Talk:List of WWII Maybach engines

Introduction

I started this list in April 2018, knowing little about these engines except they went brrrm, brrrm, and had a number of exotic letters tacked on to the numbers. I used to work as a full-time mechanic on pre-laptop John Deere 4-cylinder tractors (3040, 3050 etc.) and 6-cylinder combines (975, 1075 etc.), so feel I have a certain amount of related engineering experience. I hope I have managed to work out most of the engines' identities with the aid of reliable sources, but some still give difficulty. There appears to be no single reliable source dealing exclusively with this subject.

During WW2, the engine designers at Maybach were constantly seeking to refine and improve their products. Engines up to the HL120 (300 PS/hp) were in production by September 1939, installed (for example) in the Panzer III and IV. The usual engineering urge to create more efficient and more powerful engines continued throughout the war, resulting in a variety of projects: some came to fruition (e.g. the HL230 series), and others didn't. One of Maybach's unfulfilled goals was to develop a series of fuel-injected engines which began too late to reach series production before 1945: for example, the HL234 and HL295 (both supercharged, fuel-injected engines) which never reached series production before the end of the war. See, for example, Ernest Kneipkamp's post-war interrogation by the British Intelligence Objectives Sub-committee (BIOS): Appendix in German Heavy Fighting Vehicles of the Second World War. From Tiger to E-100 by Kenneth W. Estes, pp. 250 ff.

Maybach thus manufactured a small number of 'test' or 'experimental' engines (Versuchsmotoren) of various capacities and power outputs which were never put in to series production, but which currently appear throughout the list/table as engines with considerably greater power outputs than their earlier counterparts with similar engine capacities. For example, compare the HL85 and HL90. There are very few reliable sources for these experimental engines: it seems certain that only a very small number of these 'prototype' motors were actually built. The ensuing discussion with myself attempts to establish an approximation to 'the truth'. MinorProphet (talk) 16:15, 5 June 2021 (UTC)

Power of various engines

Looking at the table (August 2019), I noticed that all the motors from HL42–HL54 have somewhat suspect power outputs. For a believable example, the gap from HL38 (90 PS) to HL42 (100 PS) is an increase of 10 PS for 400cc extra engine capacity. However, the leap from HL42 (100 PS) to the HL45 (apparently 150 PS) = an extra 50 PS for a mere 300 cc is barely credible. All other engines up to the HL57 (mostly taken from dubious web sources) have similarly inconsistent power values. Based on the general trend demonstrated in the table, I intend to make an educated guess as to the actual figures, along with a refnote. MinorProphet (talk) 11:17, 17 August 2019 (UTC)

Nie wieder Krieg

             Naming Of Parts

 Today we have naming of parts. Yesterday,
 We had daily cleaning. And tomorrow morning,
 We shall have what to do after firing. But today,
 Today we have naming of parts. Japonica
 Glistens like coral in all the neighbouring gardens,
 And today we have naming of parts.

 This is the lower sling swivel. And this
 Is the upper sling swivel, whose use you will see,
 When you are given your slings. And this is the piling swivel,
 Which in your case you have not got. The branches
 Hold in the gardens their silent, eloquent gestures,
 Which in our case we have not got.

 This is the safety-catch, which is always released
 With an easy flick of the thumb. And please do not let me
 See anyone using his finger. You can do it quite easy
 If you have any strength in your thumb. The blossoms
 Are fragile and motionless, never letting anyone see
 Any of them using their finger.

 And this you can see is the bolt. The purpose of this
 Is to open the breech, as you see. We can slide it
 Rapidly backwards and forwards: we call this
 Easing the spring. And rapidly backwards and forwards
 The early bees are assaulting and fumbling the flowers:
 They call it easing the Spring.

 They call it easing the Spring: it is perfectly easy
 If you have any strength in your thumb: like the bolt,
 And the breech, the cocking-piece, and the point of balance,
 Which in our case we have not got; and the almond blossom
 Silent in all of the gardens and the bees going backwards and forwards,
 For today we have naming of parts.

 Henry Reed (1942)

HL90, HL100, HL101

User 82.11.219.215 (talk · contribs) recently updated the table with a claim that the HL90 had a power output of 360PS. I have reverted the edit. The well-referenced HL85 TUKRM developed approx 185 PS, but the HL90 fitted to the Heuschrecke 10 (in development from 1942-3) with an extra mere 500cc and another 500 rpm could apparently almost double the power output to 360 PS. This is sourced to Heuschrecke 10 which has no refs at all.

