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back pressure !!!!!!!!!!!


yanto
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  • 4 months later...

odd thing to see the words back presure describing the crank case pressure,.....sorry don't mean to be a pain...the back pressure is a term used to describe the pressure created in the exhaust system to stop the turbo overspeeding,....

Pressure crated by the compression leaking past the piston rings is crank case pressure.....

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  • 1 month later...

Back pressure in the exhaust is what you don't want. That is why many people remove one or both of the silencers. With less back pressure the pressure drop across the turbo increases so it will spin up faster, reducing turbo latency. The waste gate will let over pressure go to atmosphere and has nothing to do with the speed of the turbo.

The best way to overspeed your turbo is to have a blown turbo hose. Because there is no pressure on the engine side of the turbo the compressor and turbine will run much faster. So preferably don't drive for long with a blown hose.

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odd thing to see the words back presure describing the crank case pressure,.....sorry don't mean to be a pain...the back pressure is a term used to describe the pressure created in the exhaust system to stop the turbo overspeeding,....

Pressure crated by the compression leaking past the piston rings is crank case pressure.....

The waste gate stops the turbo "over-boosting"

Exhaust back pressure is created by constrictions/obstructions in the exhaust - ie the cat converter

or middle & back box.

I removed my Cat & Middle box, but then had to fit a minor exhaust blockage to create back-pressure in the exhaust to get the turbo to work properly.

With no/not enough exhaust back pressure, the turbo can spin up & be at peak revs by or before 2,500 engine revs. Should really peak out at higher engine revs than that.

This also effects the fueling & can some times put too much air to fuel at the wrong engine revs.

The turbo will over rev without an exhaust restriction, causing rapid wear on the spindle bearings.

I managed to destroy a new turbo in 6 months with this turbo over-speeding issue.

The faster the turbo revs, the faster it gets rid of lubricant thru its bearings. . . . If it's spinning its balls off at 2,200 engine revs, noting that the engine oil pressure increases with revs, then it's theoretically possible to starve the turbo of oil if it revs too fast at low engine speeds.

The turbo effiency is all down to exhaust gas density & air-speed thru the manifold.

There is a lot of development work done by manufacturers (£££ millions spent) with exhaust technology & silencers etc, So the only proper way to get more power by fiddling with the exhaust is to remove the cat only or get an aftermarket exhaust, or also remove the centre box & fit a small sheet metal obstruction in the exhaust airflow just before the rear silencer.

Some back pressure is essential.

Hope this helps.

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