Hybrid Turbo Project
 

So I guess this goes here. As many of you know, I'm planning on swapping a D24T into my 245. While I'm at it, I figure I may as well upgrade the turbo as well. With a bit of help from this forum and others I hope to have the turbo put together by winter. Here're the parts I've gathered so far:

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So here are the two compressors side by side. On the left we have a Hitachi HT-18 from a 2nd gen Mazda RX7. The housing is supposed to be .60 A/R but I have no idea what the wheel trim is. On the right is a Garrett (AiResearch) T3 out of an old turbo diesel Mercedes. The compressor housing A/R is .42, which I believe is the stock size for the D24T. I plan on using the Hitachi compressor housing and wheel.

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Here are the two turbine housings. The Garrett is on the left and the Hitachi is on the right. The Garrett housing is nearly identical to the one found on the D24T but a bit larger at .48 A/R. The Hitachi housing is enormous (supposedly a 1.0 A/R) and has a twin scroll design, but as Slobodan said in the "More power" thread it has a non-standard flange, so I'll obviously be using the Garrett housing for my project.

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Here you can see the oil-only CHRA and wastegate actuator of the Garrett. I'm still not entirely sure how the wastegate works as there's no arm that I can see. Maybe someone can explain it to me.

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Here we have the oil- and water-cooled CHRA from the Hitachi. I'd really like to use this one so I can prolong the life of the turbo and stretch out my oil change intervals. Also, when I finally get to the veggie conversion, I figure the extra heat in the coolant coming out of the turbo will help heat up my vegetable oil tank faster. Not sure if it works that way or if I can even get the CHRA to play nicely with the Garrett turbine housing, but it made sense in my head.

There you have it. The extent of my frankenturbo plans. This will be my first time taking apart and reassembling a turbo so I'd love to hear some suggestions from you all.

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I might as well throw this one in as well. Here's a pic that I snapped awhile back of the ebay intercooler I plan to use. My setup will be more or less a clone of 500dollar744ti's on turbobricks (documented here: http://forums.turbobricks.com/showthread.php?t=131057).

The watercooled center section probably wont make much difference, as the diesel turbos dont run as hot as the gasser ones do, its not needed. I don't suppose it would hurt, but that would be a bunch of extra plumbing in an already cramped area. I think the combo of the .60 compressor and the .48 exhaust will work nicely, but that exhaust housing isn't the greatest. I would keep searching around for a standard style housing like most T-3 turbos have. That factory waste gate has a actuator rod that goes straight down into the housing, and the end is shaped like a valve (think regular engine intake or exhaust valve). The turbo on my Jetta diesel was the same waste gate type, I think they did it because of space restrictions. The whole assembly is much more compact against the turbo compaired to most.

Jason

Oh, is coking not a problem for turbo diesels? I knew that diesels didn't run as hot as gassers, but wasn't sure if heat was still a problem for the oil. I was also planning on getting an EGT probe and gauge just so I could keep an eye on exhaust temps. Should I skip it though?

I think I'm going to stick with this turbine housing for now. If a cheap one from a 280ZX or Ford 2.3T comes up (I think those are both .48 with standard T3 flanges) then I'll get it. Is there a way to test if the wastegate actuator will hold pressure? Does the diaphragm or spring ever wear out or need to be replaced?

The diaphram goes bad, as mine did. If you just put some shop air to it, you should be able to see the waste gate valve open up. Coking is only a problem if you shut it down hot (like right after running the crap out of it). Just let it idle for a minute to cool. EGT probe would be a good idea if you plan to really throw some fuel at it.

Jason

So how goes this project?
I am working on using the Mercedes .48 Turbine with my Hitachi compressor. And with the stock center section. Or maybe just tap the oil inlet for the appropriate threads. Either way, I am looking forwards to the upgrade in turbine size.

Okay, I am drunk... but thats how I get motivated :)


I took both turbine housings off the TurboDiesel VW turbo setup and The Turbo Diesel Mercedes turbo setup. and swapped them.... the turbine wheels both seems identical to me, but the housings them selves are different. the .36 is smaller visually and the .48 mercedes is noticeably larger. but the wheels are infact the same size. .12 difference between the two due the housings physical size difference. That makes my upgrade seem very easy any probably not that noticeable..... Or would it? how many of you think it would be? because sooner or later I would be doing this. I do have two more negra modelo's in my fridge. I might be inspired to do it in the dark.. out side.. but then I can't drive.. because I have been driving. fvck... hmm.. I'll wait.

Nice project, first time i notice this somehow.
Jason already told how wastegate without noticeable "arm" works.
Sad i cant really much help you to choose your turbo, but ill
watch and give other comments, keep going!

I wouldn't bother changing the hot side to the larger .48 a/r as it will be a higher rpm before it spools. I would upgrade the compressor side to move more air. I would only change the hot side when you really start to push some fuel and boost and need more flow. I am told the stock exhaust housing flows very well, but at some point it is going to become restrictive.

Jason

Well, I have been aiming for keeping my cruising boost level lower. My wagon has the 373:1 rear end ratio... so doing 70mph in OD is 3000 rpms about. that also means I'm constantly pushing 5psi or so just to maintain that speed. but I know I don't need it.. so this is why I am leaning towards the slightly larger turbine housing.