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Old 02-29-2012, 12:35 AM   #1
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Default 1/8 exhaust cooler or pressure chamber

In 1/8 on-road the most drivers use either a pressurechamber or a exhaust cooler between the exhaust and the tank.

Example at the WC last year I can se from the pictures, that most drivers were using a pressurechamber, as I have noticed that at other races most drivers are using a exhaust cooler.

In what way differ the use of them, and are there any conditions where the one is to prefer instead the other?

best wishes; Jens
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Old 03-02-2012, 11:30 AM   #2
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Good question come on guys anyone.

From my personal dictionary I believe that a pressure chamber will give you better throttle response but better ask the PROs.
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Old 03-02-2012, 01:14 PM   #3
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The best throttle response is with a short and direct back pressure line from exhaust to tank, the shorter the line the directer the throttle.

The problem you can face is that there is no pressure chamber in the system when the tank is compleetly full. The pressure pulses can come at the wrong moment casing the engine maing hickups. When some fuel is used a pressure room above the fuel is created picking up the pressure pulses storing it to a more constant pressure.
Today's tank caps do have a small chamber taking away that problem but if it still exist yo need an extra chamber.

The exhaust cooler does lower the temperature of the gasses a tiny bit and with that also the fuel in the tank. It is not much but it makes the engine tuning more consistent. With that it is possible to search a better limit on the lean side making a better milage.

Then there are devices to adjust the pressure or a device as the TeamOrion CPD. These tools do soften the pressure so you have to change the needles on the carburator to get the characteristic of the engine right. One of the bad things of a normal setup is that going from full throttle to idle the huge pressure is giving a boost of fuel into the engine at a moment you do not want it resulting a rich moment when touching the throttle again. In this situation trying to lean that out can cause a fuel shortage on other moments.
Lowering the pressure or filtering out such pressure boosts will give a much directer reacting engine and also some extra milage.
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