Finally, someone who puts out the interesting technical info without posing as a post graduate engineering professor. I am a techno geek but I am mathematically lazy. I get bored quickly when the algebra starts. Keep doing what you're doing and I'll keep watching

The Allison was a VERY rugged engine and its use in aircraft like the P-40 and P-39 showed it could be significantly overboosted up to 70+ inches of manifold pressure with its single stage supercharger. I was always a great low and medium altitude engine and a shame it didn't have a better two stage two speed supercharger. In the P-38 with the addition of the turbo-supercharger it really shined!

Absolutely love what you’re doing here. I’ve been wanting a channel so badly to talk about propulsion of these interwar and WWII fighters. I know the KZfaq algorithm prioritizes shorter videos but please keep them as long and as detailed as possible. Your hard work is very much appreciated sir

My dad was a Navy aircraft mechanic in WW II who loved the Allison- he was also put into the program to develop components of the A-Bomb at Oak Ridge, so he was a pretty sharp mechanic- The Allison did power one Salt Flats racer that broke a bunch of speed records after the War.

It good to hear how good the Allison engine actually was... A few more years and the Allison would have been totally perfected

I've got both the Information Guide, TO 30-5A-1 and Air Depot Progressive Overhaul Manual for this engine. They were in my Dad's attic since the end of WW2 and are in almost perfect condition except for some slight cover tears. He was a flight engineer and mechanic on several different aircraft so have several other engine and aircraft manuals as well. Well done video...

In retrospect, Allison should have parallel path'd Superchargers and Turbochargers on the V-1710 engine. Banking everything on a developing technology-turbocharging-was not sound strategy. I recognize their development was being funded by AAC during the Great Depression years and they probably couldn't afford the second path, but what might have been had they that additional funding? The cost of tooling up to produce the Merlin under license was probably way more that what would have been needed to develop a two-stage supercharged version of the 1710. A similar story with the 'Liberty' aircraft engines from WW1 compared to the Rolls-Royce Eagle series V-12's, America brought a great design to the table, but too late to impact the course of the War. Great video by the way, as a recently retired Engineer with 47 years in Auto industry powertrains, I really enjoy this stuff! A video on the Liberty Engine would REALLY be awesome, I've read a post-war technical report by the chief designer which was absolutely brilliant. SUBSCRIBED.

Excellent video - like the new format. War surplus engines were used in earthmoving equipment by LeTourneau due to lack of Diesel engine availability and cost. Keep up the good work.

I'm really enjoying this series of excellently researched and well presented videos. Keep it up! Best wishes from Sheffield in the UK :)

You are really good at these engine videos. I'll watch them all. Amazing how they had 4 valve per cylinder and roller valve parts back then.

The Allison weighed less, had fewer parts and complexity, ran higher Manifold pressures, smaller profile, and also had better build quality. It really was only drawn back by the lack of supercharger technology and turbocharging. I mean the p-38K (and D/J) models could easily sit at or above 45,000ft with the turbosupercharger configuration.

The army air corp was sold on turbo superchargers and the navy was sold on radial engines so Allison concentrated on what they could sell, namely turbo supercharged two stage systems

Well I'm sure alot of it has to do with the fact that there was a fair bit of surplus Allsions after the war and they were used in various applications such as tractor pull rigs and boat racing.. Theres a badass hydroplane that's been coming to the race in my town for the past like 10 years or more with a twin turbo Allison and he's the only one in the Unlimited class that's not running a turbine engine which has been the standard for 25+ years. He often gives the turbine boats a run for their money and has even won the event here. Then there's of course the vintage hydroplanes that run and they almost all are running Allisons.

Have you seen the RR Heritage book “Rolls-Royce and the Mustang”. There’s a huge level of detail on the Merlin the Mustang and things like turbo compounding. By the way RR struggled with oil pumps. Merlins basically threw con-rods until they realised the oil pump was not big enough to meet demand at high revs.

You answered a question I have had for years and that was about the high altitude under powered reputation of the 1710. Thank you.

Bottom line is that the Merlin had a better supercharger because the AAC was fascinated with turbocharging.

A fabulous engine that was castrated by the Army. The two-stage engine was unwieldy but the hydraulic coupling was quite advanced. Great video, and all of you Allison fans should check out the book "Vees For Victory", an incredibly detailed history of the V-1710.

I greatly enjoyed this video. It was great to hear a more detailed history of the engine.

