Stage 1 – Starting Point and Target Definition
Original engine: M113 4.3-liter V8 (C43 AMG, W202), factory output according to original type approval.

Target engine: M113 5.5-liter V8 from the C55/E55/CLK55/ML55 family. Depending on the donor vehicle, different engine variants are used (including M113.980 in the W202 C55, as well as M113.986/.987/.988 in other model series), which differ in oil pan, oil pump, starter position, and control by the engine management system. Not every variant can be installed in the W202 without modification—the oil pan in particular sometimes needs to be adapted or replaced with a compatible version.

Important for later registration: Fully document the engine number and engine type of the donor unit from the very beginning.

DEKRA service at this stage:
Even before the project starts, DEKRA experts provide clear information about legal requirements and offer individual advice on which inspection or approval will be necessary for the specific project. DEKRA supports nationwide in the inspection of technical modifications and informs about which inspection or approval is necessary in the specific case. This early coordination prevents components from being installed later that cannot be proven eligible for registration.

Stage 2 – Technical Modifications to the Drivetrain
Engine mounts: Adaptation to the changed engine geometry.

• Engine management: Depending on the donor engine’s year of manufacture, either ME2.0 or ME2.8 Motronic is used. There are hardly any differences between the two on the engine itself, but the diagnostic interface differs, and switching from ME2.0 to ME2.8 means significantly more effort than staying within the ME2.0 system.
• Transmission and axle ratio: Recommendation to keep the original transmission and existing axle ratio in the vehicle if possible, to avoid subsequent changes to the driveshaft and control unit.
• Intake and exhaust system: Adaptation to the larger displacement and proof that exhaust behavior does not worsen the original emissions class.
• Instrument cluster and mileage: When using a donor instrument cluster, complete documentation of the actual mileage is crucial to avoid later disputes during sale or inspection.

Stage 3 – Safety-Relevant Components

• Brake system: Check whether the increased power requires modification of the brake system.
• Cooling system: Adaptation to the higher thermal load of the larger unit.
• Electrical/immobilizer: Coordination of control unit, ignition switch, and immobilizer if components from the donor vehicle are adopted.

Stage 4 – Legal Framework for Registration Eligibility
Since there is no parts certification for the individual engine swap, the simple *installation inspection according to § 19 Para. 3 StVZO* does not apply, as would be possible for wheels with valid parts certification, for example. An installation inspection requires that a parts certification exists for the modification and only the correct installation needs to be checked—this is not the case for an engine swap of this kind.

Instead, individual assessment according to § 19 Para. 2 StVZO or § 21 StVZO applies: If there is no modification approval with valid test certificate for the changes made, an individual assessment according to § 19 Para. 2 or § 21 StVZO must be carried out, which may only be performed by specially trained experts. This inspection is significantly more comprehensive: The inspector must evaluate the vehicle in its entirety, which often requires technical evidence or measurements.

Additionally, the principle from § 19 StVZO regarding operating permits still applies: According to § 19(2) StVZO, technical modifications can lead to the expiration of the operating permit if either a change in vehicle type occurs, a deterioration in exhaust and noise behavior is expected, or a hazard is anticipated.

DEKRA service at this stage:
DEKRA is one of the inspection organizations authorized to carry out such an assessment. If there is no recognized test certificate for a technical modification and the operating permit has therefore expired, DEKRA determines through an expert report for the issuance of an individual operating permit according to § 21 StVZO whether the vehicle still complies with legal regulations. Only officially recognized experts of the Technical Inspection Center for Motor Vehicle Traffic or authorized signatories for the complete vehicle of the Technical Service, who prepare individual approvals, expert reports, and certificates according to EC-FGV as well as § 21 StVZO, are responsible. In the event that an official approval mark is still missing for individual installed parts (e.g., a modified exhaust system), the DEKRA Automobile Test Center can additionally step in: As a Technical Service designated by the Federal Motor Transport Authority, it tests vehicle parts according to legal requirements and issues the resulting type approvals or parts certifications, which then serve as the legal basis for installation.

Stage 5 – Scope of Technical Inspection
The expert checks in the context of the individual inspection (according to VD-Tüv-Markblatt 751) in particular:

• Inspection of exhaust and noise regulations
• Determination of maximum speed
• Suitability of the brake system
• Electromagnetic compatibility
• Suitability of the tires
• Driver testing
• Suitability of the speedometer
• Inspection of permissible trailer load
• Operational strength

DEKRA service at this stage:
The actual assessment is carried out by the DEKRA expert personally on the vehicle—with numerous inspection locations nationwide, this usually does not require a long journey. With numerous DEKRA inspection locations, DEKRA is represented nationwide near vehicle owners. Since there is no prefabricated inspection scheme for the engine swap, the expert evaluates the vehicle in its entirety as part of the individual inspection—from engine mounting to the brake system to exhaust behavior.

Stage 6 – Documentation for Registration
For successful registration, the following must be collected:

• Vehicle registration certificate (registration certificate Part I)
• Technical documentation of the installed engine (type, power, engine number)
• Photo documentation of the installation condition
• If applicable, results of a power measurement

Stage 7 – Conclusion: Correction of Vehicle Documents
After a positive assessment, the expert prepares the expert report for the individual operating permit. On this basis, the registration office corrects the vehicle documents: Displacement, power, and possibly other technical data are updated to the new, inspected status and the operating permit is issued. Only with this step is the engine swap legally completed—the vehicle is once again fully registered in compliance with StVZO.

DEKRA service at this stage:
The DEKRA expert report for the individual operating permit according to § 21 StVZO forms the basis that the registration office transfers to registration certificate Part I and Part II. DEKRA thus assumes the crucial interface function between workshop and authority at this point—without this expert report, no correction of the documents is possible.

DEKRA Services Overview

• Before conversion begins: Advice on legal requirements and necessary documentation.
• During conversion: Parts certification/type approval for individual components through the DEKRA Automobile Test Center if no approval mark is available.
• After conversion: Individual assessment and expert report for individual operating permit according to § 21 StVZO.
• On-site inspection: Nationwide inspection locations for technical assessment of the vehicle.
• Conclusion: Expert report as the basis for correction of vehicle documents by the registration office.
• Thereafter: Regular main inspection and valuation reports DEKRA services for young and classic cars (e.g., H-plates, valuation reports