12-09-2013, 12:55 PM
(12-09-2013, 09:05 AM)Ruan Wrote:(11-09-2013, 08:30 PM)Dum-Dum Wrote: On the intake flow subject Im pretty sure that the 2.2 is a pair of 30mm valves and the 8v is a 36mm both with 6mm stems so the 2.2 16v will flow more at the valves (if a very quick mental estimate is right)
Think for a second WHY Peugeot went for the 16v head... To use TWO sets of valves to be able to have higher gas velocity all the time to give a stronger swirl (that's also why they had swirl flaps - so they can cut off a valve per cylinder at lower RPMs for stronger swirl) - it's PURELY down to emissions..
Exact same reason the 2.1 12v has an extra 2 inlet valves - two pipes with a smaller bore will result in the same amount of airflow, but higher velocity in them... But also causes more restriction - since the swirl effect uses energy to be generated...
I understand that the swirl takes a certain amount of energy as does having more smaller ports because of the percentage of the air thats (simple terms) dragging along the wall of the port. That said running a turbo charger saps engine power to the tune of about 5% and running a supercharger takes about 20%. Hell a 306 gearbox saps nearly 25% of the engines power before putting it to the road but nobody does anything to solve that do they.
Anyway back to inlet swirl, a bit of engery to get the air in means a better burn so more energy out of the fuel so more power. Think ill take that trade off especially as 75% of my driving these days is smashing up and down the A41 not ragging the tits off the car.
I know that the actual "gains" of the 2.2 ore negligible but I'm not looking for a mega high horsepower revvy screamer. Id much rather a stupidly torquey driveline destroyer and the 2.2 IS the better engine for that.
I suppose the cold honest truth is if anyone was really desperate for a big power diesel 306 they'd drop in a VAG engine. Most of us are just messing because we can doing mods that are easy enough.