I agree that my figure of approx 200 PS is merely an informed guess, but If Maybach had indeed managed to create an engine of such massive power, why was it not used in every other tank vehicle up to the Panther and Tiger? As is usual with all these experimental/prototype engines, there is very little hard information, and wildly exaggerated claims continue to be made for them.

The HL100 which developed 250 hp was apparently fitted to the Panzer IV Ausf A (Sd.Kfz. 161), in production from June 1936 to November 1937, with 35 vehicles produced. Source: Anderson, Thomas (2021). Panzer IV. Bloomsbury Publishing. p. 33. ISBN 9781472829672.

This web page discussing the E-10 says that the V-12 HL100 (theoretically 10.0 litres) developed 400hp, and the HL101 (fuel-injected 10.1 litres V-12), managed 550hp @3800rpm. "Kniepkamp revealed in post-war interrogations that the E-10 designs were completed in the Summer of 1944, and contracts were given to Magirus AG to complete 3 trial vehicles. The three hulls were being made in Silesia but were not completed when the Soviets arrived." Also, the E-25: "According to Oberbaurat Kniepkamp from post-war interrogations, three E 25 hulls were reported to be at Alkett in Berlin-Spandau, but were not found when the Western Allies went to investigate."

The reality is that only three prototype Heuschrecken were ever constructed, and the sole surviving one is now at Fort Sill, Oklahoma. I imagine that the Aberdeen Proving Ground made a report on the vehicle, but I have been unable to find any reference to it on the web.

This interesting articulated mine-clearer prototype Krupp Minenraumer S of which a single example was made in 1944 was apparently powered by two HL90s. This web page Krupp Raumer + Vs.Kfz.617 repeats the power output of 360 hp/ps, which in my opinion seems hugely exaggerated.

I have been unable to find a single reliable source about the fuel-injected HL101. Several 'World of Tanks'-type websites repeat these enormous power outputs, but there are no refs to printed sources at all. In fairness, if the fuel-injected HL295 that powered the French AMX-50 prototype produced around 800/900PS, it is possible that an injected 10-litre HL101 could have developed 550PS, but reliable evidence seems to be sorely lacking. MinorProphet (talk) 12:31, 24 January 2021 (UTC)

John Milsom mentions a 10-litre V-12 engine developing 320hp, intended to power the experimental HK 1600 Series, a replacement for the Sd.Kfz 8 and 9; one prototype was built in 1941, powered by an HL116. (Milsom, John (1975). German Half-tracked Vehicles of World War 2, p.62. See main article bibliography.) This could be the HL101, but I cannot discover whether such an engine was ever constructed, or if it was simply 'projected' or even wishful thinking. MinorProphet (talk) 22:07, 28 January 2021 (UTC)

With further info from Spielberger in Panzer IV and its variants (see below) I think that this engine of 320hp which Milsom mentions may well be the HL90. There also seems to be some confusion with an earlier HL100 fitted in early Panzer IV Ausf. A in the table (see Anderson above.) I find it somewhat unlikely that Maybach would give the same model number to two different engines, but you never know... MinorProphet (talk) 13:32, 11 May 2021 (UTC)

Well, at last I have found some more reliable (printed) information about these engines, which could be termed 'second-generation' motors, and I retract many of my doubts about their performance.

Walter Spielberger - Der Panzerkampfwagen Tiger und seine Abarten, Appendix letter I, Maybach-Motordaten, 6th Edition (1998) (in German) Stuttgart: Motorbuch-Verlag isbn 3-87943-456-5, p. 209 [268] has an extensive list of Maybach motors. It includes:

• HL66 straight-6 with bore x stroke 105 * 130mm and capacity of 6.754 l produced 180 PS @3,200 rpm
• HL90/100, V-12, 100 * 106mm, 9.99 litres, 400PS @4,000 rpm
• HL101, V-12, 105 * 115mm, 11.94 l, 510PS @3800
• HL157, V-12, 115 * 125mm, 15.58 l, 550PS @3500

On p. 153 of Die Panzer-Kampwagen I und II und ihre Abarten (Spielberger 1997), Motorbuch Verlag Stuttgart, there are a few more specs of the HL157 as fitted to the paper-only VK1602 'Leopard' of 1942, including 7-bearing crankshaft, 2 Solex carbs, the starter motor (Bosch BNG) and generator (Bosch GTLN). He gives the source as Handbuch WaA, Blatt D 27, July 1942. Still can't discover if it was ever made. MinorProphet (talk) 12:09, 20 April 2021 (UTC)

