Why No Boost In Neutral Or Clutch In?

[phatal]

Can someone please explain to me why the turbo needs to be under load to produce boost? Wouldn't the amount of exhaust gasses flowing past the turbo be the same in neutral or clutch in at a certain RPM as it would be while under load at the same RPM? Bit of a noob question but just want to know why?

[ETM]

When the engine is under load it burns more fuel and produces more exhaust gas.

You need a certain amount of exhaust gas to spin the turbo enough to create positive boost pressure on the engine. Remember that filling an engine with boost is not like filling a balloon for example, the engine creates a vacuum when it spins and therefore you must overcome that vacuum before you will start to see a positive pressure in the manifold.

Free revving the engine simply doesent produce the required amount of exhaust gas to do it

[R-SPEC]

The engine takes less power to rev itself than it does to turn a crankshaft with a drivetrain and wheels bolted to it.

There is not enough exhaust gasses at 5000rpm in neutral to create positive boost because the engine isn't using much of it's power just to turn the crank over. When under load at 5000rpm, the engine spits out a lot more exhaust gas because it's using all or most of it's power to not only turn a crankshaft, but a drivetrain with wheels attached and weight on top of it.

That's why there is 'turbo lag'. The engine has to produce enough power/exhaust to force enough of this exhaust through the turbo to spin the shaft to the compressor which creates forced air to be pumped into the plenum chamber and so on. It's all about the exhaust gas.

Please correct me if I'm wrong and feel free to add to it!

[phatal]

Thanks guys. I assumed this was why but just needed to ask.

[EZ2CME]

Does anyone know how the new FG Turbo's build up 3psi on launch control?

Edited 18/05/08 12:58 PM by EZ2CME

[Ralph Wiggum]

Retarded fuel/ignition and cam timing causes a large amount of unburnt fuel to wind up in the exhaust creating exhaust pressure.

[Twisty]

Antilag...

[ETM]

I read that it was not antilag in the traditional sense of retarded ignition timing, they were using cold air from 3 of the cylinders that would be disabled ie. no fuel or spark so it will just push a cylinder full of air into the manifold.

How effective it will be is questionable,ive never heard of it being used anywhere in motorsport before and production cars are usually 10 years behind new technology so the proof will be in the pudding I guess