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At http://www.pattakon.com/pattakonHydro.htm “clones” of the MultiAir (Fiat) / UniAir (Schaeffler-INA) are presented.



Officially, at urban cycle the Fiat Punto MultiAir (1368cc, 105bhp at 6500rpm, naturally aspirating) consumes 7.5 lt/100Km while the similar size, weight and power Toyota Yaris (1329cc, 101bhp at 6000rpm, naturally aspirating, conventional technology engine) consumes only 6.2 lt/100Km.

20% worse consumption for the state-of-the-art engine ?

Yet, the guess is that the MultiAir engine will be voted at “The International Engine of the year Awards 2010” as the best engine of the year 2010 (at engine-expo 22, 23, 24 June, Stuttgart, Germany).

It seems, either the MultiAir/UniAir principle is wrong, or Fiat and Schaeffler-INA keep missing a basic something.



It is not only about better mileage and lower emissions.

Quote from the web:
"Meanwhile Ferrari has reportedly dismissed the possibility of using the Fiat Group’s new MultiAir variable valve system, finding that it wouldn’t work at the kinds of revs and horsepower outputs at which Ferrari engines operate. "

The "oil push rod" interposed between the cam and the valve of the MultiAir ( and of the PatAir ) softens-deforms-flexes the actual intake-valve-opening-profile (because of the hydraulic system elasticity and lash, not existing in the pure mechanical valve trains); not to mention the increase of the inertia of the valve assembly (oil, oil plungers, additional springs etc) during the opening of the valve. For normal engines this is a reasonable compromise; but not for supercars, for racing/sport cars, for motorcycles etc. For top-power-density the opening ramp wildness is the must.

The PattAir opens the valves true-mechanically / conventionally (there is no "oil push rod" interposed between the cam and the valve). The opening ramp is as wild (crispy) as in the conventional high-revving top-power-density engines. Only during the valve closing the hydraulic system of PattAir gets into play to controllably delay the valve closing ( Outgoing Air Control cycle ).

Manousos
 

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You have the wrong figures, on a MITO 1.4 multiair the combined is 5.8 l/100.

This is better than the Yaris even though the Alfa weighs more than the Yaris.
 

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Discussion Starter #3
You have the wrong figures, on a MITO 1.4 multiair the combined is 5.8 l/100.
This is better than the Yaris even though the Alfa weighs more than the Yaris.
No,
I have the correct figures because, as I write, I talk about the urban cycle.

The combined cycle for the Toyota Yaris is 5.1 lt/100 Km (this results from 6.1 lt/100Km urban and 4.4 lt/100Km extra urban) as you can see at

VCAcarfueldata.org.uk - Search Results - Further Information

which is still 14% less than the Alfa Romeo Mito, as shown at

VCAcarfueldata.org.uk - Search Results - Further Information

In case the comparison is restricted to the urban cycle, it is 6.1 for the Yaris versus 7.4 for the Mito, which is 21% more.

The small difference of weight cannot justify such a big difference in the official mileage.

Besides, the MultiAir is the state-of-the-Art. Isn't it?


What I say is that there is room for improving the MultiAir at partial loads. This is what the PatAir and the PattAir do.

Manousos
 
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I've driven (a new) Toyota Yaris 1.3 and it is a ****ty car. What toyota does is to minimize consumption numbers against performance, i havent driven punto so to make a comparison but what you have there (yaris) is a very weak car with minimum active safety.
 

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Discussion Starter #7
I've driven (a new) Toyota Yaris 1.3 and it is a ****ty car. What toyota does is to minimize consumption numbers against performance, i havent driven punto so to make a comparison but what you have there (yaris) is a very weak car with minimum active safety.
Yet, Toyota Yaris is a faster car than Fiat Punto MultiAir natuarally aspirating.
For instance (data from a multicar-test in AutoBild magazine):
Yaris makes 0-100 Km/h at 11.4 sec while Punto needs 12.3 sec.
Yaris needs 19.2 sec for 0-130 Km/h, while Punto needs 21.9 sec.
I.e. Yaris's active safety is not worse.

