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 Turbs, I don't get what you are at on this one. but

 

   Any engine has  to be cooled so a certain% of the energy has to be dissipated by the cooling system at all times. Heat flow is proportional to temp difference between the bits to be cooled an the cooling medium, so if the ambient goes up 10 degrees the engines temp will rise the same amount. Aircooled engines actually cope well with high temps and aircooled tanks performed well in deserts. If the 10-20 degrees is too much then it's not ok but no engine should be that critical including any liquid cooled one.

 

 Thruster. I agree but I'm generalising across all Piston motors including diesels earth moving  heavy transport etc and piston design is critical especially with the materials used. Lycoming, Continentals Franklins etc don't really  have any problem  in a normal TBO. I can never recall a piston breaking up in one. It's usually only the valves and I can't see one "top" in say 20 years 2300 hours is too much to bear. Poppet valves are in an extreme environment.  The main problem with those engines is they don't get used enough. Nev

 

You're talking about the outside of the engine, not the combustion chamber where the temp can get to 2500 deg.C

 

2510 deg wouldn't make any difference.

 

 

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Who really knows about combustion temp, from an operating point of view? WE know the higher it is the more efficient  and powerful the engine is (all other things being equal) The Carnot cycle  covers that and it includes JET engines. Higher ambient will cause a power loss as the mass flow reduces or you can look at it as a density altitude thing (same concept) Power drops of at higher DA's as does the prop drag/thrust, which "unloads" the motor. Nev

 

 

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 Turbs, I don't get what you are at on this one. but

 

   Any engine has  to be cooled so a certain% of the energy has to be dissipated by the cooling system at all times.

 

Phil Irving certainly got it and you certainly get it when you start building race engines to pump out 2+ x the original power because you HAVE to do something.

 

What you are talking about is dissipating the heat outside the combustion chamber; what I'm talking about is dissipating/passing through/rapidly cooling the combustion chamber before temps of 1000 < 2500 deg C can melt anything, inlcuding valves.

 

 

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I am wondering about those air cooled tanks. I was a tank mechanic in the army in the fifties and the only air cooled engines I came across were LVTs  made in America. they had a radial engine with a wire shroud to keep garbage out of the fan.

 

I have not attempted to keep up with tank engineering since those days,  so maybe I am missing something.

 

 

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There was a big Steiger tractor where I used to work and it had ( so I was told ) the same engine as the main 1960's American battle-tank. In the tractor, the engine was rated at 225 hp and had a TBO of 10,000 hours. Caterpillar manufacture I think.

 

In the tank, there was an emergency over-ride and the rated power was nearly 1000 hp with a rated life of 10 minutes.

 

I never saw any documentation on this, but I repeated the story because I liked the moral of treating machinery gently if you wanted it to last.  Maybe somebody here knows more. 

 

 

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The most common tank engine I came across was the Rolls Meteor, which is an un supercharged Merlin. Churchills had a Bedford and the Yank stuff had Chev V8s, but they were LVTs mainly

 

The Bren carriers had a flat head Ford V8.

 

 

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I had a unique experience in 1969 of going across Darwin Harbour  in an amphibious tank (AT NIGHT) with about 25 other obviously mad people. It had about 5'' of freeboard and down inside the bilge was a great round engine belching sparks, smoke and flames  lying flat and making the tracks move and take us through the water at a snails pace. It was at it's best as we came out of the water on a beach and rolled up to the door of the Place we were going to eat at  and surprisingly, no lives were lost in this episode and the return trip. How  the hell would that be allowed today? It probably wasn't "allowed" then.  We transferred passengers to a conventional ferry to go from and to the wharf a short way from Darwin township. That also wasn't without hazard as it was as dark as the inside of a cows guts (as they say). Nev

 

 

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Bruce, there's a bit of incorrect information in your Steiger tractor story. The 225HP Steiger Bearcat used a 10.5L inline 6 cyl Cat engine designated the "3306".

 

The 3306 was a good engine, and still powers many items still, even though production of it ceased around about 2005, due to new engines designed to meet tighter emissions levels, replacing it.

 

However, the 3306 engine never powered any American battle tank, the American tanks up until the 1960's utilised largely petrol engines.

 

The first tank to use a diesel engine, the M551 Sheridan used a GM 2-stroke Diesel, the V6 turbocharged, 6V53T, rated at 300HP.

 

However, you are correct that many military machines have the ability to boost power to exceptional levels under combat conditions, with the power boost period being only of short duration, to prevent engine destruction.

