On one side there is TDI, which stands for Turbocharged Direct Injection and on the other side reigns CRDi or Common Rail Direct Injection. These are fuel injection system available in popular diesel engines. Both TDI and CRDi make use of the basically the same technology, just with some minor tweaks (number of valves, valve timings etc) and are marketed differently by their respective manufacturers.
The basic principles although remains the same. A conventional fuel injection system delivered through a common rail with the help of a turbocharger (TDI only) aided with an intercooler (for that extra oomph!). TDI is quintessential German technology uses in German diesel cars such as Volkswagen, Audi, Škoda whereas CRDi is used in India by Hyundai and the new entrant KIA.
Some popular examples of diesel engines using this configuration are:
- TDCI/Duratorq by Ford
- DDIS by Maruti Suzuki
- VCDI by Chevrolet
- TTID/Multi-Jet/Quadrajet by Fiat
- IDTEC/CTDI by Honda
- DCI by Renault
- D-4D by Toyota
- CRDE/M-Hawk/M2DICR by Mahindra
Fun Fact: The incredibly popular 1.3 Multijet diesel engine powered a long list of cars in India like Maruti Suzuki Swift/Ertiga/Ritz/SX4, Fiat Punto/Linea, Tata Indica Vista/Indica Manza and Chevrolet Sail/Chevrolet Beat. This 1,248CC Fiat MJD was considered as the best diesel engine in India.
Is Common Rail Direct Injection better?
The common rail direct injection configuration for diesel engines is a great example of modern diesel technology. Common rail direction injection uses a high-pressure rail to deliver diesel fuel to each solenoid valve. Unlike conventional direct fuel injection system used in older diesel cars which uses a low-pressure pump nozzle to deliver diesel fuel. This traditional technology was inefficient and wasted a lot of fuel.
What are the advantages of CRDi diesel engine?
- Reduced Emissions: CRDi diesel engine were developed out of necessity. A common problem that plagued older diesel engine was black soot-like smoke and horrible emissions. CRDi diesel engine produces significantly less smoke and tolerable emissions.
- Better Fuel Mileage: Utilising a common rail for fuel delivery, CRDi engine are not gas guzzlers anymore. They provide great mileage which is how they outrank petrol engines in terms of fuel economy.
- Reduced Engine NVH: Owing to a lot less moving parts and advancement in diesel engine technology. CRDi engines are quieter.
- Increased Power: CRDi engines are powerful, very powerful. A CRDi diesel engine produces upto 25% more torque compared to a petrol engine displacing the same amount of fuel.
How does a TDI engine work?
TDI is Volkswagen’s propriety Turbocharged Direct Injection technology for diesel engines. When it comes to talking supreme diesel, TDI is where it is at. TDI combines power, fuel economy and versatility all into one.
As the name suggests TDI or Turbocharged Direct Injection is a combination of common rail direct injection boosted with a turbocharger. A turbocharger massively increases peak engine performance by jamming more air into the cylinders. An intercooler then cools the air that has been drawn out by the turbocharger. In the final stage, the now cooled air enters the combustion engine which is where high-pressure diesel is directly injected into the cylinders. It is this combination of cooled air, atomised diesel that makes TDI incredibly efficient.
What are the advantages of a TDI diesel engine?
- More compact: Thanks to overengineered German technology, TDI engines are very small in size, This allows manufacturers to chuck-in more cabin space in their cars.
- More efficient: TDI engines can deliver more power and more fuel economy without compromising on overall driving dynamics.
- Incredibly quiet: TDI engines thanks to their better insulation and firewall are by far the quietest of all diesel engine. Honda’s I-DTEC is infamous for being “unlike Honda” in terms of noise, vibration and harshness.
- Increased torque: TDI engines can produce huge surges of torque which makes them great for heavy hauling.
