incomparable!

[Stu159]

hard to imagine what the 159 / brera forum would be without you Ascari. Sounds like it's coming along nicely and quick at that! So, dare I mention a remap, but, were you to do that, you'd have to be getting close to the Auto Delta figures achieved through supercharging, one would think? They claim 350+.
If yours still has the OEM rev limiter set in 1st, you'd want to unleash that extra hp in the sprint now too. As I mentioned to you previously, it's the most enjoyable aspect of the remap. I'm yet to engage the rev limiter in 1st since, you don't need to go that far, but it's so nice when you change through into second. It's amazing how much more springy the car is in the lower rev range as a result.

As always, looking forward to more updates

Stu

[Ascari32]

Hi Stu - Happy new year by the way.

Right now, I am awaiting some more bits for some other modifications, essentially revolving around the NTC Sensor. Whilst waiting, I have been doing a write - up, which I will post. I like to get things down in print, not least because it provides me with a record in case I find things don't work out the way they were intended.

I am still reluctant to have any software modifications done to my Q4 and whilst I can see lifting the limiter on first gear will help standard engines, I think that is because the JTS is largely gutless at low revs in standard guise. What it lacks is bottom end grunt - "Torque". Alfa acknowledge - nay, make great play about the JTS being lean burn up to 1500rpm. Thus to get it moving, without losing time between first and second, it does need to be revved!

However, with the increased torque at the bottom end, which my modifications have made, the Throttle Response is extremely sharp and it doesn't take long to get her moving quickly. Less pressure on gear changes too as the "Torque Overlap" from one gear to the next is just fabulous.

I still can't recommend the changes I have made, given the cost. But they do illustrate what could have been achieved if only more was understood about the engine and JTS technology at the time Alfa introduced the 159 and Brera. The cars would have been in production longer and I am not sure we would have seen the 2.9 Ferrari engine in the Giulia.

The remaining bits for my current modification should be here this week and I will post what I am doing with pictures of the mods as and when. 

Autodelta told me, 350 was the limit as they couldn't get more fuel into the engine. They were looking for ways to increase the delivery but there are no JTS pumps that can do it. I am not sure I agree with this and also take issue with retaining the standard camshafts, whilst going to supercharging. You  need to get the air in earlier than 11.5deg. ATDC.

However, get some decent valve timing, where the exhaust system is in depression and thus pulling air through the inlet tract, due to "Positive Valve Overlap", with the piston still at 0.5deg. BTDC and the exhaust valve still having another 23deg.ATDC to go before it closes and the engine suffers no inertial drag due to having to suck the air through the inlet tract. Then it is a different story.

If the camshafts are symmetrical, then not only are the inlets opening earlier, but so too they are closing later. With this reduction of inertial drag, and the air charging the cylinder longer, "Volumetric Efficiency", VE increases dramatically. Autodelta, in my opinion have trouble getting more fuel into the engine as although air is going in; in greater density, the engine management still hasn't sufficient time to get enough fuel in to correct the AFR, because of the restriction the valve timing creates.

Not being able to start injecting fuel until 11.5deg. into the induction stroke is a real handicap.

They have also retained the Slatted Screen inside the MAF housing which must be a great impediment to air flow, another reason the Standard JTS engine is gutless, because on pulling away, there is little "Ram Air Effect" into the inlet due to air pressure at the front of the car!

Stay safe,

Brian.   

[milospinkfloyd]

nice works you done. Few days ago I dynoed my brera Q4 (complete stock car) and results are 248hp and 335nm, but more importnant is 167hp on wheels so, Q4 eats 33% of power. Looking for ways to increase engine power

PS nice fotball team 

[Ascari32]

Hi Milo,

Nice to see some one else has gone to the trouble of getting to know exactly how their engine is performing.

Oil pressure, mechanical and hence electronic accuracy between banks, and sufficient tension on the timing chain system is the key. to any real improvements. It can be done cheaply, fitted to the car in one day and not require the engine to be removed.

