Any turbo gooroos out there

[bones]

Anybody for familar with the hair blower than i? I would like to ask some fairly(to me) complex questions and see what different answers we get to my way of thinking.

 

 

[Tomo]

Away you go..... I'm no gurru but do work on 'em from time to time.

 

 

[Guest check-in]

Are we talking turbo-chargers (which I have flown but am not expert on) or turbines/jets (which I do operate frequently) or old-fashioned fixed geared superchargers (which I had a lot to do with of old). As long as it relates to the operation thereof, I may be able to help. Tomo sounds like he is da man for the techo stuff.

 

 

[Guest Qwerty]

Lets get some terminology sorted up front.

 

There are a bunch of gadgets available to elevate the intake mixture/air pressure for engines. These are ALL called superchargers that is to say they ALL super-charge (or elevate) the mixture pressure.

 

There are two common types;

 

1. The turbocharger which utilises a turbine usually driven by exhaust gasses (and sometimes electrically I am told).

 

2. The Blower which is based on a mechanically driven vane type blower, usually a "Roots Blower".

 

 

[bones]

Righto then, i am talking about exhaust driven turbo.

 

1. what is the maximum EGT that a standard turbo could take before melting of the turbine wheel fins occurs?

 

2. As long as the temps are kept under the answer to no.1, is there anything else that could cause the fins on the inside turbine wheel to suffer what appears to be heat damage.

 

3. As long as the boost is kept under the max boost pressure for a said motor set up, is there any other major temps or pressures that need to be maintained?

 

There you go have a crack at those for starters and we can go from there

 

 

[Tomo]

(and sometimes electrically I am told).

Turbochargers are driven by the engines own exhaust gases...

 

Anything that is driven by a mechanical force is generally (99%) called a supercharger...

 

 

[Guest Qwerty]

Don't start Tomo.....don't start, they are all superchargers that is they all super---charge the combustion chamber. If it works on the turbine principle (centripetal flow and high speed radial vanes) its a turbo.

 

Just because a bunch of twits in a particular pub call them something else does not make it so.

 

 

 

[Tomo]

Don't start Tomo.....don't start, they are all superchargers that is they all super---charge the combustion chamber. If it works on the turbine principle (centripetal flow and high speed radial vanes) its a turbo.

 

 

[Tomo]

1. what is the maximum EGT that a standard turbo could take before melting of the turbine wheel fins occurs?

Exhaust gases only, I don't think you will melt the fins with just that.

 

I've seen Turbo's glowing cherry red, Turbine an all.

 

But I have seen turbo's melted too! but that wasn't from the EG... Oil feed was ripped off and it ran dry... screwed the whole show.

 

The fins haven't been hitting the edge by any chance?, to have EG temps so hot as to melt turbine fins, your engine is either running dangerously lean, or it's a dud turbo.

 

What is it fitted to?

 

 

[Guest check-in]

Dunno about the meltdown questions, but operationally:

 

On take-off, from 30 inches up, feed in the throttle slow and steady to give the turbo time to catch up smoothly - if you throttle up too quickly they surge and carry on (I think the term is 'bootstrapping'?).

 

After landing, let it run at idle for a good three minutes to allow the turbo to spin down from the huge RPM it may have been at on approach (relative to the engine RPM that is). My understanding is we do this because the turbocharger relies on engine oil pressure for lubrication and you don't want it spinning its tiny wheels with no oil to the bearings.

 

Oh, and Qwerty let's not get into semantics. When I was a boy, men were men and barmaids ate their young, and the things we had bolted to our big radials were called superchargers. By no less than Mr Pratt & Whitney hisself...Then along came Continental and Lycoming who stuck 'turbocharger' badges all over everything that had a gadget stuck up its pipes, so what WERE we to think?

 

 

[Guest Qwerty]

Tomo, when you get back to work you can take them to task over it......they are wrong. It drives some of them nuts, especially revheads with Doof Doof cars. :hittinghead:

 

Damn, where is the pot stirring emoticon???

 

 

[Tomo]

Damn, where is the pot stirring emoticon???

Here.... :stirring pot:

 

Don't understand what you mean Qwavid?

 

 

[bones]

hmmmmm good to see this site cant stay on thread either

 

After talking again with the repair man, it might have been caused from a temp fuel stavation, on full power, which i had a couple of, for some reason, i changed a few hoses and no problem ever since.

 

The carbon build up inside the turbo was more than likely caused by and incorrectly set up waste gate, and the turbo not spinning properly at idle down.

 

The carbon letting go and going through the turbo also could have been some of the problem on the wheel.

 

All in all exspensive little lesson to be learnt.

 

 

[Guest Qwerty]

..........the things we had bolted to our big radials were called superchargers. By no less than Mr Pratt & Whitney hisself......

CORRECT if it supplied an additional amount to the charge (mixture) supplied to the cylinder.

 

.....Then along came Continental and Lycoming who stuck 'turbocharger' badges all over everything that had a gadget stuck up its pipes.....

CORRECT if it did this by means of a turbine.

 

..... so what WERE we to think?

I suppose you were to think that the radials were supercharged by an unspecified means and that the Continentals and Lycomings were supercharged by means of a turbine......that's what I would have thought.

 

Semantics are important. If, in an emergency the PIC said decend, what woudl you do. pull the throttle or push the stick. The answer might just be important.

 

Think for a moment aboout the words, Gay, Wicked, Hot, Cool, the list is endless. :thumb_up:

 

Qwerty:helmet:

 

 

[Tomo]

Sorry about the thread drift Bones. I think I've been in the office a bit to long today...!

