pete95zhn

While I do not have any own car to work on/in/under, I changed turbo to my friend's car. Initially it was supposed to be a rebuild, but it became something bigger.
Reason for the rebuild idea was heavy smoking and thus excessive oil consumption. There was A LOT of play in the shaft, which appeared quite fast, without any signs of unbalance of the compressor wheel ( no marks in blades ).
I took the turbo to Garrett's official importer, and their comments of this particular item were shocking. "WTF is this puzzle, and where it is bought from? Seems to be built from various & mysterious parts. It's sad when people buy expensive polished s*** when there's OEM or reliable aftermarket ( = Garrett / Holset etc ) items available cheaper. I guess that there were no compressor charts etc available... " Oh well, there was some problems with boost threshold with this particular turbo...it spooled at 4+k rpm ( totally lifeless below ) and produced 330 crankhp while my own modified spooled at 3,5k and did 350 crankhp with all other engine mods being similar back then.
And this was not all. When the turbo was disassembled, some oddities were found, or should we say mismatches. Turbine wheel was so big that the compressor housing was machined too big, no diffuser area left. It was also not mated with the backplate...there's the notch where it should be in.

See this picture from Garrett's page, espacially how turbine wheel sits in the housing and the backplate. No such thing in this creature:



Somehow it was just raisd above it with spacer. No wonder that there were no boost below 4k. "This compressor has nothing to do with charging of air!" was the comment. The shaft's seal was of ancient coal/carbon type. The meaning of this was not quite clear to me...but apparently it was not to date.
Center piece had to be changed too, there were some threaded ( but plugged ) holes comprimising oil and water separating. The good news, shaft, turbine wheel and housing could be used.
Now it has TO4 compressor housing with appropriate wheel. It will be dynoed during the spring, but it should work better...

Pictures:





It's a tight fit, fortunately the intake flange was already modified:



The engine has GURU's AFMLink MAP-kit:



Thermostat housing is now twice midified:

Olli Snellman

Unfortunately this "Hitech turbo" was bought from respected Porsche parts company. Our friend thought he bought a superior charger which cannot be found from local turbo stores. Pete's modified 26/6 outperformed this "hyper turbo" clearly. After the dyno runs we just thought our friends system was not tuned up properly.

theedge

Looks like your friend has a nice paper weight

A bit OT, but thats the BMW throttle body right? Which BMW is it from?

pete95zhn

E28/24, 5 & 6-series 535i. And yes, one bolt is missing in the pictures....

blown 944

Ha, and I thought I did some off the wall stuff.

That wheel should not be in that housing and is definitely not a match to that backplate. To me it looks like they stuffed a "super" wheel into a std E housing. The inducers are the same but the exducers are 3.2" vs 3".

If they spaced it out to clear the backplate that is probably the reason it made **** pressure.

W/O pics of the hotside there is no telling what's going on.

Olli Snellman

That was Pete's Evo I version. On Evo II version this BMW "moped" TB was changed to this Edelbrock unit

pete95zhn

I'm sorry that I forgot to take the pictures of that hotside. I was just anxious to get it installed and out of my garage before the Christmas.

toddk911

Has anyone had much luck with more performance from other/bigger throttle bodies on the 951?

I have heard of many trying but never heard about any real gains.

blown 944

Many of them are incorporated into other mods at the same time so no absolutes.

However, after talking with Dave @ CEP, his flow bench results are encouraging regarding airflow = more power. I haven't done mine quite yet, but I will let you know.

pete95zhn

The thing that wonders me with this turbo issue is how many other 951 owners are at this very moment using similar jigsaw puzzles in their cars?

Or was this one just lemon, or sold to him because he was a foreigner? I guess we'll never know. Majority will just think that the reason for bad behaviour lies in the tuning, or other components, not in this state-of-the-art blower. Although it's interesting to know that the seller does not anymore advertise hp-figures their turbo's are capable of...

gt37vgt

I think throttle body up to 60 or 65mm makes sense after exhaust, maf,intercooler tank and pipes bigger than 65 is a bit hard and not needed until you've fabbed the inlet manifold and cammed up

toddk911

Yea, I was thinking the same that to a point you will need to upgrade the intake
itself.

What is the stock TB size in mm ??

blown 944

I find it odd myself, how this particular community gets wrapped up in vendor products.

Not that there is something wrong with that, just not what I am used to.

Raceboy

Wouldn't it be good for the community to know what products to avoid, Pete?

This case demonstrates clearly that aftermarket stuff isn't always better than OEM. And most engine hardware is just fine if the whole engine as a unit is tuned properly. That includes most of the rotating assembly, and not manifolds, engine management etc.

Every car manufacturer is looking for a way to cut costs and minimize warranty, that means most of the critical stuff (pistons, crank, rods etc) is top quality and pretty well thought out. But expensive to produce but not too critical for longetivity items (manifolds, mufflers etc non-moving stuff) is made as cheap as possible, just to make it's job.

pete95zhn

Well, bringing a Rennlist sponsor into a bad light usually ends to banning somebody...just ask Andrew...