This sign had me thinking about cylinder deactivation

[JCleary]

With the 3rd gen and its common rail injection, wouldn't it be relatively easy to deactivate two cylinders to improve fuel economy? All you'd need to do is close the injector and leave the valves closed, right?



By the way, this was at 3rd and Delaware in downtown San Mateo, Ca. Not the only station around here with prices like this. I drove by a Chevron just a couple of days ago with the same prices.



I guess this must be race fuel :-laf

 

[DLeno]

on the bright side, diesel is cheeper than the top gasoline grade!

 

[JL penner]

I got stuck paying 3. 59 a gallon in some Podunk town on the way to Laughlin... ... I'm still steaming.

 

[CLAYTON]

This sign had me thinking about cylinder deactivation



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With the 3rd gen and its common rail injection, wouldn't it be relatively easy to deactivate two cylinders to improve fuel economy? All you'd need to do is close the injector and leave the valves closed, right?



By the way, this was at 3rd and Delaware in downtown San Mateo, Ca. Not the only station around here with prices like this. I drove by a Chevron just a couple of days ago with the same prices.



I guess this must be race fuel

WOW... I can't believe how expensive that is. I won't complain about my 2. 40 a gallon.

 

[SRadke]

Our prices aren't that high... yet... but we are paying more than "super". Rediculous. As for deactivtion, definitly possible but your truck's gunna run a little rough.



-Scott

 

[tkerrigan]

Seems to me that diesels are so efficient, that deactivation is not required. They only run at a speed equal to the amount of fuel injected.

 

[LightmanE300]

Jeez, I just was whining about filling 65 gals of 50 cetane BP Supreme for $2. 32/gal. I guess I should keep my mouth shut!

 

[JCleary]

Seems to me that diesels are so efficient, that deactivation is not required. They only run at a speed equal to the amount of fuel injected.

So if you deactivate two cylinders, you'll just be injecting more fuel in the remaining 4 cylinders to maintain rpm?



How do gas engines operate differently? Don't they only run at a speed equal to the amount of fuel injected as well? Honda has deactivation on their v-6, and DC does it on the Hemi, and they tout extra efficiency.



What would the difference be? I don't know enough about gas engines to know why it works.

 

[RustyJC]

What would the difference be? I don't know enough about gas engines to know why it works.

Gas engines have throttle plates that induce pumping losses. If one deactivates 3 cylinders (one bank) of the Honda V-6, then the remaining 3 cylinders have to effectively double their brake mean effective pressure (BMEP) to produce the same power. This requires higher throttle openings which will reduce pumping losses.



Rusty

 

[tkerrigan]

Gas engines run from throttle position, Diesels from amount of fuel injected. Gas only burns in a narrow air fuel ratio, too lean and it won't burn and gets wasted. Diesel will burn no matter how lean. Too rich, different story.