Custom Turbine Housing Manufacturer
Turbine Housing
Custom Turbine Housing Manufacturing FAQs
Can SIMIS manufacture a turbocharger turbine housing from my drawings?
Yes. SIMIS handles drawing-based OEM turbine housing projects using the customer's 2D drawings, 3D CAD data, material specification, production quantity and inspection requirements. We assess casting feasibility, core design, machining allowances and the critical interfaces before preparing a quotation. These are custom manufactured parts, not a catalog of universally interchangeable turbo housings.
Should my turbine housing use investment casting or sand casting?
The choice depends on the housing size, exhaust-scroll complexity, wall section, alloy, annual volume and inspection plan. Investment casting can suit intricate high-temperature steel designs; resin-bonded sand casting or shell molding may be preferable for selected iron-based housings. No single casting method is mandatory for every turbocharger design.
Which features need the tightest machining and dimensional control?
The turbine-wheel clearance region, center-housing locating interface, exhaust inlet and outlet flanges, fastener patterns and any wastegate-related seats or ports are common functional features. Tolerances, datum references and surface-finish targets should come from the mating-component drawings rather than from a generic precision claim.
What temperature and thermal-fatigue information do you need?
Please specify the engine duty cycle, exhaust-gas temperature range, peak events, thermal cycling, exhaust composition and any corrosion exposure. Material grades such as silicon-molybdenum ductile iron, nickel-alloyed cast iron or heat-resistant cast steel should be evaluated against those conditions and the customer's approved specification.
Can inspection and test reports be included in the order?
Project-specific dimensional reports, chemical or mechanical test records, hardness checks, surface examination and selected non-destructive tests can be discussed at the RFQ stage. Radiography, penetrant inspection, leak testing and other validation are not assumed to be mandatory for every housing; the scope and acceptance criteria must be agreed before production.
Custom turbocharger turbine housings guide hot exhaust gases through a shaped scroll into the turbine wheel. SIMIS focuses on the manufacture of the metal housing itself: selecting an appropriate casting route, preserving the specified flow-path geometry, CNC-machining interfaces and checking dimensions to the OEM drawing. Typical enquiries come from automotive turbocharger, commercial diesel engine and industrial engine programs.
A turbine housing is the hot-side casting. It is different from the cold-side compressor housing and from the bearing or center housing (CHRA). Their mating interfaces interact, but dimensions and validation requirements should be identified separately in the engineering package.
What Makes an OEM Turbine Housing Different?
A turbine housing must fit a particular turbine wheel, bearing housing, exhaust manifold and exhaust outlet arrangement. Its internal volute geometry is functional, not merely cosmetic: inconsistent sections, core shift or local restrictions can affect the intended gas flow. An OEM supplier therefore needs more than a nominal overall size or a sample photograph to reproduce the design.
| Housing feature | Why OEM engineers specify it |
|---|---|
| Single-scroll or twin-scroll passage | Defines the internal gas routing; a twin-scroll housing requires the specified divider and separate inlet paths. |
| A/R geometry and volute section | Connects scroll cross-sectional area to the turbine inlet geometry; preserve the approved CAD shape and measurement definition. |
| Turbine-wheel shroud region | Works with the rotor and CHRA stack-up to establish clearance under the intended operating conditions. |
| Wastegate passage or mounting features | Requires the specified port location, seat arrangement, travel clearance and actuator interface, where applicable. |
| Inlet, outlet and CHRA interfaces | Controls assembly alignment, flange seating, pilot location, bolt pattern and serviceability. |
Single-scroll, twin-scroll and wastegate variants
Single-scroll turbine housings use one principal gas passage, while twin-scroll variants maintain separate passages to a specified point near the wheel. Integrated wastegate housings add local seats, passages or actuator-mounting features. SIMIS can review such variations from drawings, but turbocharger response, boost control and emissions performance belong to the complete engine and turbocharger system, not to the casting alone.
Internal Volute Geometry, A/R Ratio and Core Design
The scroll cross-section, tongue or volute termination, wall thickness and passage transition should follow the approved 3D model. The commonly referenced A/R ratio is a design parameter associated with a defined passage area and radius; it is not a universal tolerance value that a supplier can independently choose or guarantee. The OEM should identify the inspection sections or profiles that matter most.
