Air moves the plate
Engine airflow lifts a movable circular plate in the intake stream. Its position is mechanically linked to the fuel distributor, creating a direct relationship between airflow and fuel delivery. [1]
OWNER GUIDE / 911 SC
From CIS to EFI: the 911 SC basics, clearly separated.
A technical starting point for Porsche 911 SC owners who want to understand the original Bosch system, modern electronic fuel injection, and the questions a conversion must answer before parts or claims enter the conversation.
Scope note: this is general education, not a complete Tinfinch fitment guide, installation manual, price list, or performance promise. Confirmed fitment is 2.7–3.0L engine blocks with mechanical injection.
Ask about the 911 SC kit
Inquiry only. Submitting a question does not place a paid order or take payment.
SOURCED BASICS
The dispatch research is numbered [1]–[8], but its underlying URLs and full text were not included. Statements below stay within the supplied excerpt; unavailable details are marked as limitations.
01 / ORIGINAL SYSTEM
What CIS is doing in a 911 SC
CIS—Continuous Injection System, also known as K-Jetronic or K-Jet—is a hybrid mechanical and electronic-era approach to fuel delivery. The supplied research places CIS on early-1970s Porsche 911 models and describes the 911 SC system as a mechanical metering system with later variants that could add electronic feedback. [1]
Fuel flows continuously
Pressurized fuel is metered by the distributor and delivered continuously through injectors near the intake ports. The arrangement is more precise than most carburetors, but it is not the same control method as sequential electronic injection. [1]
Cold start has its own logic
The research identifies a warm-up regulator as a key CIS component and describes later variants with oxygen-sensor and controller feedback. The exact behavior depends on the specific CIS variant and vehicle configuration. [1]
In one line
CIS uses the airflow itself to mechanically meter a continuous fuel supply. The air plate, fuel distributor, pressure control, and injectors are the system’s central conversation.
02 / ELECTRONIC CONTROL
What EFI changes
Modern EFI replaces the mechanical metering relationship with an ECU, sensors, and electronic injectors. The ECU reads operating conditions, calculates a fuel quantity, and commands injector opening time. An oxygen sensor can provide feedback so fueling is trimmed toward the chemically ideal ratio. [2]
Typical inputs
RPM / crank positionThrottle positionAir measurementEngine temperatureExhaust oxygen
ECU / CONTROL MAP
Measure → calculate → command
The ECU combines sensor inputs with a calibration map, then controls injector duration. That creates a tunable, diagnosable control layer rather than a fixed mechanical response. [2]
OUTPUTFuel rails + injectors
At a glanceCISEFI
How fuel is metered
A mechanically linked airflow plate and fuel distributor meter fuel continuously as airflow changes. [1]
An ECU commands electronic injectors for a calculated duration using sensor inputs. [2]
Feedback and correction
Later variants can add electronic control and oxygen-sensor feedback, but the core metering relationship remains mechanical. [1]
An oxygen sensor can close the loop and let the ECU trim fueling toward the stoichiometric ratio. [2]
Intake path
The airflow plate occupies the intake path, which constrains how air travels toward the cylinders. [1]
An AFM or MAF-based strategy can place its metering device separately from the throttle and intake layout. [1]
Adjustment and diagnostics
The mechanical system is comparatively direct to understand, but its adjustment range is tied to its hardware. [1]
Maps can be recalibrated for engine and intake changes, and modern systems can expose sensor or parameter faults. [2]
03 / BEFORE A CONVERSION
The conversion is a systems question, not one part.
The supplied research says a dedicated search for a single, official 911 SC CIS-to-EFI recipe was inconclusive. The points below are therefore a verification checklist drawn from the general EFI explanation and the documented aftermarket and case-study references—not an installation sequence. [4][5][7][8]
Fuel delivery and pressure
Confirm the pump, pressure regulation, return path, rails, injectors, and electrical supply as one system. The supplied research describes these as conversion-system considerations, not as a Tinfinch specification. [2][4][5]
Sensors and ECU strategy
A conversion needs a defined approach to engine speed and crank position, throttle position, air measurement, temperature, and exhaust oxygen feedback. Which sensors are used, where they mount, and how they are calibrated must be documented for the chosen system. [2]
Intake and engine-bay packaging
Removing or bypassing the CIS metering hardware affects the airbox, filter, boot, breather routing, heater ducting, and available space. The cited 911 SC case studies describe different packaging choices, so neither is a universal recipe. [5][7][8]
Wiring, calibration, and commissioning
Plan for the harness, ECU map, cold start, idle, load transitions, oxygen-sensor strategy, and a safe commissioning process. The snapshot reports that professional installation and tuning are required for one documented aftermarket system; that statement is not a Tinfinch requirement. [5]
What the research does not establish
It does not establish one universal sensor layout, wiring plan, base map, legal outcome, installation time, or safe calibration for every 911 SC. A professional familiar with the specific engine and chosen EFI system should verify those decisions.
04 / TINFINCH EFI
A clear line between education and the verified kit listing.
The existing Tinfinch site describes the company as a purpose-built EFI conversion kit for Porsche 911 SC owners in Lithuania, with an aim to preserve the engine’s original look without individual throttle bodies. Confirmed kit fitment is for 2.7–3.0L engine blocks with mechanical injection.
The verified kit listings show fuel rails and six injector bungs at €600 (600 EUR). This guide does not establish installation modifications, power gains, drivability improvements, or other performance claims, and it does not turn another vendor’s documentation into Tinfinch documentation.
Confirmed fitment and published kit details
- Confirmed: 2.7–3.0L engine blocks with mechanical injection
- Confirmed contents: fuel rails and six injector bungs
- Listed price: €600 (600 EUR); payable destination total not confirmed
- Installation steps or required modifications
- Power, economy, drivability, or sound outcomes
05 / SOURCE KEY
Research key and limitations
Inline markers point to the numbered items below. The dispatch provided a research snapshot rather than a complete bibliography; source names are reproduced only where the snapshot supplied them. Missing URLs, publication details, and truncated passages are not filled in here.
Bosch CIS / K-Jetronic technical overview
The supplied research describes continuous metering, the airflow plate, later feedback variants, and intake-path constraints. Publication and URL details were not included in the dispatch snapshot.
Modern EFI and lambda-feedback technical overview
The supplied research describes ECU-controlled injectors, sensor inputs, oxygen feedback, calibration, and diagnostics. Publication and URL details were not included in the dispatch snapshot.
EFI individual-throttle-body conversion vendor material
Mentioned in the research as vendor material. It is not used here to make a Tinfinch fitment, installation, or performance claim.
AT Power Porsche 911 throttle conversion kit documentation
The snapshot names AT Power and describes a 1978–1989 911 application. The underlying URL was not included, and this is a separate vendor reference—not Tinfinch product documentation.
AT Power installation guidance
The snapshot reports installation, tuning, fuel-system, heater-duct, and breather considerations for that documented system. These are not Tinfinch requirements.
AT Power 911 SC 3.0L technical drawings
Named in the snapshot as a source of configuration drawings. The drawing set and URL were not included in the dispatch.
Tony's 1978 Porsche 911 SC conversion case study
The snapshot describes airbox and intake changes and reports a measured result, but the source metadata was not included. No performance number is carried into Tinfinch copy.
Ralph's 1982 Porsche 911 SC conversion case study
The snapshot describes heater-blower, fuel-tap, airbox, and air-conditioning choices. The source metadata was not included, so this remains a case study rather than a universal instruction.