Oddjob

Usually K26 "cheaters" have a K27 wheel in a machined out 26 compressor housing, and may or maynot have a modified turbine.

I have heard of modified -6 hot sides referred to as a "super 6". Somewhat larger turbine than the stock -6, and the hot housing is machined to accept the larger wheel. Not quite as big as a full -8 turbine, and the discharge opening is not as large as the -8 housing. More of a street application, as it allows for quicker spool than the -8, but somewhat lower backpressure than the -6 when running higher boost.

I was shipped a K27 Super 6 by accident from a turbo builder not too long ago, he sent me back the wrong turbo and I noticed that hot side was something unusual. When I called to return it, I was given the above explanation when I inquired about what it was.

Certainly a lot of tricks can be done and different builders will do some different things, but with the same idea.

What made you think to take it apart and measure the wheels? Is the turbine opening obviously larger than a stock -6?

Laust Pedersen

Here are some of the internal dimensions for the K26-6 and -8. The compressor wheel for the -8 turbocharger is slightly larger and I doubt housing can be machined for anything larger than that.
https://rennlist.com/forums/1380029-post4.html

On the -8 turbine housing the exit diameter is equal to the inside distance between the mounting bolts, meaning that if you draw a line, on any picture of the outlet, between the inside of two bolts/studs/holes, it will be a tangent to the exit hole. The -6 turbine exit is visibly different.

Btw, the compressor housing pictured is not a K26

Laust

Oddjob

Not that I would know, but the K26 cheater compressor wheels are 2.992" OD at the base, with an approx 1.0" height.

lart951

okay the compressor wheel inducer is 43mm and the exducer 65mm what is this thing a Frankenstein?

lart951

the turbine exhaust OD is 56mm compared to the true k26-6 which is 49mm

Dougs951S

Not a frankenstein, that is a stock k26/6 compressor.

lart951

yea but what about the turbine? the size is 64/55mm and stock supposed to be 64/48mm

Dougs951S

The 6 and 8 turbines have the same inducer size and differ only slightly in their exducers. They are both small turbines, smaller than a Garrett stage 3 for example and close to a stage 2 turbine. The number 6 hot side is also close in size to a .48 t3 housing, though it is still smaller. The 8 is closer to a .63 but is again smaller, a large reason people see gains going to a full garret with a .63 hot side. The replica hot sides are also larger than the genuines.

lart951

This is not a standard k26-6 the turbine size for the standard k26-6 should be inducer 64 and exducer 48mm, this specific unit is 64mm inducer and 54mm exducer explain?

by the way this is a turbo that I intend to sell is not for me I just want to make sure I advertise it the correct specs

Dougs951S

Sorry, I did but accidentally edited it. Those measurements are a stock number 8 turbine. You have a #8 turbine in a machined out #6 hotside with a stock k26 compressor wheel. Apparently. Not too sure what that means as far as where it came from or what it will do. Hope that helps.

lart951

according to oddjob in his quote below could be a super -6

Dougs951S

I could be wrong but iirc I mic'ed my #8 turbine off my k27/8 at ~64/55.04. Hence why I believe it to be a genuine fullsiZe 8 turbine. I could be wrong though as its been awhile.

lart951

can you verify those #'s

Oddjob

How does the inside of the hot housing look - does it appear to be machined, or has it been originally cast w/ the larger opening?

Laust Pedersen

Correction: I looked at URG8RB8’s pictures when commenting about the compressor. Sorry about that and let me try to “un-mess” my mess.

It is obviously a K26 compressor housing and the wheel diameters I have for the K26-6 compressor wheel are 44/66 mm (the diameters for the K26-8 compressor wheel are 46/66 mm).
So based your numbers and pictures it looks like you have a K26-6 compressor housing and wheel.

The turbine has a modified -6 housing. The number 6 is cast in the inlet, it has a flat spot on the scroll and has KKK embossed. The standard -6 turbine wheel has the diameters 64.5/48.5 mm, add some clearance and the exit hole is 50 mm.
The -8 wheel has the diameters 64.5/54.5 mm, add some clearance and the exit hole is 56 mm.
So based on your numbers and pictures it looks like you have a K26-6 turbine housing bored out to accept a -8 turbine wheel.

Boring the housing can be done by simply increasing the diameter, or as it should be done: increasing the diameter and follow with a radius that fits the transition between the two diameters on the wheel.


Oddjob,
The critical dimension for the max wheel in the K26 compressor housing is the inducer (small) diameter. The OD of the hose attachment is about 50mm and the K26-8 compressor wheel has an inducer diameter of 46 mm. Add to that some clearance and you have about 1.5 mm wall thickness, which I would judge to be minimum for structural integrity.

Laust

PS My numbers are taken from my earlier reference and converted to mm.