Core location and passage consistency
For sand or shell molded housings, cores form the internal passages and must remain positioned through pouring and solidification. Core prints, support strategy, minimum wall sections and cleaning access deserve careful review. For investment cast designs, ceramic cores or other core strategies depend on the alloy and required geometry. The appropriate route is confirmed during DFM rather than assumed from the finished appearance.
Clearance around the turbine wheel
The wheel-adjacent bore or contour is generally a machined or otherwise tightly controlled functional feature. Inspection should reference the locating face and pilot or bore datum used in assembly. Final running clearance is influenced by the wheel geometry, rotor position, bearing system and operating temperature as well as the housing; the casting supplier should not claim to establish it in isolation.
Choosing a Casting Process for Turbine Housings
SIMIS discusses process selection in relation to the customer's geometry, alloy, order volume and required internal quality. Our investment casting, sand casting and shell mold casting service information provides useful context for the routes considered on different housing projects.
| Manufacturing route | Where it may fit | Engineering considerations |
|---|---|---|
| Investment casting | Complex relatively compact high-temperature steel or alloy housings requiring detailed near-net-shape features. | Core feasibility, alloy castability, section transitions, tooling and qualification costs must be reviewed. |
| Resin-bonded sand casting | Iron-based or larger turbine housings, including shapes with cored internal passages. | Core support, passage cleanup, casting allowances, surface finish and machining stock are important. |
| Shell mold casting | Selected repeat-production iron or steel housings where a consistent molded shape is useful. | Tooling, core arrangement, alloy suitability and part size determine feasibility. |
| Precision CNC machining | Finishing cast interfaces or developing selected prototype features. | Machining complements casting; a complex volute is not automatically economical to make entirely from solid stock. |
Methods such as hot isostatic pressing should be treated as separate project requirements, not routine steps. Feasibility, material compatibility, outsourced operations and evidence of results would need to be confirmed before committing to them.
High-Temperature Material Selection
Turbine-housing alloys are specified primarily for the actual exhaust temperature cycle, oxidation environment, thermal expansion behavior, structural loads and manufacturing process. The relevant steel casting capabilities and material discussion can help frame a request, but a material grade should be formally approved against the engine manufacturer's duty conditions.
| Material family | Potential reason to consider it | What must be verified |
|---|---|---|
| Silicon-molybdenum ductile iron (SiMo) | An option for certain elevated-temperature iron castings where thermal cycling and oxidation behavior are design concerns. | Exact grade, maximum metal temperature, thermal-fatigue requirements, section thickness and heat-treatment specification. |
| Nickel-alloyed austenitic cast iron (Ni-Resist family) | May be considered where thermal stability and corrosion/oxidation resistance are relevant. | Correct standardized grade, mechanical properties, expansion compatibility, cost and casting route. |
| Heat-resistant cast stainless steel or other cast alloys | May be evaluated for demanding oxidation or high-temperature applications. | A designated cast grade, castability, weld-repair policy, oxidation behavior and component testing. |
| Other specified iron or steel grades | Application-dependent alternatives for less demanding or differently loaded designs. | Actual exhaust duty; ordinary gray iron or carbon steel is not interchangeable with a qualified high-temperature grade. |
A nominal exhaust-gas temperature is not the same as the metal temperature at every point on the housing. Avoid adopting a generic “up to 950°C” or “up to 1,000°C” rating without defining test conditions, material specification, thermal gradients and life-cycle requirements.
Precision CNC Machining of Turbocharger Interfaces
Casting produces the primary shape; precision CNC machining establishes the functional fits and seal-contact surfaces identified on the drawing. A sensible datum scheme keeps the critical features traceable from rough machining through final inspection.
Center housing pilot, turbine-wheel contour and flange geometry
Key features may include the CHRA locating diameter, turbine wheel shroud bore or profile, turbine inlet flange, turbine outlet connection and fastener interfaces. Geometric tolerances such as position, perpendicularity, profile, flatness and runout should be assigned to the relevant datums. There is no meaningful universal “zero runout” requirement for every custom housing.
Wastegate seats and machined ports
Where the design includes an internal wastegate, machining and checking the flap seat, pivot features or port geometry may be necessary. Other turbocharger designs omit these elements or use separate external hardware. The manufacturing plan must follow the actual drawing and assembly sequence.
If machining occurs before and after a specified heat treatment, the datum strategy and available stock need to account for possible distortion. Heat treatment through parts heat-treatment services is considered only when the alloy and OEM specification call for it.
