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Turbo help


Guest Luigi

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I orginally posted this in the Datsun L6 forum. I'm such a V8 guy, I didn't think to put it here.

I bought a 280ZXT engine and trans. low, low cost.

Has anyone extrude honed the stock exh. mainfold?did it help?

Are any of the individudal throttle bodied turbos up and running?

If so how well and was it worth the trouble?

How do you add an external wastegate to the stock exhaust manifold?

since the discharge hole is not 3" do we use a short transition to 3" or bore the housing out?

Best cam (just kidding)

thanks

Luigi

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Bore the housing of what? That one lost me.

 

Yuo can have the external welded to the exhaust manifold, alot of people like to put it where the 3rd and 4th exhaust ports come out. I have also seen people mount them coming off the port out of the exhaust manifold that the turbo mounts to.

 

I am personally thinking about having someone mount one directly to my turbine housing like turbonetics does with the grand national turbines.

 

I would think extrude honing would help alot due to the humps and stuff in there. James says there is a hump in the manifold to from the turbine outlet towards the middle that needs to be ground down, and I can feel it in mine, so it is going away. It feels like that would create a pretty good restriction.

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thanks Lockjaw, I met you at the drags in Ala.. I was speaking of the turbine discharge (downpipe) the hole that the exhaust gasses leave, where the downpipe connects. I don't think there is enough room to enlarge the housing of the turbo or the houding of the swing valve (wastegate) to 3". I'm gonna go get another swing valve and another plate without. I've got a short transotion coming from Burn's SS. I kinda wish Jeff P. would sell just the downpipe part, I could hack and slay together something.

Are the welded external wastegates giving no problems as far as the welding? I've welded cast iron a few times. Sometimes it works and sometimes it doesn't. IF anyone reading this is really good at this, please speak up.

once again thanks Lockjaw

luigi

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Ok I got you now. On the turbine housing, most everyone I know uses some sort of flange (mine is from turbonetics) that is 2.5 inches, and weld just enough 2.5 in pipe to it to get the bolts to clear, and then it is 3 in from there. That is the way mine is, although it is not near as pretty as Jeff's.

 

I usually leave welding cast iron to a professional, but on my old rotomaster set-up, I had the external welded to the turbine housing, although it attached to a piece of pipe with a flange. I never had any problems with it. I think the type of rod used has a lot to do with it. Maybe it needs to have some nickel ??? in it.

 

If you went to an external, you could just get a block off plate that fits over the back of the turbo and replaces the swing valve assembly. I feel certain you could connect a 3 inch to that by welding and not have a clearance problem. It doesn't matter that the turbine discharge is smaller than the pipe. You cannot have to big an exhaust on a turbo car.

 

Who were you at montgomery? I am awful with names, it is just one of my weak area's, always has been.

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The id of the turbine housing outlet is actually 2 1/8" and you cannot bolt up a 2.5" pipe to the housing because the bolt pattern of the 4 studs does not leave enough room to tighten the nuts. When I was making my DP, the flange that bolted up to the turbine housing had a 2 3/8" id and the 2.5" SS pipe was swaged to fit into that hole and then the other end of the DP was blown out 2.75" id, making a gradual transition for a 3" exhaust. If you are going to have multiple welds, make sure they are good as the heat and vibration will cause cracks.

 

Trying to open up the turbine outlet will have an impact on the wheel if you try going the entire depth of the hole. Not sure if that made sense.

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Scottie I think it depends on the turbine wheel what the housing is bored out to. Mine is 2.25 with the stage III wheel, but I opened it up a little with the dremel.

 

Whatver size it is, use the absolute shortest piece of largest diameter that will work, and tranistion to 3 inches ASAP. That will make some nice power.

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