LPG Compatibility Guide for TSI, TFSI, GDI and T-GDI Engines

SHARE NEWS

• Facebook
• Twitter

Added Date : 11 09 2026

If you are thinking of having LPG fitted to your vehicle, the first step is not to research prices. It is to find out which injection type your engine has.

Because that information directly determines which system will be fitted to you. The wrong match creates problems regardless of the quality of the product.

In this guide you will find what the common engine designations mean and what they signify where LPG is concerned.

First, the Basic Distinction

There are two groups:

Multi point injection (MPI). Petrol is sprayed into the intake port and mixes with air before entering the cylinder. This is a structure naturally suited to LPG conversion.

Direct injection (DI). Petrol is sprayed at high pressure straight into the combustion chamber. Because the injectors sit inside the combustion chamber and are cooled by the petrol passing through them, the LPG system has to be designed to protect those injectors.

This distinction determines everything. Now let us look at the commercial designations.

Volkswagen Group: TSI, TFSI, FSI

FSI (Fuel Stratified Injection) is the name of the Volkswagen Group's direct injection technology. It was used in naturally aspirated versions.

TSI and its Audi equivalent TFSI are the turbocharged form of it. They appear very widely in VW, Audi, Škoda and SEAT models.

There is a detail to watch in this family: in some engine generations intake port injection has been added alongside direct injection. The engine therefore uses both methods together depending on the situation. In engines of this type the engine code needs to be examined to determine the right system.

In general: falls in the DI group, a system designed for DI is required.

Hyundai and Kia: GDI, T-GDI

GDI (Gasoline Direct Injection) is Hyundai-Kia's direct injection designation. T-GDI is its turbocharged version.

The same abbreviation has also been used by Mitsubishi; that brand is one of the first widespread examples of the GDI designation in the automotive field.

In the Hyundai and Kia range both GDI and conventional multi point injection (designated MPI) versions have been sold at the same time. The same model can therefore fall into a different group depending on the engine option. The engine details on the registration are decisive here.

In general: GDI and T-GDI fall in the DI group.

Ford: EcoBoost

EcoBoost is Ford's turbocharged direct injection engine family. Its 1.0, 1.5 and 2.0 litre versions are widely found in Türkiye.

In this family too there are later generation versions to which intake port injection has been added.

In general: falls in the DI group.

Mercedes-Benz: CGI

CGI (Charged Gasoline Injection) is Mercedes' designation for direct injection petrol engines. There are versions that work on the stratified combustion principle.

In general: falls in the DI group.

PSA and BMW: THP

THP (Turbo High Pressure) is the jointly developed turbocharged direct injection engine family used in Peugeot, Citroën and DS models and, for a period, in BMW models.

In general: falls in the DI group.

Renault: TCe

TCe is Renault and Dacia's designation for turbocharged petrol engines. Care is needed here: TCe is not an injection type but a commercial name expressing turbocharging.

Some versions of this family use multi point injection while newer versions are direct injection. It is therefore not possible to determine the group by looking at the "TCe" label. The engine code is essential.

In general: varies by version, must be checked.

Toyota: D-4, Dynamic Force

D-4 is Toyota's direct injection designation. D-4S refers to the system in which direct and intake port injection are used together.

Dynamic Force is the name of Toyota's new generation engine family, and dual injection arrangements are common in it.

In general: should be assessed by engine code because of the dual injection structure.

Stellantis: Firefly

Firefly is the name of the small displacement engine family used on the Fiat side. This family includes both naturally aspirated and turbocharged versions, and the injection type can vary by version.

In general: varies by version, should be checked.

Engines with Piezo Injectors

Piezo is the name of the technology used in the injector's opening and closing mechanism; it works faster and more precisely than conventional solenoid injectors. It is not an injection type but the injector's own technology.

In engines with piezo injectors the LPG system needs to interpret this injector behaviour correctly. 2A Prime DI has been developed to be compatible with engines that have piezo injectors.

Summary Table

The table below shows the general tendency. For certainty the engine code is what counts.

Where Do You Find the Engine Code?

The engine code is the most decisive piece of information in your vehicle's identity, and it can be reached from several places.

Registration document. The vehicle registration document carries the engine number and, in most cases, the engine type.

Engine bay label. The engine code is written on the manufacturer's label found under the bonnet, on the engine block or on the front panel.

Chassis number (VIN). The vehicle's equipment and engine details can be reached through the seventeen digit chassis number. Authorised services can carry out this query.

When you send us any one of these details we will determine the right system and let you know.

Why Does This List Change Over Time?

Carmakers can keep commercial designations while renewing the technology underneath. The same name can correspond to a different injection arrangement in two vehicles built five years apart.

The tendency that has come to the fore in recent years is the dual injection arrangement in which direct injection is used together with intake port injection. This structure aims to reduce deposit formation on the intake valves while preserving the efficiency advantage of direct injection.

Where LPG is concerned these engines require a separate assessment; the decision is not made on a general rule. Looking at the engine code rather than the brand name is therefore becoming steadily more important.

The Consequence of a Wrong Match

When a standard system produced for multi point injection is fitted to a direct injection vehicle, the injectors are left without cooling because the system does not have the logic to manage petrol flow. The problem usually appears not immediately but within months, and that makes diagnosis harder.

The reverse also applies: fitting a DI system to a multi point injection vehicle means unnecessary cost and unnecessary complexity.

The right match is the most critical decision in a conversion and comes before comparing prices.

And If You Cannot Be Sure?

This table gives guidance but does not have the final word. For two reasons:

First, the same commercial name can cover different technologies in different generations. Second, the number of dual injection engines is rising and these require a separate assessment.

The soundest method is to send us your vehicle's make, model, model year and engine details. We will determine the right system and let you know. This step is free of charge and independent of your decision to convert.

You can find the technical details of the systems on our product pages: 2A Prime DI for direct injection vehicles and 2A Prime MPI for multi point injection vehicles. To find your nearest authorised point you can reach us through our contact page.

Frequently Asked Questions

What should I do if the engine type is not written on the registration document?

Sending the chassis number (VIN) is enough. The vehicle's factory equipment and engine details can be queried through that number.

Why can LPG be fitted to some cars of the same model but not others?

Because it is the engine, not the model name, that is decisive. The same model may have been sold with a different injection type depending on the engine option.

Can LPG be fitted to a dual injection engine?

These engines require a separate assessment. The decision is not made on a general rule without examining the engine code; if you send us your vehicle details we can assess the suitability of conversion.