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

[jpoole]

I've always wanted to run a Buick 231 Even Fire 3.8 in one of these trucks with a manual trans and see how it would do on mpg. Kinda got the wind taken out of my sails, and I shouldn't have let that happen when I was told it would work to hard and get crappy mpg. But, I had to many projects anyway so I sold the 231.

Hey chevy did produce a 3.8 before the 4.3 that has the sbc bolt pattern. That would be an interesting swap. I've only seen a couple of them. I think they were put in late 70s or early 80s malibus and such.

 

[Christian Nelson]

Well, 4.3 then, lets not make things more comlicated than needed.

As for it not having enough power, didn't some of these trucks come with a straight six 250CI engine in them from the factory?

 

[jpoole]

Well, 4.3 then, lets not make things more comlicated than needed.

As for it not having enough power, didn't some of these trucks come with a straight six 250CI engine in them from the factory?

Yup, in fact I almost scored a complete 1955 235 inline 6(pressurized rod journals) for cheap but I erroneously assumed it would bolt right up to my auto but that is not the case with those early sixes but a 250 would have been great.

 

[Jims86]

Well, 4.3 then, lets not make things more comlicated than needed.

As for it not having enough power, didn't some of these trucks come with a straight six 250CI engine in them from the factory?

My burb had less hp and Tq in 86 than a 4.3 had 2 years ago, and it moved just fine.
155 hp and 280 ft lbs is what it had i think.
Even with more powerful engines in the smaller category, gearing is still key.

 

[HotRodPC]

I think Hotrod was spot on when he suggested some 4.10 gears for the 4 cylinder. I would do it but I'm cheap. I actually thought about swapping a tbi 4.3 in cause it would be an easy bolt in swap but I never found one on the cheap. I don't believe the 3.4 60deg has the traditional sbc bellhousing bolt pattern so a trans swap would prob be needed also.

Yeah, my thinking was 4.10 gears since you won't have the torque to get it rolling, so with 4.10's you'll get a torque boost to get rolling and some help holding your highway speed. With a 700r4 or A manual with OD better yet, so you have an OD to compensate for the low gear, even though you might not be able to take advantage of OD very often, but a 700r4 should hold up to a 4 cyl with 4.10's if built right.

You're right, the 60 degree V6s, 2.8,3.1, and 3.4 have a bell pattern of their own. Maybe even the same as like the old 4 cylinder Vega motors. The Buick 231 3.8 is a Buick, Pontiac, Olds bolt pattern, and the Chevy 3.8 that many aren't aware even exists is a Chevy bell pattern. IIRC, like the 4.3 being a 350 with 2 cylinders cut off the back, the Chevy 3.8 is a 305 with 2 cylinders cut off the back.

 

[HotRodPC]

Yup, in fact I almost scored a complete 1955 235 inline 6(pressurized rod journals) for cheap but I erroneously assumed it would bolt right up to my auto but that is not the case with those early sixes but a 250 would have been great.

EIther the OLDER 250 wo the integral head would be a good one, OR even better the 230 which superceded the 235. Those 230's can't be killed. Probably the best combo would be the 250 with a 230 head on it. By the time the 250's came about, I think that's when compression started falling and EGR bumps started getting put in heads. The 230 head will have a bit smaller combustion chamber for about a .5-1 higher compression ratio, and breath much better with less restriction in the runners.

 

[davbell22602]

 

[jpoole]

cold start

So I just made a cold start video of the burb but unfortunately the fan noise is overwhelming. I can do videos of driving it also as time permits.http://www.youtube.com/watch?v=Rnm1EC4zsXg

Sorry about the wrinkled shirt, country accent, etc lol!!

 

[Jims86]

So I just made a cold start video of the burb but unfortunately the fan noise is overwhelming. I can do videos of driving it also as time permits.http://www.youtube.com/watch?v=Rnm1EC4zsXg

Sorry about the wrinkled shirt, country accent, etc lol!!

She fired right up...very smooth. now for a driving video!

 

[HotRodPC]

So I just made a cold start video of the burb but unfortunately the fan noise is overwhelming. I can do videos of driving it also as time permits.http://www.youtube.com/watch?v=Rnm1EC4zsXg

Sorry about the wrinkled shirt, country accent, etc lol!!

No need to apologize for being a redneck on this forum. I think the rednecks outnumber the Yuppies and who cares about the yuppies???

That's sounds damn good to me for a limp along motor. I'm ready to see some mpg results. I'm getting a real wild hair to do this with the 454. Sure I expect to lose some power, but I still think it'll have enough to get by. If I could get from 13mpg hwy to say 17 or 18mpg, I'd be tickled shitless.

Just so no one is getting their expectations set up to high, I just want to warn, doing this, you're not going to get the mpg like you would if it were a 4cyl. Reason being, you've still got the weight of the V8. You've still got the weight of the rods, pistons and lifters on the rotating assembly that motor has to carry around and put strain on the motor. So those dead 4 cylinders are not only a power loss for not working, they are also an additional negative carrying dead weight. Also need to consider, you'll still have the friction of the 4 dead cylinders too.

 

[crazy4offroad]

Very interesting, I'm waiting for mpg results as well. Might be ok for the long straight flat roads of Texas but I think it would get someone killed going up/down the hills around here!

 

[bucket]

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.

Didn't mean to say it wouldn't work. It just sounds crazy as all get out, lol.

Very interesting, I'm waiting for mpg results as well. Might be ok for the long straight flat roads of Texas but I think it would get someone killed going up/down the hills around here!

Yeah, a loaded down 350 Burb is bad enough pulling a steep grade, can't imagine losing half the cylinders.

 

[woodsrider250]

You should plumb the 4 dead slugs to an air accumulating tank w/ a 100psi plow-off valve on it. Years ago I had this idea for using a VW diesel as a generator/air compressor combo. The kits were out for the generator part, and were capable of 15+kW. I didn't need that much power especially if I didn't have to power an air compressor at the race track so came up with the idea of halving the power output, and turning 2 dead cylinders into air compressors. Never did even get the project started, but know some who have done similar things....esp w/ air-cooled VW gassers.

 

[jpoole]

You should plumb the 4 dead slugs to an air accumulating tank w/ a 100psi plow-off valve on it. Years ago I had this idea for using a VW diesel as a generator/air compressor combo. The kits were out for the generator part, and were capable of 15+kW. I didn't need that much power especially if I didn't have to power an air compressor at the race track so came up with the idea of halving the power output, and turning 2 dead cylinders into air compressors. Never did even get the project started, but know some who have done similar things....esp w/ air-cooled VW gassers.

The problem with that is that there is no valving to allow anything to compress in the tank or a place to draw air from. You would need at least two check valves for each dead cylinder with the one allowing air in to be open to the atmosphere. And the other allowing discharge to the tank. Not to mention the extra load.

 

[jpoole]

mpg

I couldn't wait for a whole tank so I fueled up at 163.5 miles and got 16.8mpg. It's not that great but is in an improvement over the 13-14 I usually get. There has only been one driveability issue that I've had a couple of times. When idling with the a/c on and max blower in gear the idle has dropped so low that it died. I can deal with that. The funny thing is that I had an '87 burb years ago with the same engine/trans/gearing and it would regularly hit 17 on all 8.