Deciphering KKK numbers - Shout out to Goran, Craig, Rarly and other gurus

[juicersr]

Thought i would give a little help to our friend Turboo934, aka 'Turbo Che', in helping him decipher the number plate on his K28. I too, am interested as i have a K27 that i am curious about as well. Is there a cold/ hot A/R in there somewhere?

Here is his K28

[RarlyL8]

K28-7028
Porsche P/N 965.128.004.85
KKK P/N 5328-988-7028
11RS housing

[juicersr]

Thank Bri. Does anyone have a A/R flow diagram for the various KKK models 26-29?

[Turboo934]

Brian: Will this work with Cristine's 3.0 or am I going to have to increase intercooler size? Will the CIS handle the increase? Thanks for your help.

[Porschepilot79]

Originally Posted by juicersr

Thank Bri. Does anyone have a A/R flow diagram for the various KKK models 26-29?

I have this diagram for a K27 7006 but hard to understand it since I don't know how to read these? I wish I knew what that turbo can hold to red line with our engines.

[Turboo934]

Juicersr: Thanks for posting this , I have called KKK's head office and no one has any information on this Turbo.Hopefully my K27 isn't damaged it worked sweet.

[911st]

I am not an expert but I suspect that is not a factory KKK plate or part number.

That is probably a hybrid like most the K28, K29, and HF's.

By the way, the K27-7006 has the same compressor wheel as the K27-7200. However, the 7006 has a larger hot side. This make for a little later boost onset but lowers back pressure in the exhaust manifold and increases efficiency (VE) so that it makes more HP.

Most the K28 & 29's used to be based on the larger 7006 hot side. The newer generation of K29 Quick Spool and HF's now seem to use the smaller K27-7200 turbine. This makes for even earlier boost onset but can lead to over-boost (.8 bar spring delivering 1+/- bar of boost).

[911st]

I am just guessing but the 11 migh be because it started out as a K27-11/11 which was sized to improve low end (smaller hot side).

I know just enough to make a mistake about all of this.

[911st]

Now I am really guessing and making stuff up.

Built on Feb 22, 2002.

It was a hybrid K28 made to fit in place of a K27-7200 on a 91 (or 92) 3.3 C2 turbo using an 11/11 hot side and a larger compressor wheel.

This was probably the HF of its day.

Sorry, I just can not seem to help myself.

Nite nite.

[RarlyL8]

Kieth is likely correct about that turbo.
No K28 was ever produced for a factory 930, and therefore no "965" Porsche part number for that turbo. I have never seen the numbers "7028" follow the proceeding KKK part number series.
Looks like someone was producing a high flow replacement for the C2T 7200. There must be more of them out there so someone has an answer.

I wish I knew what that turbo can hold to red line with our engines.

That depends on where your redline is and what boost you run.
A 7200 can pull the stock 6300rpm redline at 0.7bar but it takes a K27HF to power through 7000rpm at 1.0 bar. The 7006 should pull through the stock redline at 1.0bar.

[gogomobil]

does anybody know how much later the 7006 kicks in compared to the 7200?
how much power will it give compared to the 7200 @ 1bar of boost?

[Turboo934]

Cristine's 3.0 has a 6800 redline with 1.0 bar boost,0.9 at 7000 ft. Her K27 would come on at 2800 and be at max boost at 5500 but still pulls to redline. Just wondering if her intercooler is big enough for this K28?

[911st]

Originally Posted by Porschepilot79

I have this diagram for a K27 7006 but hard to understand it since I don't know how to read these? I wish I knew what that turbo can hold to red line with our engines.

The 2.0 is 1 bar boost.

Look at the smallest numbers on the bottom line. That has to do with how much air the compressor wheel is flowing. This is very rough but the smaller sized numbers are not far off from the HP That is, the very small .03 is loosely equal to the air flow required to support 300hp +/- say 20%.

The loops are islands of different efficiency levels. The center island is where the turbo is at its most efficient level.

This compressor wheel is at the center of its effecency islands at about .6 bar boost at about 220hp worth of air flow. The center looks like it operates at about 74% efficiency.

1 bar at roughly 300hp the turbo is still running at about 70% efficiency. This is actually good.

It looks like the peak efficiency island for the compressor wheel corisponds with about the same place most 3.3 930s make peak TQ. This is where the motor naturally runs at its most efficient level to (max VE).

The hard line that is on the left side of the map and the steeply goes up is I belive the surge line. This is where the turbo starts to work. At 1 bar is looks like it starts to work at about 100hp in air flow.

Looking at my normaly asperated 3.2 dyno chart it makes 80rwhp at about 2750rpm and 100rwhp at about 3200. Thus, one bar boost is going to be first made somewhere about 3000rpm. (Depending on the hot side.)

Overall it shows the K27-7006 compressor wheel (same as the K27-7200) is a good fit for cars up to the mid 300's hp.

Having said that, a larger compressor wheel that suppors more air flow would likely operate more effecently at peak HP and upper air flow levels.

The choice of hot side effects how the compressor wheel may actually perform. It is possable that while a larger compressor wheel be more effecent. If put with a to small hot side, effecencys may be lost there in the exaust . The very most power is going to be made when the peak HP is at the center of the effecency island and when using a hot side that is as big as possable but can get the turbo spinning at the righ speed without dumping much of any air out the wast gate. Unfortunitaly, it would be a dog to drive and would not bit boost untill like over 4k rpms or so. This is also why a 7006 makes more HP than a 7200 with both having the same compressor wheel. The 7006 creats less back pressure in the exuaust system.


I am rusty and not an expert in this stuff but that is how I read it and I could be wrong.

[Turboo934]

Brian : I tried to Email these to you , but they wouldn't go . So I posted them here.

[911st]

If you wanted you could take the housings off and measure the impeller and turbine. Might get you better info.

[Turboo934]

That's a good idea 911st

[RarlyL8]

After pouring through all of my files and talking to my turbo guru buddies we have an answer.


Drum roll please ...




It is not a K28.
It is a K27.
More precisely an early version of the K27HF developed by UltimateMotorWerks.

[911st]

The first ones used 7200 or 7006 hot sides. Any clue from the numbers which one this is?

I had one of there early ones before the move over to became an IA product. It was built off my core and used my 7006 hot side. They were just starting to see if there large compressor wheel would work with the 7200 hot side. Even with the larger hot side I alwas pulled about .93 bar boost with my .8 spring. (Ports, B&B, C2/S2 intercooler, SC cams, EBC). However, the EBC could keep it at 1 bar on most days.

[RarlyL8]

This one is derived from a 7200.

[Turboo934]

Thanks for all the info on this turbo. I owe you all a beer. Now to get with the rebuild and see how this turbo will perform. Thanks all.