How much is a NEW #8 turbine shaft?

wild man · 12-12-2009, 05:39 AM

The only thing I need now to complete my hybrid project is a #8 turbine shaft. I am assuming that the turbine wheel and shaft are 1 piece, like they are on garrett turbochargers, right?

Does anyone know what the bottom-line price would be for a brand new one, and where to find such a deal?

TRP951 · 12-12-2009, 04:57 PM

I believe most aftermarket turbos for our cars use the #8 housing are using the stage 3 turbine wheel

wild man · 12-13-2009, 06:20 AM

I think I need some clarification here. Am I correct in thinking that there are NO modifications required to the turbine housing to run stage 2 or stage 3 wheels?

Also, it is my belief that the advantage to using higher stage wheels is to allow for better flow through the turbine, correct? And that would LOWER the amount of torque available to drive the compressor wheel, and RAISE the (engine) rpm's required to spool the turbo. With the size compressor wheel that will be going on the shaft, I cannot afford to give up ANYTHING, in either of those areas.

I was not really impressed by the size of the compressor housing that I am going to use. But when I saw the size of the wheel, I was, how should I say, slightly intimidated, by it. It has a diameter (exducer size) of 3". And, hold on while I put it on the scale, weighs in at almost 1/4 pound.

To produce the same amount of flow as the stock turbocharger, this hybrid should be able to do it at a considerably lower shaft rpm. But it is going to need as much "drive power" from the turbine, as it can get. It is my opinion that a stock #8 turbine already has plenty of flow. Does anyone see any flaws in my logic, here? I understand that I will have "slow" spool with such a massive compressor wheel, but what I want to avoid, is "late" spool, at least in higher gears (in lower gears, slow=late).

Rogue_Ant · 12-14-2009, 07:25 PM

hmm, without really getting into it - a larger turbine wheel can provide more torque to drive a big compressor. Think the lever effect of using a large lever vs small...
That said, you will probably be fine with a true #8 turbine wheel and hotside.

-Rogue

wild man · 12-15-2009, 12:50 PM

Quote:

Originally Posted by Rogue_Ant

hmm, without really getting into it - a larger turbine wheel can provide more torque to drive a big compressor. Think the lever effect of using a large lever vs small...
That said, you will probably be fine with a true #8 turbine wheel and hotside.

-Rogue

I understand that. I'm looking at the 7006/8 that I'm building, as a sort of "big brother" to the 7200/6 that most of your (non-S, anyways) 951 up-graders run with. It will sport larger compressor AND turbine wheels.

But what I think (but no one will confirm, nor deny) is that the higher stage turbines are less restrictive, like with the blades being clipped (that also means that the housing doesn't have to be altered). And what that means, is that the "higher stages" of turbine are NOT larger. Would someone who knows (and has the guts to say), either confirm or deny this please (and whether or not the turbine wheel is part of the shaft on these turbos)? They will allow higher flow at top-end, but at the price of later spooling - which, for my intents and purposes, is unacceptable. If this correct, it leads me to the conclusion that a "factory" stage turbine will not only be fine, but MORE desirable, than a higher stage one.

I've played around with some T3's (rebuilt, and reconfigured with different housings), but not sure if everything I know about them is transferable to K26's & K27's. It seems that, either I am on a subject that very few people know much about, or those that do know won't discuss it on a public forum, like it's privileged information or something. I'm much appreciative of those who DO know, and WILL say.

Rogue_Ant · 12-15-2009, 01:13 PM

You are correct in thinking that higher stages flow more... This is a general rule of thumb, as "stage" is simply a marketing term. That said, the higher the stage wheel, the larger it is going to be.
Yes, the turbine wheel is part of the shaft, just like normal Garrett turbos (and any other turbo).

-Rogue

PAUERMAN · 03:11 PM

Quote:

Originally Posted by wild man

But what I think (but no one will confirm, nor deny) is that the higher stage turbines are less restrictive, like with the blades being clipped (that also means that the housing doesn't have to be altered). And what that means, is that the "higher stages" of turbine are NOT larger. Would someone who knows (and has the guts to say), either confirm or deny this please (and whether or not the turbine wheel is part of the shaft on these turbos)? They will allow higher flow at top-end, but at the price of later spooling - which, for my intents and purposes, is unacceptable. If this correct, it leads me to the conclusion that a "factory" stage turbine will not only be fine, but MORE desirable, than a higher stage one.

In a nutshell, a Stg 3 turbine wheel is what is commonly used in aftermarket "street" turbochargers for the 951. The title Stg 2,3,5 etc are used by manufacturers like Garrett, Turbonetics, Precision etc. These labels are not used for KKK/Borg Warner turbochargers.

The higher Stg numbers mean that the turbine wheel is larger. So, some turbo resellers opt to clip smaller turbine wheels to increase flow up top and hopefully bypass the increased lag characteristics that is expected from a larger wheel. Many turbo builders will argue that changing the profile of the turbine blades will affect spool efficiency, so clipping the blades isn't necessarily a "win-win" situation.

Bottom line here is that a turbocharged engine is one of compromise. The configuration of a given turbo will be based on what you're wanting to accomplish. Want quick spool then expect less top end and vise versa for bigger power.

I've datalogged backpressure readings with a Stg 3 wheel in a #8 and #10 housing using a comparable Garrett/Turbonetics compressor wheel similar in size to a K27. I can say that if you are intending on using a smaller, factory #8 turbine wheel and housing, you will be encountering a greater than 2:1 backpressure to boost ratio at 16-18 psi. My #8 housing and Stg 3 wheel had readings of 42 psi BP with 18 psi of boost.

