Disabled 4 cylinders on a TBI motor :) MPG Gain???

[jpoole]

I disabled every other cylinder in the firing order on my TBI 350 by pulling the rocker arms and pushrods on those cylinders, removed the throttle plate and plugged up the hole that feeds those with a rubber expansion plug, disconnected the injector and plugged in a dummy injector so the computer "thinks" it's still there. Power is down(no surprise there!) but is very driveable. I'm very curious what kinda gas mileage I can knock down on my "4 Cylinder" Suburban

100 miles so far and still no check engine light!

 

[foamypirate]

I disabled every other cylinder in the firing order on my TBI 350 by pulling the rocker arms and pushrods on those cylinders, removed the throttle plate and plugged up the hole that feeds those with a rubber expansion plug, disconnected the injector and plugged in a dummy injector so the computer "thinks" it's still there. Power is down(no surprise there!) but is very driveable. I'm very curious what kinda gas mileage I can knock down on my "4 Cylinder" Suburban

100 miles so far and still no check engine light!

Hmm, this could be interesting. I would think you would get better on the highway if geared right, but city might suffer due to accelerating such a heavy vehicle with only 4 cylinders (i.e. high load on those cylinders burning more fuel).

 

[jpoole]

Hmm, this could be interesting. I would think you would get better on the highway if geared right, but city might suffer due to accelerating such a heavy vehicle with only 4 cylinders (i.e. high load on those cylinders burning more fuel).

I think just as you but up past 60mph or so it starts requiring a lot more throttle so I'm sure highway wouldn't be much better than city if driven really fast. My commute is a mix and I'm content to keep it under 65. It will pull itself along in top gear converter locked @ 65. I believe it has a 3.42:1 gear.

 

[HotRodPC]

Ahhhh Helll Naww Dawg !!! We're not letting this get lost and blended in on the What Have I done to my square lately. Way to cool of an idea, and needs to be discussed at length and results posted.

So you're doing it in a heavy ass Burb? And 3.42 gears. I'd like to see someone else do it in a light truck, like maybe a half ton. Next would be to see how it performs with a little more gear. Someone with some 4.10's and a 700r4, this might be a real cool deal. Putt around town on 4. Need to tow the boat, go back to all 8.

So how long does it take to make this mod?

BTW, Rep Points and Commnet added. Thread Rated 5 stars.

 

[Jims86]

you can unplug the injector...the ecm wont notice.

 

[jpoole]

Ahhhh Helll Naww Dawg !!! Where not letting this get lost and blended in on the What Have I done to my square lately. Way to cool of an idea, and needs to be discussed at length and results posted.

So you're doing it in a heavy ass Burb? And 3.42 gears. I'd like to see someone else do it in a light truck, like maybe a half ton. Next would be to see how it performs with a little more gear. Someone with some 4.10's and a 700r4, this might be a real cool deal. Putt around town on 4. Need to tow the boat, go back to all 8.

So how long does it take to make this mod?

BTW, Rep Points and Commnet added. Thread Rated 5 stars.

"Heavy ass burb" is what I got! It takes longer to get the valve covers off than anything else. The cost was about $5 for the rubber expansion plug. I already had an extra injector. The check engine light wasn't the only concern about running it unplugged. I thought it needed the right electrical load for the injector driver but whatever. Of course without fuel through the dummy injector maybe it will run hot(the dummy injector) and crap out anyway? We wil see. It runs good, I can tell the gas mileage will be better already, and parts are cheap
One caveat with Doing this and it is a big one is that I currently do not have anything to keep my lifters from coming out of their bores On the disabled cylinders. I am relying on 200,000 miles of varnish to keep them put. If you were to have a lifter exit its bore, you would then lose all your oil pressure

 

[jpoole]

I actually thought about fabricating some retainers to keep the lifters put but I ran it without the covers and noticed they didn't come out. If its a squeaky clean motor you might not be so lucky.

 

[jpoole]

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[jpoole]

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[Shawn]

Anyone tried this with a carbed engine? This would let me drive my truck around for a while. Gotta wait to put in another engine at this point because of a bad intake on #2.

 

[bucket]

You sir are either a pioneer or a nut job. I guess we will know soon enough though if it works or not

 

[jpoole]

Anyone tried this with a carbed engine? This would let me drive my truck around for a while. Gotta wait to put in another engine at this point because of a bad intake on #2.

There is no reason it wouldn't work on a carbed motor but the disabled cylinders need to have their valves closed. If you have one cylinder with an intake valve that won't close/seal, it's gonna shake and do some weird stuff! Not to mention it will eventually backfire in the disabled intake tract. the disabled half of the intake, even in the carbureted ones, is still connected by small passages in the base of the carburetor and possibly the intake so your cylinder with a non sealing intake valve will allow flow in and out of that cylinder from the side in use and if your ignition system is still intact it will eventually light off. That in and out from one side to the other will also jack with the "signal" the venturis need to work right on the side in service.

 

[jpoole]

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Low, slow, and NOT for show!

 

[bigcountryguy19]

Better take the spark plugs out, with no valves opening the suction and compression from those pistons has to go somewhere.

 

[HotRodPC]

You sir are either a pioneer or a nut job. I guess we will know soon enough though if it works or not

I see no reason it wouldn't work. What's different about this than DOD (displacement on the demand)? Other than it's done manually rather than electronically. I hear of it being done on diesels many times. Not killing half the cylinders, but when they have a failure on a cylinder, they manually eliminate it and drive across country that way.