Direct Exhaust Injection

[zxr_maniac]

im agreeing with rover220, unless they'r recirculating dump valves, then they r crap, they dumping power thats so useful for ur next gear.

[rover220]

im agreeing with rover220, unless they'r recirculating dump valves, then they r crap, they dumping power thats so useful for ur next gear.

how are you agreeing with me?

ive not said dump valves are crap??

[RedexRobB]

[deviant]

just a load of hot air blowing about...

[Northern ANdy]

even a recirc dumpvalve means the air has to be re-compressed.

Also as rover says, it doesn't force any more air in because the exhaust turbine has little gas flow through it and is practically rotating on inertia

[RedexRobB]

just a load of hot air blowing about...

oh yeah i know that, just thought id add my tuppence

[superman]

ah i never heard of a blowoff valve, sounds better

Dump valves are fitted to the engines of (usually older) turbo charged cars and sit between the turbo outlet and the throttle body. When transitioning from a boosted state to a closed throttle state (as in between shifts), due to inertia, the turbo continues to pressurize air, but the closed throttle prevents the compressed air from entering the engine. In this case the pressure exceeds the preset spring pressure in the dump valve and the excess pressure is bled off to atmosphere.

Even with a dump valve the compressed air acts as a brake on the turbo (slowing it down), because the pressure on the backside of the turbo is at a higher pressure than on the front side (and the air actually wants to flow through the turbo backwards).

A blowoff valve is a more elegant solution to this problem by allowing the turbo to "freewheel" when the throttle is closed (equalizing the pressure on both sides of the turbo). Unlike a dump valve a blowoff valve can be used at multiple boost settings without reconfiguration.

Blowoff valves are sometimes incorrectly called dump valves because they serve a similar function, but they are very different solutions to the same problem.

[BANJO]

have a look at this vid about compressor stall
http://www.youtube.com/watch?v=MU5Y6d9r ... ed&search=