<<BACK TO PREVIOUS

Renault predicts a revival for small gasoline engines. Simon Bickerstaffe reports

Developed with downsizing in mind, Renault launched a 1.2 litre engine at the Paris Motor Show. The D4Ft is turbocharged to develop 100bhp and offers good performance with low consumption and emissions.

Renault is predicting an upturn in the popularity of gasoline powertrains after Euro V emissions laws come into effect in 2010. Reducing diesel particulate matter (PM) levels to 5mg/km will probably result in standard fitment of diesel particulate filters (DPF), the on-costs of which will be hard to absorb in the small car market, it believes

Referred as TCE100 (turbo control efficiency), the engine has been developed for Renault’s A- and B-segment cars and will appear in early 2007 coupled to a five speed manual transmission in the new Twingo as well as the Modus and Clio.

Developed from the existing 75bhp 1.2-litre 16V unit, Renault claims the TCE 100 offers “the fuel economy of a 1.2, the power of a 1.4 and the torque of a 1.6.”

The low inertia turbo appears to do a good job of making 1.2 litres imitate Renault’s larger capacity engines, with peak outputs arriving at lower engine speeds.
Capacity: 1149cc
Power: 100bhp @ 5,500rpm
Torque: 145Nm @ 3000rpm
CO2: 139g/km

Transient overboost is available above 4,500rpm in the intermediate gears, lifting output by 5bhp and 6Nm.

The 1.6 litre VVT unit used in the Clio develops 111bhp at 6000rpm; 151Nm at 4250rpm; 160g/km C02; 6.7l/100km. So, it broadly meets Renault’s claims for performance but with reduced emissions and better fuel economy: a Clio fitted with the TCE100 returns 5.9l/100km (47.9mpg).

“It’s a downsizing concept to reduce CO2,” said Kazumasa Katoh, senior vice president, powertrain engineering for Renault. “We looked in depth at making sure that driveability and reliability with higher rated power and torque was maintained. To avoid a loss of torque through knocking we improved combustion by optimising tumble.”

Stratified direct injection has not been used because of cost and practicality. Katoh said: “The cost is greater because of aftertreatment for NOx and there are market limitations because of high sulphur content in gasoline.”

Katoh explained that, ideally, to use such technology requires a sulphur content of 10ppm or a maximum of 30ppm; some Eastern European markets have levels as high as 300ppm which would poison the NOx catalyst. For this reason, port injection (MPI) has been retained.

Small capacity turbodiesels have become very popular in small cars because of their high torque rating: the least powerful Clio 1.5dCi has only 68bhp but develops 160Nm at 1700rpm and emits only 120g/km CO2, and returns 4.5l/100km (62.8mpg).

But Euro V will have a much lower PM limit than Euro IV and OEMs are going to have to work hard to meet it, strengthening the case for efficient petrol engines.

“If we compare gasoline and diesel engines, we have much more room to improve the gasoline side. But we will also adopt a downsize approach with diesel engines,” said Katoh. “Diesel will also have to improve but because of NOx and PM reduction, the cost will increase initially.”

Katoh believes that changes to diesel combustion strategy and adding a particulate filter (DPF) will bring compression ignition engines into compliance, but at a price. Including a “fifth injector” adding fuel periodically into the DPF for regeneration (otherwise city driving can clog the filter with soot), he estimated the extra cost at €300-400, but pointed out that filter prices were falling as volumes increase.

The TCE 100 is made at the Douvrin plant which has a capacity of 13,500 1.2 litre engines per week. Investment costs for the new powertrain were €80 million.

With a specific output of 87bhp/litre, the TCE 100 seems an entirely respectable offering, with scope for further development.

[BACK TO TOP]