Above all, the chains need to be kept taught, an impossible feat with the most important element of the whole system; the lower primary timing chain tensioner. being at the remotest point from the oil pump.

The stainless steel line which goes across the bottom front of the engine feeds oil directly into the rear gallery, very near to where the lower timing chain tensioner is fitted.

Even with engines which are never going to sport performance cams or expensive exhaust systems benefit from this system, as the last plot attached illustrates.

The Brera is my mates 40.000 mile car, in mint condition. The 159 is mine with its original engine at 112,000 miles. However, only the 159 has the prototype C.L.L.S. fitted.

[Ascari32]

Plot of Brera and 159.

These plots were taken after the prototype C.L.L.S. was fitted to my 159. The Brera is my mates, which was pristine at 40,000 miles and standard, whereas my 159 had 112,000 miles on the clock.

He was never going to buy the Brera as, although he loved the model from new, he couldn't justify it. After I took him for a jaunt in my 159 with the C.L.L.S. fitted, he sheepishly said during a telephone call, some weeks later, "Guess what! I went and bought a Brera. I never realised how good they could be until that ride in your 159".

[Stu159]

it's funny you say that 159 is gutless down low Ascari. It's no sprinter, we all know that, but it has always felt more restrained to me, not lacking guts. More fighting to release them, then zapped by the 1st gear rev limiter the moment it finally starts to show promise. I've documented my minor engine mods + suspension and brakes and all in all, it's turned it into an excellent cruiser that you can absolutely throw around bends with minimal to no body roll and a much more desirable stance. The exhaust mods gave it an excellent note, that was further enhanced by the BMC air filter, which was then tweaked really nicely with the remap. In first it still feels somewhat restrained, but it gets up now and the change into second launches it forward at high revs with spring in it's step that it never had from new. There's no need to go to the stage where you engage the rev limiter. Having said that, I would like to see it raised in 2nd now as there is much more that could be had there.

The whole exercise has motivated me to step it up a little further now. I've just ordered in Wizard headers that will be added on the near future and I'll update this thread further then. It will add a new dimension to this editorial. As I understand this will bring more noticeable improvements to response etc, so I'm very much looking forward to it.

Stay tuned....

Cheers
Stu

[Ascari32]

Removing the rev limit from first gear does not improve the torque, it simply enables one to get the engine speed up sufficient to support a gear change without the loss of momentum.

The reason for the lack of torque has always been an issue I have wrestled with. Although my suspicions were always drawn to to the matter of valve timing, it never crossed my mind that it the MAF could be connected with the issue. It was only after studying the last dyno plot and the quiet intimation by Clive Athhowe for me to "look at the torque curve", that it began to dawn on me where the problem lies.

Fact: - the inlet valve does not open until 11.5deg. ATDC., whilst the exhaust valve closes at 9deg. ATDC., creating  2.5deg. of NVO. So air flow through the inlet tract has been stymied - no flow for 2.5deg. Importantly, induction is now entirely down to the piston's ability to draw air into the cylinder. Essentially, the piston is "Dragging" air into the cylinder for the remaining induction stroke - 168.5deg. and little velocity is possible to generate much by way of volumetric efficiency (VE).

It is recommended that turbo - ed engines are fitted with a honeycomb to linearise the flow across the MAF element and eliminate surge due to air flow turbulence. This too is a function of the "Slatted Screen" within the 159/Bosch MAF., given that the 159 has a cold air intake from the front of the car which also forms a "Ram - Air Intake".

The screen is effective in compensating, to a degree, for the lack of air flow at Top Dead Centre as it creates linear air flow across the sensor face. Essentially, the "Slatted Screen"; at very low air  flow, causes very little restriction.

Moving away from "Idle" however, the combination a valve timing and the increasing restriction the "Slatted Screen" presents; as air flow velocity increases, results in "Choking"/Starving the engine of oxygen. This generates considerable inertia which is only overcome when the engine speed is sufficient to nullify it, i.e., ram air effect + VVT action is greater than "Slatted Screen Inertia".

