The current Kaveri Derivative Engine (KDE), developed by India's Gas Turbine Research Establishment (GTRE), is an evolved version of the original GTX-35VS Kaveri turbofan engine. It is a non-afterburning variant designed for applications like unmanned combat aerial vehicles (UCAVs) and other platforms.

The Kaveri Derivative Engine (KDE) is being further developed to include an afterburner module capable of producing around 73–74 kN of wet thrust.

This is close to the thrust of the French Safran M88-2 engine (≈75 kN) powering Rafale jets but still less than the current General Electric F404-IN20 engine, which powers the TEJAS MK-1A and produces about 84 kN wet thrust.

The ultimate Kaveri 2.0 engine version aims for thrust levels of 90 to 100 kN but is targeted for future aircraft like the TEJAS MK-2 and Advanced Medium Combat Aircraft (AMCA).

The TEJAS MK-1A fighter jet currently operates on the GE F404-IN20 engine, which delivers reliable performance with 54 kN dry thrust and 84 kN wet thrust.

This engine has been integrated, tested, and optimised specifically for the MK-1A airframe, ensuring full operational capability and certification. HAL and the Indian Air Force have reaffirmed their commitment to continuing GE F404 deliveries at a steady rate until 2026 and beyond due to the complexities and extensive re-certification effort needed to change engines on the MK-1A airframe.

As of 2025, GTRE and the Indian Air Force are working together to mature the Kaveri Derivative Engine with an afterburner to eventually reduce dependence on foreign engines like the F404. However, the KDE is not yet ready to fully replace the GE F404-IN20 on the TEJAS MK-1A due to several reasons:

The KDE's thrust output at 73-74 kN is still lower than the F404’s 84 kN, meaning it would limit some of the MK-1A's performance and payload capabilities.

Engine integration on an operational fighter requires extensive re-design, flight testing, and certification, which the MK-1A was not originally developed for with the Kaveri.

The current plan is to use the KDE for mid-life upgrades or replacements around 2035 or later, once the engine’s maturity and reliability are proven.

The Kaveri engine family, including the KDE and the advanced Kaveri 2.0, is viewed as a strategic, long-term indigenous engine development program that supports India’s self-reliance goals but requires more development time.

The Kaveri Derivative turbofan engine in its current form cannot be immediately used in the TEJAS MK-1A due to thrust and maturity constraints, as well as certification challenges.

The TEJAS MK-1A continues to rely on the GE F404-IN20 engine for the near and medium term. The KDE represents a promising indigenous step toward future engine replacement and self-reliance, potentially powering upgraded or next-generation TEJAS variants in the 2030s after further development and successful demonstration phases.

Key differences between the Kaveri 2.0 engine and the GE F404 engine:

FeatureKaveri 2.0 EngineGE F404 Engine
Engine TypeLow-bypass afterburning turbofanLow-bypass afterburning turbofan
Dry Thrust~55-58 kN~49.1 kN
Afterburning (Wet) Thrust~90 kN or higher (targeted 90-100 kN)~85.4 kN
WeightTarget ~1,200 kg (aiming for reduced weight using advanced materials)Approx. 1,036 kg
Bypass Ratio~0.16~0.34
Thrust-to-Weight RatioTargeted improvement with lighter design componentsApprox. 5.13 (dry), 8.03 (afterburning)
MaterialsAdvanced materials such as titanium alloys, nickel-based superalloys, single crystal turbine bladesMature material tech with robust durability
Digital Engine ControlFull Authority Digital Engine Control (FADEC)Proven FADEC system
Development StatusUnder development, targeted for next-gen aircraft like TEJAS MK-2 and AMCAMature and operational with global track record
Operational UsePlanned future use, still undergoing testingWidely used in operational fighters including TEJAS MK-1A
ReliabilityYet to prove long-term reliabilityProven reliable with low maintenance requirements
Fuel EfficiencyLower bypass ratio may lead to relatively lower fuel efficiencyHigher bypass ratio giving better fuel efficiency
Temperature HandlingDesigned to handle high temperatures with advanced turbine blade techProven performance in high-temperature operations
Geographic AdaptabilityFlat-rated performance to maintain thrust across varying climatesMature for diverse operational environments