 

The Merlin in the Spitfire is the first engine that I know of, that had an overboost capability for a short period to get away from, or catch up to, Luftwaffe fighters. There were strict limitations imposed on Spitfire pilots as regards the overboost use.

 

 

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Thanks guys, I should have checked more 30 years ago, but better late than never I guess.  I reckon those engines like the Merlin were over 1000 hp, so that Caterpillar engine at 225 hp would have been a bit small maybe.  But it is a bit surprising that diesels were not used for tanks, you would think that they were a better option than petrol, especially with the extra risk of petrol with respect to refuelling fires.

 

 

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Thanks guys, I should have checked more 30 years ago, but better late than never I guess.  I reckon those engines like the Merlin were over 1000 hp, so that Caterpillar engine at 225 hp would have been a bit small maybe.  But it is a bit surprising that diesels were not used for tanks, you would think that they were a better option than petrol, especially with the extra risk of petrol with respect to refuelling fires.

 

Torque x rpm = power

 

 

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 It's only been in the last 20 years or so that some of the fastest cars produced are diesel. That situation may well change when and if direct injection is more widely used on "non compression ignition" (previously petrol) motors.Nev

 

 

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... the American tanks up until the 1960's utilised largely petrol engines.

 

The first tank to use a diesel engine, the M551 Sheridan used a GM 2-stroke Diesel...

 

 

 

...it is a bit surprising that diesels were not used for tanks, you would think that they were a better option than petrol, especially with the extra risk of petrol with respect to refuelling fires.

 

Bruce it surprise me too; I believe during WWII only the Russians used Diesel engines in their tanks. 

 

 

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The Allied forces tanks nearly always used petrol engines, because in WW2, the Americans decreed that petrol would be the primary fuel of the Armed Forces.

 

It was much easier to have one primary fuel, as having multiple fuels would possibly result in the wrong fuel, at the wrong place, at the wrong time.

 

In addition, there was a need for high power levels, and that only came from petrol engines. Diesels of the day were relatively low powered.

 

But the British tried diesels in tanks during WW2, because of diesel engines better economy, resulting in more range before refuelling was needed. AEC and Leyland diesels were used in some of the British WW2 tanks.

 

The big supply of U.S. aircraft radial engines, meant they were slotted into tanks, due to their ready availability, and high power output.

 

Thus the General Grant (M3) tank got the Wright Cyclone R975 - which was also built by Continental during the War, due to its ability to churn out huge numbers of engines.

 

But the tank builders were always desperate for more engines and more power - so Ford built a 500HP tank engine - the Ford GAA, a DOHC, 32 valve, all-aluminium V8 that was designed and built purely for tank use.

 

Then Chrysler designed and built the amazing 30 cylinder multibank A57 engine - essentially, 5 x flathead 6 cyl Chrysler industrial petrol engines, buttoned together on a common crankshaft. This engines reliability was below par, and it was a nightmare to work on.

 

But the Sherman (M4) was the main battle tank of WW2 - and it was powered by a range of engines, depending on where and when it was produced, and for what specific tank order.

 

The main Sherman engine was the R975 Continental radial, but it was also supplied with 2 x inline 6 cyl GM 2 stroke diesels, coupled side by side - the Ford GAA - the A57 multibank - and interestingly, a diesel radial, which was a Wright R-1820 converted to diesel by Caterpillar, and called either an RD-1820 or the D-200A. Not many RD-1820's were produced, only a few hundred.

 

Not surprisingly, Australia ordered the largest number of GM Diesel-powered Shermans. There were two main reasons for this - One, the substantially extended range of the GM-diesel-powered Sherman was regarded of utmost importance in Australian Defence Force leaders eyes, as fuel supplies could be very few and far between in Australia, and in many areas where the Australians were operating.

 

Good fuel range often meant the difference between a successful mission, and a failed one where tanks ran out of fuel - as Rommel found to his dismay, when his tank forces ran out of fuel in the Middle East, because the Germans had underestimated the fuel requirements of the German tank forces.

 

But the second reason the Australians ordered diesel Shermans was because of watching the bitter early experience of the petrol powered Shermans in the Middle East and Europe, of "lighting up" in horrendous fashion, when hit with powerful German shells. The petrol tanks were a major disadvantage in fighting.

 

Not for nothing were the Shermans nicknamed "Ronsons"(after the WW2 cigarette lighter), because of the fact they caught fire and burnt crews to death, in large numbers.

 

The Germans simply adapted their 88mm AA guns to fire horizontally and used them as an anti-tank gun with devastating effect.