Thank you! You scuttled some assumptions I nurtured based on hearsay about the Allison being under-developed because of political considerations between GB and the USA. Later of course, Allison became the masters of large turboprops in planes like the Electra, Orion and Hercules. One felt very safe in an Allison powered Electra.

I enjoyed to know that you and a few watchers also knew the V1710 was incially intended to replace the german V12 Maybachs used in the Akron and Macon airships. Airship tech was widely used in airplanes and I like both types. The Crecy book is a dead giveaway of an airplane engine geek, that's cool! If you intend to do a video only about compound engines, don't forget the Napier Nomad, which you certainly know that was a 2-stroke diesel aero engine prototype - a complete alien in the scene, but an interesting one. Great video, keep doing them in any format you like best!

Good stuff! Like the new format! Good luck growing the channel and getting the algorithm to show it to more people. You already have the production to a great level, the research is good, delivery is plesant and friendly, like especially the way clips are formed to be like a story with little details of the times and about the people behind also.. not just facts and numbers. Ps: great old school radio voice :D

Great video, I think one thing worth adding is that while in hindsight we often remember the p38 taking a background role in Europe to the p51, it is well worth considering that before the p51 really came into its own with the merlin equipped p51b and p51c in late 1943 USAAF commanders were clamoring for as many p38s as they could possibly get. The p38 bore the brunt at perhaps the peak of the luftwaffes strength in well trained pilots, and before the fuel shortages and impact of the bombing on parts availability and quality were felt as the allied war effort strangled nazi germany. The p51 with the merlin just changed the game in having a fighter that could go the distance with the heavies at a far cheaper per plane price than the p38. Anywho, I really liked the video and will be subscribing, you clearly put a lot of effort into making this fantastically nuanced video on this fascinating topic, well done.

Nice video, the Allison has always been the described as a dog by the uninformed. Glad you mentioned the Allison Engineering bearings which were its real bread and butter before the war. A little mentioned note about the 1710 was it passed the 100% power for 100 hours requirement that the Army specified, which the RR and RR/Packard were never subject to. And finally, the Allison is always compared to the later Merlin Mk XX engine with it 2 speed charger. Thanks for an interesting vid.

The engine was actually smoother than the Merlin but where the Merlin beat it was in supercharging. It was the Merlin supercharger which allowed it to excellent at height.

Thank you for this very informative, both mechanically and historically, video! I enjoyed it and learned quite a few things.

During Korea my grandfather was stationed in Japan as a stockyard manager. Somehow they managed to loose one of these engine and well they all got into a bit of hot water so they said It must have been stolen. They sent out a search crew but nothing was ever found, he thinks its still at the bottom of the ocean. lol

Thank You for your channel. Great Job!

The best presentation on the Alison engine I've seen. Well done!

I love your optimism in this engine that I first saw on display at Dover AFB museum. "Keep it American" is what I've always said! Give it a chance⚠️

Allison still carries a great name for quality and heavy duty performance....hope they never lose that reputation....

Fantastic analysis of the Allison! Thank you!

I glad i'm not the only one who delights in intricacies of these legendary engines.

Allison had altitude issues overall, for points you addressed, but from a marketing standpoint, the engine was reliable, and was great for low altitude aircraft designs (Soviet Union?). And it did prove to be capable if someone could design a proper forced induction system for it.

Yes!!!! In plain English, gentlemen explained history that even 5 year old would cherish. Thanks for sharing your knowledge 🙏

You've got a new fan and subscriber here. Excellent work you're doing. The power figures for the turbo compound engine are astonishing. I didn't how how how such a sysyem worked until your beautifully concise explanation.

The Allison engine was in several drag race cars one I remember was called Big Al 2 I did something like 9 seconds at 160 something because tires and clutches weren't developed yet. And I remember always being impressed with those powerful engines and asking my dad if they ever put one in a big truck and he thought that someone had but it tore up the transmissions.

Excellent video and very well explained. The merlin engine had it's problems as well, often solved by testing to destruction, inspection and redesign. This resulted in an extremely strong and reliable engine which could easily cope with the power increases that came later. The main problem in the early days was with the supercharger but a scientist (not engineer) called Stanley Hooker solved that. His speciality was fluid dynamics, and it is said that anything that flows is a fluid, including air. Anyway he transformed what had been expensively and laboriously made into a good and reliable engine into something special. I should add that rwo other things helped a lot... high octane fuel and ethyline glycol, both from the USA!

Keep up the vids! I can nerd out on these engines for days. Enjoyed seeing your bookshelf and had a chuckle that it parallels mine quite well. Cheers.

