What do you mean by 'shorter runners'?
I guess the exhaust system isn't going to fit either really...
-=this=- reckons there is variable valve timing, which might explain all that power
:D:D
I reckon with throttle bodies and that head we might get our 200bhp NA
So... where do you reckon we can get the heads from? Looks like they may actually bolt straight on - assuming the bore is right (which it looks like it is, from the article below!!).
Main technical features
To start with, the Twin Phaser system adopts new cam lobes which allow the phase angle to be varied by 50° on both axes; this makes it possible to improve performance on one hand because the best phase can be chosen at all engine speeds, and to reduce consumption and emissions with partial loads, by the so-called Miller cycle. This combustion system, which is based on the postponed opening and closing of the inlet and exhaust valves - extends the expansive phase (converting more heat into energy), guarantees internal EGR (by preventing the release of the last exhaust gases, full of unburned particles) and postpones the closure of the inlet valve (reducing pumping losses).
Another peculiar feature of the 2.2 and 1.9 JTS engines that equip the Alfa 159 is the camshaft drive system which uses a chain; unlike a conventional belt drive, this system has the advantage of not needing to be replaced during the lifespan of the engine.
And to guarantee the performance one expects of an Alfa Romeo, the timing diaphragm has also been reviewed, adopting larger profiles which made it possible to achieve a maximum power output of 6500 rpm (the system is fine tuned to operate at over 7,000 rpm, the maximum rev speed allowed by the electronic speed limiter).
That is not all. To achieve the best volumetric efficiency, the maximum lift reaches 10.3 mm, while to enhance vibrational and acoustic comfort, the engine is equipped with two counter-rotating balancer shafts which virtually eliminate the second degree alternate forces that are typical of straight-4 engines. The generous power delivery of the engine (80 bhp/l on the 2.2 JTS) made it necessary to adopt sodium-cooled exhaust valves.
The combustion chamber is shaped like a roof with four valves per cylinder: with a bore of 86 mm, the large inlet valves measure 35.3 mm and the exhaust valves 30.3 mm, guaranteeing excellent permeability to enhance engine performance. And, in spite of the stroke of 94.6 mm, in order to limit the overall height of the engine, the engineers have modified the piston height, achieving a compression value of just 28 mm, which is excellent in view of the high power delivery. Where the exhaust, injection and ignition systems are concerned, the two 4-cylinder JTS engines both adopt the strategies and features illustrated for the new 3.2 V6 engine.
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