Holset HT4B?

H

Headcase98002

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Sep 14, 2010
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I'm having a hard time finding the the turbine housing size on my newly acquired Holset HT4B. I had a HT3B a few years ago and it was clearly marked with a 26 inside the volute. Well, my problem with this turbo is that all that is stamped in the inside is a single line. There are a few numbers on the outside, but nothing stands out to me. I found a thread on here in the for sale section and he stated his housing was marked the same; from what he gathered it was a rare 21cm single scroll housing. Link to thread below.

http://www.competitiondiesel.com/forums/showthread.php?t=73501&page=2
 
I'm actually surprised I haven't gotten any replies, but I stopped in to a old Holset retiree on Friday to see what he had to say. Being this does not have a Map Width Enhancement Groove, it is one of the first designs and they measured the turbine housing size in AR ratio instead of CM at the time being. He stated this single scroll housing is a 1.05AR which was a 28cm housing. I found this interesting, but I trust his info considering he worked for Holset for over 20 years and now has his own shop.
 
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Thats a big girl, amazing it took that much turbo for 400hp back in the day.
 
motorwood said:
Thats a big girl, amazing it took that much turbo for 400hp back in the day.
Click to expand...

When you check these out in quickserve they only seem to show up for the VT1710 applications which is a v12 version of an 855, all the ones I find on the big cams are usually HT4Cs, I looked at a 444 the other day that had a C series on it with a 36cm housing, I can't believe it ever spooled up on the road.
 
Found another part number that appears to be stamped in by hand on the side of the flange. Your gonna need to do a handstand to read it.

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That housing could have been on either a 400 cummins 6 or one of a pair on a 800horse v12
 
Are you happy with it? I've been eyeballing a used 4b without any numbers to determine the exh housing size. I was worried that the one I was looking at might have a really large housing like 42 cm. pn 3523591

Is there an advantage to mounting the primary that way ?
 
Yeah, I really am. It starts to build boost around 1800rpm and I build about 7psi or so just accelerating to get on the highway. I haven't went full throttle quite yet, but I've seen a max of 42ish psi of boost to 17psi out of the HT4B.
 
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