Very entertaining, informative video! Thanks!

Great stuff👍 Really interesting and I like the new format. Is the RR Griffon next? Maybe a Bristol Centaurus👍

A very enlightening video thank you for all the new information!

Excellent video. Longtime aircraft mechanic. Truly enjoyed it.

This channel has become my favorite KZfaq channel. It’s amazing to discover all these complex technical issues that were figured out 70+ years ago. The Second World War was the pinnacle of technological achievement in my mind, though obviously many could successfully argue that, but I would posture that much of the post war technological development was cheating by using either jet propulsion and later, digital control systems. Yes the planes were better post war, but jets bore me. Nothing beats a good ol warbird with big ol air screw bolted onto a massive power plant that harnesses a bunch of explosions to make it fly. I wish I were born in an earlier era!

A mechanic for 40 years and I just learnt about turbo compounding, very interesting.

It's easy to forget, they didn't have the design tech for good compressors and turbo impellers, They were still working out how to actually make boost. And it's much different at altitude compared to car or truck use.

Great video. Your comments closely match what my father told me. He was working in the Allison test bed during the war.

I wish you were able to touch on the late war/post war installation in the P/F 82 and whether all of these almost solved problems had been finally put behind it or not. Very good presentation. I am surprised someone during the war didn't "accidently" you got your chocolate in my peanut butter the 2nd stage system from the V1650 to the V1710 1st stage.

My Pops was a Allison factory trained mechanic. Thanks! Miss him.

Went down a rabbit hole recently with the American M6 heavy tank which began development in May 1940. Being 57 tons it needed a decent engine and the committee of SAE engineers assigned to look into it selected the Wright 1820 to supply ~825 hp. What I don’t know is if they looked into the 1710, which would have been in production at the time. Later in the war the Merlin would be used in tanks quite successfully. What’s interesting about the 1710 in this application is that it was a GM product and GM also had Hydro-Matic transmissions. In theory a 1710 with a Hydro-Matic would have made one of the best tank engines of WW2 and potentially a viable power package for decades. What I’d love to know is if a 1710 was ever arranged like that, for use in heavy vehicles?

One important application you missed: the Joe's combat version of the P82 twin mustang. It didn't serve in huge numbers but was important holding the line till more advanced olanes

This video nails it, fantastic job of covering the Allison story.

I had to listen to the turbo combining twice, that's brilliant.

Love the format. Am loving these new vids. Used to be so into aircraft. Good to be back

Great soup-to-nuts review of the engine. Did not expect such detail.

Love these videos. I'm gonna put one of these in my chevy sonic. I'm going to sit in the trunk.

Enjoyable read on a fantastic engine, and it's development path. Thanks much. Time well spent.

P-38 Allison configuration outperformed the Merlin at altitude. The Allison powered P-40, A-36, and others dominated the likes of the P-47 and others at low altitude (where a fair amount of combat did occur). The P-51J was considered to be potentially the best P-51 model. A key reason the Allison was ignored was the lack of a common/standard high altitude configuration that could be easily designed around in multiple airframes, and constant carburetor issues throughout the war. The engine was tough, durable, reliable, and could be pushed harder than the official rated numbers. I'm not a diehard Allison fan, but I can't stand the undeserved hate the Allison gets, and the overhyped praise the Merlin gets when in reality it wasn't as straight forward as people try to claim. Meanwhile low altitude Russian fighters are heaped with praise, as are low altitude Japanese planes and low altitude UK planes. It's hypocritical and inconsistent. It's exactly like how the P-51 is the only aircraft that gets hate as a ground attack aircraft for being "inline water cooled". But I present the following ground attack aircraft in WW2 that are legendary and/or heaped with praise for ground attack. Mosquito, A-36, Ju-87, IL-2, Hawker Typhoon/Tempest, Hurricane, P-39, etc. Notice something about all of these?

The final evidence of the Allison potential is their use in tractor pulling. 3,000+HP is being produced without superchargers ( running nitro methane)

Outstanding!! Please continue with this format!

You are a nice complement to Greg's channel. I have subscribed. Please discuss "turbo compounding" in the context of the Wright R-3350, where I understand it was perfected in the 1950s in airliner service. I used to work for Curtiss-Wright (for real) beginning in the 1980s and some of the old-timers there discussed this configuration of the 3350. I never really understood the difference between a two-stage turbo-supercharged engine and "turbo-compounding."

