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GTE USDM Turbo Engine dual chamber BOVs?

Time:2018-02-13 11:18Turbochargers information Click:


a pop off valve is a method of controlling boost pressure. it's essentially a valve that leaks boost above a certain pressure. indycars (CART/champcar) used them for boost regulation. basically if the engien's boost pressure exceeded a level mandated by the rules, the valve would open completely and dump all the boost pressure, slowing the car down. it was to keep people from cheating by edging the boost up.

but as a boost control method, it's a VERY VERY poor method of controlling boost, even as a failsafe. the problem is that a turbocharger is a positive feedback device. the more boost it makes, the more boost it makes. if you just dump boost pressure above a certain amount, there's no feedback pressure to the wastegate, which causes the turbine to just keep accelerating. it's possible to overspeed the turbo to the point that it essentially explodes, especially when the turbo is already close to it's operating limits (like running 18+ psi on a stock turbo).

this actually happened with the champ cars when they were testing the "push to pass" function up in denver. they turned the boost up on the P2P (essentially a button on the steering wheel that gives the driver up to 1 minute of 50 extra HP over the course of the race). they exceeded the limitations of the turbocharger trying to get some of the performance back in the thinner air up there and one of the turbos exploded in the back of the car. a turbocharger at full speed has about as much energy as a flywheel at redline, and that's not something you want ticking away 2 feet behind you in the car.

i'd stick with the BOV as a BOV.

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