Revs, how high do they go?

[Mr2Mike]

CraigyMc said:

Why the need to have a dig at diesel drivers in an otherwise perfectly reasonable post?

It wasn't a dig, it was an observation gained from reading countless "torque" threads on PH.

[Mr2Mike]

oilspill said:

Whilst comparing bikes and cars, how much more efficient is the drive chain on a bike than the drive shafts/diff on a car?

Chain drives are very efficient when in good condition, one of the most efficient power transfer mechanisms around. Shaft drives reduce efficiency on a bike since there has to be at least one set of bevel gears in the drivetrain, and sometimes two (for transverse engine installation). Shafts are also heavier and don't permit the easy changes of gearing that sprockets and chains do.

[anonymous-user]

The McLaren P1 revs to 18krpm (well, the Emachine bit of it does..... ;-)

[CraigyMc]

Max_Torque said:

The McLaren P1 revs to 18krpm (well, the Emachine bit of it does..... ;-)

If we're not talking about crankshaft rotation speeds, I expect that the turbines inside the turbochargers spin quite a lot faster than that.

C

[anonymous-user]

CraigyMc said:

Max_Torque said:

The McLaren P1 revs to 18krpm (well, the Emachine bit of it does..... ;-)

If we're not talking about crankshaft rotation speeds, I expect that the turbines inside the turbochargers spin quite a lot faster than that.

C

True, but they don't (yet) directly drive the wheels..... ;-)


(150 -> 220Krpm btw for a typical passenger car turbo shaft)

[AW111]

Max_Torque said:

CraigyMc said:

Max_Torque said:

The McLaren P1 revs to 18krpm (well, the Emachine bit of it does..... ;-)

If we're not talking about crankshaft rotation speeds, I expect that the turbines inside the turbochargers spin quite a lot faster than that.

C

True, but they don't (yet) directly drive the wheels..... ;-)


(150 -> 220Krpm btw for a typical passenger car turbo shaft)

I was playing with a new truck diesel a couple of years ago (DD60 iirc), and it has some sort of power takeoff from the turbine to the flywheel, adds about 10% to the total power output.

So your "(yet)" is probably not far away for cars.

[Mave]

AW111 said:

I was playing with a new truck diesel a couple of years ago (DD60 iirc), and it has some sort of power takeoff from the turbine to the flywheel, adds about 10% to the total power output.

So your "(yet)" is probably not far away for cars.

So is it actually aacting like a supercharger?

[AW111]

Mave said:

So is it actually aacting like a supercharger?

No, a gas turbine. The turbine feeds power to the flywheel, if I read the manual correctly.

[Mave]

AW111 said:

No, a gas turbine. The turbine feeds power to the flywheel, if I read the manual correctly.

But how does the power know if you want it to go to the flywheel; or from the flywheel to the compressor side of the turbocharger?

[anonymous-user]

Turbine is coupled to the crank with a variable speed drive, something like the good old Torotrak unit.


Lots of people are currently investigating the technology for the prime mover market segment, where the road load is generally high and fairly continuous.

[AW111]

Max_Torque said:

Turbine is coupled to the crank with a variable speed drive, something like the good old Torotrak unit.
...

To vaguely return to the original topic, it's a hell of a reduction ratio : turbine at say 150,000 rpm -> flywheel at 1,000 rpm

The time to spool up to full power (on an engine dyno) gives a whole new meaning to the term turbo lag - my memory says around 5 seconds to max boost (which was several bar I think).

[Mave]

doogz said:

A clutch? That can engage or disengage on demand?

Ever used a ratchet? I'm not suggesting that mechanism is used here, but it's a manner of being able to apply additional force/torque in one direction whilst allowing it to freewheel in the other.

I actually think the power does know where you want it to go anyway, if you manage to sort out the gearing. At low exhaust flow, the flywheel has to drive the compressor as they're mechanically linked, and it acts like a supercharger. At high exhaust flow the turbine drives the compressor and flywheel.

[otolith]

Huff said:

TREMAiNE said:

My RX8 R3 will to 10,000 rpm off the bounce. Apparently they're capable of hitting as high as 13,000.

One thing to note about the wankel - the output shaft is geared up to 3x the rotor speed. So in a Mazda with an output shaft speed of ~8000rpm the rotor is only actually spinning at about 2600rpm.

Of course, the flipside of that is that if you think of it that way, it has peak torque of 468lbft @ 1833rpm