Upgrading the K27 or something else? smoke issue update.
 

Gentlemen.

The K27 on my 3.3 has been repacked twice. It is one hell of a smoker on each start up. The turboshop down the road suggested to rebuild and upgrade. He was absolutely dead serious when he said that these cars are better off with the K27 instead of changing it out with a more "modern" ball bearing turbo. What I want is a turbo that is a little more efficient at lower rpm's. As it is now, 3000 rpm's before it happens.
Any suggestions or opinions are greately appreciated.

G

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Hoyo,

A couple things here. What year and model is your car, what mods have been done, do you have a K27 7200 on it now, is your smoking issue on start up only or is it constant while you are driving. Don't go out and buy a bunch of s--- until we find out what your working with here. if you don't have boost until 3000 RPM something is wrong. My old 7200 started building boost by 1800 RPM.

The more information we have the more we can help.

Cole

just got a Kokeln hooked in and running, a direct replacement aside from having to run an-3 oil supply, I have 1 bar by 2750 rpm.

I assume that you are getting full boost at 3000rpm. That would be correct for a K27-7200 with stock exhaust heat exchangers.
Yes the K27 series is an easy swap for the 930, as they were designed for the 965. There are many things that can be done to reduce boost threshold. Tell us a little more about the engine and suggestions will come.

Alright...thanks.

The engine itself is an -79 3.3. It was rebuilt by Precision in CA 3 years ago. The smoke lasts for no more than a minute after start up. Blue smoke. More when after sitting still for a day or so. Not much smoke on hotstarts. No smoke whatsoever while driving. The engine has a mild cam, Electromotive ignition, twin plugs, headers and a somewhat noisy muffler. On the turbo plackard it says on the top line....k27....
I had it dynoed and it came out with 280 at the rears. When I say 3k rpm before it happens, it could be a little less but it is in that neighbourhood. Then it takes off like a rocket. I can also get the serialnumber of the turbo if that is of interest. The intercooler is aftermarket.
I really appreciate all inputs.

G

G,
I suspect the oil is welling up into the turbo bearing(s). There have been reports on this forum that the rebuilt/new K-27's have a different thrust bearing that flows more than the earlier bearing configuration.
The turbo sump pump can't keep up with the additional flow, primarily at low engine speeds. A quick test to confirm this is;
Before shutting down the engine after the car has been driven, increase the engine speed to about 1500-2000RPM for about 30 seconds. Then let the engine return to idle speed just before turning off the ignition. Let the car sit for several hours and restart, testing for smoke.

If the smoke at startup is greatly reduced or gone, you've isolated the problem.

Before what happens? Do you mean...before you get full boost? Or do you mean you don't get any appreciable boost until 3000. What does your boost gauge say?
On the smoking issue...I would agree with WERK's suggestion.

Something is not right, you are about 50WHP down from where you should be.
A 7200 (if that is what you have) should be at full boost by 2800rpm at the latest with headers.
I would run a full diagnostics on the engine, checking compression, timing, AFR's, fuel pressures, and inspecting all hoses, CIS components, and your exhaust system.
The turbo type number is on the ID plate, in the lower right hand corner, the last 4 numbers.

Werk...
How funny, I have always strived to keep low rpm for at least 2-3 min before shutting down. I will try Your suggestions tomorrow. Way back when, I had a Volvo turbo and that thing was red hot after not that hard driving. Ever since, I always let the turbo cool down before shutdown.

Mark.
The "it" is my somewhat loose description of ka-booom...vroooom....woaaahhhh. When it really takes off is what I really mean.

Rarly8.
Thank You, I learn something new every day. I'm just in from my turboinspection. The last 4 says 7006. Can that explain something? The car in question will also, in the very near future, get a complete tune up. I was thinking that getting the turbo issue out of the way first would be the way to go.
G

Sounds like seals. Pull the intercooler and see if there is a fair amount of oil in there to.

