[How do I?] Turbo machining

[mxmatt15]

I am trying to do a hybrid turbo build, reusing the factory turbine housing as my car has a Mazda specific flange and using a large compressor housing and of coarse using a CHRA that can flow more, I am looking to obtain 45lbs/min for my power goals. Then ofcoarse I would have to have the housings machined to allow for the bigger wheels. Being that I have no experience in machining, I am looking for advice on how I should go about doing this, and how I can find a machinist that can do this. For my plans, I plan on still usign a journal bearing housing, as it is rebuildable and cost effective. The current turbo I have is rated at about 35lbs/min, K04 turbo. Any advice would be greatly appreciated.

These are the specs of the stock turbo:

Measurements: K04

Compressor Inducer 45.1mm
Compressor Exducer 56.0mm
Turbine Inducer 50.00mm
Turbine Exducer 44.47mm
Shaft journal dimension 6.96mm
Shaft end 4.56mm

And a GT28 for reference for something I would like to get close to

Compressor Inducer 47.21mm
Compressor Exducer 60.00mm
Turbine Inducer 53.80mm
Turbine Exducer 46.82mm
Shaft journal dimension 9.15mm
Shaft end 5.97mm

 

[Phils69]

To be short about it sketch up a print along with the type of material and we can better assist your goals.

 

[Jon K]

I am trying to do a hybrid turbo build, reusing the factory turbine housing as my car has a Mazda specific flange and using a large compressor housing and of coarse using a CHRA that can flow more, I am looking to obtain 45lbs/min for my power goals. Then ofcoarse I would have to have the housings machined to allow for the bigger wheels. Being that I have no experience in machining, I am looking for advice on how I should go about doing this, and how I can find a machinist that can do this. For my plans, I plan on still usign a journal bearing housing, as it is rebuildable and cost effective. The current turbo I have is rated at about 35lbs/min, K04 turbo. Any advice would be greatly appreciated.

These are the specs of the stock turbo:

Measurements: K04

Compressor Inducer 45.1mm
Compressor Exducer 56.0mm
Turbine Inducer 50.00mm
Turbine Exducer 44.47mm
Shaft journal dimension 6.96mm
Shaft end 4.56mm

And a GT28 for reference for something I would like to get close to

Compressor Inducer 47.21mm
Compressor Exducer 60.00mm
Turbine Inducer 53.80mm
Turbine Exducer 46.82mm
Shaft journal dimension 9.15mm
Shaft end 5.97mm

I have a 76mm T4 on a BMW making 700 RWHP. I am pretty familiar with turbo geometry and the like. The issue you will have is how much material is available in the original casting. You're only opening the inducer up a bit and the exducer up 5mm, but the problem is theres a swept curve between those two points that 1) is most likely NOT the same on both wheels 2) needs to be supported by enough aluminum 3) Needs the proper machining to have a gentle radius that follows the curvature of the compressor wheel. You also need to keep in mind that the cast wheels shrink and grow a bit both based on temperature and RPM... so...

The problem is, you can stuff GT35R into that and preserve your housings, but you end up with TINY A/R turbine and compressor covers. You would sooner have much better having a cast/tubular/billet transition to take your stock small Mazda size to something else. You probably have a round flange shape, right? Getting that adapted to a T25 flange or T3 is MUCH more practical than retrofitting +2 - 4mm wheels into a small housing.

Sorry but a machine effort for this will be well over the price of a manifold on your car + T25 flanged or small frame T3 (like a GT2871R).

In short - let the professionals design the comp and turbine housings, just buy the stuff

 

[mxmatt15]

Well, I am not knowledgable with and CAD so not sure how I can help there. I know the turbine/hotside is cast iron and the compressor housing is aluminum.

 

[Brandon]

My professional opinion, don't mess with the turbo. I was a machinist for a company that manufactured industrial turbo compressors. They spin at 150,000 rpm. You have to figure out how much the impeller flexes when it's at it's highest rpm. That was figured out by the engineers for me, I just profiled the impeller and machined the housing. When at speed, the impeller will contact the housing if not enough clearance is provided sending chunks of metal into your engine. Too much, and you will lose efficiency. I won't even get into the balancing issues. I would recommend you read the book Turbochargers by Hugh Macinnes (HPBooks) it's dated, but it has a lot of useful information.

 

[mxmatt15]

I have a 76mm T4 on a BMW making 700 RWHP. I am pretty familiar with turbo geometry and the like. The issue you will have is how much material is available in the original casting. You're only opening the inducer up a bit and the exducer up 5mm, but the problem is theres a swept curve between those two points that 1) is most likely NOT the same on both wheels 2) needs to be supported by enough aluminum 3) Needs the proper machining to have a gentle radius that follows the curvature of the compressor wheel. You also need to keep in mind that the cast wheels shrink and grow a bit both based on temperature and RPM... so...

The problem is, you can stuff GT35R into that and preserve your housings, but you end up with TINY A/R turbine and compressor covers. You would sooner have much better having a cast/tubular/billet transition to take your stock small Mazda size to something else. You probably have a round flange shape, right? Getting that adapted to a T25 flange or T3 is MUCH more practical than retrofitting +2 - 4mm wheels into a small housing.

Sorry but a machine effort for this will be well over the price of a manifold on your car + T25 flanged or small frame T3 (like a GT2871R).

In short - let the professionals design the comp and turbine housings, just buy the stuff

There is a guy that does this modification, but that the price they go for, you can get one off the shelf. That was another idea I had, was to make a flange. I was thinking of getting a Mitsubishi type flange and running a tdo6 20G. Here is something I would need have made





The threads seem to be the same for the oil return so it should bolt up to my factory one.

 

[Brandon]

Now that's do able. Looks like something that I was planning to do in my free time lmao to drop a Garrett unit from a 7.3 power stroke on my drag car. Kinda a junkyard performace mod like they did way back, before Jegs and Summitt took the backyard inovation out of racing... Anyhoo, I'm sure if you get accurite measurments someone can whip up a few flanges. Remember, this is a hobby forum, most guys on here do this for fun and deadlines are flexable due to day jobs (myself included).