Thermal Cycling and Design for Manufacturability
High exhaust temperatures and rapid engine load changes can create thermal gradients between thick flange sections, thin scroll walls and ribs. Design reviews should consider transitions, casting radii, constrained expansion and the choice of material. Thicker walls are not automatically better: they can increase thermal mass, create hot spots or make sound casting more difficult.
Wall thickness, radii and casting allowances
Where possible, avoid abrupt metal accumulations, unnecessarily sharp internal corners and narrow sections that cannot be reliably cored or inspected. The engineering drawing should distinguish as-cast surfaces from machined surfaces, define minimum wall requirements and set the inspection approach for hard-to-access channels.
Post-casting treatment and surface condition
Cleaning, scale removal, localized coating or other surface-treatment processes may be evaluated for specific material and application requirements. Not every high-temperature housing should receive the same coating or finishing operation. Service temperature, finish adhesion and the possibility of affecting mating surfaces need to be considered.
Turbine Housing Inspection and Acceptance Criteria
A credible inspection plan starts with the critical drawing characteristics and actual casting risks. SIMIS can discuss the appropriate checks with customers during RFQ and sample approval, rather than presenting every optional test as an automatically performed or certified service.
| Inspection or verification | What it can establish | Typical project decision |
|---|---|---|
| Material identification and chemical analysis | Checks the specified alloy designation against agreed material limits. | Material certificates or test reports to the agreed standard. |
| Dimensional and geometric inspection | Checks mounting interfaces, machined bores, flange position and selected volute profiles. | Drawing callouts, datums, sample plan and report format. |
| Hardness or metallographic assessment | Can support material and treatment verification where required. | Acceptance criteria and sample location stated in the specification. |
| Surface or internal NDT | Penetrant, magnetic-particle or radiographic methods may be selected for relevant materials and defects. | Procedure, inspection zones, acceptance level and inspector qualifications. |
| Leak, thermal-cycle or functional testing | Provides project-specific evidence when a suitable fixture and method are defined. | Usually requires an agreed housing or assembly-level test plan; not inferred from visual inspection. |
See our quality control information for the wider manufacturing inspection approach. Casting dimensional acceptance does not automatically certify exhaust leakage, thermal-fatigue life, turbocharger efficiency or long-term engine reliability. Those claims require the corresponding validated component or assembly tests.
Applications: Automotive, Heavy-Duty and Industrial Turbochargers
Passenger vehicle and performance engine programs
These projects may emphasize compact housing envelopes, detailed scroll geometry, closely packaged flanges and precise interfaces to manifolds and CHRA assemblies. The applicable alloy and heat-resistance requirements depend on the engine platform and duty cycle.
Heavy-duty diesel and off-highway engines
Commercial and industrial designs may prioritize robust flanges, serviceability, cyclic thermal loads and repeatable casting quality across production batches. The housing should be evaluated alongside the related intake and exhaust manifold and connected exhaust system.
Marine and stationary power applications
For stationary power or marine engines, long running periods, atmosphere, condensate and maintenance constraints may influence the specification. Related hot-side parts such as EGR valve housings have different internal functions and should be separately detailed and tested.
From OEM Drawing Review to Production
1. RFQ and technical review: Supply a dimensioned drawing, 3D model and assembly references. Highlight the critical volute sections, mating interfaces, expected operating environment and annual quantity.
2. Material and casting review: Agree on the material standard, manufacturing route, core feasibility, machining allowances, tooling approach and any special process requirements.
3. Sample machining and dimensional evaluation: Confirm the agreed functional dimensions and inspection records against the drawing. Any changes to the as-cast passage or pilot geometry should be approved through the OEM engineering process.
4. Production and quality documentation: Define batch identification, inspection sampling, any required NDT and acceptance documentation before the production order, rather than assuming universal certification or test coverage.
Request a Quote for Custom Turbine Housings
For a practical quotation, send SIMIS the 2D drawing and 3D CAD model, desired material grade or approved alternatives, single- or twin-scroll arrangement, critical A/R or flow-path requirements, turbine-wheel and CHRA interfaces, specified heat-treatment and test requirements, estimated annual volume and delivery destination. Clearly identify whether the request is for an as-cast blank or a fully machined housing.
Please email info@simis-group.com with your turbine housing drawings and RFQ details. We can review manufacturability and quote the scope that your documents actually define.
