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Discussion Starter · #1 ·
I wanted to post this separate from the other H1C threads so as to not hijack.

I found a fella on ebay who is selling NEW H1C turbo's - I had him look at the exhaust size housing, and verify that it had the smaller (compressor?) housing - it does, a 12 is stamped on the inside, so I assume that it is indeed the preferred 12cm2 for our engines as has been documented on this site.

I went ahead and placed the order, $300 later it shows up on my doorstep. When I opened the package, the exhaust side appears correct, but the intake side - where the air filter would be attached - is only 2.25 OD instead of the 3.00 like what came on my 4BT. I wasn't aware, and didn't think to ask about the front side of these.

After reviewing the H1C rebuild thread - it looks like I might be able to disassemble the intake housing of both and swap my old housing onto the new turbo. Does anyone know if the internals are all the same on the H1C turbos?

If anyone knows how to interpret the data plate info on the Holsets;

original 4BT turbo
ASSY. 3524312
Serial 942052
Engine 3909317-1-2/6
Type H1C

New Turbo
ASSY 3521536
Serial 1130675
Engine 127-0313-02
Type H1C
 

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There are 2 different size compressor wheels available on the H1C, 82 and 72 mm. I would almost bet that with the small air inlet the small wheel is inside. My turbo has a compressor wheel that is 82+ mm with the 3" inlet and a 16cm exhaust turbine housing. The assembly number on mine is 3525699. I wonder if the 12 cm exhaust housing is paired with the 72 mm compressor wheel? I would expect that the parts could be swapped around and you could make a super turbo out of this. Use all the new parts up to the diffuser. Put your old diffuser, compressor wheel, and compressor housing on the new turbo. You would use all the new bearings and shaft. The problem with this is balancing. You would have rotating parts from both turbos with no balance reference points. There is a "rig" refered to in the Holset manual for balancing. I don't know what that is.
True it isn't what you thought you were buying but if you bought a new exhaust housing it would be about $150 to $200. If you bought a new "center housing rotating assembly" it would probably be at least that much more. My rebuild kit was $61. You still got your $300 worth.
 

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You would use all the new bearings and shaft. The problem with this is balancing.
As I understand it, all the parts are balanced individually. The residual imbalance that results when all the parts are bolted together is small and mainly affects turbocharger noise.

I read somewhere that only automotive turbos used to be balanced as an assembly, the noise wasn't a problem on truck and industrial turbos.
I have swapped compressor wheels from turbo to turbo without rebalancing and without problems. But final balancing is still the proper way to do it.
 

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Discussion Starter · #4 · (Edited)
Beck,

I opened up the two turbo's, the old original one has a 72+mm compressor fan, the new one actually has an even smaller 62.95mm fan. Both of these measurements were on the incoming air compressor fan, not the fan on the exhaust side - I obviously need to learn the turbo vocabulary.

I tried to get the 21.5cm2 exhaust housing off my old one, but it is "rust-welded" together - I have the seam soaking in PB Blaster over night, and will try again in the AM. I wish someone had a "build sheet" with all the possible combo's for a H1C - I had no idea there were so many variations.

Craig
 

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Beck,

I opened up the two turbo's, the old original one has a 72+mm compressor fan, the new one actually has an even smaller 62.95mm fan. Both of these measurements were on the incoming air compressor fan, not the fan on the exhaust side - I obviously need to learn the turbo vocabulary.

I tried to get the 21.5cm2 exhaust housing off my old one, but it is "rust-welded" together - I have the seam soaking in PB Blaster over night, and will try again in the AM. I wish someone had a "build sheet" with all the possible combo's for a H1C - I had no idea there were so many variations.

Craig
I followed BobS's recomendations and soaked mine in carb cleaner for a day. After that he suggested soaking in kerosene with parts washer additive (I don't know what that is). Anyway I was lucky. I tried removal after the carb cleaner and it came apart. I used 2 chisels as wedges. I placed them between the turbine housing and the oil return or inlet boss on the turbo. Put one in one direction and the other opposite. Use them together on the same side. Tap one of the chisels and it applies seperation pressure to the housing. Don't get carried away. This could still damage the turbo.

Download the Holset turbo manual for the H1C from the net. The link was on a recent post here. That is where I am learning the turbo vocabulary. I had no idea what these parts were called. That manual only lists 2 compressor wheel diamaters. Your small one is not listed.
 

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As I understand it, all the parts are balanced individually.
The following if from the H1C Holset manual.
"This range of turbochargers are fitted with alternative hexagon and bi-hexagon compressor wheel locknuts. Older units have the hexagon nut which indicates that the unit was rotor balanced during original manufacture. Units fitted with the bi-hexagon nut are core balanced and will not feature alignment marks of shaft and compressor wheel. Where no alignment marks exist asways mark shaft and compressor wheel prior to disassembly of CHRA (core)."
"Caution: Rotor balance MUST always be checked before re-assembly."

I don't know exactly what "rotor balanced" and "core balanced" means. I did mark my compressor wheel to match the shaft. I did not see a factory match mark on my compressor wheel. The shaft was marked. My parts appeared to have been sepeately balanced. There was material removed from both wheels for balance from the factory. I had the hexagon nut indicating it was rotor balanced.
 
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