Was the Hispano-Suiza 12Y the worst ≥25L V-12 of WW2? (2 Viewers)

[Shortround6]

Was it the supercharger or the supercharger drive or the fuel injection system?

You could use either Packard or RR engines as spare parts to overhaul each others basic engines. Difference were pretty much external (accessories like pumps)

 

[Simon Thomas]

I agree with TM06, the 12Y wasn't a truly bad engine. It did have some good qualities.

The valve actuating and adjustment is light, robust and simple. The supercharger discharge ducting cross sectional area appears to be quite a bit larger than its contemporaries. The head to block sealing is not an issue, being cast in one piece.

On the other hand, the two valve design might have been fine in 1932 but was inadequate within a few years. The yardstick for supercharger design in the mid 30's is the Merlin, and every other supercharger falls short. The 12Y falling particularly short.

I can't work out if the six carburettors after the supercharger was better or worse than one large carb before the supercharger. Maintenance on six carbs would have been tedious. The cooling effect of fuel evaporation might be argued either way, possibly the carbs after might give a nett overall increase in cooling? The six separate carbs would no doubt be heavier than one large carb.

description_12Y31

 

[Shortround6]

the 12Y wasn't a truly bad engine. It did have some good qualities.

It did but it had hit a dead end.
To make more power (around 1000hp depending on altitude) it needed two things.
1. a stronger bottom end, crankshaft and crankcase.
2. a better top end, more valves/increased air flow.

Fix both and you have a new engine, VK-107 or Saurer or Hispano 12Z.

 

[Admiral Beez]

You could use either Packard or RR engines as spare parts to overhaul each others basic engines.

That's handy. Not like my old Triumph motorcycle that used Whitworth threads and fasteners that were incompatible with North American specs and tools.

 

[MIflyer]

Some sources say that believe that the Soviet AM-30 V-12's were based on the Hisso 12Y but the Soviets said they were based on the BMW V1 and the VK series were based on the 12Y. The VK-105 was 2147 Cu In and produced 1100 HP, and that was better than the 1940 12Y 860 HP. The VK-107 was 2075 cu in and produced 1600 HP, but at 1655 lb weighed far more than the 12Y's 1000 lb.

 

[Shortround6]

Some sources say that believe that the Soviet AM-30 V-12's were based on the Hisso 12Y but the Soviets said they were based on the BMW V1 and the VK series were based on the 12Y. The VK-105 was 2147 Cu In and produced 1100 HP, and that was better than the 1940 12Y 860 HP. The VK-107 was 2075 cu in and produced 1600 HP, but at 1655 lb weighed far more than the 12Y's 1000 lb.

The VK-105 got 3 valve heads instead of two valve, had a beefed up bottom end and had the 2mm smaller bore.

"Based on" does not mean you can take a 12Y and turn it into a VK-105 with some spare parts. The M-100(VK-100) was pretty much a 12Y.

 

[bf109xxl]

Some sources say that believe that the Soviet AM-30 V-12's were based on the Hisso 12Y but the Soviets said they were based on the BMW V1

Mikulin's engines starting from the AM-34 can be considered as an independent design - there is almost nothing left from their progenitors (BMW VI).

 

[MIflyer]

Herschel Smith points out that if the AM-30 was based on that BMW then they took a welded block engine and turned it into a cast block engine, which is an even bigger design divergence than the 12Y and the VK.

Big question is: Which WWII V-12 engines WERE NOT ultimately based on the Curtiss D-12 Conqueror?

 

[bf109xxl]

Herschel Smith points out that if the AM-30 was based on that BMW then they took a welded block engine and turned it into a cast block engine, which is an even bigger design divergence than the 12Y and the VK.

There were no "AM-30" prior to AM-34. M-17 was a licensed copy of the BMW VI.

 

[Engineman]

Was it the supercharger or the supercharger drive or the fuel injection system?

You could use either Packard or RR engines as spare parts to overhaul each others basic engines. Difference were pretty much external (accessories like pumps)

The Japanese versions of the DB V-12 engines were really quite re-engineered in detail. The Fuel injection system is listed as not being a copy of the Bosch PZ12 type, but a locally designed and built type. This may have been a choice by the Japanese, as I cannot imagine Bosch refusing an RLM directive.

Rolls-Royce built Merlin, Packard built Merlin and V-1650 engines did have differences, sometimes quite major. The Magneto's and accessories were American specification but there were some major differences. The supercharger drive was a different type of mechanism completely, the Packard engines always had a Bendix Stromberg pressure carburettor (and very late with Simmonds FI) that was immune to negative-G, the early Packard Merlins had their own design of detachable heads (changing later to the RR type), propeller shafts had splines etc for American props and reduction gears could have slight ratio differences. Beyond that, the modification states of the Packard engines could lag the UK production.
That said, the majority of parts in the same build-state engines were identical and so, interchangable.

Eng