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http://www.drive.com.au/Editorial/ArticleDetail.aspx?ArticleID=37286

posted by  Wally

so how would that work? do they stage the firings and lower the revs, or run at effectively twice the combustions of a commy?

posted by  windsonian

It seems interesting, but I doubt it will sell well.

posted by  chris_knows

bump for wally's purposes :mrgreen:

posted by  windsonian

:mrgreen: You wanker

posted by  Wally

hhmmmmm .... while my initial question was serious, it seems my impatient pestering wasn't the best plan .... oh well... too late now ... may as well keep pestering .... I'm already a wanker regardless :smoke:

posted by  windsonian

Well you are Australian so it comes with the territory.:wink2:

I guess you are asking if they would continue to fire at 120° or 60° ?

posted by  Wally

now you're onto it. for example, would the firing order be (complete guesses as i don't know the order and couldn't be bothered looking it up):
1,7,5,11,3,9,4,10,2,8,6,12 at even intervals (where 1-6 is the 1st motor, and 7-12 is the second)
or would it be
1&7, 5&11, 3&9, 4&10, 2&8, 6&12

I assume that the arrangement used would determine the gearing used and therefore the operating rpm??

posted by  windsonian

Well even with a 60° banked V6 there is still some vibration issues. Given the cadillac is a luxury vehcle I would assume they would want a tighter firing interval to provide a smooth running (less torsional vibration :- a six has about a 250% instantaneous peak to mean torque compared to 140% for a twelve), so therefore a 60° even fire. The actual firing order would depend on the best crank for the job.

posted by  Wally

Hi Wally,

I would be interested in what you think about GM's Active Fuel Management system. I believe it uses hydraulics to shut down the valves and close off 4 cylinders.

Is that correct?

Do they really close off 4 cylinders on the six?

What prevents unburnt fuel from entering the exhaust?

Do you think there would be a component wear issue?

It doesn't appear to save that much fuel.

Thanks.

posted by  jcutsh

I'm a little miffed that my LS2 doesn't have displacement on demand... just so I could say I have it.:laughing: The Alloytec Six motor is designed for DoD, VVT and port deactivation.


I haven't bothered too much looking at the inticacies, but I understand it uses the LOMA system, with switching lifters i.e. hydraulic actuators.

posted by  Wally

As they get some miles under their belt, it will be interesting to see if those unloaded pistons slapping around in those cylinders cause uneven wear problems.

posted by  jcutsh

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