Holset Turbo Install FAQ, and Holset Info w/ Maps


  • Holset Turbo Install FAQ, and Holset Info w/ Maps

    The Holset Turbocharger FAQ
    By: Roastin300

    This FAQ is provided to help with the installation of a Holset turbocharger from the Dodge Cummins turbo diesel trucks. While each turbocharger can be fitted, this particular install is an HX35 model turbo from the 5 speed Cummins.

    Why choose a Holset turbo you say? Well, there are many good reasons. Some include their very low cost used, comparable specs to the Garrett aftermarket high performance turbos (in fact, Holset started out making outright Garrett knock-offs), they are easy to come by online used and still in good working condition, most have T3-compatible turbine housing flanges, and some have internal wastegates.

    First, lets take a look at some of the different models of Holset turbochargers that can be obtained, and their specs in comparison to a Garrett turbo:

    HY35 – Came on the Automatic 5.9L Dodge Cummins. Turbine housing roughly has a .55 A/R and a T3 stage 3 turbine wheel. The compressor housing is about .60 A/R and the compressor wheel flow is .46 kg/s, which converts to 60.8 lbs/min.

    HX35 – Came in the 5 speed 5.9L Dodge Cummins Turbo Diesel. Very similar to the HY35, has the same turbine and compressor wheels but utilizes roughly a .80 A/R turbine housing and a .70 A/R Compressor housing. Also flows 60.8 lbs/min.

    HX40 – Came in the 8.3L Dodge Turbo Diesel motors. Everything on this turbo is much larger, the turbine housing is a 1.00 A/R+ and the turbine wheel is approximately a P trim in garret specs. The compressor housing is approximately a .70 A/R and the compressor wheel flows .53 kg/s, which converts to 70.1 lbs/min.

    HX50/55 – Enormous, never seen one in person but the compressor wheel flows .75 kg/s which converts to 99 lb/min.

    H1C
    – Came on the much older Dodge Cummins. Very similar to the HX35 but flows slightly less and is said to spool a little slower due to older and less efficient technology.

    H1E
    – Comparable to the HX40 specs, but the older version just like the H1C is to the HX35.

    This information I have given is not exact, however, it is composed of good approximations from my research I have done along with a margin of error for unit conversion.

    Choosing Your Holset:


    Selecting the “right” model from these turbos to fit on a Z31 300ZX’s VG30ET engine is fairly simple.The HY35 will support about 400RWHP, will spool very fast, nearly as fast as a stock T3. I am currently running the HX35 and it will support roughly 450RWHP, and my spool time is around 3600-3800 full 18lbs boost. This is comparable to the spool you would expect from a Garrett “stage 3” turbine and a large T4 compressor, and the same performance, but at a fraction of the cost. I used to run a HX40 in the past, but I didn’t get full 18lbs of boost until around 4300RPM, making for a very short power-band. Because of its larger sized turbine and housing, the HX40 should support 550RWHP+.

    I don’t recommend the H1C or H1E because they are outdated and harder to find anyway; the HX50/55 is just stupid-huge for our 3.0 Liter V6 and would be a very poor investment (unless you plan to spool it with gobs of nitrous).

    Installation:


    To fit a HX35 into a Z31 300ZX, a few relatively minor modifications must be done to the turbo and oil delivery system. Let’s look at the mechanical side of it:

    The compressor housing needs modification. You need to grind down the V-band outlet on the 2.5” compressor outlet. This needs to be done so a normal 2.5” silicone coupling can be slid over it and clamped. This picture kind of shows it, you will fully understand what I mean when it comes time and you have the turbo in front of you.



    Some Holset models have two studs and four holes for the turbine housing inlet flange, instead of the “usual” 4 holes with 4 studs on the manifold. You can simply drill the studs out of the turbine housing with a clearance hole large enough for the studs on your manifold to clear.

