Engine Bolts / Studs

Fits:
Porsche 911 1970-89
Click picture for large parts diagram.
Diagram Ref No 24.
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
Normally 24 studs per engine.

Solves the problems of loose head studs, The exhaust leak you hear in the 911 may actually be the cylinder head leaking where the studs have pulled loose. As Porsche increased displacement of the 911 engine, the different rates of thermal expansion have caused head studs to break or pull out from the engine case.
Superior Tested/Proven strength. (compared to Dilavar & Raceware)
Fits:
Porsche 911 1965-89
Porsche 964 1989-94
Porsche 993 1994-98
This product supersedes Porsche's old part numbers:
- 993 101 170 51
Click picture for large parts diagram.
Diagram Ref No 2.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310117054
The product you are viewing cross references to these numbers
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
- Porsche 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
- Porsche 964 (911) RS 3.6L 1991-93
- Porsche 964 (911) RS 3.8L 1991-93
- Porsche 964 (911) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
- Porsche 993 (911) C2 1994-97
- Porsche 993 (911) C4 1994-97
- Porsche 993 (911) RS 1994-97
- Porsche 993 (911) C2S 1994-97
- Porsche 993 (911) C4S 1994-97
- Porsche 993 (911) TURBO 1994-96
- Porsche 993 (911) GT2 1994-97
- Porsche 993 (911) TURBO S 1994-97
Fits:
Porsche 911 1974-89 (12pcs Required)
Porsche 911 2.7L Carrera 1973 (24pcs Required)
Diagram Ref No 2
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
91110117200
The product you are viewing cross references to these numbers
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
Price is for each.
Fits:
Porsche 911 1974-89 (12pcs Required)
Porsche 911 2.7L Carrera 1973 (24pcs Required)
Diagram Ref No 2
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
91110117200
The product you are viewing cross references to these numbers
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
SET OF 24
Head stud kit for Porsche 2.0L-3.8L air-cooled engines
Fits:
Porsche 911 1965-89
Porsche 964 1989-94
Porsche 993 1994-98
Diagram Ref No 2
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99310117054
The product you are viewing cross references to these numbers
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
- Porsche 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
- Porsche 964 (911) RS 3.6L 1991-93
- Porsche 964 (911) RS 3.8L 1991-93
- Porsche 964 (911) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
- Porsche 993 (911) C2 1994-97
- Porsche 993 (911) C4 1994-97
- Porsche 993 (911) RS 1994-97
- Porsche 993 (911) C2S 1994-97
- Porsche 993 (911) C4S 1994-97
- Porsche 993 (911) TURBO 1994-96
- Porsche 993 (911) GT2 1994-97
- Porsche 993 (911) TURBO S 1994-97
Sold each.
Fits
Porsche 911 1965 - 83
Click 'Zoom in' for large parts diagram.
Diagram ref no 6
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
90006010601T
The product you are viewing cross references to these numbers
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC

• Ultra-high-performance product
• Use of Titanium Ti6Al4V technology
Contains 12 x Studs, Nuts & Washers
Fits:
Porsche 911 1965-77
Porsche 964 (none Turbo)
Porsche 993 All
Porsche 996 (none Turbo)
Porsche 997 (none Turbo)
Porsche 986 All
Porsche 987 All
Porsche 718 4 Cyl Turbo
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
TITANSTUDS12
The product you are viewing cross references to these numbers
- Porsche Boxster 986 2.5L 1997-99
- Porsche Boxster 986 2.7L 1999-02
- Porsche Boxster S 986 3.2L 1999-02
- Porsche Boxster 986 2.7L 2003-04
- Porsche Boxster S 986 3.2L 2003-04
- Porsche Boxster 987 2.7L 2005 -08/08
- Porsche Boxster 987 S 3.2/3.4L 2005-08/08
- Porsche Boxster 987 MKII 2.9L 2009-2012
- Porsche Boxster S 987 MKII 3.4L 2009-2012
- Porsche Boxster 718 2.0L Manual (300 Bhp)
- Porsche Boxster 718 2.0L PDK (300 Bhp)
- Porsche Boxster S 718 2.5L Manual (350 Bhp)
- Porsche Boxster S 718 2.5L PDK (350 Bhp)
- Porsche Boxster T 718 2.0L Manual (300 Bhp)
- Porsche Boxster T 718 2.0L PDK (300 Bhp)
- Porsche Boxster GTS 718 2.5L Manual (365 Bhp)
- Porsche Boxster GTS 718 2.5L PDK (365 Bhp)
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
- Porsche 964 (911) RS 3.6L 1991-93
- Porsche 964 (911) RS 3.8L 1991-93
- Porsche 993 (911) C2 1994-97
- Porsche 993 (911) C4 1994-97
- Porsche 993 (911) RS 1994-97
- Porsche 993 (911) C2S 1994-97
- Porsche 993 (911) C4S 1994-97
- Porsche 993 (911) TURBO 1994-96
- Porsche 993 (911) GT2 1994-97
- Porsche 993 (911) TURBO S 1994-97
- Porsche 996 C2 3.4L 1997-08/01
- Porsche 996 C4 3.4L 1997-08/01
- Porsche 996 C2 3.6L 09/01-2005
- Porsche 996 C4 3.6L 09/01-2005
- Porsche 996 C4S 3.6L 09/01-2005
- Porsche 997 MK1 Carrera 2 3.6L 2005-08
- Porsche 997 MK1 Carrera 2S 3.8L 2005-08
- Porsche 997 MK1 Carrera 4 3.6L 2005-08
- Porsche 997 MK1 Carrera 4S 3.8L 2005-08
- Porsche Cayman 718 2.0L Manual (300Bhp)
- Porsche Cayman 718 2.0L PDK (300Bhp)
- Porsche Cayman S 718 2.5L Manual (350Bhp)
- Porsche Cayman S 718 2.5L PDK (350Bhp)
- Porsche Cayman T 718 2.0L Manual (300Bhp)
- Porsche Cayman T 718 2.0L PDK (300 Bhp)
- Porsche Cayman GTS 718 2.5L Manual (365 Bhp)
- Porsche Cayman GTS 718 2.5L PDK (365 Bhp)