TDI vs CRDi: The final verdict
| TDI (Turbocharged Direct Injection) | CRDi (Common Rail Direct Injection) | |
| Configuration | Uses a turbocharger for exhaust gas recirculation to improve efficiency | Uses a high-pressure fuel injection system for efficient fuel delivery |
| Manufacturing Cost | Cars with TDI diesel engine cost more | CRDi is cheaper to manufacture |
| Ownership | TDI is only exclusive to VW owned cars/car brands | CRDi can be used to a myriad of cars/car brands |
| Maintenance | TDI is simple and relatively cheaper to maintain | CRDi is complex and thereby expensive to service and maintain. |
What is #DieselGate?
The Volkswagen emission scandal, also known as Diesel Gate or Emissions Gate came to light in September of 2015 when the Volkswagen Group was found violating The Clean Air Act institutionalised by The United States Environmental Protection Agency (EPA). It was found that Volkswagen had planted a Cheat Device with their TDI diesel engine cars in order to fool the system during an emission testing.
Volkswagen fitted this cheat device in about 11,000,000 cars worldwide, including 500,000 in the United States, between 2009 through 2015. This cheat device caused the NOx (Nitrogen Oxide) output of the car to meet US standards during routine testing. The actual output was later on found to be upto 40 times above the permissible limit.
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What is the future of diesel engines in India?
There was a time when one out of every two cars sold in India used to be a diesel car; now that number is down to only one in five. The future of the diesel engine in India is rather grim. With the inevitable arrival of the BS6 (Bharat Stage 6) norms in India by 2020, major car manufacturers like Renault, Maruti Suzuki, Volkswagen are pulling the plug on the diesel engines. The Indian market will say its last goodbye to small capacity diesel engines.
Read BS6 (Bharat Stage 6) | Explained
A report compared new diesel car sales in India in 2012-2013 vs 2018-2019 and found a massive drop from 47% to a mere 19% share in sales. Even the share of diesel SUVs has declined from 98% in 2012 to 83% in 2018-19.
Moreover, the new BS6 standard will pull car manufacturers back to the drawing board with an estimated investment of more than billions into developing cleaner diesel engines. Indian car manufacturer, Maruti Suzuki has decided to stop producing diesel cars altogether citing the high cost of compliance with small diesel engines (it may still produce bigger capacity diesel cars). Adding fuel to the fire was the #dieselgate that exposed Volkswagen malicious intent to fool emission standards. All in all, diesel has (or rather is) losing its credibility and the day isn’t far that we bid adieu to the diesel engine once and for all.
Also Read: The Future Of The Diesel Engine
Will diesel cars be banned in India?
As per the Supreme Court mandate, diesel cars that are more than 10-year-old are banned. Also, diesel vehicles displacing more than 2000CC are now liable to pay environment pollution charges and environment cess is collected from each litre of diesel sold in Delhi.
But, it should also be noted that the SUV market in India has remained strong. With 7 out of 10 cars sold in India falling the hatchback or sedan category, Diesel SUVs have held a bullish position for the past many years. 70% of SUV buyers prefer the diesel variant with 30% going for petrol. There is also no denying that Diesel engines are remarkably efficient and cheap to maintain which is why they find use in all sorts of commercial transportation activities pan India. Banning Diesel fuel is not a smart move to make.
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I need the difference between tdi, cr4 & crdi enginws. Which is best to buy in tata?
Hi Raja,
Tata has now equipped its cars with a new family of highly advanced engines named Revotron and Revotorq. Revotron is for petrol engine which is an MPFI engine and the Revotorq engines are the diesel ones. Talking about your question, the best buy depends upon the choice of fuel. The difference between TDi and CRDi, you must have gone through in the article. CR4 family of engines launched by Tata was an advanced version of the CRDi engines. If you are planning to buy an old car, go for the ones equipped with CR4 tech, as the fuel delivery system is advanced than the others. I hope I was able to answer your question. Stay pinned!
Hello Ritvik,
Good organized article to read. Thanks for the article. How about tata’s revotorq diesel engines? Can you please share pros and cons of it.
Thanks for sharing this !