    Next is the wastegate actuator. The stock Holset wastegate actuator should not be used as it is designed to run a lot more boost and will probably not fit well if at all with the turbocharger mounted. Almost any internal wastegate actuator from another car can be used because they all work in the same way. I chose to use a Ford 2.3 Liter turbo actuator diaphragm. I cut the rod and welded in an adjustable end to adjust my preload on the actuator’s internal spring. It will also need a new bracket to hold the actuator itself physically to the compressor housing. I was able to cut, bend and drill the stock Ford bracket to work. As you can see the actuator rod is pretty short and I bolted it to one of the threaded holes on the turbine housing that the original unit bolted to.



    The next part is much harder and requires some real fabrication skills. You need to make either a downpipe adaptor to the stock downpipe or aftermarket exhaust made to fit the stock turbo exhaust elbow’s 3-bolt flange. Another solution is to make a completely new custom downpipe. I chose to make an adaptor; here are a few pictures of it. First I made the flange to fit the turbine outlet.



    Then I used the 3” mandrel bent pipe I purchased online to mate up with my 3” downpipe. I bought a 3 bolt universal 3” flange and welded it at the bottom to bolt to the downpipe. You can also see that I took the extra time to weld in a smoother transition for the wastegate opening rather than going straight into the flange and intersecting with the turbine exhaust flow. In theory this should give slightly better flow and more precise boost control.









    Here are the pictures with the turbo installed:







    Now as far as the oil system, the stock oil return works perfectly on the HX35. Mine is different because I have a N/A oil pan with a fitting welded on it. But I know it will work for a fact because I had this setup with a stock turbo, and when I swapped my HX35 in the oil return lined up and sealed perfectly.

    The oil feed line must be swapped as the oil inlet on the Holset turbos are threaded and need a fitting. I purchased a stainless steel –4 AN line with an adaptor fitting to go from the block to the line, and bought a fitting that screwed into the holset turbo inlet and had the –4 AN fitting on the other end, presto, a great oil feed setup! The fitting size for the holset's oil inlet is 12mmx1.5, the oil feed hole from the vg30 block is 12mmx1.25

    For the intake before the compressor you can go many routes from a pipe motor mount setup, a new motor mount to route big 4” piping to it, the sky is the limit. If you have a MAP sensor with a speed-density system like myself, I run a little butterfly filter right on the compressor inlet with no extra piping to deal with!

    You will need to rotate the center section and compressor housing as needed to fit right in the vehicle to line up the compressor outlet, oil feed and oil return. This is called “clocking” the turbo and is fairly easy to do with it test-fitted in place.

    That’s it; happy hunting for a used Holset!

  • #2
    I have a H1E sitting in my garage for no use, what do you think about that on a VG? I'm currently running a T70, But doesn't like to have a ebay-turbo in my car… Should I go with the H1E?

    Current spec is forged internals, ported heads and cams, pathy intake and FMIC + some other fun stuff. Goal for this summer is 15-20 PSI boost… T70 or H1E?

    http://Jocke.z31turbo.com 11.842s car
    http://www.youtube.com/watch?v=UfRwqC3jkAk
    If Nissan motorsports is Nismo, wouldn't Honda Motorsports be Homo?

  • #3
    Well its hard to say, i am not very familiar with the H1E. As i said in my FAQ, the H1E has very similar specs to a HX40 but is a little older technology. The main thing is what size turbine housing it uses. The HX40 uses a 16cm turbine housing which is about a 1.10 A/R, which is pretty damn big. Alot of those H1C and H1E turbos use even larger turbine housings. The compressor on the H1E will flow almost as much as the T70 but the turbine housing is probably too big and will have even more lag than the T70. Look on the turbine housing and look for a 16cm or 18cm or 20cm or 22cm marking. It might just even be a number casted in there sitting by itself without "cm" following it. Thats how my HX40 is. I have an HX40 im selling you know that i already modified to make it fit and work in a Z31, i even have a downpipe flange to start with that i fabricated because the stock holset v-band hit the steering rack. At my high altitude on a stock low compression motor i got full 18lbs of boost around 4300RPM. The HX40 on 20 pounds on a VG would do close to 500RWHP.

