A thought about WWII turbo chargers longevity

[BrendAn]

On 10/12/2023 at 11:12 AM, facthunter said:

Having all that plumbing doesn't help efficiency. A turbo charger uses exhaust heat for it's energy.  Nev

never heard of this before. turbo is only a fan driven by flow. its designed to work in a high temp enviroment. certainly doesn't use heat for energy.

[onetrack]

The temperature of the exhaust gas going through the turbo affects its output - because of gas expansion. So the hotter the exhaust gas, the more power the turbo produces.

[facthunter]

It Does, Brendan.   The same principle is used in Bootstrap air conditioners.  Nev

[LoonyBob]

1 hour ago, BrendAn said:

never heard of this before. turbo is only a fan driven by flow. its designed to work in a high temp enviroment. certainly doesn't use heat for energy.

The turbocharger turbine outlet temperature is always lower than the turbine inlet temperature, and the change in temp (delta t) by the change in pressure (delta P) is always greater than the shaft power out of the turbine. As the pressure drop can only be negligible* - no turbine is a small orofice! - the most of the energy transfer occurs in the temperature drop.

 

*A gas turbine jet engine has several orders of magnitude more volume flow than a piston engine of similar fuel usage; in which case, the turbine does throttle the exhaust - in effect, it becomes a small orofice.

 

For a not overly mathematical explanation, I strongly recomment Hugh McInne's book "Turbochargers"...

[BrendAn]

1 hour ago, LoonyBob said:

The turbocharger turbine outlet temperature is always lower than the turbine inlet temperature, and the change in temp (delta t) by the change in pressure (delta P) is always greater than the shaft power out of the turbine. As the pressure drop can only be negligible* - no turbine is a small orofice! - the most of the energy transfer occurs in the temperature drop.

 

*A gas turbine jet engine has several orders of magnitude more volume flow than a piston engine of similar fuel usage; in which case, the turbine does throttle the exhaust - in effect, it becomes a small orofice.

 

For a not overly mathematical explanation, I strongly recomment Hugh McInne's book "Turbochargers"...

don't need to read anything. in this group you just type an answer . if its wrong you learn from reading the comments from the experts waiting to shoot down you down. as i just learn't something new from the above comments.

[facthunter]

No one wants to shoot you down. I'm happy to see anyone seek more facts and often they are not intuitive at first glance. It's actually all in the universal GAS Equation. (P1V1/ T1 =s K.  Nev

[BrendAn]

1 hour ago, facthunter said:

No one wants to shoot you down. I'm happy to see anyone seek more facts and often they are not intuitive at first glance. It's actually all in the universal GAS Equation. (P1V1/ T1 =s K.  Nev

its a great way to learn though.😁

[facthunter]

The HARD way is by personal experience. Easier and safer using someone elses.  Nev

[spacesailor]

I have been advised " that the exhaust silencer Is Not required " with a " turbo " . As it chopps the highs of the noise, by way of that spinning turbo,  & that silencer  is slowing the gasses

Passing through the turbo .

I haven't tried it yet ,

but have seen one with only a ' particulate filter ' only .

it wasn't that  much louder .

spacesailor

 

[Thruster88]

That is indeed the case Spacesailor, we had Steiger tractors with straight pipe Cat 14litre 3406 turbo diesels and they were fairly quiet. I think the noise produced also has a lot to do with cam timing. Straight pipe Lycoming engines are not head turning due mild cam timing.  

[LoonyBob]

4 hours ago, BrendAn said:

its a great way to learn though.😁

Glad you don't mind the infodumps! Soz, I'm just so glad someone is actually interested...

[facthunter]

Turbo's do silence the exhaust a bit but some of them are Bad for your Hearing as they create their own high frequency noises.   Opening the exhaust valve earlier makes more noise.   Nev

[skippydiesel]

Can't remember the km's/many years in service but when the Daihatsu Rocky 2.8  turbo,  OM muffler, finally developed a crack or two, I replaced it with a straight through exhaust pipe.  Slightly better performance. Noise level, in normal operation/exceleration, much the same as with muffler. Put the boot to the firewall and the noise level  rose dramatically - sounded like a semi on a steep climb 😈.

[danny_galaga]

Of course the boys and their ricers were all about the noise. I remember when blow off valves WEREN'T illegal, I saw an ad in a ricer magazine for a blow off valve proudly stating theirs was 25% louder than the competition 😄. At least they weren't hiding why bogans would install them!