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3.1 rotating assembly in a 3100 block?


eclipse5302

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Will this work? The 3.1 and the 3100 have to same bore/stroke and a bunch of other things are the same. Compression is more on the 3100, so with the 3.1 pistons it would be less...but I'm planning on running higher boost with an aftermarket ECU so less compression is OK there. Anyone have any thoughts on this?

 

Jason

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If anyone was wondering about this, it WILL work. I've talked to many people, and did my own research. The crank journal bore, and piston bore/stroke is the same. These are the only things I really need to worry about when doing this kind of project.

 

I'm hoing to hear about an engine Monday or Tuesday. Apparently the engine I might get (for free) still ran, and I'm hoping it was replaced because of a rod knock or something like that...since I'm using a rotating assembly from a turbo 3.1.

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I wanted to reply to this the other night.

 

The only thing that is really different dimensionally would be the pistons and deck height. The rods and crank SHOULD be the same, including the rolled fillets, which i'm pretty sure was the only hardening done to the TGP crank. This would be a good idea if you wanted to use a roller cam, and get the benefits of the powered metal caps and sidebolted pan. Crane makes a couple of HYDRAULIC roller cams, but its hard to determine what application they intended them for, as they won't work in the 3100 for a 3100 application as they don't ahve the sync ring on them for the cam sensor. They might be leftover from the days of circle track racing or something.

 

You will have to figure up something for the timing set, as the original is a single bolt, and the crane should have a 3 bolt pattern. Also, the block/cam gear is clearanced for a thrust plate so there might be an issue there. Shouldn't be a big deal, at worst you might need to have the cam and cog machined down a little. The factory 3100 cam isn't bad though.

 

IIRC, you will need to use the 3100 cover, and find a new place to mount the coils (oh the tradgedy!), since the 3100's don't have the bosses for them. Some of the water taps might be indifferent locations, and the knock sensor is mounted on the front, but should be able to be mounted on the back, or you could just extend the harnesses

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I was planning on using the complete 3.1 turbo ra...pistons, rods, crank. I realize the compression will be down, but that allows me more headroom for boost. Since I building it for a T3 now, a T3/T4 Hybrid will bolt up no problem later. I'm sure the extra block strengthing will help out there.

 

I'm also planning on basically running the thing basically stock. Stock cam, mild head porting, blah, blah. And I'm going to need to either play with burning my own chip for this, or use an aftermarket ECU to provide the extra fuel.

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It will be down from a 3100 but up from the 3.1 V. Not much, but no less than the normal turbo motor. Sounds good! Hope it works out. I had planned on doing this for mostly the same reason, but doubt I ever will.

 

Chris

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