  • #4
    HY35 – Came on the Automatic 5.9L Dodge Cummins. Turbine housing roughly has a .55 A/R and a T3 stage 3 turbine wheel. The compressor housing is about .60 A/R and the compressor wheel flow is .46 kg/s, which converts to 60.8 lbs/min.

    HX35 – Came in the 5 speed 5.9L Dodge Cummins Turbo Diesel. Very similar to the HY35, has the same turbine and compressor wheels but utilizes roughly a .80 A/R turbine housing and a .70 A/R Compressor housing. Also flows 60.8 lbs/min.
    I've actually heard that the HY35 has a slightly smaller/different compressor wheel than the HX35 (maybe depending on the year perhaps?). I know there's a guy selling Holsets on Ebay that modified an HY35 to accept the HX35 compressor wheel. Maybe he meant the housing itself though… I'll try finding it again to verify.

    Its also probably worth mentioning that the HY35 has a single scroll turbine housing while the HX35 has a twin scroll turbine housing.

  • #5
    good call. the HY35 has a normal single entry turbine housing like the stock Z31 housing and the HX35 has a divided housing. Im just going off of the info i gathered online searching, the HY35 and HX35 flows the same amount from the compressor. The way i know the compressor housing is physically larger on the HX35 is that my friend has a HY35 and we put my HX35 next to his and the compressor housing seems to have a larger A/R because my HX35 is bigger, physically.

  • #6
    Interesting… I wish Holset, now apparently Cummins Turbo Technologies, would post some maps. I'd like to see the difference the housing makes if the two wheels are the same.

  • #7
    Re: Holset Turbo Install FAQ***

    roastin300 wrote:
    H1C – Came on the much older Dodge Cummins. Very similar to the HX35 but flows slightly less and is said to spool a little slower due to older and less efficient technology.

    H1E
    – Comparable to the HX40 specs, but the older version just like the H1C is to the HX35.
    I've been seeing more and more H1C and H1E's poping up on Ebay latly and for way cheaper than the HY/HX. Has anyone actually tried running one of these to see just how much slower spoolup might be?
    I mean if they only spool a little slower than thier newer counterparts then it might be worth saving the cash at a cost of what? 200-500rpm slower spoolup?

    I could live with HX spool up but HY power if it means saving a good $300+.

  • #8
    I missed out on an incredible deal for an HY35… brand new they only wanted 400 for it. I was… quite mad when I saw it sold. :lol:

    You can definitely tell a huge size difference between the H1 turbine housing and the HX and HY turbine housing. They're quite large. The H1C's came with two different turbines from the Dodge Cummins, a 21 cm/2 exhaust housing and an 18 cm/2 while the HY is a 9 and most HX's are 12. Some modified HX's are 14. I would think the spooling difference would be pretty drastic but have no proof to back that up.

    If the HY is the equivalent of a .55 a/r then I would assume that the H1 would theoretically be over a 1.00… somewhere in the area of 1.28 since the 21 housing is 2.33 times larger than the HY's 9. 21 is 1.75 times the HX's 12 cm housing which comes out to 1.4 on the H1… so maybe its somewhere between there?

    If its the 18, being 2 times the HY, I would think it would be in the area of a 1.10 a/r… but I could be totally wrong.

    This is a pretty good Holset info site:
    http://dodgeram.org/tech/dsl/FAQ/turbo_faq.htm

  • #9
    Just thought I'd look up some prices on ebay for fun. I actually couldn't find any hx-35's, however I did find an hx-35W. I kinda assume they are the same thing. Would I be correct in this assumption?
    ~es3

  • #10
    actually you want to get a HX35W to be more specific. The "W" stands for "Internal Wastegate". Like the HX40 i have, its really a HX40W and has an internal gate on that big ass thing. But you can just get a HX40 that uses an external gate instead, just like you can on alot of the H1C's and H1E's. I know the HY35 ALWAYS comes with an internal gate and i thought all the HX35's did too. Forget what the poeple selling them say, look at the pictures and determine if it has an internal wastegate or not.

