Dougs951S

I've got a few questions concerning the holsets. I know a few guys have managed to stuff them into our cars and even mate them to a garret hotside, I want to know if an HY35 or HX35 cold side can be mated to a K26 center section and #8 hotside with either an HX35 or garret stage 5 turbine wheel. This is probably a pipe dream, but I am wanting to turn my k27/8 into a sort of holset mongrel and keep my exhaust. Possible, or must I convert my exhaust to a T3 flange and use a garret hotside?

alxdgr8

I should try bolting this bad boy to my 951 engine, it might get full boost by redline
Good thing it's going on a V8 instead!



But to be on topic, I don't think it's the right idea to use a Holset compressor as a hybrid besides just having a cheap compressor (which probably still isn't saving you that much money). One of the biggest benefits of a Holset turbo are their turbine wheel designs that allow a a journal bearing turbo to spool as quickly as their equivalent flowing BB Garrett, so you wouldn't want to put a different wheel on there. If you kept a Garrett/KKK turbine wheel I doubt you would gain anything besides taking up more space with the larger Holset compressor housing.

blown 944

The proper way to go about it is to use the whole Holset minus the turbine housing. You cannot use the HY variety though.

You can use a kkk replica housing and use the hx 35 turbine wheel. It requires slight machining of the exducer (small side) of the turbine opening and slightly reducing the od of the center section where it slides into the t- housing .

All of this can be done with a dremel and a DA sander.

I havnt tried to use a kkk hot side yet. It's been awhile since I've messed with it.


The real benefit in addition to the turbine wheel design is the durability of the thrust bearings.

Or you can easily change the flange and use a t3 housing. We used a .63 on daves and that thing spooled very quick!!!

Reimu

Would a hx35 with a t3 hotside fit my t3 crossover flange with no other modification besides the usual grinding of the bottom of the throttle body? (I have an a/c delete anyway).

Dougs951S

Sid, what is the real difference between the genuine KKK hotside and the replica? Is it just that the replica is slightly larger, or are there other differences that would motivate me to obtain a good replica housing to use vs my own perfectly good original number 8 housing? If it turns out I will have to buy another hotside anyway, this may just motivate me to go T3.

blown 944

I couldn't tell you off hand what the 8cm hot side difference is but iirc the wheel is much smaller. The t3 housing you need is for a stg 5 wheel.

@reimu, it should fit with the minimal grinding mods.

1987Porsche944WithRealLongName

How well do the holsets spool? Or are they more of a top end turbo?
I'd be happy with 1 bar at 3500 or below

Dougs951S

Is it possible a turbo shop could machine out my 8cm housing to accept the holset turbine? Is the physical fitment of the wheel the only issue vs using a replica 8 machined for a stage 5 wheel? I too an curious about spool with these turbos. The k27 7006 isnt the fastest spooling turbo so I would trade a few hundred rpm lag for considerable top end flow.

blown 944

I can tell you that a hx 35 with a .63 hot side will spool way faster than a 27-8. Matter of fact I'd compare it to a gt3076 easily.

I've driven all three configurations and the above mentioned is the best imo.

Even my full hx 40 with a very large hot side spools at under 3800rpms. And believe me it blows right past once it gets going.

I just drove it tonight and at anything over 2200 rpms it starts to make good power.

blown 944

I'd have to look at some parts again to remember what needed to be done to use the kkk hot side.

Dougs951S

Flow wise, could you compare it to say, a GT35R? I know both the turbine and compressor are slightly smaller, and that the turbine is slightly smaller than a stage 5 wheel as well. 3076 spoolup is impressive indeed! What would such a turbo be good for at say, 15 and 18 psi?

blown 944

At those boost levels on a 2.5 they are all going to make similar power. The billet 7 blade wheel will flow 60# per minute. The std hx 35 will flow 50+.

At those boost levels the mentioned hybrid setup will outperform a gt 35. It really is on par with a gt30r. Once you start running over 20 psi or making over 400 rwhp I'd look at either the billet wheel or go to a 40/35 hybrid. I ran that setup for a long time and it spooled before 3500 easily.

The only reason I'm running the bigger stuff now is for top end pull in the 1/4 and for standing mile.

If I were wanting a turbo that made power practically off idle and made a true 400 rwhp I'd go with the hx35/.63 combo. It spools so fast the car is practically undriveable. Full boost in first gear and massive tire spin, even on 295's.

Reimu

How about the hy35? Isn't it basically the same as the hx35 but with less lag and a little off the top? The hotside is 9cm compared to the 12 or something on the hx iirc

blown 944

The HY is a great turbo. Especially the 7 blade billet wheel.

Personally, I just like using the garret hot sides for more flexibility in AR.

The HY is honestly a perfect little turbo for our configuration, due to its small compressor size. The problem is, that the center section uses a large v band to connect the turbine housing.

I don't know how it would spool in comparison, but the DSM guys love them.

You can swap the wheels into a H1c turbo and then use a garret hot side. We did this on Dave's car and it worked great. H1c's are very cheap, so they make great donors for doing that.

blown 944

Did you think to look at the motives on the above link?

Also, take a quick read through and tell me how accurate he is in regards to how much boost some diesel engines are running. I've seen over 40 psi and pretty high egts as well.

IMO that is one mans opinion.

I've personally had most turbos completely apart and I don't see where the "Holset" turbos are inferior. In fact, I'd easily say the bearing designs are far superior!

There are many euro cars running holsets and have been for years. In America, we are just brainwashed by advertising.

The only thing I could think of that may cause all of this confusion is that diesel turbos use much larger hot sides for more flow. However, holsets have a very well designed turbine wheel for maximum flow for each size.

After all, it is all just pieces of metal. The Holset uses a robust material that holds up to high egts without problems.


I've studied turbochargers extensively, and I'll take a strong proven design at a low cost over what is being marketed as the "latest greatest".

Read the compressor maps, compare the materials and I doubt you'll find that a Holset is inferior.