What are the options for converting a K26/8 to a hybrid with a K27 front-end?
 

It's way past the "due" date for replacing my turbo seals. What is holding me up (other than laziness), is indecision on whether to stick with my stock K26/8, or upgrade the turbo to a K27 compressor. If I was to upgrade, now would be the time, because the rebuild kit that I have purchased will do K26's and K27's, plus balancing is free with the kit. And balancing would definitely be required if a different compressor wheel is put onto the turbine shaft.

The first question is whether or not to upgrade. With 20psi of boost, it seems to make sense, as I'm worried that the K26 is running "off the map" by the time I reach redline. Is this a valid concern, or is the K26 OK for what I'm running? The other deciding issues are cost and downtime. I'm looking for the bottom line on both of those.

From what I have learned so far, K27's use a larger turbine shaft diameter, and do NOT use a water-cooled center section. I would like to retain the K26 center section and turbine shaft, if that is possible. Along with a K27 compressor wheel, housing, and backplate, what else is needed to adapt those items to fit the K26? Also, I've heard the the 7200 series of K27 compressors is the best one to use. Is that correct?

If what I'm asking isn't possible, what is the feasibility of going with a larger K26 wheel, and having the housing milled out for it?

OK, with 0 responses in 3 days, apparently it is NOT possible to adapt a K27 front (compressor) section to fit onto a K26 center, and rear, section. Since I am hell-bent on retaining the water-cooled center section, it appears that a K26/27 hybrid is simply not an option that is possible for me.

Let me ask one final question for the KKK experts, before I make the final decision to leave the K26/8 as it is, and just install the rebuild kit.

Is there any person (or company) out there that will send you a (bolt-on) modified K26 compressor section with a larger size wheel, if you send him/them your usable core?

P.S. I really don't want to go over the $200 mark, either.

The K27 compressor can be mated with the #6 or #8 hotside. So yes you can retained the water cooled bearing section. Yes the 7200 is the compressor you want.

Thanks for the reply, TD. By the lack of responses, I was starting to think that what I was asking about was impossible, and people though I should have know it, or something.

Knowing that it IS possible, my plan would be to remove the compressor housing and backplate from the water-cooled bearing section of my K26, and replace it with a K27-7200 compressor housing and backplate, You are saying it will fit, right?

Then I would put the K27-7200 compressor wheel onto the K26 shaft. From what I gather, the K27 shaft is larger diameter, but if building this hybrid is possible, then the part of the shaft where the compressor wheel goes must be the same size, correct? Then I would send in the K26 shaft with K27 wheel attached, to have it balanced. When it came back, I would then install the rebuild kit, and be good to go. Is this feasible, or am I still missing something?

No one responded because you'd find information on this if you looked around first. Either here, or on Rennlist etc.

I'm not versed on the specifics, but as I know, this is possible, and has been done. Did you search?

5 minutes returned a few threads that you posted in, which elluded to the fact that you can do this converstion as well as one thread from 2008... Info is out there...

Technoduck makes an appearance in a few of these threads; this one talking about the k27 hybrids:
http://forums.pelicanparts.com/porsche-944-turbo-turbo-s/447000-k27-k26-exhaust-housing-possible.html

This thread loosely covers it:
http://forums.pelicanparts.com/porsche-944-turbo-turbo-s/497614-kkk-turbochargers.html

That search query was just "k26 to k27" This is why I do as much reading on the information available, before asking about specifics regarding my intentions/situation.

Now that my memory is refreshed, I do remember asking about this, a little while back. But I got held up by something, and forgot about it. I think the issue was availability of K27's (especially the 7200), if I recall correctly. I remember talking to a guy who had lots of KKK turbochargers lying around, but he said they were all K26's - he did not have ANY K27's. Apparently they are alot less common than K26's.

I'm not prepared to spend 400-500 bucks on a freshly rebuilt K27-7200 (or hybrid), or a thousand on a new one. It just isn't going to happen. If that's what it takes, my k26 is just going to have to suffice. I was hoping someone would have a K27 with beat seals/bearings, or a bad turbine section, lying around that I could pickup for between 1 and 2 hundred. At this point it DOES NOT have to be a 7200 - I'll take ANY usable K27 compressor section that I can get my hands on, to build a hybrid. I there ANYone out there who can help me out, before I just say effit, and throw the rebuilt K26 back in?

PM sent

Since I posted in the 911 classifieds last night, and my last post here this morning, the PM's are starting to come in. No 7200's, though - maybe it's only those that are hard to find. So far, I've got one for a working 3LDZ with 57K for a reasonable price. But I think I recall (the last time I looked into this) a guy saying he had to have the compressor backplate milled to fit the K26 center. Can anyone confirm this?

I also got one for a good 7006 compressor (with bad turbine due to worn bearings) for an even more reasonable price (and close enough for me to go and get). If I recall correctly, the 7006 is the "big" one, isn't it? If so, will it even fit between the intake manifold and balance shaft housing (with a little bit of grinding, here and there)?