  • #11
    roastin300 wrote: actually you want to get a HX35W to be more specific. The "W" stands for "Internal Wastegate". Like the HX40 i have, its really a HX40W and has an internal gate on that big ass thing. But you can just get a HX40 that uses an external gate instead, just like you can on alot of the H1C's and H1E's. I know the HY35 ALWAYS comes with an internal gate and i thought all the HX35's did too. Forget what the poeple selling them say, look at the pictures and determine if it has an internal wastegate or not.
    I'm just starting to learn how to read compression maps…but I was wondering if the HX30 is good too?
    I heard the HX25 flows as much as the T3.
    I'm starting to wonder about other turbos now too.
    What other turbos besides garrett and Holset are great?
    Whats with this SCHWITZER turbo…I think they came off MACK trucks?
    I'm curious because it took this long for Holsets to catch on and now I'm
    curious if there are others like it out there.
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  • #12
    Im sure there are other brands that would work with our cars. Thing is about holset is its actually a T3 flange, has an internal gate and has appropriate size turbine housing wheel and A/R and ideal compressor flow ability. Most turbos on turbo diesels are improperly sized for an engine like ours. Most are huge ass 1.00+ A/R turbines and have compressors that flow even less. Very unideal. The HX30 i wouldnt even deal with. I dont know much about it but im sure it flows quite a bit less than the HX35. If your going with an aftermarket fuel system i would never use anything less than a HX35. I personally think the HY35 turbine side is too small for our engine, but obviously better than stock so.....depends on what your going for.

  • #13
    roastin300 wrote: Im sure there are other brands that would work with our cars. Thing is about holset is its actually a T3 flange, has an internal gate and has appropriate size turbine housing wheel and A/R and ideal compressor flow ability. Most turbos on turbo diesels are improperly sized for an engine like ours. Most are huge ass 1.00+ A/R turbines and have compressors that flow even less. Very unideal. The HX30 i wouldnt even deal with. I dont know much about it but im sure it flows quite a bit less than the HX35. If your going with an aftermarket fuel system i would never use anything less than a HX35. I personally think the HY35 turbine side is too small for our engine, but obviously better than stock so.....depends on what your going for.
    really the HY35 is not bad. The max choke load limit or whatever it is called is 29 compared to the HX35's 32. It's really not that much difference. Who's gonna run beyond 29psi anyways? The HY35 just spools up a bit faster because the HY was designed for the autos(for better stop and go). It has the same flow ratings as the HX35 and can make the same HP gains and you'd need the same fuel upgrades as if you were going HX35. Both compressor housings and compressor wheels are exactly the same(except for the HY's extra elbow). In fact I would prefer the HY because its faster spool up makes it close to the T3 spool up. It's crazy man. I'm thoroughly convince that Holsets ARE the shit. HY just has a bad rap…and are cheaper because of it. Even so, I'd still like to know everything that is out there. I hear ya on other Diesel Turbos though…
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  • #14
    I was just thinking, you could machine a spacer plate with a conical section attached that slips into the turbine housing making the entry narrower for higher velocity

    you could do this to any large turbine and very likely get quicker spool by cheating it into behaving like a smaller a/r

  • #15
    G-E wrote: I was just thinking, you could machine a spacer plate with a conical section attached that slips into the turbine housing making the entry narrower for higher velocity

    you could do this to any large turbine and very likely get quicker spool by cheating it into behaving like a smaller a/r
    Holset beat you to it

    http://www.holset.co.uk/files/2_5_1_5-VGT.php

    They actually had one on ebay that no one bought for $50.
    I was tempted to get it but I wouldnt know what to do with it since it
    is computer controlled with all kinds of sensors.

    EDIT: I found another one on ebay but this one has some people's attention.
    http://cgi.ebay.com/ebaymotors/New-H…QQcmdZViewItem
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