1916-17 Benz BV.IV engine research

Long shot, but the depth of knowledge here never fails to amaze.

I'm doing a research project involving a 1916 or 1917 Benz Bz.IV engine and looking for any information I can find. The engine is an in-line 6-cylinder with 18.8 liters of displacement. Yes, I have done internet searches and found the reasonably accessible sources, so I have some basic knowledge and specifications to work with. Yes, I'm also aware that several of these engines were installed in cars when the war ended.

I believe the engine would have been built in the Benz factory in Mannheim, Germany, but looking to confirm.

The particular engine I'm researching has a serial number on the top of each piston and each cylinder, so would really like to learn more about that numbering system. If possible, I'd love to determine where it was installed. Lore suggests it was either in a Zeppelin airship or a Fokker airplane. Yes, I have access to the engine, so I don't need generic photos of the engine. I'm looking more for history about its production a century ago.

Photo attached of the top of one of the pistons. Any ideas?

Thanks much for all help.
Kevin
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I can't help you, but I would love see see more pictures!

 

Early days, but lots more in store in due course when a few more pieces come together (hopefully)...

 

Aluminum piston. Pretty racy stuff.

Interesting piston design. Is it spark ignition or compression ignition?

 

I'm no expert on old engines but the displacement and vintage indicates an aero engine. The B&W 111A was listed as 19 liters and it was a contemporary of the Mercedes that powered the Fok. D-7 and the Albatross. Interesting , please continue.

 

Spark.

Engine produces roughly 228hp at 1400rpm. Given the hp, the engine is sometimes informally referred to as the Benz 230hp.

Since there is some interest, here's a diagram of unknown origin I found on the interweb:
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If it was compression ignition it would explain the dome shape. Being a spark ignition more likely it is that way because they didn't know any better at the time.

I would think, knowing the company that they may be a good source of information. During the later years of WW2 they were severely damaged and records may have been lost but you should try contacting them. I would also get in touch with historic aircraft organizations here and in England and Germany. Ask tazandjan here about that. He is retired Air Force but he is also an avid WW1 aircraft aficionado.

Very interesting motor. I too would like to see more pictures, especially if it is apart.

Where is it? Here in USA? Is it going to fly again?

 

Just thought of something else. Not too far north of you in Tehachapi is a company called Vintage V12's. They specialize in Merlins and Allisons but one of the guys has done some DB600 series engines. Much later I know but he is close and if he doesn't know he might know who does.

 

I too would try the manufacturer first and foremost: as for their archives, they are very well organised. I'm pretty sure that they would know.

Rgds

 

The aluminium pistons appeared with the later variant of the engine, and caused quite a stir at the time:

https://www.flightglobal.com/pdfarchive/view/1918/1918%20-%200746.html

Rgds

 

It was very high tech at the time and allowed higher piston speeds. A few years ago all the talk in the industry was ceramic pistons. Now it looks like steel is the coming thing. Not sure why ceramic was dropped suddenly. Maybe reached a dead end in development but we know aluminum has gotten us about as far as it can.

 

The Germans used a hp rating system for the numbering on the engines (0, I, II, III, IV, etc) and the IV was for engines with 200+ hp. If the company built a second engine in the same hp class, they added a letter (starting with a) for that different engine. So the Daimler (Mercedes) D.IV was an inline 8 cylinder, while the D.IVa was an inline 6 cylinder, but both were 200 hp class (220 and 260 respectively) engines.

Benz and Co. in Mannheim won a Kaiser Prize in 1913 for a 4 cylinder engine and that evolved into their later 6 cylinder engines.

There was a high altitude version of the Bz.IV called the Bz.IVü with the ü standing for overcompressed or high compression. The Germans used volatile mixes of Benzene and other aromatics to increase the octane rating of gasoline for high altitude performance. Many of these engines had dual range throttles because the high compression would lead to detonation if full throttle was used at sea level. The Bz.IVü was rated at 225 hp at 1400 rpm with a bore of 145 mm and a stroke of 190 mm. This increased to 275 hp at 1300 meters and 1500 rpm when full advantage of the high compression pistons and ignition advance could be used.

Aluminum pistons were a common upgrade for WW-I aero engines by both adversary's manufacturers. As an example the LeRhone 9J rotary engine was rated at 110 hp with steel pistons and 120 hp in later versions with aluminum pistons. The German version of the LeRhone 9J, the Oberursel UR.II, used aluminum pistons exclusively. Both sides noted an increase in performance from the lighter weight of aluminum pistons.

The Benz Bz.IV powered several German two seaters, the most notable of which were the LVG C.V and C.VI, of which a couple thousand were built. The Bz.IVü was used by Fokker in an experimental fighter that competed at the second Adlershof competition, the V.24, as did the Pfalz D.XIV. The Bz.IV was also used in Zeppelin giant bombers, various Halberstadt 2 seaters and a large number of floatplanes.

"Der Flugmotor" has several illustrations of the BZ.IV and "Prüfung. Wertung, und Weiterentwicklung von Flugmotoren" has performance specs and some charts of consumption and hp curves. "German Aircraft of the First World War" and many other general books on WW-I aviation show engine types powering each aircraft type.