Never lose sleep again over a bent or broken exhaust stud on a 911 engine. This new tool is a must for every 911 mechanic and will pay for itself the first time you use it. This is a quick and totally accurate tool to repair and replace broken studs without damaging the head, or worse, having to remove the engine. The SR065 fixture indexes off of the exhaust port (by using one of the various sized port bushings included), secures to the opposite stud, and allows you to drill out, tap, and replace the stud dead on, every time. Includes LH drill bits, tap with extension, drill jigs/guides, port bushings, and a sturdy storage case.
Now includes our SR065D drill guide.
Fits ALL of the 911 heads including the 993.
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
- Porsche 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
- Porsche 964 (911) RS 3.6L 1991-93
- Porsche 964 (911) RS 3.8L 1991-93
- Porsche 964 (911) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
- Porsche 993 (911) C2 1994-97
- Porsche 993 (911) C4 1994-97
- Porsche 993 (911) RS 1994-97
- Porsche 993 (911) C2S 1994-97
- Porsche 993 (911) C4S 1994-97
- Porsche 993 (911) TURBO 1994-96
- Porsche 993 (911) GT2 1994-97
- Porsche 993 (911) TURBO S 1994-97
Sold each.

Fits
Porsche 911 2.7L / 3.0L 1974-83
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99906200602
The product you are viewing cross references to these numbers
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
Sold each.
Fits
Porsche 911 2.7L / 3.0L 1974-83
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99906200602
The product you are viewing cross references to these numbers
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC

Fits:
Porsche 911 1972-73 (TYP 915)
Porsche 911 1974-89
Porsche 911 (930) Turbo 1975-89
Click 'Zoom in' for large parts diagram.
Diagram ref no 7
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99906218202
The product you are viewing cross references to these numbers
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)

