Ok so today we're talking about a cheat....well no....technically this wasn't a cheat it was a very very creative interpretation of the rules of the world rally championship.

So the year is 2003 the car is the Ford Focus RS WRC 03 and the motor-sport discipline is the World Rally Championship.
Now in 2002 Ford introduced newly designed version of the Focus for the WRC. Most of the important stuff was redesigned from the ground up, the body shell was made lighter and aerodynamic enhancements were introduced.
But one of the most noticeably changes was the replacement of the front and rear bumpers with US spec bumpers which was a bit weird as the car was based on the European Focus. But fitting different bumpers isn't against the rules and most initially suspected that the US bumpers offered some sort of aerodynamic advantage or something.
Now the real reason for the US bumpers is that US safety regulations demand larger and more prominent bumpers. A regulation that's notorious for uglifying many cars. But this time a larger bumper had a completely different agenda because inside the bumper the Ford World Rally team concealed a 45 liter tank made from 2mm thick titanium sheets.

So what was the titanium tank used for? It was used to store boost. I know it may sound ridiculous but this was it's actual purpose. The tank was connected to the engine via 4 meters of 30mm diameter piping. When the car was off throttle and the turbo was generating boost that the engine wasn't ingesting this excess boost was fed into the tank. When the car got back on throttle a special valve would open and release all of the stored boost back into the engine for increased power.

So here we have an engine and here we have a turbocharger. Combustion happens inside the cylinder and creates hot exhaust gasses. These hot gasses then exit through the exhaust manifold and drive the turbine wheel. The turbine wheel inside the exhaust side of the turbocharger is connected to the compressor wheel via a common shaft. The compressor wheel inside the intake side of the turbo sucks in air, compresses it and then sends it through the intercooler into the engine.

So logic tells us that the faster the turbo spins the more air it can suck in. The more air it sucks in the more air it can compress generating higher boost pressure and more power. The higher the boost pressure or the pressure of the intake air the more we are stuffing into the same volume. The more air we stuff the more fuel we can add and the more powerful the combustion becomes. The more powerful the combustion the more power the engine makes and the faster the car can go.

Now when you open the throttle fully you're letting in more air into the engine so the ECU adds more fuel to compensate and we create more powerful combustions inside the engine. This also create more exhaust gasses and more heat which is then used to drive the turbocharger faster. So the turbo starts spinning faster and faster sucking in and compressing more and more air. As it does so it starts increasing the air pressure inside the intake manifold until we reach the peak pressure our turbocharger can generate. Let's imagine that in our case that's 2 bar, which is approximately 30psi. So the turbo is stuffing air at the peak pressure it can generate which leads to the engine generating it's peak power as well. Now let's imagine we're approaching a sharp corner and we suddenly release throttle.
At this moment we have pressurized air that has nowhere to go because entry into the engine has suddenly been blocked by the throttle plate. This is excess boost. Pressurized air inside the intake manifold that can not go into the engine.

So here's Ford's valve, here's the tank and here's the engine. When the driver releases the throttle and anti lag kick in the valve opens. Increased boost pressure fills up the intake manifold and any excess beyond that goes into the tank. When you get back on throttle and if pressure inside the intake manifold is higher than inside the tank the throttle remains closed to prevent boost pressure being wasted on filling the tank and reducing power output. Driver let's go off the throttle again, anti lag kicks in excess boost pressure goes into the tank until eventually the pressure in the intake manifold becomes the same as in the tank. The valve now closes because tank pressure can not be increased further.
The next time you get back on full throttle the pressure inside the tank is higher than inside the intake manifold. The valve now opens and extra air pressure rushes into the intake manifold generating higher pressure in the intake manifold than would normally be possible thus increasing the power output.

A special thank you to my patrons:
Daniel
Daniel Morgan
Pepe
Brian Alvarez
Jack H
Dave Westwood
Joe C
Zwoa Meda Beda

#d4a #ford

00:00 Ford in the WRC
02:28 Hidden boost tank
05:46 Boost pressure basics
09:19 What is excess boost?
13:29 Anti lag fills the tank