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Engine superchargers?


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shapeshifter #1 Posted Jan 21 2015 - 03:47

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Basically a supercharger allowed more air to enter the combustion stage increasing overall power. Air + fuel = boom. more air allows more fuel = bigger boom.

 

Was there a rule of thumb for performance increase? I see many places quoting "Supercharging adds an average of 46 percent more horsepower and 31 percent more torque" but if this is true or only applies to modern day engines I have no idea.

 

Did many tanks in world war two have a super charger? I know a planes did, and I know the Germans had some plans to supercharge some of their tank engines but they never seemed to get put into production.

 

 

Reason I ask is I learned recently the T1E2 heavy tank (M6) in January 27th 1942 they replaced the old carburetor with a new one featuring a supercharger, when installed which gave greatly improved performance.

 

And that's all they have to say about that on the subject. They still go on to list specs as a 960 Hp engine @ 2300 rpm. but never list what the supercharger did for the engine. if the 46%/31% is accurate that would make it act like a 1168 - 1401 Hp engine with anywhere from 2358 - 2882 lbs of torque depending on listed specs used for engine.

 

 



Windows_Are_Tasty #2 Posted Jan 21 2015 - 03:49

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Due to how a supercharger works, it's generally not a good choice for a diesel engine, and most tanks have diesel engines. Even still, I don't think many tanks have turbos either.

shapeshifter #3 Posted Jan 21 2015 - 03:51

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Some Shermans had Radial engines and the M6's used a Wright Radial as well. (aircraft engines)

Edited by shapeshifter, Jan 21 2015 - 03:51.


MastuhWaffles #4 Posted Jan 21 2015 - 04:09

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Usually diesels use turbos. The main problem with supercharging and engine is keeping the engine cool. And tank's aren't really the best when it comes to it.

NutrientibusMeaGallus #5 Posted Jan 21 2015 - 04:11

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I think superchargers during that time still had some reliability issues.

Strike_Witch_Tomoko #6 Posted Jan 21 2015 - 04:14

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View PostIOC_Cartmen, on Jan 20 2015 - 19:49, said:

Due to how a supercharger works, it's generally not a good choice for a diesel engine, and most tanks have diesel engines. Even still, I don't think many tanks have turbos either.

 

boom boom?

Meplat #7 Posted Jan 21 2015 - 04:17

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View Postshapeshifter, on Jan 20 2015 - 19:51, said:

Some Shermans had Radial engines and the M6's used a Wright Radial as well. (aircraft engines)

 

All the gasoline radial mills used in U.S. armor had a supercharger, better thought of as an induction blower as their boost ratios were not that high.

I forget if the A1020 Guiberson had an induction bower, being direct injected.



Moguai #8 Posted Jan 21 2015 - 04:18

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View PostMastuhWaffles, on Jan 20 2015 - 20:09, said:

Usually diesels use turbos. The main problem with supercharging and engine is keeping the engine cool. And tank's aren't really the best when it comes to it.

 

Actually Superchargers run much cooler than a TurboCharger.

 

Turbo chargers are basically Free horsepower whereas Superchargers take horsepower to make horsepower.



shapeshifter #9 Posted Jan 21 2015 - 04:21

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So for a tank, were these constantly helping boost power or was it like WEP on a plane, something they could boost with.

Edited by shapeshifter, Jan 21 2015 - 04:21.


Meplat #10 Posted Jan 21 2015 - 04:24

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View Postshapeshifter, on Jan 20 2015 - 20:21, said:

So for a tank, were these constantly helping boost power or was it like WEP on a plane, something they could boost with.

 

No, they were fixed ratio.

collimatrix #11 Posted Jan 21 2015 - 04:27

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It would depend on the isentropic efficiency of the compressor, the mass flow of air, maximum RPM, and a lot of other things.

 

The octane rating and intercooling of the supercharger would also be a concern.  The supercharger needs to be cooled; not so much because you're worried about the compressor being hurt by the heat, but because if the air is too hot it will prematurely ignite the fuel in the cylinder.  This would cause engine knocking which could demolish the engine.



collimatrix #12 Posted Jan 21 2015 - 04:32

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View PostMoguai, on Jan 21 2015 - 04:18, said:

 

Actually Superchargers run much cooler than a TurboCharger.

 

Turbo chargers are basically Free horsepower whereas Superchargers take horsepower to make horsepower.

 

Please enlighten me as to how a supercharger and a turbocharger with identical mass flow rates and isentropic efficiency will cause different amounts of adiabatic heating.  This could be the secret to free energy we've been looking for all these years.

ket101 #13 Posted Jan 21 2015 - 04:41

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A turbocharger is run with exhaust gases, and thus heats up a heck of a lot, keeping heat in the engine bay area.  The exhaust restriction is also a drag on horsepower, to a degree, though not as much as a supercharger.  The supercharger uses a mechanical drive from the engine, and has no contact with the exhaust gases, and is thus a bit cooler than a turbocharger.  There's power recovery turbines as well, but they don't necessarily provide forced induction.

