Turbo performance?

[haydes55]

Do turbos gain pressure from the air being heated up as it passes the hot turbo as well as the fan forcing more air in? Or would it be ideal to have the turbo cold (If it could be done) so the air passing through it is still cool?

If heating and cooling the air plays no part in the building of air pressure then developing a cool turbo of sorts could eliminate the need for an intercooler, so lighter weight.

(Random late night engineering ideas)

[schrodingers cat]

Do turbos gain pressure from the air being heated up as it passes the hot turbo as well as the fan forcing more air in? Or would it be ideal to have the turbo cold (If it could be done) so the air passing through it is still cool?

If heating and cooling the air plays no part in the building of air pressure then developing a cool turbo of sorts could eliminate the need for an intercooler, so lighter weight.

Do some reading about thermodynamics.

While you're at it can you also circumvent the laws of physics so I can ride as fast as I like without consequences?

[2Seat_Terror]

Simply: More pressure = higher air density = more boom.
More heat = lower density = less boom. This is why the intercooler is used (that and other heat-related problems like detonation).

[Woodman]

Cooler air is more dense of oxygen. Oxygen plus fuel is what makes fire.

[haydes55]

What I'm getting at is, why does a turbos design incorporate pumping cool air through a hot fan? Surely it would be better to have a shaft driven by the turbo that drives a separate fan which will be away from the hot exhaust?

[quickbuck]

What I'm getting at is, why does a turbos design incorporate pumping cool air through a hot fan? Surely it would be better to have a shaft driven by the turbo that drives a separate fan which will be away from the hot exhaust?

EH???
Well, it is a seperate fan... The exhause drives on wheel that is connected to a hafe that drives the compressor.
The heat from the compressor side of it is something that occurs when you squeeze any quantity of air up.

[scumdog]

What I'm getting at is, why does a turbos design incorporate pumping cool air through a hot fan? Surely it would be better to have a shaft driven by the turbo that drives a separate fan which will be away from the hot exhaust?

I see where you're coming from - a long shaft between the exhaust impeller and the intake impeller?

Unfortunately as mentioned by quickbuck, the very act of compressing air will make it hot - just feel what the temp the pump on an air compressor can get to...

[FJRider]

Simply ... Variations abound.

The exaust gasses are directed through a turbine, this turbine is on the same shaft as a fan which forces air into the cylinders (Through the carbs). The increased fuel/air mixture (in the same space as normal) makes a bigger bang. More revs ... more fuel/air in ... more power. Most turbo are lower compression engines (to compensate for the larger fuel air mixture and higher compression that bigger bang makes) ... that rely on the turbo to get power. So at low rev's ... they are a dog.

[FJRider]

Cooler air is more dense of oxygen. Oxygen plus fuel is what makes fire.

But fuel would burn better in warm air ... wouldn't it ... ???

[haydes55]

EH???
Well, it is a seperate fan... The exhause drives on wheel that is connected to a hafe that drives the compressor.
The heat from the compressor side of it is something that occurs when you squeeze any quantity of air up.

That explains it thanks

[FJRider]

EH???
Well, it is a seperate fan... The exhause drives on wheel that is connected to a hafe that drives the compressor.
The heat from the compressor side of it is something that occurs when you squeeze any quantity of air up.

Not to mention the heat from the (usually) ceramic bearings ... as the RPM of the turbo shaft is spinning mind-blowing fast. (makes the red line figure of a 4 cylinder 250 seem slow by comparison)

[quickbuck]

Not to mention the heat from the (usually) ceramic bearings ... as the RPM of the turbo shaft is spinning mind-blowing fast. (makes the red line figure of a 4 cylinder 250 seem slow by comparison)

True that.
The Bell 47 uses a VERY large Turbo... and it spins at over 40000 RPM.
100000 isn't too far fetched for some of the smaller turbos out there.

[superman]

But fuel would burn better in warm air ... wouldn't it ... ???

All that would do is increase the risk of self detonation and reduce the oxygen content.

[2Seat_Terror]

You could skip the whole air compression thing and gear the turbo to the crankshaft! Turbo-compound engines on the last big propliners did this.

[FJRider]

You could skip the whole air compression thing and gear the turbo to the crankshaft! Turbo-compound engines on the last big propliners did this.

Then it would be supercharged. A similar principal ... with different characteristics in the final result.

Turbo's usually have a "lag" between throttle movement ... and response from the engine.(due usually because of distance from cylinders, through the exaust to the turbo)... Supercharging is (by comparision) instant .... as the "turbo" is driven directly off the engine.