If spool is the most important variable you're interested in and you still want to make more up top then I'd recommend you look into some ball bearing CHRA's. I'm using a GT30R dual ball bearing turbo now and I would invite anyone with a 26/8 turbo to compare their spool characteristics against this "larger" turbo. I know many would be very surprised.

wild man · 03:39 PM

OK, so the higher stage turbine wheels ARE larger? That means, of course, that the housing would need to be milled out to accommodate it. That's more than I want to get into, so the stock wheel is still looking like what I want to go with.

I could have gone with a 7100 compressor off of a 3LDZ, but I'm now starting to believe that the 3LDZ was actually a K26 (wrong flange for a 951, though, right?), and not a K27. I dunno, maybe that would have been the better choice of compressor. But the 7006 is what I ended up with, so that's what I'll be using. Haven't heard of anyone else running a 7006/8 configuration, so maybe this'll be a first. There IS the possibility that it might not work so well, but I'm "strongly" hoping against that. It's funny that I kinda enjoy the "danger" aspect of blazing a previously un-run trail, since I don't consider myself much of a gambler - never been in a casino, nor do I have any desire to ever visit one. There must still be some of that "wild" blood in me, after all, even though I consider myself to be fairly old, now (be knocking on 50's door before too long).

pauerman, you say that factory #8 turbine will mean higher than 2:1 pressure ratio, but you say stage 3 is 42:18, and THAT is a fair amount more than 2:1. I plan on running 20psi, maybe a little more, if A/F ratio stays good. What would back pressure be for 20psi, using a factory #8, as opposed to a stage 2, or 3? And would that make my EGT's unacceptably high? Would it be better to go with a factory #10?

Ceramic BB's are outside the price range that I have to work with.

PAUERMAN · 12-15-2009, 03:32 PM

From what I know of K27 turbos, I thought the 7200 wheel is the one to go with. If the 7006 is even larger and you're staying with a smaller #8 wheel and housing, I would be concerned about the lag/surge potential of this arrangement.

wild man · 05:48 PM

Quote:

Originally Posted by PAUERMAN

From what I know of K27 turbos, I thought the 7200 wheel is the one to go with. If the 7006 is even larger and you're staying with a smaller #8 wheel and housing, I would be concerned about the lag/surge potential of this arrangement.

Well, here is the situation: I started looking for a 7200 compressor section several months ago, when I noticed how bad my 26/8 seals were leaking. But I had no luck in finding one. This may sound like a "conspiracy theory", but it looks like the aftermarket turbocharger outfits snatched 'em all up, so people like me won't be able to find one. Once I realized this was the case, and the fact that my seals are now leaking even worse, I was forced to "take whatever I could find", which ended up being a 7006. But realistically speaking, how much difference could there be between the 2. If my instincts are on the "money", it appears that "they" also launched a dis-information campaign making everybody believe that you "have" to use a 7200 compressor on a hybrid. And guess who the only people that have them are. But don't bother asking them to sell you one, because, they won't. They will only sell you (for $800-$900, or so) a complete hybrid turbo.

So my "countermeasures" plan (I'm NOT thrilled with the fact that I am now revealing it for them to see) is to get another #8 turbine shaft, put the 7006 wheel on it and have it balanced (already paid for). Then when I do the rebuild (K26/K27 rebuild kit is already paid for), I will also do the 7006 compressor upgrade. But if the 7006/8 hybrid isn't working out well enough, I can fall back on reinstalling the original K26 compressor and turbine shaft, which will be marked for proper re-alignment before being removed.

The only thing holding up the plan at this point, is locating the #8 turbine wheel/shaft that I'm going to need, to send in with the 7006 wheel, for balancing. As long as "they" are not also controlling the availability of K26 turbine shafts, my plan should work. I can do without finding another turbine shaft by using my current one. But that is plan B, which I would prefer not to invoke, due to the downtime involved with sending it out and getting it back, and the lack-of-a-backup-to-revert-to if, god forbid, it becomes necessary.

Sadly, I am one of those people who has a lot more time ON my hands, then money IN them. So if I am going to do this, my only option, is via the poor-man's route.

BTW, there IS also a plan C. And that would be to just rebuild the K26 and reinstall it, without upgrading it to a hybrid. I REALLY hope I don't have to invoke that one, but it does remain a possibility.

PAUERMAN · 12-16-2009, 07:47 AM

Are you sure that the 7006 or 7200 compressor wheels use the same backplate? What about the compressor housings - different wheels mean that you've gotta use the appropriate housing for each wheel.

Try giving Charlie at Evergreen Turbo a call. He does a bit of work on KKK turbos.

wild man · 12-16-2009, 01:56 PM

I have (recently purchased) a complete 7006 compressor section, with the correct housing and back plate for the wheel. That is really all I need to complete the project if I use the turbine/shaft from the K26/8 that is on the car now. But the issue I have with that is the 2 weeks or so of down time that would be required for getting it balanced with the 7006 wheel on it. I'm looking for another #8 turbine/shaft so that I can get the balancing done ahead of time, and reduce the down time to a day or so. But at this point, I will also consider using a higher stage #8, or even a #10 turbine/shaft, if someone has an extra one lying around that is usable. But for those, I would also need the turbine housing and back plate.