 

In a lot of cases, superchargers were removed from aero engines when they were put in tanks.  They produced more power than was wanted, and also put additional stress on the engine.  Case in point: the Meteor engine used in the Cromwell and others.  It was, in the most basic explanation, a Merlin without a supercharger.



Meplat #14 Posted Jan 21 2015 - 04:49

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View Postcollimatrix, on Jan 20 2015 - 20:32, said:

 

Please enlighten me as to how a supercharger and a turbocharger with identical mass flow rates and isentropic efficiency will cause different amounts of adiabatic heating.  This could be the secret to free energy we've been looking for all these years.

What little cooling you saw with the U.S. radials was because they were 'wet'.  Basically downstream of the carb.

View Postket101, on Jan 20 2015 - 20:41, said:

A turbocharger is run with exhaust gases, and thus heats up a heck of a lot, keeping heat in the engine bay area.  The exhaust restriction is also a drag on horsepower, to a degree, though not as much as a supercharger.  The supercharger uses a mechanical drive from the engine, and has no contact with the exhaust gases, and is thus a bit cooler than a turbocharger.  There's power recovery turbines as well, but they don't necessarily provide forced induction.

 

In a lot of cases, superchargers were removed from aero engines when they were put in tanks.  They produced more power than was wanted, and also put additional stress on the engine.  Case in point: the Meteor engine used in the Cromwell and others.  It was, in the most basic explanation, a Merlin without a supercharger.

The Meteor's parent mill also had a very complex (and physically large) mechanical supercharger compared to the radials used in U.S. tanks where the blower was an integral part of the engine's accessory drive and induction system.

 

There's not much external dimensional difference between a ground and air R975, but there's a huge external difference between a Merlin and a Meteor.

 

 



Walter_Sobchak #15 Posted Jan 21 2015 - 04:56

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As far as I know, the Ford GAA of the M4A3 and the Chrysler Multibank engine of the M4A4 were the only engines used in the Sherman tank that were not supercharged. 

Meplat #16 Posted Jan 21 2015 - 05:00

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View PostWalter_Sobchak, on Jan 20 2015 - 20:56, said:

As far as I know, the Ford GAA of the M4A3 and the Chrysler Multibank engine of the M4A4 were the only engines used in the Sherman tank that were not supercharged. 

Pretty much.

 


 



shapeshifter #17 Posted Jan 21 2015 - 05:15

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In that case did those engines have more power then what the engine spec listed available to them? At least with the M6 when they list it's specs they never took the supercharger into account and only listed the base specs of what they engine had.

 

An M4 with radial and a supercharger would outperform the same M4 with the same engine with no supercharger correct, even if they listed as having the same specs.



Meplat #18 Posted Jan 21 2015 - 05:28

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View Postshapeshifter, on Jan 20 2015 - 21:15, said:

In that case did those engines have more power then what the engine spec listed available to them? At least with the M6 when they list it's specs they never took the supercharger into account and only listed the base specs of what they engine had.

 

An M4 with radial and a supercharger would outperform the same M4 with the same engine with no supercharger correct, even if they listed as having the same specs.

 

In the case of the radials, for the most part it's "no". 

 

The M6 used a R1820 variant, and those produced everything from 700 to 1500 HP depending on what it was being used for. 

IIRC the one used in the M6 was ~900/950 HP. I guess if someone wanted to really see how much whatever transmission was stuffed into that M6 could handle, they might be able to persuade one of the -60's from a SBD to bolt up and break stuff.

 



shapeshifter #19 Posted Jan 21 2015 - 05:40

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Then what was the point of installing a supercharger into it? and why did they report "Greatly increased performance" otherwise?

 

I also have a document that mention they wanted at least a 1000 Hp engine in the T1 heavy tank, and they ended up choosing a Wright 1000 HP engine. with an allowance for HP losses due to cooling fan and other accessories ahead of the transmission.



Meplat #20 Posted Jan 21 2015 - 05:47

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View Postshapeshifter, on Jan 20 2015 - 21:40, said:

Then what was the point of installing a supercharger into it? and why did they report "Greatly increased performance" otherwise?

 

I also have a document that mention they wanted at least a 1000 Hp engine in the T1 heavy tank, and they ended up choosing a Wright 1000 HP engine. with an allowance for HP losses due to cooling fan and other accessories ahead of the transmission.

 

Because the blower was needed to ensure proper distribution of the fuel/air mixture to the jugs. That's why I called it an "Induction Blower" a few posts back.

Some small radials will work without an induction blower, but much past 600 CID you need some way to keep the lower jugs from running fat.

 

Otherwise, 1000 HP is not out of the range of the 1820 series, and not far removed from the 900/950 HP figure I'm aware of. 

Not sure how much difference that additional 50~100 HP would have made considering the range of transmissions and armament that thing ended up toting about.






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