This weekend at the Belgian round of the FIA World Rallycross Championship, Finnish driver Riku Tahko will debut his Mini Countryman RX. While a Mini has already raced this year in World RX, JRM Racing ran a pair of similar machines at Hockenheim at the turn of the month (using 1.6 WRC-derived engines), Takho’s version features a two-litre motor and is the first car to make use of the new Custom engine regulations for 2015.
The Custom engine regulations have been conceived as a method of ensuring that there would always be a way for Supercars to use two-litre engines when manufacturers move towards smaller capacity units. Takho shook his new Mini down earlier this week and is pleased with the performance of the new engine, and says the new regulations are the only way he able to compete in rallycross. “The first time on track, it felt really good. We’re a bit heavier than the JRM Mini but on the other hand we already have more power than they have. For us as a small team, this is the only chance to do Supercar. To go to BMW Motorsport and buy a manufacturer engine to fit the Mini it would be completely impossible for us. If you want to run a Mini you can only find an engine that has done WTCC or WRC and they are really, really expensive. When the Custom engine rule came out it was a really big thing for us to be able to do the RX project,” explains the Finn.
As the name suggests, the new Custom engine regulations allow the opportunity to construct the whole unit from scratch, but also allows existing components to be used, as long as they fit within specified dimensions. Tahko’s motor uses a cylinder block from an existing manufacturer. “We’ve used an engine block from a manufacturer and everything around it is more or less custom made. The engine block is one of the key parts. If you have to build a non-custom manufacturer engine, you have to use a block that is from a car that has maybe only 150 horsepower, and these days they are of lightweight materials.”
Tahko is now in the unique position of having driven a two-litre production based engine (LD Motorsport’s Citroen DS3), a 1.6-litre WRC-based engine (JRM Racing – Top Gear, Lydden) and his own Custom engine. “At the moment I feel that I have the drivability from the JRM Mini but the power of the engine from the Citroen. I can really feel that power from the two-litre. We are down on power and really safe on the engine at the moment – we have a limited about of spare parts until we have the spare engine finished but I believe that once we get to Germany and Norway and we can tune things more, we will be really competitive with this car and engine.”
The Custom engine regulations have been tightly specified to ensure the engines are the equal of, but not superior to, the current engines which are based on production cylinder blocks. The Custom unit can only be a four-cylinder, 16v whereas the production-based engine has freedom in configuration. The maximum capacity for both types is 2058cc (with 70% equivalency applied for turbocharging, that equates to 3500cc). There is no limit on engine speed for the production-based motor, but the Custom engine is restricted to 8500rpm.
Custom engine regulations allow specialist tuners to offer an off-the-shelf motor that could be used in any make of car, as well as offering a quick and easy solution for new teams entering rallycross, this also means that competitors could more easily switch between marques. British engineer Julian Godfrey is one of those specialist tuners, and has already begun the development of a bespoke unit. “The regulations are good, they aren’t too strict but are controlled. I think in the long term, it will certainly be good for me and the number of different spares that I keep in stock. At the moment I’ve got kits for five different engine manufacturers,” says Godfrey. “Hopefully it will bring more different types of cars and more manufacturers into the sport. For instance, a Chinese company would be able to bring a car out and can use a decent engine, they don’t have to worry about developing one from scratch themselves. Before these rules, if you had a Ford, you had to run the original homologated block. With the custom engine, you have a custom made block. You’re restricted to the minimum bore centres and maximum bore size, to stop having a big bore engine, and there is a limit of bearing sizes and width, so you don’t use exotic materials on the crankshaft, because you don’t need to do that. The head has slightly smaller valve sizes than on the non-Custom engine, but you can make any type of cylinder head you want, as long as it fits within the dimensions in the regulations. There are minimum weights on all the parts too. It’s no too expensive. Even the Citroen engine fits in the regulations, so you could even use that in another car, but we’ve gone ahead with our own engine and hopefully we’ll have it running by the end of the year. We’ve got people interested in it already.”
While the Custom engine rules allow for different marques to be used in the sport, Yannis Loison, who heads up the engine programme at Ford Olsbergs MSE, believes the new regulations can bring reliability to the existing teams. “For us it can be much easier to work with, because there are many things that we don’t like on the standard engine, just because it’s not especially made for motorsport; where you put your mountings and oil pump, all those things can be thought about before manufacturing a block or head. That will also make things much easier for the car installation. The cylinder blocks that we are using are not really made to reach 600 horsepower with a big torque curve, so we can make something stronger. Honestly I think it will bring reliability and I think we can try to get more out of the engine if we decided to it, we need to be sure it was reliable before introducing it.”
While Tahko will become the Custom engine newbie this weekend in Belgium, the next car expected to appear using a similar motor will be the Eklund Motorsport Volkswagen Beetle, due to appear later this year.
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