92DuallyCTD

Hey gang, how's it? :-) I recently acquired a 12cm turbo housing from 1995(and the cold side housing along with), so I was wondering first if it might be better to go with at least a 14cm or 16cm, as I will never modify my stock 92 for any reason. But I probably would like to help that 21cm original a little!! Anyways, that's the first part...second part is how can I best compare the cold side housings to see how the inner cartridge matches(if it isn't already a direct bolt-in)? About the only other thing I may modify, seeing's how it came with the motor I bought, would be to gain the newer(HX35?) intake side of the turbo from my H1C. Man, I love that unsilenced turbo whistle!! ;-) Oh BTW, if the 16cm is a better way for me to go(non-high performance minded here), anyone wanna trade for the 12cm?

edwinsmith

Does the 12cm housing have a wastegate and actuator? If so, use it! you can hook it up to a port for that purpose on the intake manifold or else anywhere in the compressor housing output or the crossover.

If you got the wheel and compressor housing for the WH1C which is where I assume you got the 12cm turbo housing you should use that also since the WH1C has MAP width enhancement ports. You have to change the wheel also to match but the conversion is well worth it. The WH1C is essencially the same as the HX-35 but is built a bit differently.

Check my gallery for pics of the finished job.

Edwin

MikeThomas

With the auto, Im not sure how good the 12 would be. You will probably run out of air at the top end and bring up the EGTs because of that. I think the 16 is the magic size, but that has been debated many times. If you tow alot, the 18.5 would be good too...

edwinsmith

That's why the wastegate is important. A 12cm non-wg would choke off the exhaust to much. Also I drilled the center divider through the WG hole to allow the front three cylinders to breathe better.

Edwin

92DuallyCTD

Great! Thanks guys, I appreciate the input. Edwin, I'll check your pics and follow up. The wheel/center cartridge is with the 12cm housing, but both are damaged, so that's why I wondered if the H1C would swap directly. And yeah it's wg'd and all. Mike, I would imagine there'd not be any concerns about top end(I rarely exceed 65mph), but do tow occasionally, so you think the wg would suffice at the lower speed? As mentioned the only reason to consider using it was because it came w/other parts, but I'd pretty much decided earlier upon the 16cm as the best option. Thanks again, anyone else add something? I appreciate it!! :-)

edwinsmith

Just be sure to drill the center divider through the WG hole. The H1C compressor may surge on you at low speeds though but at higher RPM you should be OK.

Edwin

G1625S

The 12 is the bees knees on a truck with stock injectors. Every p-pumped 12v came with one from the factory, so they can't be ALL bad... Ask yourself this: Is your foot primarily to the floorboards or do you usually only use the first 3/4 of your throttle travel? If you answer the latter then the 12cm housing will never be a restriction...JMO. I run one and have ported it to the point that even with a maxed pump and the larger non-ic injectors the wastegate will hold 32psi comfortably even at WOT in 5th from 1400 RPMs. That's my experience with the 12, anyhoo....

If the donor turbo is a WH1C, then the compressor housing and wheel will bolt right up. If the donor turbo is an HX35, the compressor housing and wheel will NOT fit your H1C.

wannadiesel

If the whole turbo is OK, bolt it on and enjoy.

Like Greg said, with stock injectors on an intercooled truck it is hard to beat the 12 cm. Makes it an entirely different truck.

And you don't need to drill out the divider if the stock injectors are staying. You will probably not even need to connect the wastegate line.

92DuallyCTD

Aha!! Now THAT'S what I'm talkin about! ;-) The perfect answers...just what I was looking for...To Greg - no, I never floorboard it(at least had no reason yet), will not be modding any further, and glad to hear 12cm works well for stock applications. I think it will make the difference I expect(perhaps a bit 'quicker' takeoff power w/o too much fuel efficiency loss?), so that's good news. To Dave - unfortunately the entire turbo is not an assembly at the moment; both outer housings are separated and the center bearing housing has the top 2 bolt flanges broken off(hey, not me, it came that way!), so that was the need to ask if my original center cartridge/wheel assembly might 'bolt-up', you see? So am I correct in that they should do so? That would be just too easy...something's gotta go wrong(Murphy is always around). :-) Oh, and with all stock motor/injectors, if the wastegate is alot of trouble to get going, it may be ok without eh? Thanks alot guys, I'll let'cha know how it comes out, seeya!

wannadiesel

See Greg's reply, he covered that. Yeah, on a stock truck it'll only make about 25 psi. If you start seeing more than 35 psi, then hook up the boost line to the wastegate.

edwinsmith

Did I see in a previous post that the compressor side of the donor turbo was hosed? If not then you can swap the compressor housing and the wheel to your center. This is assuming the donor is a WH1C. This is exactly what I did except it took 2 donor's to get all the parts because one had a melted turbine and housing. (See the pics)

I really love the WH1C. I have a boost controller to limit the boost to about 35# and even with the outlet connecting to the squeezed down 2" crossover it performs great! It spools real fast for good in town and lots of up/down shifting. It doesn't seem to choke off any but I wouldn't know anyway since I have a stock exhaust straight piped. Eventually I'll get a 2-1/2 inch crossover fabbed up which should help some.

Edwin

92DuallyCTD

Edwin: Thanks for all the helpful info(wannadiesel you too!!), I finally did get out to the barn and check the turbo housing...it is indeed a WH1C, so it seems pretty much a bolt-on. Now, let me throw this curve ball into the mix - what about the swap of the 12cm exhaust housing onto the existing 21cm cartridge? I don't think I've seen any threads on which will/will not interchange directly onto my existing center cartridge/wheel. You see, I'd be tempted to try some of these upgrades if it does not involve any removal/disassembly of the innards - know what I mean? But I would have the courage to attempt a straight external bolt-on swap, and if it didn't work correctly or I messed it up somehow (w/o damage I mean), I could always 'undo' whatever I tried, right? ;-) Thanks in advance for all your help/ideas, I appreciate it!

wannadiesel

There's nothing wrong with just swapping turbine housings - but if you have the WH1C compressor the whistle is nice.

92DuallyCTD

heh heh Yeah, that big ole turbo whistle is kewl...just don't know if it'll 'whistle while it works' as well with my H1C compressor wheel(now just try to say THAT really fast 10 times!!). LOL But let's hope so...then do I understand the other half is a bolt-on also(no problem with the original 21cm exhaust side wheel matching the 12cm housing)? Man, I sure can muddle up a conversation!! Ok, look, what I'm after is whether or not I can A: Install the WH1C turbo housing onto my original H1C cartridge/wheel/housing w/o removing anything more than the 3 clamps, tapping the old one off, and replacing it with the other. I think Greg pretty much said it would...and B: If I can do the same with the exhaust side 21/12cm swap. The whole problem I'm having is that I pretty much don't want to get into taking the center cartridge apart or have to change the wheels or anything deeper than removing/replacing the 4 bolts to the manifold, right? I'm just a believer in the 'if it works don't fix it' motto, but long as it doesn't involve delicate technical stuff, I'm good! :-) Anyways, sorry for the lengthy messages/explanations, I wasn't sure how to ask all this(and still ain't really...). :-) Thanks for all you all's help!

gman07

The exhaust housing is a direct swap. The compressor housing will require you to move the WH1C compressor wheel to the H1C. It's really pretty simple, you just have to remember they're reverse threads.