Cylinder deactivation discussion

[Frank Lee]

There has been more than a couple of those projects. Moser made Cadillacs for sale IIRC.

[diesel_john]

Originally Posted by Frank Lee

John: I've disabled 1 & 4, and 2 & 3, and there was no noticeable difference in "rocking couple" vibes.

cool

[MetroMPG]

Here's an excerpt from a really interesting message I had from an older XFi owner. I invited him to participate, of course, but in case he doesn't show up, I don't think I'm breaching any privacy issues by omitting his name from this quote:

Many years ago, I experimented with a Model A Ford by removing two pistons and making sure that the valves on those cylinders would stay closed and not touched by the lifters. Gas mileage increased to 42 mpg, and the only big disadvantage was reduced speed on long uphill stretches of highway and slower acceleration.

[diesel_john]

Frank Lee,
I just realized that the two injection pulses that I was going throw away are EXACTLY equal to amount of fuel that i would be burning. So if i put these two together and measure the volume, i will finally get around using two flow meters to measure total and subtract the spill volume. HOT DOG!

[aerohead]

John,I think your question requires context.If you are willing to settle for slower acceleration,reduced load-carrying capacity,greater engine and powertrain wear,etc.,then the smaller displacement,lower-power engine may be acceptable.The Eaton valve dis-enablers used on prior Diesels(don't know what Dodge is using today) did allow for full power on demand,and then for economy,during light load conditions.They were plagued with reliability issues and subsequently dropped from GM.Today,I think Chrysler claims only modest fuel gains for their technology.Only a life-cycle-cost analysis and crystal ball will determine the viability of the technology.

[wumpus]

how many hours are you willing to spend to avoid buying a cheap(?) used smaller engine and replacing it with your larger engine (it doesn't sound like anyone has proposed a 1.0l 2-cylinder ecotec). Last I heard, swapping GM-to-GM engines was pretty easy (maybe not not-really-GMs like the metro, but bear with me), and would be a better place to start (many examples on this thread mentioned GM products).

From the sound of it, chevys use of extremely tall gears with big V8s seem to work a lot better than cylinder deactivation. Maybe trying to use a "nerd gear" (term from a request for special green models on this site) combined with a low rpm cam.

[diesel_john]

aerohead,
let me put this project into context.
i am bored with 5% here and 5% there.
iam more interested in the outside limits. i have extra engines some of which have dead cylinders. So i am starting with a 1.6L diesel, 52 hp, 71Lb-ft. I am taking out #2 & #3 pistons and cam followers. Cutting off the big ends of the rods, taking out the clearance and clamping them soild on the crank. Then measuring the unused injection pulses from 2 and 3 for mpg info. see post#34
My limit of acceptable performance presently is 60 Lbs per Lb-ft of torque.
I arrived at that number like this 80,000 Lbs./1300 Lb-ft = 61 Lbs per Lb-ft
My car is 2100Lbs/60Lbs/Lb-ft= 35 Lb-ft of torque minimum.
The 0.8L diesel will have approx. 35 Lb-ft I am taking almost half the friction out of the engine. And I now have an aircleaner, exhaust, water pump, oil pump and radiator designed for 52Hp but i am only putting 26Hp through it. So i can run full rack for hours if i want to, without overheating.

[roflwaffle]

Just don't climb hills, unless you don't mind going up at 15mph in first.

[diesel_john]

on second thought i'll redo that calculation with ft-lbs of torque instead of hp.

whoops, looks like 0.8 Liters is as low as i can go, without losing weight.

i'll be able to run with a loaded truck. hopefully without turning up the fuel on the two remaining cylinders.

[roflwaffle]

I don't think so, those trucks have way more gear ratios than you do. If by trucks you mean semis that is...