How reliable are turbo engines?

"Scott en Aztlán" wrote

Did you forget "torque steer"?

FloydR

Reply to
Floyd Rogers
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Turbojets are just turbocharged piston engines without the piston engine. :-)

Reply to
Bill Funk

Well, gosh, if I knew I'd be dealing with some kind of pendatic asshole, I'd have used the words "allow for" instead of "provide." Or substituted "airflow" for "power".

But see if you can follow along. More airflow means more oxygen. More oxygen means, if one meters the air properly, one can burn more fuel with that increased oxygen. Burning more fuel per rev means more power. Thus, for those who can't seem to follow along at home, turbos provide more power.

It was clear to everyone except you.

Actually, I was right the whole time. I just didn't want to type so as to preclude every pedant from getting his panties in a bunch.

E.P.

Reply to
Ed Pirrero

IIRC, most of Amtrak's locos are 'fly-by-wire'; it's pretty hard to damage them by agressive driving. Most downtime is either for maintenance (planned), or equipment defects (bad brakes, for example).

Reply to
Bill Funk

Did you DAGS on this subject?

Since everyone else has corrected you, I'll not pile on.

One of the things you learn when you own a turbo car is how a turbo works. Especially a car that can generate 500whp on the stock internals, with the proper mods. And the beginning of that mod train is the turbo.

Read up some on the subject. It's actually quite interesting. Especially the WWII use of turbos in aircraft.

E.P.

1995 Audi UrS6
Reply to
Ed Pirrero

Others have answered, but I'll pile on. To reduce lag. But if you look at most turbo compressor maps, you'll see a "sweet spot" at higher rpm where the turbo is most efficient.

Wastegates prevent overpressures, or spinning the turbo hard when it's not needed. Cruising at high speed, fer instance. That would be running the turbo in the lower portion of it's boost map, but why do it if all you're doing is a steady 95mph? Have the exhaust shunted around the turbine so that the car isn't making boost when it's not needed.

Also as a safety feature - overboosting is bad for the motor.

Methinks you need to do some research before showing your ass. DAGS and come back enlightened.

E.P.

Reply to
Ed Pirrero

Poor analogy. Jet engines don't use the jet's compression to drive a piston engine.

Reply to
AZ Nomad

Smarty pants. :P

Wanna talk about turbo-compound engines? Those are turboprop engines with some pistons and a crankshaft stuck in the middle of the works :-)

Reply to
Steve

Sorry; didn't realize you were running a quiz show.

Reply to
Matthew Russotto

Well, I lost track of the attribution, but I think the argument that "turbos work better (see, I avoided "power" altogether) at higher engine RPM" is a bit off-track. When you get right down to it, the turbocharger's function is fairly independent of engine RPM. If you put a turbo engine in high gear and lug the snot out of it at 2500 RPM with the throttle WFO, an appropriately-sized turbo for general street use will *still* spin up and deliver the same amount of wastegate-limited boost that it will produce with the engine spinning at 5000 RPM. That is because there's sufficient volume flow through the system. Now the

*engine* will probably still produce a bit more power at 5k, for exactly the same reason that a normally-aspirated engine will produce more power at 5 grand. But OVERALL, turbochargers tend to BROADEN, FLATTEN, and FILL IN THE LOW END of the torque curve of an engine when compared to the same size/type engine configured for normal aspiration. So I would still contend that turbocharged engines really shine at the LOW end of the RPM range, because thats where the boost provides such a big advantage over normal aspiration, where the induction system is typically tuned to work best at near-redline RPM.

That's really true of all forms of forced induction, not just turbocharging. The Reno air racers (on my mind because the races just concluded yesterday), particularly the Rolls-Royce Merlin powered ones, run absolutely enormous boost pressures (over 110 inches of mercury, compared to 60" HG max for the stock engine). But they only increase the RPM by a relatively small percentage (3300-3400 RPM instead of 2900 to

3000 stock). The horsepower doubles compared to stock, though.
Reply to
Steve

Just about all locomotives built in the last 20 years are "fly by wire" (more accurately, computer controlled both in terms of the diesel powerplant and the electric traction motors). There's not really any such thing as a "passenger locomotive" anymore. The GE Genesis and EMD locomotives for Amtrak are basically just re-bodied versions of freight locomotives, and sometimes equipped with a different gear ratio after the traction motors to allow higher top speeds. Oh, and in some cases small auxiliary diesel engines to generate "head end power" for the coaches when the prime mover isn't running.

Reply to
Steve

That wasn't the point. The point is that its the same basic mechanical layout, and because there are no reciprocating masses both are very reliable machines.

Reply to
Steve

It depends on the compressor map. But at low RPM, the engine doesn't move as much air, and the turbo won't spin as fast. Obviously, there's a physical limit to how much air a turbo can push, but you'll approach those limits on a street car pretty high in the RPM range.

No it isn't. The amount of air moved by the engine determines the rpm of the turbine wheel.

Have you ever owned a turbo car? This last paragraph is patently untrue. DAGS and educate yourself on the subject.

E.P.

Reply to
Ed Pirrero

"Steve" wrote

You lost track because Ed is incapable of posting correct and accurate information, in most cases. Also (not his fault) he didn't post over the weekend and is out of sync with everyone else.

FloydR

Reply to
Floyd Rogers

Yes it is. The turbo is driven by exhaust gas, and that's not as dependent of RPMs as it is on throttle position. IOW, half throttle at 1500RPM will produce more exhaust than cruising at 2000RPM, and thus more pressure from the TC.

Yes, but that's determined by more than engine RPM.

Reply to
Bill Funk

How about super-turbo-charged engines? :-) Or, turbo-super-charged engines?

Reply to
Bill Funk

They're a piston engine with a turbo wheel that drive the crank instead of compressing more air for the intake. They were sometimes used on pre-jet age airliners.

See:

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Dan

Reply to
Dan_Thomas_nospam

Well, the rhetorical nature of my questions wasn't obvious. ;-( I need practice in online sarcasm and such, I guess.

But Ed, being predictable, immediately dropped to an ad hominem attack... and post admirably unfocused and rambling dissertations.

FloydR

Reply to
Floyd Rogers

OK, then tell me, at 2000 rpm, how many liters of gas per minute goes through the turbo of a 2.0L turbomotor?

Now, tell me how many goes through at 4000rpm? Remember that the motor is an air pump, and that volume of gas going out is directly related to how many times per minute each cylinder gets filled. Unless you're claiming that the air is somehow not making it to the engine cyclinders...

That makes no logical sense. The volume within the cylinders is fixed. More revs means more gas.

Show me the math.

How? Show me with MATH. I want to know where this air is going. In my car, once the air moves past the MAF, it's going to the exhaust. There ain't nowhere else for it to go.

Reply to
Ed Pirrero

I can't help it that you're an idiot who can't do your own research.

Get back to me when you know what you're talking about, or can point out somebody who does.

Corky Bell, anyone?

E.P.

Reply to
Ed Pirrero

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