• Spielberger, Walter (1993c). Panzer IV and its variants. Atglen, PA, USA: Schiffer Military History. ISBN 9780887405150. mentions the HL90 on p. 131 and p. 132, confusingly giving 350 HP and 320 HP on consecutive pages. On p. 131 he also mentions the HL100 as developing 400 HP. I am really interested in finding out more about these engines, but details still seem thin on the ground. MinorProphet (talk) 13:32, 11 May 2021 (UTC)

The confusing discrepancy in Spielberger between "350 HP and 320 HP" may be due to power being measured at maximum and normal revs. MinorProphet (talk) 14:04, 19 June 2021 (UTC)

Also, Spielberger's Panther and its Variants, Atglen, PA: Schiffer p. 15 [13] has a diagram from Maybach (dated in or after 1941) proposing how the multiplicity of six existing engines was to be replaced by three new ones, quite possibly fuel-injected:

• HL42 → HL50 [180 PS @4000 rpm, from above table]
• HL52 & HL62 → HL57 [this may be a misprint for the HL67 - all these 3 were to have alloy blocks.]
• HL85, 108 & 120 → HL100 [400 PS @4000 rpm] (or perhaps HL101)

The engines were to have a much greater proportion of alloy to replace ordinary iron and steel, allowing a reduction of 300% of steel per PS: the new HL100 made with un-alloyed components would need 3.1 kg per PS: and with alloy components, only 1.0 kg per PS. There would be a much greater number of interchangeable parts: the six earlier engines had 2,356 different components between them: the intended 3 new ones would have a total of only 1,198 different parts. In other words, the new engines would be much lighter and produce more power than the engines they were intended to replace.

Nevertheless, there are still considerable differences in the claimed power outputs, from various sources. As far as I can work out, none of these engines were fitted in production vehicles, and their true capabilities still remain something of a mystery. I intend to make another section in the article incorporating this info. MinorProphet (talk) 11:21, 14 April 2021 (UTC)

As far as I can work out, by the time these later high-powered motors (what I am calling 'second-generation' engines, but this is only my own invented term) came to be developed from late 1943-44, the military reverses which Germany suffered from the battle of Kursk onwards, and the increased Allied bombing campaigns, all meant that further development of the new engines took a back seat. Germany never really had enough industrial capacity to be able to win the war, and the various factories were hard-pushed to even provide existing engines for later designs of AFVs. Thus all the majority of production tanks etc. from the Tiger and Panther onwards until the end of the war used the HL230.

It still appears to me that only a handful of these later engines were ever made and fitted to experimental/prototype vehicles. Tooling up to develop and produce a new generation of engines takes a long time. The rushed nature of the Panther's development meant that it took at least 18 months of improvements to the engine before it came to be anywhere near reliable, and even then the HL230 P30 had an average life of about 1000 km., max 1500 km. (Spielberger Panther & Variants p. 161).

It may be better to group all these experimental motors in a separate table for engines which didn't reach series production. MinorProphet (talk) 13:32, 11 May 2021 (UTC)

Maybach '2nd generation' and other experimental engines

"It may be better to group all these experimental motors in a separate table..." : or maybe just in italics in the existing table, + explanatory note/sub-section.

Potential list of Versuchmotoren which never reached series production. [Later edit]: All the engines with max power @4,000 rpm are almost certainly fuel-injected. MinorProphet (talk) 16:32, 25 June 2021 (UTC)