Fits:
Porsche 911 / SC / Carrera 1977-86
Porsche 911 Turbo 1977-77
Porsche 924 1976-79 with 5-Speed Gearbox
Porsche 924 Turbo/ GT 1980-85 Manual Gearbox G31.01/02/03
Click 'Zoom in' for large parts diagram.
Diagram ref no. 2 (for 911) or no.19 (for 924)
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99906209802
The product you are viewing cross references to these numbers
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 924 2.0L 1976-79
- Porsche 924 Turbo 2.0L 1979-81
- Porsche 924 Turbo 2.0L 1982-84
Sold each
Fits:
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
- Porsche 924 2.0L 1976-79
- Porsche 924 2.0L 1980-85
- Porsche 924 Turbo 2.0L 1979-81
- Porsche 924 Turbo 2.0L 1982-84
- Porsche 924 Carrera GT 2.0L 1981
- Porsche 924 Carrera GTS 2.0L 1982
- Porsche 924S 2.5L 1986-87
- Porsche 924S 2.5L 1988
- Porsche 928 4.5L 1978-82
- Porsche 928S 4.7L 1981-83
- Porsche 928S2 4.7L 1984-86
- Porsche 928S4 5.0L 1987-92
- Porsche 928GT 5.0L 1989-91
- Porsche 928GTS 5.4L 1992-95
- Porsche 914 (1970-1976)
The Hex Head Bolt M8 x 16 is a versatile, high-strength fastener used in multiple locations across classic Porsche models—including the Porsche 911, 914, 924 and 928. As a critical component in securing brackets, covers, engine parts, underbody panels and suspension-related hardware, this bolt ensures structural integrity and reliability throughout the vehicle.
What This Bolt Does
The Hex Head Bolt M8 x 16 plays a crucial role in securing various mechanical and body components on a Porsche.
Common Functions
- Secures brackets, panels and trim pieces
- Anchors engine and drivetrain components
- Holds suspension hardware and mountings
- Fastens interior and underbody parts
- Provides structural rigidity where load-bearing fasteners are required
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
90007508704
The product you are viewing cross references to these numbers
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1987-1989 3.2L G50
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 911 1978-1989 3.3L Turbo (930)
- Porsche 924 2.0L 1976-79
- Porsche 924 2.0L 1980-85
- Porsche 924 Turbo 2.0L 1979-81
- Porsche 924 Turbo 2.0L 1982-84
- Porsche 924 Carrera GT 2.0L 1981
- Porsche 924 Carrera GTS 2.0L 1982
- Porsche 924S 2.5L 1986-87
- Porsche 924S 2.5L 1988
- Porsche 928 4.5L 1978-82
- Porsche 928S 4.7L 1981-83
- Porsche 928S2 4.7L 1984-86
- Porsche 928S4 5.0L 1987-92
- Porsche 928GT 5.0L 1989-91
- Porsche 928GTS 5.4L 1992-95
- Porsche 914 (1970-1976)
Novel ultra-high-performance product
• Use of Inconel 718 and aerospace technology
• Extreme perceived quality
Contains 12 x Studs, Nuts & Washers
Fits:
Porsche 911 1965-77
Porsche 964 (non Turbo)
Porsche 993 All
Porsche 996 (non Turbo)
Porsche 997 (non Turbo)
Porsche 986 All
Porsche 987 All
Porsche 718 4 Cyl Turbo
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
SL-In-12
The product you are viewing cross references to these numbers
- Porsche Boxster 986 2.5L 1997-99
- Porsche Boxster 986 2.7L 1999-02
- Porsche Boxster S 986 3.2L 1999-02
- Porsche Boxster 986 2.7L 2003-04
- Porsche Boxster S 986 3.2L 2003-04
- Porsche Boxster 987 2.7L 2005 -08/08
- Porsche Boxster 987 S 3.2/3.4L 2005-08/08
- Porsche Boxster 987 MKII 2.9L 2009-2012
- Porsche Boxster S 987 MKII 3.4L 2009-2012
- Porsche Boxster 718 2.0L Manual (300 Bhp)
- Porsche Boxster 718 2.0L PDK (300 Bhp)
- Porsche Boxster S 718 2.5L Manual (350 Bhp)
- Porsche Boxster S 718 2.5L PDK (350 Bhp)
- Porsche Boxster T 718 2.0L Manual (300 Bhp)
- Porsche Boxster T 718 2.0L PDK (300 Bhp)
- Porsche Boxster GTS 718 2.5L Manual (365 Bhp)
- Porsche Boxster GTS 718 2.5L PDK (365 Bhp)
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
- Porsche 964 (911) RS 3.6L 1991-93
- Porsche 964 (911) RS 3.8L 1991-93
- Porsche 993 (911) C2 1994-97
- Porsche 993 (911) C4 1994-97
- Porsche 993 (911) RS 1994-97
- Porsche 993 (911) C2S 1994-97
- Porsche 993 (911) C4S 1994-97
- Porsche 993 (911) TURBO 1994-96
- Porsche 993 (911) GT2 1994-97
- Porsche 993 (911) TURBO S 1994-97
- Porsche 996 C2 3.4L 1997-08/01
- Porsche 996 C4 3.4L 1997-08/01
- Porsche 996 C2 3.6L 09/01-2005
- Porsche 996 C4 3.6L 09/01-2005
- Porsche 996 C4S 3.6L 09/01-2005
- Porsche 997 MK1 Carrera 2 3.6L 2005-08
- Porsche 997 MK1 Carrera 2S 3.8L 2005-08
- Porsche 997 MK1 Carrera 4 3.6L 2005-08
- Porsche 997 MK1 Carrera 4S 3.8L 2005-08
Fits:
Porsche 911 /S (1965 to 1977; with 2.7L engines)
Porsche 914-6 (1970 to 1972)
Click 'Zoom in' for large parts diagram.
Diagram ref no 29
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
90110117300
The product you are viewing cross references to these numbers
