From another thread...I would say its anectdotal but interesting. He claims something about plugs (spark plugs?). I thought diesels didn't need them. More than likely he is just rambling..
I can contribute something to the discussion on the T-34 engine.
Basically, it is very robust IMO incredibly so. The thing will run on about half cylinders, it will run for quite a while in extra-hot and extra cold weather without the appropriate support system (cooling fan, sufficient engine warmth) functioning. It will run when half the mounts are loose. It will run with a 5 cm. layer of mud on much of the underside, and all over the drive shaft. I have seen it run without a hitch at 35 centigrade above and 40 degrees below, although of course in the latter case the lubricants and fuel started out frozen, and the drivers had to melt the liquids by building a fire under the engine. But it worked fine, none of the tubes or cables caught fire, and the sucker cranked right up.
I have seen a ten ton steel girder dropped on that engine from about a five meter height, with nothing more than 20 gauge steel protecting the engine, and the only thing that happened was that some fuel, electric, and glow plug lines got torn off. They got reattached before the mechanics started it, but they told me it probably would have started even without that repair. No way of telling if that's true, but that's what the guys supposedly knowing all about the engine said.
In my opinion, a 20mm or 37mm round would certainly have the potential of hurting that engine if it hit it, but to my mind there would be a greater chance the thing would keep running, maybe less efficiently, but on the other hand it might well even shrug off the hit. We are talking about the engine the Soviets considered the best tank motor they every built.
(All of which could lead me to one of my pet peeves about CM which argues the Soviets are screwed because AP pentrations to a T-34 engine absolutely were less catastrophic than AP penetrations to typical panzer engine - but I will spare you.)
Anyway, these impressions are all from my personal experience - once upon a time I worked with an oil company in west Siberia, and some of the heavy trucks used by the firm were military surplus MAZ-437s originally designed for hauling SCUD missiles. The engine in that vehicle is the same as the T-34, unchanged after a half century.
The big problems with the engine from what I could see was that it required a lot of maintenance and fiddling, plug distance settings, filter cleaning, lubricant checks and top-offs, that kind of thing. A hands-off driver will kill that engine in no time flat.
Also I remember the engine had a tendency to rip itself free from the truck transmissions, but that wasn't the engine's fault, it was just developing a lot more torque than the MAZ engineers had designed their trucks to resist - the trucks were heavy, but naturally weighed nothing like a combat-loaded T-34 (That, and our drivers thought they were Mario Andretti and were running the trucks a good deal faster than MAZ thought they ever would go!)
I would add that diesel fuel isn't nearly as explosive as petrol. I have no idea to what degree, but to me, intiutively at least, an explosive round puncturing one of the exterior fuel tanks on a T-34 would be far from guaranteeing a detonation, and even if there had been I am far from convinced an explosion like that would have hurt the tank - after all, it was designed to resist explosions.
But that's just me speculating, I am sure there is some one reading this that can tell us in detail exactly how explosive Soviet wartime diesel fuel was and was not.
Looking at the T-34 drawings, it seems to me the Soviets had that engine protected quite well. This is not to say the tank was invulnerable to air cannon attack, but rather that the tank - in itself not a huge target - really doesn't offer a whole lot of super vulnerable bits to an engine deck pentration. Those grates aren't that big, after all, and if the AP round gets through the deck armor, bully for it but it's lost a lot of its energy.
If a round actually managed to strike full square on the "cylinder" heads, then sure that would mess up the engine - I guess it would just freeze 2-3 cylinders, leaving the rest of the engine either to clunk on, or maybe grind itself to bits. But there's no way to aim for that specifically, and those things are relatively tiny: maybe half a meter by 15 cm. Also, obviously, a pilot can't see them.
If an AP round made it through the engine deck armor my guess is that it would lose a good deal of pentrating power, and if it hit that big aluminum block it might well do nothing. It might also get a kill, of course, but "frail" is absolutely the very last word I would use to describe a T-34 engine.
I'm not trying to say the T-34 engine was as tough against air-fired AP as say a TigerII front was to ground-fired AP. But assuming all you need to do to hurt that engine, is to get a German round somehow to just touch it, is very wrong. You're going to have to hit that engine with some serious violence in a vulnerable spot. Hit it with less force, not particularly squarely, or just in the block, and I bet the thing would do an Everyready bunny.
< Message edited by Yoozername -- 4/18/2006 8:51:15 PM >