 

It's good to hear you've got it sorted.

 

Running the engine on idle for a few minutes is a turbo's best friend. Reason being is: 1 as Check-in said, to allow oil to be pumped to the bushes while it slows down. 2, rapid cooling isn't good for anything that gets red hot, especially when we are playing with minor tolerances. So running at a lower rev just lets everything calm down to a bit more of an even heat.

 

And yes Unfortunately, turbo's are a bit like injector pumps, extremely expensive!

 

 

[Tomo]

I suppose you were to think that the radials were supercharged by an unspecified means and that the Continentals and Lycomings were supercharged by means of a turbine......that's what I would have thought.

Sorry Qwerty, I'm being mean again!

 

I was just being silly and picking you up on where you said "1. The turbocharger which utilises a turbine usually driven by exhaust gasses (and sometimes electrically I am told)."

 

See if it were 'Turbo' (turbine, exhaust gases) Charger (impeller, boost) were driven electrically, it would no longer be a 'Turbo' Charger... But rather a 'Super' (mechanically driven, electric motor) Charger.

 

Because Superchargers use mechanical drive's (direct, belts, gears etc) it wouldn't have a Turbine. So you couldn't call it a Turbocharger, unless the charger was driven by a turbine!

 

So as not to be confusing... you see!

 

Ps. For those that are lost, they both blow into the engine!

 

 

[turboplanner]

He's been eating mutton birds again, sure warning of mischief to come Tomo, watch out.

 

 

[Guest ozzie]

Another problem with not letting a exhaust driven turbine type supercharger go through a cool down period at idle is that if you shut them down hot the case cools faster than the turbine and can close on the blades which can lock them or distort them. signs of this are a scrapping noise either on start up or shut down. turbo prop and jet engines can suffer from this as well. shock cooling, rapid closing of the throttle and poking the aircrafts nose down for a fast decent can cause a heap of problems. chieftans are well known for this. At night in a chieftan you can see thru the cooling gills on the side of the cowls and on take off you can see the driving 'snail' get cherry red/white hot then you can actually see inside the turbo charger.

 

suddenly running lean at high power settings will do more damge to the engine than just screwing up the vanes. If you have a 'exhaust driven air pump' i strongly recommend the fitting of insulation blanket around the snail and wrapping the exhaust pipes with insulation material. keeping as much heat inside the pipes and charger will help not only with performance but under cowl temps will be lower and electronic and fuel componets will benifit as well.

 

If you are unsure or do not realise the effects that suddenly running lean does try this little experiment. grab an old two stoke mower. start it up get it warm and then return it to idle and turn off the fuel and wait. as it starts to run out of fuel the rpm starts to increase until just before it cuts out the rpm will race,almost go to max. during this short period the EGT will go off the scale.

 

back in my wild youth i had several two stroke tripple cyl bikes. thirsty buggers these are. several times racing around i ran out of fuel before i could switch to reserve i blew a hole in the center piston. If you start to run out of fuel it is better to either just switch the mags off or quickly open the throttle do not close i,t it will just lean out quicker if you do that.

 

Ozzie

 

 

[Guest Maj Millard]

Bones, the 914 turbo system is very complicated with sensors and electrical circutry etc....then the whole thing is overseen, and regulated by a computer box. You also have your warning /operating lights which tell you what the turbo boost is doing. The turbo itself is a no-repair item...if it's stuffed than the whole unit must be replaced. Generally the whole set-up is designed to be electronically self regulating and self controlling IE: it is a hands-off system requiring only checks, and generally no adjustment during the 1200 hrs of it's life.

 

I don't know if you are talking inlet or exhaust turbo rotor damage. The damage you mention could be caused by the following.

 

1. Simple component failure.....it does happen.

 

2. Operator ignoring the turbo warning lights, especially the overboost one.

 

3. Failure of sensor, or other wiring fault delivering false or no info to the controller box. (Check for wire loom chaffing around the engine).

 

4. Somebody not knowing what their doing, and adjusting the waste gate flap cable or generally fiddling otherwise.

 

5. Not operating the engine per the manufacturers' guidelines, as Ozzie says cool down/warm-up times are so important..................Good luck.....................................

 

 

[Guest Maj Millard]

Tomo,Quesy, A supercharger driven by exhaust gases is a Turbocharger, a mechanically driven one like on real round engines (Crank/gear driven) or dragcars (belt driven) are Superchargers. If you run either, you just put a sizeable amount in the bank for when they fail...not if.....................

 

 

[bones]

Maj,

 

Not on the 914 havent even started playing with that devil yet

 

 

[Guest Maj Millard]

Sell it, get a good 912 ULS 100 hp, with a TBO of 2000hrs...................................................................

 

 

[Tomo]

supercharger driven by exhaust gases is a Turbocharger,

Some people just put things so simply! Thats what I was trying to say Maj, thanks.

 

 

[Tomo]

Ok so check out the supercharger, in a mini...

 

[ATTACH]9665.vB[/ATTACH]

 

And it's not mine either! I got a naturally 'in-spirated' ute... (doesn't need help from anything else... ;) )

 

 

 

[Guest Qwerty]

Ok so check out the supercharger, in a mini... [ATTACH]14546[/ATTACH]

 

And it's not mine either! I got a naturally 'in-spirated' ute... (doesn't need help from anything else... ;) )

After all that talk about turbos, he shows us a blower....you are a bloody legend Tomo.