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Old 01-20-2010, 01:30 PM   #21 (permalink)
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Quote:
Originally Posted by dcb View Post
I think you should try to do it without taking the heads off or it will never get done

so:
1. pop off the oilpan.
2. remove the big end caps on the two cylinders you want to deactivate.
3. pull the sparkplugs on those cylinders
4. take a washer and a long drywall screw and drill it into the piston through the sparkplug hole to "secure" it at the top of its travel.
5. sawzall off the bottom end of those con rods so the crank doesn't hit it (perhaps do this earlier so you don't stress out your drywall screw).
6. remove lifters on those cylinders
7. enjoy 2 cylinder goodness
I was thinking about something like this last night, except cutting the conrod right below the wrist pin, then topping out the piston in the bore and fastening it in there. Alternatively, if I wanted to break the piston, I could take it out the bottom, but the wrist pin would fight me every step of the way.

I don't want to be putting screws and such into things, though, especially when that might introduce metal shavings to the oil.

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Old 01-20-2010, 01:46 PM   #22 (permalink)
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Have you considered re-using the head gasket Or is my neck to red for you! A propane torch and some gental heat will help anneal the metal ring surounding the cylinder and it "may" seal up again, at least only two of the four would have to seal, so your odds just doubled! I've never tried it, but have contemplated it when the funds were low. I have done it with copper head gaskets and it worked every time.
On the issue of counterbalance, consult with an engine shop that does balancing of rotating assemblies to determine how much wieght should be attached to the the crank in the position of the missing cylinders. I'd just use the old con rod and weld an attachent on that would be ok to float, ie. cylindrical.
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Old 01-20-2010, 01:51 PM   #23 (permalink)
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I've never had good luck trying to reuse head gaskets, especially if they had any kind of miles on them. First of all, you'd have to get it off cleanly to reuse it, which probably ain't gonna happen with over 100,000 on the engine.

I had considered using a sheet of copper to make a gasket from the old template, though I'm not sure about the combustion rings (would copper hold up, or require plating?)

Remember, it still has to seal oil returns and water jackets that are around the dead cylinders.
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Old 01-29-2010, 10:56 PM   #24 (permalink)
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The SOHC Geo Storm fuel injectors run 12.7 ohms resistance, so I'd imagine that if you put some 12.7 ohm resistors in the wiring harness on the dead cylinders you could trick the ECM into thinking that all 4 injectors are working.

Copper gaskets should hold up fine a while back there was a guy who made a few for these cars and he's been running one for a couple of years without any trouble.
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Old 01-29-2010, 11:01 PM   #25 (permalink)
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I'll try those resistors.

I use copper gaskets on race engines, but I have no need to pull the head in this case. I don't intend for this engine to ever be reused, so I'm going to draw the pistons down, cut the rods, then shove 'em back up in there and see about fastening them in place.
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Old 01-29-2010, 11:16 PM   #26 (permalink)
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Not having to pull the head will be nice, It's never a fun job. I think and hope this plan will work because the Storm gets decent mileage as is, and with two less cylinders I would be interested to hear the results.
The one hurdle that may be hard to overcome is the MAP sensor because, and my physics are a little rusty here; the manifold pressure may be out of the sensors operating range bringing you back to limp mode. I'm not sure if this would actually occur, but it was just my first thought.
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Old 01-29-2010, 11:18 PM   #27 (permalink)
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If that occurs, and it really shouldn't, as far as I can tell, I'll have to pull the intake and plug the two empty runners with expanding foam or something to make up the volume difference. Since the MAP is only detecting vacuum, it should still be in range, though.
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Old 01-29-2010, 11:20 PM   #28 (permalink)
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Claimed fe benefit for current deac is up to 20%. Since this would cut down internal friction and whatnot my WAG places potential improvements at 10 to 25%??? 30? It'll be something but it won't be like WOW my fe doubled.
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Old 01-29-2010, 11:23 PM   #29 (permalink)
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Claimed fe benefit for current deac is up to 20%. Since this would cut down internal friction and whatnot my WAG places potential improvements at 10 to 25%??? 30? It'll be something but it won't be like WOW my fe doubled.
This, and the "no 100%" throttle mod that will accompany it, I'm hoping will yield about 20%. 25% is probably pushing it.

The throttle mod is going to have to be there, though, because we both know I'll be putting the go-pedal through the floor the way this thing is going to run.

If it runs, but doesn't quite make enough power to hold 45 through my paths, I'll see about putting a small turbo on it or finding another way to increase the power output slightly. Or, I'll eventually scrap the idea and put a diff engine in it. It needs body work, so I don't mind playing with it for now.
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Old 01-29-2010, 11:29 PM   #30 (permalink)
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I don't really think it will happen either, just a thought , but if it does than plugging the runners would certainly do the trick.

Even a 10% increase would be pretty nice for a pretty cheap although labor intensive process; especially on a car that already gets pretty good mileage and you get to keep one more car out of a junkyard.

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