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Discussion Starter #1
I have an old h1c that I've had sitting around for a long time. The Assy. Number is 3528741. I haven't been able to find any info on it at all. I measured the compressor wheel and got 50mm inducer and 80mm exducer. It has a non wastegated 18.5cm on it that I know I'll replace if I use this thing. My main question is how much power can I get from this thing? I only paid around $50 for it so spending a little on it is an option.
 

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the artist formerly known as drexelstudent11
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H1C/WH1C:

In 1994, there was the Wh1c which has pretty much the identical compressor as the hx35 but with a Vband compressor cover. The turbine wheel is the same. It will bolt into the BEP bolton hx35 turbine housing. It has 4 bolts at the housing instead of 6. So you will need to buy 2 more bolts and use 6 washers cut to make a flat side. Honestly, I just used bolts that were cut a little short and the bolt head was wide enough to pull the chra to the turbine housing. No sealing issues. Since the Wh1c is for all practical purposes an 8blade hx35 the spool and flow is the same too.

I have the big h1c. It comes on the INTERCOOLED 1991-1993 cummins pickups. It has the webbing for MWE but no groove cut like the hx35/wh1c has. This turbo I term the big h1c because it has a 54mm compressor inducer and same exducer than the 8blade hx35/Wh1c. The other h1c is the small h1c found on the NON-intercooled cummins pickups. This has a 50mm inducer but only 7blades and has no webbing for MWE. Less blades helps flow, but so does a larger inducer diameter. The most whp ever recorded on a gas 4cylinder with the small h1c was done on a KA24 nissan: 411whp. Since the big h1c has a 4mm larger inducer and the same turbine wheel as the hx35, it is safe to say that it flows enough for between 411whp and 500whp. The diesel sources state that it flows SLIGHTLY less than the early hx35. So 4lb/min less than the 8blade hx35 puts the flow of the big h1c at 48-49lb/min right where a 50-trim or 20g is. The small bep housing is all that's needed to get the most from the compressor and the spool speed is 20+psi by 3500rpms.


stolen shamelessly from dsmtuners' holset thread.

sounds like you have the "small h1c"
 

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the artist formerly known as drexelstudent11
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Supposedly the small h1c is a 7 blade but mine is an 8
nope, they had both blade counts back then. it's still a 50mm inducer so you're good for 45+lbs/min of airflow.

I'd say it'll take you to around 400whp conservatively.
 

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D-series Janitor
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nope, they had both blade counts back then. it's still a 50mm inducer so you're good for 45+lbs/min of airflow.

I'd say it'll take you to around 400whp conservatively.
x2 . . .

I'm sure the compressor map is out there wandering the interwebs somewhere.

The H1E was the next size up and the map I saw was extremely close to a 62-1 which I made just a touch over 500whp with.
 

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If your housing is twin scroll you could save yourself some money and do what I did to my hx35 12cm twin scroll housing. I cut the divider down into the flange, welded the one size shut and smoothed it into a nice ramp to cut the effective housing size down to 6cm





 

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The way I understand it is that the 7 blade is capable of about 10lbs/min more airflow up top than the 8 blade. Also, for our little D motors, there are a few options for getting it to spool quickly. You can use the 12cm^2 divided turbine housing and use a true twin scroll manifold, you can weld it up like Mark did, or there is a guy called Tim's Turbo's on eBay that sells 7cm^2 non-divided housings, I think it's 7cm at least. Bullseye Performance (BEP) also makes a smaller housing, but I don't see them available that often anymore.

I have an H1C, 8 blade, 12cm^2 on a non-twin scroll manifold that I will be getting dyno'd in a couple weeks. I'll put my results in the dyno chart section of the forum when I get my numbers. I'm shooting for about 350whp. If I remember I'll post it back here too.
 

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Discussion Starter #11
I have already been talking to the turbo guru "shodan" on h-t and he thinks it could get around 500hp give or take based off of the compressor and exhaust wheel measurements. I also already contacted Tim's turbos about a different exhaust housing so that will be taken care of also. I'll probably go with the 12cm
 

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I have already been talking to the turbo guru "shodan" on h-t and he thinks it could get around 500hp give or take based off of the compressor and exhaust wheel measurements. I also already contacted Tim's turbos about a different exhaust housing so that will be taken care of also. I'll probably go with the 12cm
If you're going to use a 12cm exhaust housing, you should try and find a stock divided housing. That way you can use a twin scroll manifold and get faster spool. If you use a 12cm non divided housing you won't be able to leverage that. Not that you have to go that route, but if you're going to go 12cm, might as well, IMO.
 

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Ended up on deciding on the .63 a/r that he offers
Awesome. I've heard good things about those housings, that's the one that I've heard translates to about 7cm^2 in the Holset world. I'm not sure how accurate that is, though, could be random forum nonsense. Anyways. Good luck with your build!
 

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Discussion Starter #15
Awesome. I've heard good things about those housings, that's the one that I've heard translates to about 7cm^2 in the Holset world. I'm not sure how accurate that is, though, could be random forum nonsense. Anyways. Good luck with your build!
I think he said the .63 is about 9cm
 

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Got this from turbo dodge forums

6cm2 = 0.41 A/R
7cm2 = 0.49 A/R
8cm2 = 0.57 A/R
9cm2 = 0.65 A/R
10cm2 = 0.73 A/R
11cm2 = 0.81 A/R
12cm2 = 0.89 A/R
14cm2 = 0.97 A R
15cm2 = 1.05 A/R
16cm2 = 1.13 A/R
17cm2 = 1.29 A/R
19cm2 = 1.37 A/R
 

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Off of a Mitzu forum

For turbine housings..

((CM x 8 ) - 7) / 100 = a/r ratio

Example: 7cm housing = .49 a/r

7cm x 8 = 56 ... 56 - 7 = 49 ... 49 / 100 = .49 a/r

6cm = .41
7cm = .49
8cm = .57
9cm = .65
 
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