Fortuitously, I chose to pause my investigations surrounding the MAF at a time when I felt real gains had been made and I needed to qualify "What those Gains Were". Hence my last visit to the Dynamometer Station, which drew Clive's observation.

After the Dyno run, I asked him why he had started the run at 2500rpm when hitherto it was started at circa 2000rpm. "I was getting funny/unstable readings", he said.

It is my contention, PVO generated by the C.B. cams, in conjunction with the free flowing nature of the exhaust system has exposed the true inertia the "Slated Screen" presents to air flow. In essence, the restriction it presents to air flowing through it, has induced the air to flow around it and avoid being metered by the Air Flow Sensor. Thus the AFR becomes extremely lean and as a consequence torque suffers and Clive was unable to get stable figures much below 3000rpm.

So far, I have only addressed the consequences of the "Slatted Screen" at the bottom end. Before modification, the mechanical limits were not being tested to the full, so air flow at the top end seemingly had a a minimal effect on torque.

However, after modification, the torque response appears to be limited/clamped. It is extremely rare to find a tuned device with a response anywhere near that flat. Closed loop systems are generally applied to systems to "Linearize" the response over their working range. But this is not such a system and there can be only one reason for the linearity; and that is something is causing a restriction. I.E. the level would be "X%" higher, were it not for some factor which is limiting it.

It is accepted in engineering circles that substantially, the torque curve mimic's that of the Air Flow Response. This being the case, just as the "Slatted Screen" is impacting upon the bottom end torque, so too it is limiting the ultimate torque response at high RPM.         

[Stu159]

"Removing the rev limit from first gear does not improve the torque, it simply enables one to get the engine speed up sufficient to support a gear change without the loss of momentum." - I get that, which was part of my point, Brian. The slight increase in power from the remap + improved throttle response + high flow custom exhaust, has significantly changed the cars acceleration off the mark. "Add to that", I can stay in first for longer until change, improves that even more. I change from feel now, instead of attempting to anticipate the intro of the rev limiter. What's the point of a manual with a rev limiter anyway?

I don't think there has been anything on the Wizard headers on here yet as they have only been a fairly recent introduction for the 159. A much more cost effective purchase than the Auto Delta ones, which was part of my motivation. I'll go for ceramic coating and also look to some other minor mods at the same time they are installed. I'll ideally choose a couple of cost effective changes from your extensive research and experiences for further tweaking at that time.

It's never going to be the rocket ship your's will become, but I don't have the technical knowledge to go there, nor the desire to spend that sort of budget on a car that is currently worth about 15k AUD. I'm considering the Mace cams (yes I've read your editorial on Mace cams on the UK forum), then that will be it for me. I'll be happy with the final outcome at that point and as I've pointed out on here before, there's no use for high performance cars here anyway now as there is no where you can use the power. For me it's more about the subtle changes in feel, that come from the handling improvements thanks to the PU bushes and B16 shocks + the Ti seats so that I can stay in around corners + the better sound & improved drive experience in raising the rev limiter. The latter has always been the most annoying aspect of the car for me. I've never owned an automatic car for good reason. I've owned the car since new (almost...dealership demo 2008), so each minor adjustment is an enjoyable, anticipated change. From there it's fine tuning of things like door card replacement, that is already in work and wider rims. The car has never stopped attracting attention and comments and I think it's fair to say at this point, that's not going to change. Once you remove that awkward OEM stance by lowering, it changes the appearance from a nice looking family car to one of a sports saloon.

Cheers
Stu

[Ascari32]

I get all that Stu and it sounds like the changes you have made so far are subtle, yet benefit the car overall. However, if the car had been that good from new, you wouldn't have touched much or been proposing to do more. Either way, your affection for the beast is obvious.

However, I wouldn't want to see you spend money in areas where you will get little tangible gains, when balanced against the cost of doing them. I started with the dubious advantage of having to rebuild the engine so what I proposed to do could be incorporated whilst the engine was out.

