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Old 05-18-2008, 04:11 PM   #11
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Originally Posted by needmorempg View Post
If I'm unhooking two cylinders in the end why #2 and #3? These cylinders are not 180 degrees apart are they? I would think to even have a shot at success it would have to be 1 and 3 or 2 and 4 or vibrations would be much worse.
If I remember right, the firing order is 1-3-4-2, so you're going to want to disable either 1 and 4 or 2 and 3.

My question was, by disabling 2 cylinders, how will that improve your FE? As far as I can see, you aren't really reducing weight, pumping losses, friction losses, thermal losses, etc. Maybe there is something I'm missing?

Would still be fun to try! Nothing wrong with a glorious explosion.

If you have some serious spare time, you could attempt to cut out those 2 cylinders, and then weld the crank, block, cam, head, manifolds back together. =)
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Old 05-18-2008, 04:29 PM   #12
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If I remember right, the firing order is 1-3-4-2, so you're going to want to disable either 1 and 4 or 2 and 3.

My question was, by disabling 2 cylinders, how will that improve your FE? As far as I can see, you aren't really reducing weight, pumping losses, friction losses, thermal losses, etc. Maybe there is something I'm missing?

Would still be fun to try! Nothing wrong with a glorious explosion.

If you have some serious spare time, you could attempt to cut out those 2 cylinders, and then weld the crank, block, cam, head, manifolds back together. =)
You are correct about the firing order and which cylinders to disconnect. I just verified it in my service manual. I know I'm not reducing weight and am decreasing hp. There will be a little less work done by the motor as it does not have to open and close the valves and yet I realize the frictional loses of the non productive cylinders. The test is to see if the fuel is cut to one less cylinder would the power loss be enough to negate any mpg increases? Where is the main difference between what I am doing and some production vehicles are made to do automatically? I know they close the valves too. Again, I'm doing this for the fun of it. It's not a ton of work and in the end the motor is going to be swapped out anyway.
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Old 05-18-2008, 05:08 PM   #13
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Originally Posted by needmorempg View Post
I thought about that too. If there was a way to remove the piston without pulling the head I would love to try it. One would have to cut the connecting rod short to the crank and leave it installed to maintain oil pressure.
Cut both ends of the connecting rod and shove the piston up to the head.

I didn't realize that the connecting rod is required to maintain oil pressure, but wouldn't it need to remain pointing up? If you cut it short, isn't it going to spin around freely?

I haven't been inside a crankcase since I did a 5hp Kawasaki in high school so it's hard to remember some of this stuff...
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Old 05-18-2008, 05:17 PM   #14
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Cut both ends of the connecting rod and shove the piston up to the head.

I didn't realize that the connecting rod is required to maintain oil pressure, but wouldn't it need to remain pointing up? If you cut it short, isn't it going to spin around freely?

I haven't been inside a crankcase since I did a 5hp Kawasaki in high school so it's hard to remember some of this stuff...
Yes, it can spin freely but this shouldn't be an issue if its cut really short (it won;t hit th pan/block if its cut really short. Be sure to use a punch or something to knurl up some metal in the cylinder bore so the piston doesn't side back down out of the cylinder and fall onto the rotating crankshaft.
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Old 05-18-2008, 05:38 PM   #15
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Yes, it can spin freely but this shouldn't be an issue if its cut really short (it won;t hit th pan/block if its cut really short. Be sure to use a punch or something to knurl up some metal in the cylinder bore so the piston doesn't side back down out of the cylinder and fall onto the rotating crankshaft.
You guys are on the same track I was. This would take more time and I would not want to try it unless I could get some mechanism in the cylinder to lock the piston in place and I don't know there is room from the bottom side to do it. This motor would be shakin like crazy to that piston would drop pretty easy. If there was time after all the other testing was done maybe I would try it.
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Old 05-18-2008, 06:17 PM   #16
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Remove the rockers to the pistons you want to disable and pull the plug., disconnect the injectors of course.

No valve activity will eliminate and intake or exhaust. The only pumping losses you would still have would not be related to air moving in or out of the engine. There would be a slight restriction to airflow through the plug holes, so you could open the holes up some. if you added a tube between the two dead cylinder plug holes it would keep the noise down.

I had a 59 Austin Healey Sprite (bugeye) that had two burnt valves (think they were exhaust). Compression was less than 35 psi per cylinder with about 1/5th of the valve head gone.

It ran but it didn't have enough power to climb any kind of significant grade.
My brother managed to blow the tranny before I figured out whether the mileage was better that the normal 32 mpg. This was in 1968 but I do remember I could get it up to a decent speed. 1 liter engine in about 1200 pounds of car, normally it would do about 82 MPH max.

regards
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Old 05-18-2008, 06:51 PM   #17
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Here you go.

http://www.gassavers.org/showthread.php?t=6137

I should have held the cam followers up with hose clamps so they did not contact the cam. Maybe next time. The V8 on 4 cylinders was a lot more practical.

As for leaving rods off of an engine you can do that and cover the hole in the crank with a hose clamp. In this case you would want to make an odd fire engine for best balance. That is leave off 1 & 2 or 3 & 4. I am not recommending this just saying that is the way I would do it.

By all means have some fun if you want to.

No pain no glory.
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Old 05-18-2008, 07:42 PM   #18
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he if its anything like my s-10 when 2 of the cylinders were misfiring a few times last winter, you will NOT want to try to pull out on a busy road... i suggest taking it around your neighborhood and gunning it to see how much power you have left, i could barely get going and had to pull over and rev it to evaporate moisture that condensate on the ign module...
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Old 05-19-2008, 10:19 AM   #19
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Remove the rockers to the pistons you want to disable and pull the plug., disconnect the injectors of course.

No valve activity will eliminate and intake or exhaust. The only pumping losses you would still have would not be related to air moving in or out of the engine. There would be a slight restriction to airflow through the plug holes, so you could open the holes up some. if you added a tube between the two dead cylinder plug holes it would keep the noise down.

I had a 59 Austin Healey Sprite (bugeye) that had two burnt valves (think they were exhaust). Compression was less than 35 psi per cylinder with about 1/5th of the valve head gone.

It ran but it didn't have enough power to climb any kind of significant grade.
My brother managed to blow the tranny before I figured out whether the mileage was better that the normal 32 mpg. This was in 1968 but I do remember I could get it up to a decent speed. 1 liter engine in about 1200 pounds of car, normally it would do about 82 MPH max.

regards
gary
I'm thinking that the dead cylinders need to be opposing to minimize out of balance issues. That means both would be coming to TDC at the same time, one normally on the exhaust stroke and one normally on the intake therefore I could not connect a hose between the two cylinders as they will both compress at the same time. I don't think there would be very much restriction from the spark plug holes. I live in a rural area and will just put up with the noise for the test.
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Old 05-19-2008, 10:25 AM   #20
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In this case you would want to make an odd fire engine for best balance. That is leave off 1 & 2 or 3 & 4. I am not recommending this just saying that is the way I would do it.

By all means have some fun if you want to.

No pain no glory.
Could you explain how odd fire would make balancing better? Every two full revolutions of the crank will normally fire all four cylinders so I would think if you were to remove two it would need to be every other one to give it the smoothest possible outcome.
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