The 7006 is a great turbo in that it has a larger hot side that makes for less exhaust pressure which adds about 20hp up top over a K27-7200. This delays boost about 300rpm over a K27-7200.

I agree, the HP numbers seem down.

You are a good candidate for a turbo up grade depending on your goals.

Do you want peak HP or drivability (less lag)?

Do you want a stock bolt up install or are you willing to do a little adapting if it can get you a turbo that is a better fit for your goals?

OK, I'm clear on the vrrrooomm being "IT". With a 7006 what you're experiencing is about normal for that turbo. Depending on which gear I'm in, I don't think I hit full boost until around 3400...and I also run with 7006 variation of the K27 turbo. What I do get for the trade-off of a bit later onset is strong boost all the way to the top. My car really shines and gets with the program from about 3800 through 6000 (I don't rev it past that). As us old MX dirt bikers are known to say "you gotta be on the pipe" (sorry, I digress).

The 7006 should kick with your mods right where you say it does.
Problem now is you are low on power. I'd check everything on the list and see what has malfunctioned.
The K27-7200 will give you a quicker spool but a little less kick on the top end.

Gentlemen.

I should have started this tread with....Gentlemen, forgive me my ignorance, I'm just a humble 928 driver just getting into the joys of the 911.

As far as tuning etc. I have done none so far. I am not even quite sure what I have on there and how it really works.

As far as the 280 on the wheels with this setup...if it is on the low side, is it possible that the turbo output/pressure is too low? I have bought some of Wayne's books but have not had the time to dig too deep into them so far.

I still have to do something to the smokeissue and the lag is still bothering me a bit. Would the recommandations be to modify the 7006 or get either another K27 of some kind or something completely different?
The ideal would be bolt on but as Mr 911st was getting into, some adapting could be done.
Ideally, I would prefer both peak and drivability.

Rarly8
What would Your recommandations be?
I also have to mention that the engine block number says that the engine is an 3.0. I asked Tony at Precision Porsche about that. He told me that the 3.3 block was cracked and they just did a block swap. The dyno also estimated 330 in the engine and said 280 at the rear wheels.
I will also dig into Your other suggestions.

G

Hoyo,
Before going off the deep end here and replacing what may be a fine turbocharger, could you relay to us in what state of tune is the engine?
For instance;
1.) you dyno'd the car - what were the AFR's? Were they recorded?
2.) what state of tune is the ignition? What's your timing?
3.) Do you have a stock exhaust? (i.e. heat exchangers, muffler, smog equipment)
4.) stock cams?

All the above factors can influence the dyno results. Geez, a fouled air filter can cause you to suck oil and reduce the engine output.

Looks like there are 3 issues, the turbo is blowing oil, the lag characteristics of the 7006 are not favorable, and the engine is down on power.
I sent you an email concerning your 7006.
Afraid you won't get to the bottom of the power issue without testing components and verifying ignition and fuel system tune.

When you say the K27 was repacked twice, what do you mean by that?
If the turbo has already failed twice it's likely not the turbo causing the problem.
Was this engine recently rebuilt? Was there any work done on the CIS?
More directly, was the oil sending unit at the back of the engine leaking and/or replaced?

I had a similar problem after my motor was rebuilt as well as the turbo. My mechanic sorted the problem and it seems the oil tank for the turbo was way too small. Ordered a new one from GSF and all is well.

The "repack" would be the $89 "superior k27 turbo overhaul kit" from ebay. I think.....from what I was told by one of the po's.
The "overhauling" was done by a buddy who was in the posession of a screwdriver and a wrench.
How can u beat that?

G

smoke
 

This appears to be somewhat common with the 930. Mine does the same thing, only sometimes though. I suspect the internal shaft seals in the turbo unit. Is there a test to confirm this source of smoking? I would like to know the turbo has an issue prior to removal and sending out for rebuild.

Thanks all,
John G

This does not inspire confidence that the rebuild was successful, unless your buddy has a lot of experience rebuilding KKK turbos. The 7006 has some unique parts and is not inexpensive to rebuild.