• HL50 Z in the Katzchen supposedly developed 200 PS @4,000 rpm (Pz Tracts 20-2, Paper Panzers vol 2 p. 20-72)
• HL57, planned by Maybach from 1941? to replace the HL52 & HL62. (Spielberger's Panther and its Variants, Atglen, PA: Schiffer p. 15 [13] ) MinorProphet (talk) 14:40, 30 June 2021 (UTC)
• HL90 - may be HL90/100 (?perhaps invented term?) 100 x 106 mm, 9990 cc, 400 PS @ 4000 rpm. c/ratio 6.5:1 (Spielberger Panzer IV & Variants, p. 160)
• 'New'? HL100 rated at 400 PS , planned by Maybach to replace the HL85, 108 & 120 (Pz Tracts Paper Panzers vol 1, p. 20-40), (Spielberger's Panther and its Variants, Atglen, PA: Schiffer p. 15 [13] )
• HL101 engine rated at 550 HP @ 3,800 - fuel injected. [Later edit]: slated to replace the experimental HL100 (which may be the mythical HL90/100) for the E10.(Pz Tracts 20-1 Paper Panzers vol 1, pp. 20-40, 42). Neither engine reached series production. MinorProphet (talk) 16:32, 25 June 2021 (UTC)
• HL116 Z - Sturer Emil
• HL157 P - (?probs. earlier than HL101?) developed 550 PS @3.500 or 3,600 rpm - perhaps fuel-injected (Pz Tracts 20-2, Paper Panzers vol 2 p. 20-66 and 20-94) - 'Leopard'
• HL174 - VK 36.01 (H) (Henschel pre-Tiger prototype), one chassis only completed.
• HL224 engine rated at 600 HP/PS - (Pz Tracts Paper Panzers vol 1, p. 20-22). (heavy tank prototype by Henschel based on Panzer IV)
• HL234 - fuel injected and supercharged - see also Kniepkamp interrogation see Kenneth W. Estes im main bibliography: developed 850 PS @ 2,800 rpm, (Spielberger Panther p. 175) and 900 PS @ 3,000 rpm (Pz Tracts Paper Panzers vol 1, p. 20-18). Max. torque = c. 260 mkg @1,750 rpm (Spielberger Panther p. 175) (from graph) - NB never reached series production.
• HL295 - c1,000 PS. MinorProphet (talk) 11:45, 17 June 2021 (UTC)

Another list of Maybach heavy tank engines appears in Jentz & Doyle (2000) Germany's Tiger Tanks: D.W. to Tiger I, p. 10. Nine engines are listed, with only three (in bold) making it into series production. The three in italics are not in the above list.

year	name	bore	stroke	cyls.	HP	rpm	HP/L	refs
1936	HL120	105	115	12	300	3000	25.0
1937	HL320	145	160	12	600		18.8
1938	HL190				375		19.7
1938	HL116	125	150	6	300	3000	25.9
1938	HL224	125	145	12	600	3000	26.8
1939	HL150	150	150	6	400	3400	26.7
1940	HL174	125	130	12	500	3000	28.7
1941	HL210	125	145	12	650	3000	31.0
1942	HL230	130	145	12	700	3000	30.4

Onwards and upwards... MinorProphet (talk) 23:08, 18 June 2021 (UTC)

Things to do

1. The main article table should be sortable, and also contain approx. start dates of engine production as above.
2. Add other production engines to main table, eg the HL109, fitted to some Pz IV, made at Maschinenfabrik Bahnbedarf Orenstein & Koppel at Nordhausen, Thuringia in the Harz. (This concern was founded in c1916 after a merger with König & Gerlach.) 1,935 HL109s and 955 HL120s were made from March 1944 - March '45. Nordbau produced HL120s from Feb. 1943 average 1000 motors per month, and MAN Nurnberg made 2,415 from Jan 1944 to April '45. (Spielberger, Panzer IV & variants, p. 73)
3. Fix order of columns in above table (power→revs)
4. Run through table in Spielberger Tiger & Abarten p. 208 and collate with the article table. For non-series engines which are not in the article, add details to the above table.
5. Add to this table all the other non-series engines listed at the start of this section, w/refs, and all other engines mentioned in the previous sections. That way there is just one source ready to merge into the main table (Ha!).

Notes

References

Alloy cylinder blocks

Following on from the post above re Spielberger's Panther and its Variants p. 15 which has

" a diagram from Maybach (dated in or after 1941) proposing how the multiplicity of six existing engines was to be replaced by three new ones, quite possibly fuel-injected:

• HL42 → HL50 [180 PS @4000 rpm, from table in Spielberger above]
• HL52 & HL62 → HL67 [the text states HL57, but this seems to be some sort of error]
• HL85, 108 & 120 → HL100 [400 PS @4000 rpm] (or perhaps HL101]

The engines were to have a much greater proportion of alloy to replace ordinary iron and steel."

The proposed high alloy content reminds me of the aluminium alloy block of the HL210, which also fits the above description. It strikes me that there wasn't anything particularly wrong with the 210, it just wasn't powerful enough, being limited by the relative lack of strength of cast aluminium alloy. According to the table in the '2nd generation' section, the HL210 was in production from 1941.