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 914 (1970-1976)
Fits:
Porsche 914/6 (1970 - 1972)
Porsche 911 F (1965 - 1973)
Porsche 911 Carrera (1984 - 1986)
Porsche 911 Turbo (1975 - 1986)
Click 'Zoom in' for large parts diagram.
Diagram ref no 6 (and no 7 for 914 only)
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99906103402
The product you are viewing cross references to these numbers
- Porsche 911 1965-1968 2.0L / 912 SWB (F)
- Porsche 911 1968-1973 2.2L / 2.4L / 2.7L RS LWB (F)
- Porsche 911 1974-1977 2.7L / 1976-77 3.0 Carrera
- Porsche 911 1978-1983 3.0L / SC
- Porsche 911 1984-1986 3.2L
- Porsche 911 1975-1977 3.0L Turbo (930)
- Porsche 914 (1970-1976)
Precision Engine Bolts & Studs – Strength, Accuracy, and Reliability for Porsche Engines
Engine bolts and studs are the unsung heroes of your Porsche’s powerplant — small but vital components that ensure structural integrity under extreme stress. From securing cylinder heads and connecting rods to fastening crankcases and manifolds, every fastener must deliver uncompromising strength, precision, and clamping force to maintain your engine’s performance and reliability.
At Design911, we offer a comprehensive selection of standard and high-performance bolts, studs, nuts, and fasteners designed specifically for Porsche engines. Each high performance component is precision-engineered from high-tensile steel, titanium, or ARP-grade alloy, delivering exceptional resistance to heat, vibration, and torque fatigue.
Whether you’re rebuilding a classic air-cooled 911 or tuning a modern GT model, our manufacturer-quality fasteners guarantee secure fitment, consistent torque retention, and long-term durability.
What Do Engine Bolts and Studs Do?
Engine bolts and studs hold critical components together under immense pressure. They maintain precise torque and tension, ensuring the engine block, heads, and internal assemblies remain perfectly sealed and aligned.
Core Functions:
- Provide
secure clamping force for key engine assemblies (head, crankcase,
rods, etc.).
- Maintain
torque integrity under thermal expansion and vibration.
- Prevent
component movement, preserving internal clearances and sealing
surfaces.
- Support rebuild precision, allowing components to be serviced repeatedly without distortion.
Motorsport-grade fasteners are designed to handle repeated torque cycles and extreme stress, making them essential for both performance tuning and professional engine restoration.
Why Do Engine Bolts and Studs Fail?
Over time, fasteners experience stretching, fatigue, and corrosion from heat, oil exposure, and repeated torque cycles. Even the strongest bolts have a finite service life — and failing to replace them can lead to catastrophic engine damage.
Common Causes of Failure Include:
- Metal
fatigue or stretching from repeated torque applications.
- Corrosion
and oxidation, especially in humid or high-heat environments.
- Over-tightening
or under-torquing, compromising clamping force.
- Thread
wear or damage from improper installation or debris.
- Thermal cycling, weakening material structure over time.
Replacing aged or stressed bolts and studs during every rebuild or major service ensures your Porsche’s engine remains structurally sound and leak-free.
Why Replace with Precision-Engineered Bolts and Studs?
Upgrading to high-performance fasteners delivers the security and strength demanded by Porsche engines. Precision-engineered bolts and studs ensure consistent torque retention, improved reliability, and extended component life — especially in high-load or high-temperature conditions.
Key Benefits:
Superior
clamping strength and torque retention for critical assemblies.
High
fatigue resistance, preventing loosening or failure under pressure.
Improved
corrosion protection with zinc, nickel, or black oxide coatings.
Ideal
for rebuilds, upgrades, and performance tuning applications.
Precision-thread
machining ensures repeatable installation and alignment.
Available
in titanium and high-tensile steel for maximum strength-to-weight
ratio.
These bolts and studs provide the perfect balance of motorsport-level performance and road-going durability, keeping your Porsche engine secure mile after mile.
Highlights:
- Comprehensive
range of bolts, studs, and fasteners for Porsche engines.
- Manufactured from ARP-grade steel, titanium, or high-tensile alloy.
- Precision-machined
threads for perfect alignment and consistent torque.
- Improved resistance to heat, corrosion, and vibration.
- Essential for rebuilds, tuning, and restoration projects.
- Designed for air-cooled and water-cooled Porsche engines.