Dougs951S

I've been doing a lot of reading about holset turbos and plan to install a complete HX35 with a replica #8 housing soon. Most of the info I've gathered is from the DSM guys so I will be referencing their info. It seems a common choice amongst that crowd is a .55 T3 hotside very similar in size to the hotside in question, which I believe works out to .57 A/R. The common consensus among DSM guys is that their .55 bolt on housing chokes the compressor and does not allow the turbo to reach its maximum flow potential. They say that high 40's-low 50's lb/m is pushing the limits. Anecdotal evidence also says that while the 7 blade billet wheel flows more on the top end vs the 8 blade, it is slower to spool within a pressure ratio that a 951 engine would be working in, IE below PR of 2.5. That all being said, my question is will the replica #8 hotside allow the 7 blade billet wheel to reach its full 60 lb/m flow and will it make a difference vs the 8 blade at a boost level my engine is likely to live at? I'm shooting for 375 rwhp/tq at no more than 18 psi as that is about all my clutch will take, and I dont know if that is unreasonable for a typical MAF setup with supporting mods. I'm also hoping to have better spoolup than my current k27/8 which I've so far been very pleased with.

pole position

http://timsturbos.com/products/turbine-housings

Dougs951S

I'm not sure what the point of that link was...I asked about flow limits and you linked to a site that sells hotsides. I don't need a hotside, I already have a turbonetics replica #8 that is going to be machined to fit the holset turbine wheel. Its very roughly the same size as the garrett stage 5 but with much better aero. The word from the DSM guys is that a lot of the stuff provided by that vendor is chinese knockoff stuff anyway. I basically just want to know if the #8 housing can flow more than the ~52 lb/min that the 8 blade compressor can provide, and if the 7 blade will still flow more at lowish ( read less than ~21 ) boost levels.

blown 944

I don't think enough people have pushed that hotside to a maximum limit. Personally, I think it would be good for around 400 hp with a large enough WG bypass. I do know that it can be done, as I've seen one machined for Josh that has yet to be installed.

I do know that a 7 blade HY using a .63 hs spools very quick.

I currently have a 7 blade with a .63 hs on a DSM and it seems to spool on par between a 30 and 35 garrett.

Rogue_Ant

An HX35 turbine wheel is very similar in size to a garrett T350 (aka stage 5). 400rwhp has been done on a smaller stage 3 turbine wheel in a #8 housing.

Will the #8 turbine housing allow full potential from a 7-blade compressor? Possibly not, but it would still be a good match-up.

Dougs951S

Thanks Sid, I was hoping you would chime in on this. The HY concept is interesting. I know the way to do it is to put the compressor and turbine onto an H1C CHRA and then bolt to the hotside of choice; does it matter whether you use the HY or the H1 compressor cover since they are both Vband? From what I know the HY compressor is the same 60# billet compressor as found in the HX35 right? Could I just snag the turbine wheel (and maybe compressor) from an HY and use that with an HX35 inside an 8/stage 3 hs to get the same effect? I'm aiming for a quicker spooling, more durable version of a 60-1 hifi/stage 3/#8.

blown 944

The easiest way to get around the issue of the HY center cartridge problem is to get a specific hx351. I don't know the part number off hand.

Tbh, using an hx vs an hy is of minimal consequence in regard to compressor. The hy also uses a smaller turbine wheel (close to stg 3). That is where the quicker spool comes in.

What option to go with depends on what you have to start with.

Any of the holsets will be durable. For simplicity though, an hx35 is the easiest due to the bolt on turbine housing.

I realize this is scattered, but I don't want to re type it

Edit; the compressor wheels are not the same between the two, with the exception of the specific hx I mentioned. However, idk the turbine specs on that one.

blown 944

Also the hy poses a problem for size (it doesn't interchange with other center sections) The hy is great bc it is small (to4b small). The h.1c uses a larger cover but also uses the bolt on style t housing vs the small v band.

Dougs951S

Right, for our applications the HY center is useless. Sorry if what I said before was confusing, because its a bit confusing to me reading what I read

I remember you saying some time ago though about another lister ( maybe Dave? ) just swapping the HY wheels into an H1C, but wasnt that turbo using the HX turbine? What was the reasoning for using the H1C donor? Wouldnt it be easier to just pull an HX35 apart and stick the HY turbine wheel in since the hotside I have is currently set up for a stage 3 wheel anyway and would require less machining than if I were to try and fit the larger HX turbine wheel? My research seems to suggest this is posible. That would give me the best of both worlds since IIRC the HX35 compressor housing is a bit better due to the MWE webbing( and probably fits better in our cars ) than the H1C's, the wheel flows ~4-12 lbs more depending if its 7 or 8 blade, and the CHRA is more robust. Bonus too is that if I decide the smaller turbine is choking me, swapping to the HX turbine would just be a matter of machining the hotside to fit. Right now I can snag a complete HY35 that is already disassembled really cheap on ebay, and cheap HX35s abound. Am I making sense here or talking nonsense?

blown 944

You are on the right path with using an hx and swapping the hy turbine wheel. I don't remember why we went the route we did, but more than likely was due to parts in hand. I don't think we had a full hy yet, just the comp housing.

Dougs951S

I feel confident in taking apart a turbo and rebuilding it if needed, but if I just replace the turbine and make sure to mark thr position of everything before I take it apart, will I need to have the turbo rebalanced? If I use the hy turbine in my stage 3 housing I think it may fit with very minimal machine work needed. The exducer is .3 mm larger and the inducer is 1.4mm larger on the holset vs A t31 turbine. Will the holset bolt to the stock mount with the standard grinding to the tb, and what should I do about oil feed? Custom fabbed line or will stock feed work? I know it will need a 2mm restrictor. Does the factory rubber connection pipe work for the holset compressor outlet to intercooler inlet, or will I need a larger one?

blown 944

They are component balanced, do no need to mark or rebalance.

They bolt to the mount. You have to grind the mount and dldo grind the mount where the comp housing interferes, you also have to grind on the bottom side of the intake and tb.

I forget the feed only ATM, iirc it's around a 12mm metric thread. I used a .060 nitrous jet for a restrictor.

The outlet is bigger, so you will need a larger coupler.

Dougs951S

Good info, I really appreciate all the help sid, I'm taking notes. As far as grinding on the mount and intake, is it because the compressor housing is so large it contacts the mount and the amount I need to take off will be obvious when I go and try to bolt it up? The oil feed for the HX35 is 12mmX1.5 which can be drilled out to 1/4 npt while I have the turbo apart to makes fabbing up connections easier. I cant think of any way to reuse the factory oil feed since it has that weird flange, so my best bet may be the 1/4 npt hose offered by lindsey racing. I can also get male 12X1.5 to female 1/4 npt adapters. How did you set up the n20 jet in the line? I know a jet will sit inside a -4 AN fitting but thats not going to work here with other fittings involved. I guess I could chop the AN-NPT 90 degree fittings lindsey supplies and stick the jet in there.

Joshua you have a pm which admittedly isnt completely relevant now that I've pulled the trigger on a holset setup.

Dougs951S

just picked up a perfect condition 7 blade HX35 with zero shaft play for a song. Trying to decide now if it will be worth my time and money to locate an HY35 turbine/shaft and throw it in or just run what I have.

Supachink

awesome! please keep us (or at least me posted) about this. I have an old to4B with a replica #8 that i was interested in building a similar style hybrid out of! out of curiosity, any reason that you chose to go with the holset over a garret?