 

What was the definition of high altitude at that time Terry? Or service ceilings? Were there any oxygen systems in use?

I suspect the material used for the earlier pistons was gray iron and not steel but I could be wrong. Hard to believe, I know.

Do you know when aluminum pistons first saw use in aviation? It looks like an obscure Italian car builder first used them in about 06 but Packard is credited for their first production use in their automotive V12 in 15.

A look at the Benz motor will show it was a 4 valve. Some still think that came around in the 80's. The French were using it not too long after the turn of the century and were winning races in 1912 with desmodromique actuation.

 

Some good stuff here and good suggestions. If all goes according to plan, I should be able to share a lot more info in a month or two. Here's another layer -

There are numbers stamped on the opposite side of each piston from the serial number. This number appears to the same on each piston. Any ideas what the numbers mean?
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I seem to remember that they had attained ceilings of around 20,000 ft. and used a tube in their mouth to breathe oxygen. The drawing of the Benz looks similar to the Mercedes in the Fok. D-7 except for the intake manifold.

 

Must have been mighty cold in an open cockpit at 20,000 in December.

 

Brian- High altitude varied with engine type, but all could use full throttle by about 3000 m/10,000'. The Germans did have oxygen in some of their two seaters with overcompressed engines, like the Rumpler C.IV family with overcompressed Mercedes D.IVa and Maybach Mb.IV engines, the latter of which also powered Zeppelin airships. Those Rumplers could reach altitudes up to 25,000'. The crews wore very heavy clothing, even in the summer, and some of the 2 seaters had provisions for electric flight suits. The front engine provided some heat to the cockpits, but it was still pretty miserable in the winter in an open cockpit. McCudden flew a pusher DH-2 early in his career and stated he was so cold, he did not much care if he was shot down or not.

Aluminum pistons came into widespread use in late 1916/early 1917. Both pushrod and overhead cam engines were in service, some with four valves as noted by Brian. Rotary engines are another whole subject. They generally had higher power to weight ratios than fixed cylinder engines, but all lubricating oil was expended into the atmosphere through the exhaust valves, so long flights required a large oil tank. Many WW-I fixed cylinder aero engines had no valve covers so there was a certain amount of loss from those engines, too.

Those Bz.IV pistons were likely weight matched before being stamped, so that each set was relatively well balanced. Those are big pistons and weigh quite a bit.

 

I'm reading a little book on the Bentley BR2, and author L.K. Blackmore says WO Bentley used aluminum pistons in a competition Doriot, Flandrin & Parant [DFP] engine when the Bentley's were agents for the French cars. These pistons were cast from an 88% aluminum, 12% copper alloy. During the war WO was assigned to Gwynnes, who were making the 130HP Clerget radial. Bentley then designed the similar BR1 and larger, improved BR2 radials, both with aluminum pistons. The BR1 first ran in early summer 1916. The Bentley-DFP competition engine was built in 1913? [not clear] and the aluminum pistons were soon adopted by the DFP sport models.

--Carter

 

Kevin, Contact Mercedes directly. They have very fine records and tons of old machinery.

 

Good point. Could be a weight class system.

 

The German Technical Museum in Berlin should have info from Benz and they also have all of Peter Grosz's archives.

Deutsches Technikmuseum - Home

 

Marvelous suggestion. Thank you.

 

Yes, in the plans but need to wait for them to return from holiday break. Cheers to the burgh!

 

Update:

Work has culminated in the publication of a story on this project. See link here:
https://view.publitas.com/fitzhugh-media/southwest-star-magazine-2017-1st-quarter/page/30-31

Let me fill in some details - the engine is housed in a race car that ran after the first World War in England at Brooklands. It is a 1921 or 1922 project that mated a Benz BV.IV engine with a strengthened 1907 Mercedes chassis - well before Mercedes and Daimler formally got together in 1926.

The car was created about the same time as the original Chitty Bang Bang cars and, at times, was even confused for one of them. The car found its way to New York where it had a material restoration to make it more streetworthy and put it in its current form. After living in Maryland for several years, Jay Leno added it to his collection.

The metal cooling jackets around each cylinder grew porous over the years and leaked, so Jay's team is rebuilding them with sheet brass. Amazing craftsmanship. If you watch his Restoration Blog videos, you've likely seen this work there as well. Two cylinders down, four to go before the car returns to the road but each is very manually and time intensive.

Nobody at Mercedes or any museum that I've been able to find has been able to provide any historical information. I presume that someone knows something, so I'm not giving up. I'll be in Germany later this year and hope to make a personal visit or two.

It has been a fun project to research and the car is interesting to examine. It will be great to see it back on the road at some point.

A few more pics attached. The resolution is a touch more grainy than the original, but you should have a decent sense of what things look like between these and the photos in the article.
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Water jackets were welded up from sheet steel on most of the Daimler style aero engines (Mercedes, Rolls Royce, Benz, Liberty, etc), so it will be interesting to see how the copper works. Different properties on heat transfer, etc, but probably nothing that cannot be balanced in the end. They sure look pretty and Leno has a lot of experience with brass age automobiles.