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Black smoke?

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Budgie:
I always thought it was the exhaust gasses passing over the fins on the turbo's drive fan that drove it, hence the increase in boost pressure as the revs increase.  :?

Xtremeteam:

--- Quote from: "Bulli" ---Often oil in the turbo , a little normally get past the seal when its been stood. The reason why the turbo doesn' repond to the increase in fueling is that it isn' exhaust gas that makes it spin. THe turbo spins as a result of heat,thats why it lags more when the engine is clock cold.
--- End quote ---

NOPE:lol:

The turbo is driven by the exhaust gasses exiting the system,the reason you have lag is to get more go you need more in,to get more in you need more coming out to drive the turbo,thus thens spins it up & pushes more in,did a talk on this for a module at college but cant fiind anything that would be useful to abny 1 else

Basically the gasses coming out drive the turbo spinning it up & pushing more in

Bulli:
:oops: Read below, perhaps they need a new module??Seems your colege stuff wasnt entirely accurate but then again neither was i. After speaking to a mate who has worked on F1 ans BSB he said as shown below that the spin up is a result of both gas volume and heat! heat being the Key ingredient.....as shown below from an american turbo theory site
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TURBO THEORY

 




The larger the compressor and the higher the pressure (boost) we want, the quicker the power from the exhaust turbine is used up. Put in a larger exhaust turbine and it will take the engine longer to develop enough hot expanding exhaust gas to spin it, slowing down the compressor and causing turbo lag. At this point I am going to repeat something stated earlier, do not think of a turbo charger as a bolt on piece of equipment, think of it as a system.

The turbine is powered by hot expanding exhaust gas, a lot of hot expanding exhaust gas, the more and the hotter the expanding exhaust gas the better. I am sure many of you have seen pictures of turbo charged engines with cherry red hot exhaust systems and turbo housings

rollazuki:
Turbos spin due to gas expansion into manifold, and hence turbo!
Heat is the culprit which makes it spin, not any volume of gas.
A hot motor will suffer less turbo lag than a clock cold motor.
Heat expansion is the key!
to reduce turbo lag, use a turbo with a lower A/R ratio(clearance of rotor to housing it runs in)
or generally a smaller lighter turbo.
Top end performance will suffer then though.
Some form of dump valve(recirculating is even better) will keep turbine speed up, allowing the turbo to 'spool up' quicker.
Rollazuki :D

muddyweb:
I think we are getting a little confused with our terminology here...

Yes... heat plays a big part in turbo operation because expanding gas creates gas flow, and gas flow turns the turbine.....


So... exhaust gas turns the turbine... by virtue of the fact that it is expanding and creating gas flow.... more heat creates faster gas flow and as such the lag effect is reduced.


Turbos don't operate on heat... they operate on gas flow.

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