Inside the 800-hp Olsbergs Fiestas – update 1


x-games pikes peak rallycross olsbergs fiesta cooling system

Look in the rear window, and this is what you'll find. Air gets sucked in two massive rear window scoops and dumped into the rear hatch. At the back is the radiator, with a suction fan on the back pulling air through, and a nitrous spray bar on the front to throw an extra chill on things. In the middle of the hatch is an oil cooler. There is no natural air flow going through it, so a large fan does all the work. The giant metal can in the foreground is the engine's oil tank. Naturally, it's dry sumped.


With all the fluid cooling in the back, the front is all intercooler. In the foreground is what appears to be just the huge blow-off valve you'd need to prevent all that compressor surge chirping, but Eriksson has it set up only as a safety valve to blow off in the case of wild overboost or backfire.


Additional safety is provided by this pressure relief valve on the intake manifold.


X-games rallycross pikes peak olsbergs fiesta engine, intake side

The intake side is also busy with details. First, and most difficult to spot, is the fact that the intake runners are spaced farther apart than a stock Duratec/MZR head. The production intake ports are surprisingly large and high, but the #1 and #4 runners angle inward slightly toward the center. The Olsbergs head has four identical ports for perfectly even flow distribution.

The intake manifold consists of individual Jenvey throttle bodies fed by a plenum of Olsbergs' own design. The three cars at X-Games had slightly different plenums, each a different stage in the evolution of the design. This one is the most recent evolution. To ensure even distribution into all four runners, the cold-side intercooler pipe forks and feeds into two inlets in the bottom of the plenum.

In engines with extremely-high intake air flow rates, it often helps to move the injectors farther upstream to get better atomization. As is common practice on ludicrously high-output engines, Olsbergs' injectors are across the plenum from the runners, giving the fuel maximum time to mix with the air charge and aiming the fuel directly down the runner so less of it gets stuck on the port walls. 

The four conspicuous red banjo bolts feeding braided lines into the top of each port are actually vacuum lines. With individual throttle bodies there is never vacuum in the plenum. Instead, vacuum is collected before the throttles at each port, and fed into the conspicuous distribution block. From there, the vacuum signal goes across to the anti-lag valve and also to a small accumulator chamber just out of frame to the right. Another line goes from this chamber to the diaphragm just behind the throttle cable (the red doohicky just behind the vacuum block). The diaphragm pulls the throttle back open slightly, helping send the fuel and fire into the exhaust manifold to feed the anti-lag.

So, thanks to needle dick and his power trip, that's all I've figured out so far. Wanna know more? Wanna know something specific? Leave your questions in the comments section and I'll update the story as I get more info.


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