Lean Burn -vs- Cylinder Drop

[ChazInMT]

Originally Posted by AlienBlood

we cut cylinder activation by removing fuel pulse, so if we're removing 2 cylinders out of 6, we gain 33% economy (excluding the pumping loss of compressing the cut cylinders) right off the bat, plus the lower pumping loss of the "more open" throttle body.

I never thought of it this way to tell you the truth. If I had, I'd have thought to myself...why stop at 2 cylinders, lets cut out 2 more and just run on the last 2 and get 3 times the mileage because if we only use 1/3 of the fuel, that means we go 3 times farther than before, so yer right, you'll get about 75-80 MPG by deactivating more cylinders.

Seriously dude...it takes a certain amount of power to go a certain speed, if you reduce the number of cylinders, you now must make more power with the remaining cylinders to keep moving, this means more fuel is dumped into the remaining cylinders than before, so fuel consumption remains about the same.

I'm now guessing that my pumping losses statement must have blown through your head at the speed of sound. I suggest you do research on pumping losses, and truly understand their impact. Be able to discuss it intelligently, then come back and make further comments, till then we're all gonna need sunglasses while viewing this thread.

[AlienBlood]

Originally Posted by AlienBlood

......... we gain 33% economy (excluding the pumping loss of compressing the cut cylinders) right off the bat

wow, guys... really? Don't be dicks. I'll read more about pumping losses when you learn to... well... read the WHOLE statement.

1) You have identical pumping losses due to compression in EITHER scenario, assuming the valves are operated via camshaft only (i.e. no hydraulic/pneumatic/electric actuators).

2) You have to give more throttle input in EITHER scenario due to less power development, which slightly increases fuel flow to the active cylinders, but reduces pumping loss across the throttle body. (And for the sake of clarity to the people who are just learning reading comprehension, in a lean burn setup, it is still less than running stoichiometric.)

To the Lean Burn guys, I'm leaning that direction (no pun intended) already, but considering both routes because of the damage that a lean-burning engine can potentially (theoretically) do to a catalytic converter if spark is not re-tuned to compensate.

[Frank Lee]

Do it, test it, report the results to us please.

[t vago]

Originally Posted by AlienBlood

wow, guys... really? Don't be dicks.

Let me Google that for you!

Originally Posted by AlienBlood

(And for the sake of clarity to the people who are just learning reading comprehension, in a lean burn setup, it is still less than running stoichiometric.)

Let me Google that for you!

[AlienBlood]

Originally Posted by t vago

lmgtfy . com, etc

Hey thanks for the links to threads I've already read. Were you referring to the "what happens if I pull two rods/pistons/valves/spark plugs out of my engine?" (i.e. the "bad idea") threads, or the "VW gets a 16 mpg gain by disabling 2 (out of 4) cylinders via fuel injection"?

TONS of bad ideas and bad information on this site along with tons of good stuff. I suppose for some reason I was hoping to find someone who was at least partially knowledgeable about BOTH systems without this turning into a bunch of fanbois with no real knowledge... and at best, I'd have been happy with someone who'd actually tested both systems on similar cars.

Since it's obvious that no one in this thread has much positive information to share, I shall venture out on my own (and do exactly what Frank Lee suggested and test both). I would say that I'd report back with my findings, but nahhhh... you guys do what you want.

[Frank Lee]

Oh no, now I shall forever wallow in ignorance.

[ChazInMT]

Alien dude. I was just having a little fun with ya. Your statements above still depict a woeful ignorance about how cylinder deactivation and pumping losses work. I and others here are simply trying to not so subtly tell you that, but you seem unwilling to believe anything that you don't guess to be true to begin with.
I can assure you with 100% certainty that cylinder deactivation on an engine not highly engineered to operate that way will yield awful results. The fundamental process that explains why it is doomed is the concept called pumping loss. This is why I say learn about what this is and what its implications are before you try to move ahead.

[2000neon]

Originally Posted by Alienblood

Since it's obvious that no one in this thread has much positive information to share, I shall venture out on my own (and do exactly what Frank Lee suggested and test both). I would say that I'd report back with my findings, but nahhhh... you guys do what you want.

In my post, I addressed your idea, and explained why it wouldn't give you the results that you hoped for. I did not intend to come off as insulting or negative in my post, and if I did, I apologize, that was not the intention. I was simply trying to address your questions and inform you since I was not sure how much previous knowledge you had on the subject. I also run a lean burn equipped car (1994 Civic VX), and have done a ton of reading on cylinder de-activation. There are some even more (incredibly) knowledgeable people on this site. If you would like any input or help, I don't think calling us a bunch of fanboys with no real knowledge is the way to get it.

[t vago]

Originally Posted by ChazInMT

I can assure you with 100% certainty that cylinder deactivation on an engine not highly engineered to operate that way will yield awful results. The fundamental process that explains why it is doomed is the concept called pumping loss. This is why I say learn about what this is and what its implications are before you try to move ahead.

Meh. Alien d00d has already given himself an out - he's never going to post any results of his no-doubt brilliant plan to deactivate several cylinders without also deactivating said cylinders' valves. He can't state how his wonderfully crafted plan will somehow be different than all of the other failed attempts to cut fuel and/or spark from cylinders to achieve the same thing that he wants to do.

Oh, well.

[pete c]

I'm not as smart as some of the folk here when it comes to engine operation, but, I will attempt to 'splain to you (alien) what they are saying.

Every engine has pumping losses which consume energy. In a normally operating engine each piston rewards you by going boom every other stroke to give back more power than they consumed during the other 3/4 of their cycle.

With a proper cylinder deactivization setup, the deactivated cylinders stop being power hungry air pumps. They don't go boom, more like boing, boing, boing (spring sound). This means the still active cylinders have to pick up the slack for the others, but little more. Those cylinders that are no longer pulling the wagon are in it, but, they're rather light. In your scenario, they are in the wagon and they are dragging a foot over the side. So, yeah those cylinders still working are working a hell of a lot harder than before. Not "slightly" harder as you claim.