You do not want the 3LDZ or 7006 wheel. The lag with that compressor, especially with a #8 hotside will be huge. If your going to do it, do it right.. you gotta pay to play sometimes. I was quoted about 2 years ago no more than $500 to have my 26/6 converted to a 27/6 with the 7200 wheel. That included them buying a new wheel and balancing. For a turbo upgrade, and a good one at that its not that much money.

i'm just curious, where did you get this quote?

last i checked it was over $800 for a k26-to-k27 conversion rebuild with 1year warranty from a kkk authorized shop. this was over two years ago so the price most likely went up.

Well, that doesn't do me any good, either way. 500 is still way over what I can spend. That's why I have no choice but to build my own hybrid. I already have a paid-for balancing and rebuild kit. But I looks like I'm just not going to be able to play the 7200 game (nobody seems to have the 7200 parts that I need). I'm curious that if the 7200 game is the best one going, what is the 2nd best? That doesn't really matter though, because the only game I am able to ante up to at this point, is the 7006 game. I can only hope that it is a worth while improvement over the stock setup. I had concerns that the 7006 might not fit under the intake, but the person who I will be buying it from said that he got it from a guy who was using it on a 951, so that concern has now been alleviated. I will be getting the parts and starting the project very soon.

Is there anyone else running a 7006 hybrid setup?

You can also fit modified garrett wheels in the kkk housing for a better trim selection ...k 27 or the k 26 8 another option is enlarging the # 8 cold side and run a larger trim wheel. in the smaller cold housing thus no fitment issues... but you need to modify the intake side of the turbo ..

I'm not sure what you mean by a #8 cold side. I not going any bigger on the hot side. It's nice that bigger garrett wheels can be cut down to fit a k26 cold side, but without a larger housing, I wouldn't be expecting a whole lot of difference. And unfortunately, difference IS what I am going to be expecting, now that I'm considering a 7006/8 hybrid. Basically, I'm looking for the big HISS - that will warn them not to PISS (around with me).

I ve cut the bell off the #8 cold side and enlarged it I don't trim the wheel to fit .. if you look inside a normal 6 and 8 cold side you'll see a difference. in the cold side the normal 6 tapers in on the in let , the # 8 inlet has no taper on the hot side the number tells the story #6 stamp and # 8 stamp the #8 of course has the larger exhaust wheel . The best way to go on the build is the #8 hot side using the smaller 6 hot side does not offer the gains of f the larger # 8 wheel ...this is why the Turbo S models come with the larger .... Ive built and used both and I would always go with the * or a Garrett wheel with similar size or larger .

turbos
 

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Check with the 930 guys.

There is one company that takes the 7200 turbos and puts larger wheels in them. They should have lot of take offs.

Not sure about the 7200 housing. I belive the limit to a 7200 compressor is about 400hp as a suck through or about 425 on a MAP or maybe a good MAF motor.

Ok, I understand what you are saying now now. You are saying that a K26/8 already does have a larger cold side than a k26/6. I honestly did not know that (thought they used the SAME cold side). But anyways, it is still not big enough for my intents and purposes. I am putting together a 7006/8 hybrid. The 7006 compressor wheel is almost the size of a tuna can, so it should make difference. So far, nobody has come forward to say that they have tried this combo, but their is a recent thread floating around here, where someone posted a pic of a 7009/8 hybrid, which is just a little bit smaller. What is holding me up is the inability to locate a usable #8 turbine shaft. So it looks like I am going to have to wait for the warm weather because my secondary means of transportation is a motorcycle. I will have to use the turbine shaft from MY K26/8, and with having to send it out to Utah for balancing, I'm expecting about 2 weeks, or so, of down time.

Let me add to this that I like the sound of 400hp, but I will not go higher than that. I wonder if the 7006/8 upgrade that I am planning to do will get me to 400 without having to go any higher on boost, then (my current) 20psi. I know I will have to change the MAF intake pipe to a larger size to accommodate the7006 compressor, which I did purchase from of a 930 guy, by the way.

I do not know if it matters but a 7006 and 7200 compressor wheel flow just about the same. The main difference between a K27-7200 and 7006 is the 7200 has a smaller hot side for quicker spool and the 7006 has a larger hot side for less back pressure.

The limit of those compressor wheels is about 425hp.

I think you are correct. I have a used K27/6 that I picked up last week from a race shop. I'm also trying to gather info on this setup. I have K27-7006 cold side with a #6 obiously. I also have a thread on rennlist regarding this matter. I read that the 7200 is the updated version for the 3DLZ. The 7006 came on the 911 turboS and therefore the hot side was bigger(more lag). Since you are matting with a #6 that shouldn't be an issue.
My turbo looks in good shape but before I install it I'm going to have it rebuilt. I got the following prices for a rebuild:
Cheetah turbo:$400(local, Portchester NY)
Lindsey:$375
I don't know much about cheetah turbo but the guy actually knows a lot about rebuilding these. Lindsey guys offer great support and products therefore I think I'm going to ship it to them. I also need new gaskets and hardware.

Wildman Hurry up building that K27/6 with a 7006 compressor since I want know your results before I send mine for rebuild. OH also 400hp on a K27/XX may not be possible but I leave that answer for the guys who have the knowledge.

Well said.

Yes, just because a compressor wheel is capable of supporting say 425hp dose not mean it will. A small turbine will often cost HP as will restriction before the turbo like from an AFM, metering assembly, or such.

The 7200 compressor wheel is the more modern of the 7006/7200 and would probably be the better choice. It is also a tad larger.