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Bigger Jugs?


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Okay.. so I just did a compression test on the brat. #1 - 148.. #2 - 155.. #3 - 150.. #4 - 130 (Nooo!) I'm thinking bad rings.. Junkie told me maybe gasket though.. Anyway.. since I'm going to be in there messin with that stuff anyway.. Jessica's uncle thinks we should try and get bigger jugs and pistons (going 2.0) I was wondering if anyone has done this.. any info on this.. do they even got 'em.. etc.. So, let's hear it!

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Maybe you could get to 2.0l with a custon crankshaft giving longer stroke, but theres not nearly enough thickness in the cylinder walls to bore out that far.

I think the boring limit is 0.5mm over.

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Those numbers really aren't toooo bad. If it's a HG, you'll be losing coolant. If that's not the case, it's probably going to be rings.

 

As far as boring out, it would be really expensive as you'd probably have to get custom pistons made and all sorts of crap since nobody has done much of that sort of thing with these engines. I've had good luck just honing the cylinders and replacing the rings. If you want more power, swap in an EJ motor. That could be done for less than rebuilding your engine even with keeping it stock.

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some moters you can pull the cylinder off the block and just replace that. this design is very common in two strokes and the bigger diesels. your ea81 is not like this though the cylinder and the block are all one piece. i hope this all makes since.

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some moters you can pull the cylinder off the block and just replace that. this design is very common in two strokes and the bigger diesels. your ea81 is not like this though the cylinder and the block are all one piece. i hope this all makes since.

 

Makes perfect sense to me.. Thanks for clearing this up for me. I'm just going to hone and do the rings then. I will have to replace the head gaskets and valve cover gaskets while I'm in there? Any recommendations of other stuff I need to do while I'm in there? Thanks!

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If you get the head gasket set it comes with HG, valve cover gasket, valve stem gaskets for intake only(or was that exaust) anyway one per cylinder, therastat gasket, intake man. gaskets, and several others. I just finished on on my 82' Brat and it cost about $70.00. You will have to buy new exaust man. gaskets though cuz the ones that come in the kit are crap. Hope this gives you a better idea. :burnout:

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Thanks avenger, sounds like a good kit. Got a URL for a place to buy it? Yeah.. I want to redo my exhaust gaskets anyway.. good idea / bad idea to use ultra copper gasket sealer on exhaust?? and uhmm.. anyone know a good place to get an aftermarket or oem y-pipe / catalytic converter? It's kinda getting hard to try and weld the holes shut!

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Cant the sleeves be removed? Isnt that what SuBrat84 is asking? I have heard about people pulling the sleeves out and redoing them with larger ones. And not just on metric bikes and diesels.

 

Anyone?

 

 

Alex

 

This is what I was asking.. my uncle was calling them "jugs" ... he said people do them all the time in VW's and Porche's .. but i can see where they'd be a solid piece.. my atv is solid... I'm not too worried about it.. just wanted to see what kind of info i could get about it.

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Just so you all know, jugs are more air cooled terminology than sleeves. motor with jugs will have cylinders that are bolted onto the crankcase. Because VW and Porsche are air cooled, they have these style of cylinders. I believe the corvair is the same way. Jugs will have the sleeve and the exterior all in one piece.

 

 

Alex

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Just so you all know, jugs are more air cooled terminology than sleeves. motor with jugs will have cylinders that are bolted onto the crankcase. Because VW and Porsche are air cooled, they have these style of cylinders. I believe the corvair is the same way. Jugs will have the sleeve and the exterior all in one piece.

 

 

Alex

 

That's the best answer to this thread I've seen yet ;)

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Just so you all know, jugs are more air cooled terminology than sleeves. motor with jugs will have cylinders that are bolted onto the crankcase. Because VW and Porsche are air cooled, they have these style of cylinders. I believe the corvair is the same way. Jugs will have the sleeve and the exterior all in one piece. Alex

IIRC, the term originated with aircooled aircraft engines, specifically radial engines. It was not uncommon to change out cylinders in large bombers/transports while the airplane was in flight!

 

Many engines have removable cylinder liners, but few modern engines are designed this way. I believe that the Subarus use cast-in-place liners (I don't think that that is the proper term, but it will do): The iron or steel liners are placed in the casting mold and the aluminum is cast around them. That would make them very hard to remove.

 

Of course, you could do what some motorcycle makers did (do?): Use aluminum cylinder walls and then coat them with chromium and such. Could use Honda's method of exploding metallic wire in the cylinder to plasma-coat the walls. Then, all you would need to do is have custom pistons cast or forged, and then you would have...

 

... an 11% increase in displacement. hmmm....

 

The displacement per se is not really the issue, but how much air you can get into the cylinders. Grand Prix (Formula 1) cars used to be limited to 1.5Litres...

 

It would be more cost effective to either improve the breathing of the engine or go to a later engine such as the EJ22. "Big Bore" kits are pretty much a thing of the last millenium. Sorry.

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Not worried, and yes, the old radials on airplanes were the original jug style motors.

 

Thanks for the nice technical info. Yes, more breathing is far better than big bore, I was just trying to bring about a clearer definition on jugs/sleeves. The more I hear stroked and bored the more I hear about starter problems etc... If you want a reliable vehicle, worry about how it breathes, what the ignition is like, cooling. You can do a lot on performance with these factors.

 

If you want an unreliable maintence track only vehicle and can afford it, go ahead and do a bore and/or stroke. I think the basic motors are pretty damn good, just need some simple mods to help them aspirate.

 

If you know anyone with bored or especially stroked big inch motorcycle, ask them honestly how much up time they have. youd be surprised. The number one complaint from the big inch owners is starters and daily drivability. Sorry, I know motorcycles arent exactly subes, but they still share the same concept 4-cycle engine. Just saying a lesson should be taken from them.

 

Alex

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Are you going to do a complete rebuild while you're in there? (That's what I would recommend). For my EA82, I got rings, bearings, gaskets, and an oil pump for around $600 or $700, I can't remember which, from 1stsubaruparts.com. OEM is the only way to go for most engine parts in my opinion. (People have had BAD luck with NAPA headgaskets, and you can get SOA parts cheaper than NAPA from the place I just mentioned.) Then you could get the heads done up by a machine shop with a resurface and valve grind for about $150. It's up to you, but if I was tearing the motor apart that far, I'd go ahead and replace everything because then you're set for another gajillion miles.

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A new "factory stock" replacement Y-pipe is spendy to say the least, upwards of $260.00.

 

www.discountconverter.com They have a listing for the stock converter, you'll have to have the header pipes bent though. They also have a multitude of other converters 'specially in the universal listings. Like a Dual 2" in/outlet one, both with and without O2 sensor fitting. Thinking of that one myself for use on all of the 'Roos I have here.

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