I wondered whether if a shortage of aluminium might had led to cast iron being used. It seems that aluminium may have been always relatively plentiful in Germany during the war (see draft article here for thoughts), so the HL210 perhaps wouldn't have been cancelled for lack of aluminium. The change to the cast iron block of the 230 seems to have been because the only way to increase the capacity and keep the dimensions the same was to use a cast iron block, since the mechanical properties of cast iron allowed the bored-out cylinders to be closer together: but they ended up being so close that cracks developed along the length of the side wall of the inner sleeves. Since the HL230 actually worked by 1944 (at least for 1000 km or so), and was needed for all current tanks (except the projected 38D) it was best to keep on making them.

The main thrust of German tank development in 1945 was to have been in the 38D, a series of fixed-gun variants on the Czech Pz.Kpfw. 38(t) chassis (like the Hetzer and to replace the Stug III). It was to have used the 220 hp V-12 Tatra Typ 103 air-cooled diesel (the design favoured by Hitler), as fitted to the Sd.Kfz. 234 Puma or Tatra 111 (perhaps V850 or V910) with some 2,000 vehicles planned for production in July-December 1945. Only 300 Panthers, 150 Jagdpanthers, 150 Tiger IIs, 50 Jagd Tigers and 50 6-wheel armoured cars (using the same Tatra diesel motor) were planned.

Also after the Normandy landings in June 1944, all the civilian designers and engineers in the industry lost heart, knowing that the war was basically over - and in less than a year it was. MinorProphet (talk) 15:06, 23 June 2021 (UTC)

References

Finally, some proper answers

• Zima S. (1987). Entwicklung schnellaufender Hochleistungsmotoren in Friedrichshafen. (Reihe: Technikgeschichte in Einzeldarstellungen, Band 44/1987) ["Development of high-speed high-performance engines in Friedrichshafen". (Series: History of technology in individual representations Volume 44/1987) ] (in German). ISBN: 9783181500446. Just 886 pages, that'll be £210 2nd-hand, ta.

The essence of this book appears to have been translated into Russian at Development of Maybach tank engines in the 1930s-1940s (new model range of engines with crankcases cast from aluminum cn).

This lengthy article translates almost flawlessly into excellent technical English (except the layout of the tables) with eg G**gle translate. It confirms almost everything in this WP article so far, and makes complete sense of Spielberger's bare list of engines in his Tiger book I mentioned earlier. It also clears up almost every single question I've been wondering about on this talk page, including the engines with aluminium alloy blocks, plus a whole load of extra info about Maybach's attempts to develop a series of supercharged diesel engines based on the corresponding fuel-injected motors. The article goes into some detail about the immediate post-war development in France of the HL295 by a team of some 70 engineers from Maybach led by Dr. Karl Maybach at the fr:Laboratoire des Rechnersches Ballistiques et Aerodynamiques (LRBA), where some developmental work was done by a different team on the V-2 rocket motor. Unfortunately there are no page references at all which makes things rather difficult, and there may well be some copyright issues: but I now feel much happier about the whole thing. MinorProphet (talk) 06:57, 14 July 2021 (UTC)

(Later edit) Another non-starter: A 200 hp Maybach HL76 was proposed for the MKA (mittlerer Kampfwagen fur Ausland), a proposed export version of Krupp's early design for the Panzer III. The HL76 was not complete by October 1937 and the DSO8 was proposed instead; and only one trial example of the MKA (using an HL98) was ever made.(Panzer Tracts 03-01 Panzerkampfwagen III. Ausf. A, B, C & D, pp. 3-32, 3-39, 3-70) MinorProphet (talk) 17:04, 22 July 2021 (UTC)

Here's a summary of the above article and book. After the first series of engines was finished c1940, a new range of engines was proposed, all with [one-piece?] cast aluminium alloy engine blocks: I-4 HL30 (100 PS), I-6 HL45 (150 PS), HL66 (180 PS) & HL116 (300 PS), and a V-12 HL 224 (600 PS). Most of these had different cylinder dimensions except the HL30 and 45. Although a few engines were built and bench-tested, none reached production. There was also the HL90 from c1939, 100 x 106mm, 360 PS @4000 rpm. 14 of these were made, fitted to perhaps Panzer II Luchs, and /or perhaps VK 9.03 Panzerbeobachtungswagen [1] NB These cylinder dimensions actually result in a V-12 of 9.99 litres, which may be the source of the strange HL90/100.