But this is not the point.
The point is that the MultiAir, a theoretically superior technology, proves not so good in practice.
And the challenge is to milk from the MultiAir engines (of Fiat / Alfa Romeo cars) what they really can achieve in fuel consumption and emissions.

The Pressure - Volume GIF animation explains where the problem is.

Manousos
 

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Discussion Starter #10
What about power output/delivery. It's not all about fuel consumption.
And what is the point of this thread anyway? It's a very strange way to introduce yourself to AO.
The point is that you have the state-of-the-Art system that can, by a little modification (different intake cam-lobes, reprogramming of the Digital Control Unit) be way better in terms of mileage / emissions, keeping or increasing the power output. It also improves the cranking and the start-stop reliability. This is the PatAir.

If you need more, there is the PattAir that fits even to Ferraris. Think why.

Manousos
 

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Officially, at urban cycle the Fiat Punto MultiAir (1368cc, 105bhp at 6500rpm, naturally aspirating) consumes 7.5 lt/100Km while the similar size, weight and power Toyota Yaris (1329cc, 101bhp at 6000rpm, naturally aspirating, conventional technology engine) consumes only 6.2 lt/100Km.

20% worse consumption for the state-of-the-art engine ?
Your later link to VCA data seems to be for the 135bhp MultiAir engine. So it appears to be approximately 35% more powerful than your Yaris yet uses only 21% more fuel in the cycle you quote.

References to 0-60 times are completely specious since weight, gearing, aerodynamics and other factors come into play.
 

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Discussion Starter #14
Your later link to VCA data seems to be for the 135bhp MultiAir engine. So it appears to be approximately 35% more powerful than your Yaris yet uses only 21% more fuel in the cycle you quote.
References to 0-60 times are completely specious since weight, gearing, aerodynamics and other factors come into play.
Here is the link for the 105 bhp Punto MultiAir

VCAcarfueldata.org.uk - Search Results - Further Information

As you see, the high-tech MultiAir cannot compare to the old technology conventional Yaris.

Manousos
 

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And BTW, isn't the Yaris a 3 cylinder? Not new tech, of course, but not quite on a like-for-like basis?
 

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No.
It is the Yaris with the 1329cc four cylinder engine.

Manousos
I had a 3 cylinder in my head for some reason but I've just checked and you are correct.

The Yaris engine would appear to be better using the parameters you have chosen. The Yaris car is broadly slated for being too expensive and having poor levels of refinement (partly an engine issue??), poor quality ride and a terrible driving position. Ignoring, of course, the overarching fact that it is a Toyota and by definition must be boring! ;):lol:

I'm sure they'll have sorted their widespread quality and brake problems by now if you are considering one, so good luck with it.
 
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Nothing.
On the other hand, think of the same 1.4 MultiAir 170 having 25% less emission and consumption at urban cycle. For such a little modification (correction?).

Manousos
Maybe you should mail FPT to get the answers you are looking for
 

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Interesting thread. I think you would need to put both engines to the same test (not with the whole car, just the engine) and see how they perform to compare them. As far as I see it the emissions aren't just down to the engine, but also the whole cycle of air intake and output i.e. exhaust, whereas the fuel economy depends heavily on the resistance to motion of the car.
There must be a reason why the multiair engine is performing less well, but I'm guessing it's how it's designed to work with the car all round..
 

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Discussion Starter #20
Maybe you should mail FPT to get the answers you are looking for
Try by yourself (for pure curiosity) to get such an answer, either from FPT (Fiat Power-Train) or from Schaeffler-INA (that actually makes the cylinder heads of Fiat MultiAir engines).

I don't know why, but I bet you will take no answer, whatsoever.
I did it, and I know.

Manousos
 
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