Headers, for instance are going to cause trouble for you, as one has to balance the improved air flow with the effect it is going to have on the NTC Sensor in the region of cylinder two exhaust port. It is critical insofar as keeping the man - cats at "Light - Off" and the way it responds to temperature change is pretty damned quick. A drop of a few degrees will cause the ECU to up the injection of fuel to ensure there is an over - rich mixture which burns in those cats which maintains their temperature.

With your Wizards fitted, that excess of fuel is going to appear at the secondary cats, and burn there instead, causing the racket I was faced with. There is no easy solution to the function the NTC sensor performs in conjunction with the ECU, which adds a secondary action of modifying the advance/retard timing.

Principally, this all comes about as a consequence of the headers; Autodelta or Wizard have in lowering engine temperature. And this is a function, which cannot be programmed out, well not according some authoritative sources I have spoken with on the subject. I am still pursuing this issue and nothing as yet is entirely satisfactory.

Of course, the racket may not be as severe as mine if you keep the standard camshafts, but it will non the less cause you problems. The improved performance of my car I just love, but there is no question, it is much cruder at urban speeds, where constant throttle adjustments invoke the "Dosing" of extra fuel to maintain light - off, despite the fact there are no man cats. On full chat, she is absolutely glorious, with a beautiful sounding exhaust wail, but if as you say, there is no opportunity for high speeds in Australia, you may end up being both bored and frustrated by the sound at low revs, when constantly on an off the throttle. You will certainly end up by changing the central Alfa cat for a sports cat, just to rid yourself of the awful, loud 2500rpm drone.

I am still working on modifications to, and around the NTC Sensor and fitting a second NTC Sensor into the thermostat housing is part of the plan. Indeed, my current thinking is to use some electronic control circuitry which takes both the standard NTC sensor and the Thermostat Housing and derives a signal/voltage to drive the ECU input. But a solution as yet is not altogether clear and I am working around very little concrete information from so - called expert sources. But one cannot get away from the fact that the NTC Sensor acts as both a choke for cold start enrichment, provides the correct amount of fuel for idling AND enriches the mixture when the manifold cats are dropping off light - off temperature.

I am sceptical about the claims of MACE. However, I have bought from them and their service has been very good and parts excellent quality. But their camshafts for the JTS and a standard PFI Holden - the same! Unless they provide more information, I cannot help but think their claims are fanciful. But if however, it is one direction you intend to go, it may be worth going their first, given the price. And keep the Headers in abeyance until more comfortable with any progress you make.

For me, the man - cats will never go back on - indeed I put them in the skip, rather than sell them on. But the reasons for doing all my modifications are fundamentally different from yours. Don't get me wrong, it is a fascinating engine and I continue to enjoy the issues it throws up. I lived my life with these kind off issues at work so they feed the engineering masochism that is part and parcel of a prototype engineers existence.

That I think, is not something you are looking to do.   

[Stu159]

I had the central cats removed some time ago as one was gutted, so I eventually did away with both and replaced the whole system from there back with a high flow custom fit out. There is no noticeable drone, I'm not saying it's not there, but certainly not an issue. I think GTV6SA is running Autodelta headers with a back end supplied by the same place that installed mine + a remap. I don't recall him complaining about droning, but maybe he can correct me? I recall him commenting on one of your posts some time ago when you were trying to work things out. AutoModa, that work on my car in Sydney have fitted the Autodelta headers before to other cars. He has stated it's a big job!

I'll investigate Mace further before I go there. It's just an idea at this stage. If they'll back the fact that I'll get around x 30kw, I'll do it, with the other necessary mods to protect the engine. Seems odd they'd make the claim in writing in their advert were it not possible, but, I certainly don't have the expertise to judge them! A dyno would be the judge, which is part of the process they recommend

My sincere thanks again for all the advice. The parts I get, do help 

Stu