 

But the Shermans only overcame German tanks purely because of sheer numbers, plus the Allied air forces doing a good job of protecting tanks in battle - and the Allies also making the German 88mm guns a primary target at all times.

 

 

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 It's only been in the last 20 years or so that some of the fastest cars produced are diesel. That situation may well change when and if direct injection is more widely used on "non compression ignition" (previously petrol) motors.Nev

 

We're there now with compression ignition petrol; take a look at the new Mazda SKYACTIV-X engine range: https://www.mazda.com/en/innovation/technology/skyactiv/

 

While not compression ignition, for some years the Nissan Patrol petrol model's total cost of ownership has been less than the diesel, and you gate back the benefits of lower noise level, and cleaner hands after refuelling.

 

My prediction is the diesel will be phased out in the medium term in Australia due to the difficulty of getting clean fuel (needed to comply with the latest emission levels.

 

  • In the 4x4/SUV market several shifts have occurred.
     
  • Lower taxed off-road diesel is no longer available for them
     
  • The  much lower fuel consumption of diesels than petrol has gone with the spectacular reductions in petrol consumption.
     
  • For the average person who pays someone to service their cars, Diesel Particulate Filter replacement can cost more than the car's value. I was quoted $3,800.00 last year on DPF replacement for a Subaru Outback, and even replacing it myself cost around $1,500.00
     

 

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Kamaz do not build, and never have built tanks. They build trucks and tank transporters. Kamaz did not come into being until 1976.

 

The most successful WW2 Russian tank was the T34, which used a Kharkiv model V-2, V12 all-aluminium diesel, produced by the Kharkiv Locomotive Works. An amazing effort to produce a powerful 38L lightweight diesel engine like that, from scratch.

 

However, due to a shortage of Kharkiv V-2 engines, many T34's were produced with the Mikulin M-17 engine, which was development of the BMW V12 petrol aircraft engine of the 1920's. BMW gave a licence to the Russians in 1930, to build their petrol V12 water-cooled engine.

 

The T34 was built on a rejected U.S. military design built by the famed tank suspension designer, J Walter Christie.

 

The Russians set to, and churned out WW2 tanks at a phemonenal rate, often sending them out the door with unfinished detailing, straight into the field.

 

They produced 84,000 T34 tanks, as compared to 50,000 Shermans. A staggering performance, when you consider the Americans turned a lot of their car and truck factories over to tank production, Chrysler in particular.

 

 

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There are lots of videos on YouTube of Russians pulling T34s out of swamps. They have been submerged since 1942 or so. They wash them down, clean them out, throw them into neutral and the tracks roll for towing. The engine and gearbox are full of oil.

 

 

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PM, the reason so many WW2 Russian tanks are pulled from Eastern European bogs and swamps in good condition, is because those bogs and swamps are surrounded by poplar trees. The bark from the poplars contains iron tannate, an excellent rust-prevention coating.

 

If you buy the commercial rust treatment called "Exit-Rust", it's simply a solution of iron tannate. It's a very effective product for combating corrosion.

 

 

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  • 4 weeks later...

So , DMech what do you believe to be the cause of failure. and is it related to pre-valve relief pistons ? I replaced my pistons after 500 trouble free hours with VR pistons, new valves, dual valve springs etc...... Bob

Sorry did not reply earlier , we went on nbn wireless , nothing but trouble since.

All the pistons , except for one set , were VR pistons. the other 4 were Silverlite brand, we tried these because they had a lot more material in the skirt area where the VR pistons were cracking, they only made 130 hrs before cracking , they cracked from the oil ring slot downwards and inwards, where as the VRs cracked from the bottom of the skirt upwards and inwards. We had 2 sets of VRs only made around 260hrs each with about 8 hrs difference between them. We are experimenting with another piston , and have close to 1000 hrs on one set and 700 on another set, but not without some problems, which I think we have now overcome, how ever there has never been any signs of cracks, and produce more power

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Sorry did not reply earlier , we went on nbn wireless , nothing but trouble since.

All the pistons , except for one set , were VR pistons. the other 4 were Silverlite brand, we tried these because they had a lot more material in the skirt area where the VR pistons were cracking, they only made 130 hrs before cracking , they cracked from the oil ring slot downwards and inwards, where as the VRs cracked from the bottom of the skirt upwards and inwards. We had 2 sets of VRs only made around 260hrs each with about 8 hrs difference between them. We are experimenting with another piston , and have close to 1000 hrs on one set and 700 on another set, but not without some problems, which I think we have now overcome, how ever there has never been any signs of cracks, and produce more power

What did you change to produce more power?

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