In c1942, Maybach decided to consolidate its designs, using just two cylinder sizes: 100 x 106 mm (0.8325 litres), and 125 x 145 mm (1.92 litres). This resulted in five engines: I-4 HL33 (120 PS), I-6 HL50 (200 PS), V-8 HL67 (240 PS), V-12 HL100 (400 PS), and the V-12 HL230 (700 PS). The HL50 and HL100 reached max. power @4000 rpm, which possibly indicated fuel injection. There was a proposal to increase the HL100 cyl. dimensions to 105 x 115 mm [which works out as 11.95 litres], definitely with fuel injection, to develop 600 PS @3,800 rpm.

(Later edit) Two things: a) The article says that the 125 x 145 mm cylinder relates to the HL230. However, these are the dimensions of the alloy block HL210, and I suspect a mistake somewhere. b) The proposed expansion of the HL100 to 105 x 115 mm: this is what Spielberger says is the HL101, V-12, 105 * 115mm, 11.94 litres, 510PS @3800 (list in Tiger und Abarten, p. 209, mentioned above.) Again, a huge discrepancy in power, but the cylinder dimensions tend to indicate it is the same engine. How Maybach came to name it the HL101 when it should have been an HL119 is something of a mystery.

In addition, the supposed HL100 TR currently in the table which Anderson says was fitted in the Panzer IV Ausf. A conflicts with Jentz & Doyle in Panzer Tracts p. 4-18 (they state an HL108 TR), and I think it is a mistake or misprint which should be removed. MinorProphet (talk) 21:55, 17 July 2021 (UTC) Y

The HL230 was developed into at least two more engines of greater power, none completed by the end of the war:

• HL232, fuel injected and supercharged developing 1,000 PS with the with its own auxiliary engine, the 2-cyl 1-litre HL10; or up to 1,200 PS with the 4-cyl 1.06 litre HL11 (60 PS @6,000 rpm.)
• HL233, no details. See [2]
• HL234, fuel injected only, described on the main page. Power increased from 800 to 940 PS on the test bench by the end of 1944. All the 230 series engines had the same cylinder dimensions,

Maybach also designed and built a number of diesel engines starting in late 1938: HL87 and HL140, HL174, HL 211 with same cylinder dimensions as the HL210, and the supercharged HL232 R with auxiliary diesel power unit HL 25 R. There was also a HL232 RT with a turbocharger. Diesel versions of the HL67 and HL101 were also tested, developing 176 and 300 PS respectively with 4-valve heads and different shaped piston crowns. Like almost all these engines described above, none reached series production.

Between between 1934 and 1950, Maybach designed approximately 100 different types of HL engines, 70 of which reached bench testing. Some were proof of concept single-cylinder designs. Only around 15 engine designs ever reached production, as shown in the table in the main article. MinorProphet (talk) 02:10, 17 July 2021 (UTC)

Faced with an ever-expanding list of experimental engines, I am more and more tempted to limit the main table to actual production series motors, and to make a separate table or tables listing everything else. MinorProphet (talk) 21:55, 17 July 2021 (UTC)

Started Y MinorProphet (talk) 12:04, 26 July 2021 (UTC)

Another list...

Maybach motorliste#Maybach HL og NL motorer (In Norwegian) lists large numbers of Maybach engines, with dates of 1st production, and notes re alloy blocks, diesels etc. MinorProphet (talk) 14:15, 27 November 2023 (UTC)

Which is amended and adapted at WW2 Maybach gearboxes, which is where it probably shouldn't be. MinorProphet (talk) 03:06, 26 February 2024 (UTC)

 leading to...

• Zima, Stefan (2021) [1992]. "Hochleistungsmotoren 1933 bis 1950". In Eckermann, Erik; Treue, Wilhelm; Zima, Stefan (eds.). Technikpionier Karl Maybach - Antriebssysteme, Autos, Unternehmen. [Originally published as 'Hochleistungsmotoren - Karl Maybach und sein Werk', ed. Zima & Treue] (in German) (3rd ed.). Wiesbaden, Germany: Springer. ISBN 978-3-658-25118-5.
  • NB! Query the Pump

Zima's earlier book which I quoted was apparently his Dr.Ing. thesis, but this above book is not nearly so technical or detailed. However, it lists all the vital statistics for every main series WW2 production engine. Plus all the wartime diesels, inc. HL232 etc., + yer actual pics of the saddle-back HL11; railway locos, railcars etc.; all the DSO-type series etc.; and more. It's a bit light on the Maybach pre-selector gearboxes, though... MinorProphet (talk) 22:02, 14 December 2023 (UTC)