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Eric, I was talking to a guy the other day that works as a technician at a local dealership and he stated that he knows of someone who has installed a switch that would cut out two cylinders thereby increasing fuel mileage up into the mid-30s range. Just wondering if you had come across anything like this before. I am trying to get more info on the exact wiring and which two cylinders were cut, so I will let you know as I get more info.
 

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that guy isnt working on my truck!!!!


If you kill the cyls, you have to cut power to them, that would trip a ses light, set injector driver codes which could shut down 4 of the injectors instead of just two... plus the misfire codes. plus the ........Not worth any gains....


Eric
 

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There wouldn't be much for gains anways. If you cut off 2 cyls out of 8 you could theoretically see a 25% increase as 2 cyls is 25% of 8. So theoretically you are saving 25% fuel usage. 25% of 20mpg is 5 mpg. So theoretically you would get 25mpg not 30. Now this isn't taking into account that the remailing 6 cylinders are going to require more fuel to make up for the lost 2. I wouldn't be at all surprised if the fuel milage would DECREASE. Not to mention all the other problems that Eric brought up. I am sure the lack of lubrication from the fuel in the 2 cylinders has to be an issue too.
 

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I worked for one of the OEMs investigating fuel economy, and one of the projects was VDE (variable displacement engine), and with a crude program, you could get 10-15% gain. With a customer tolerant program, the gain was more like 2-8%. Note some things though: this was alternating cylinders which were shut off, and had extensive hardware & programming to accomplish/monitor it. There's no possible way to get 30-40% as that guy states. Think about it, you'd still have 6 cyls firing, and still have ALL the running losses. He's had one too many wacky tobackys.


I agree with Eric - I wouldn't let that guy touch my vehicle either.
 

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displacement-on-demand (DOD) engines will be 5.3-liter V-8s in the midsize 2005 Chevrolet TrailBlazer and GMC Envoy XL and Envoy XUV sport-utility vehicles.

DOD increases mileage by at least 8 percent by using only half the engine's cylinders in most driving conditions, GM said. The car starts using all 6 or 8 cylinders. Once up to cruising speed, electronic sensors shut down intake and exhaust valves on half the cylinders to conserve fuel without any loss in vehicle performance. When more power is needed, such as to pass, climb a hill, or tow, the valves automatically reopen and all cylinders function again.

story
 

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Yeah, what Hoot said. Keep in mind, that to keep it somewhat transparent to the customer, the logic is usually on the conservative side, thereby reducing the possible gains. The biggest gains come from highway driving, also the least noticeable by the customer. So your everyday around town driving won't see a dramatic improvement...
 

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Remember how much of a success the Caddy 8-6-4 was? That's why it's still around isn't it?


On edit,


there are no 100 mpg carburators either
Edited by: a64pilot
 

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a64pilot said:
there are no 100 mpg carburators either




Yeah there are! My neighbor's uncle's son in law's cousin had one that GM accidently sent him by mistake! It got 100 miles to the gallon and GM BOUGHT it back from him for $100,000. He couldn't refuse!!




LOL how many times have I heard that one over the years!
 
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