Extremely reliable engine, perfect for lew-level air-work. The British used their P-51As (Mustang I and II) until 1945 in the army cooperation mode. At those heights it could outrun anything the Germans had. The Allison also had good behaviour at low revs (a perennial problem with the Merlin), perfect for long range missions at economic throttle settings. The Russkis loved their P-39s too and put them to good use in another low-level scenario.

I cannot believe the amount of work that went into the development of this engine to make it durable, dependable and possessing adequate horsepower. Whew!!

Here's the timeline I'm imagining: When the engine was first built, the supercharger was designed during that initial stage. During the reinforcements and engine structure alterations made in the next few years, the induction team would have been able to make the 2 stage supercharger work, which would have been done by 1941, making there be a version with or without 2 stage supercharging depending on turbocharger presence or not. At that point, by the time experiments in turbocompounding started, they would have been more easy to continue given they would not be focused on doing the most with the supercharger they had.

Well done. Thank you. I actually understood almost all of that.

One of the best aero engines ever!

They were still using 1710s and Merlins in the piston-powered hydroplanes in the 80's that were raced at Seafair here in Seattle. The turbine hydros always won (Miss Budweiser, Miss Miller, etc...) by using the GE gas-turbines from Bell helicopters

Engines before the widespread use of plastic components hanging off it were such a mechanical thing of beauty. When everything was machined metal . Things were a piece of art.

Other points to consider: the Allison made more power at any given level of boost and weighed less than the equivalent Merlin and it lasted longer because it had much better bearings!

I have one in my '71 Ford, Pinto. I love it.

It seems i hear more about the war time Rolls-Royce engines than the Allisons. Good video. The first time i heard these engines were in Unlimited Hydroplanes that raced in my hometown. I tell you there is no comparison when you hear 5 or 6 of these engines racing to the start line. You feel them.

The Allison engine was arguably a generation in advance of the Merlin in many ways, but the lack of a two stage supercharger hamstrung it.

Deep dive explanations of these monsters needs to be done, great vid. The engineering done that led to the launch of Apollo in this era is as high tech and clever as any modern engineering. It seems so long ago.

Great review of a great underrated engine

Fascinating that there were the 3 main-stay high output V-12 engines between the Brits, Americans and the Germans especially for their fighter aircraft. I have been to the Evergreen Flight Museum here in Oregon to see the Pratt & Whitney R4360 28 cylinder water cooled radial engines which are still fitted on the Hughs 'Spruce Goose'. It is very amazing how the jet engine simplified & improved everything so quickly.

The P-40Q was a good looking aircraft and achieved test speeds of 414mph at 20,000ft. But this was a test aircraft and not service aircraft which was typically quite a bit heavier. It was already way behind the performance of the P-51C when tested 1944-45. Turbo-superchargers were big and heavy and took up a lot of nacelle space on the P-38. The secret of the Merlin was the superb two-stage mechanical supercharger that needed just a 9 inch extension in the engine bay.

I heard these 1710's every august in Seattle when the unlimited hydroplanes came to town. They were running Allisons and Merlins into the 80's before mostly shifting to large turboshaft turbine engines.

Thanks for another very inciteful analysis.

Packard gets no recognition for actually building the merlin engines. Thank you.

Very well done! Nice work 🫡🛩✅✈️😊🇺🇸🇺🇸

Rolls-Royce constantly improved their supercharger. Battle of Britain engines were all single stage. The two stage blower came into the Merlin 61. It was the RR test engineer who noticed the 61 would go well into the Mustang. The Packard Merlin was a mass production version of the 61. By war end RR was working on a turbo compound system. It was never developed because they found their supercharger was so good that early jets just worked. Early RR turbojet compressors were basically the Merlin supercharger.

fascinating story .... and great to actually see the face behind the voice!

While not a piston engine; The Allison T-56 turbine engine was a huge success for the Allison company. In fact Allison produced many reliable turbine designs for aircraft and helicopters. I would like to know your comments on these engines.

Excellent video, as always. Your speaking ability is excellent, and the logical development in presenting the material is also excellent. Off topic but related, I am always amazed at the shear volume of technical and engineering development in the early part of the 20th century, especially in the 1930's. No doubt you have noticed this in the research of your videos. Perhaps it could be a subject of a video, if you can pin down exactly why this was the case. Regards.

Great video. Love the new format

Super interesting video. Very well done. Thank you.

Really excellent presentation, thank you

Allison engine was solid. Problem with the single stage Allisons was that the airframes were too heavy. P-39, P-40 and P-51A weighed 7650#, 8400# and 8600# respectively for an engine of 1150HP. Spitfire V weighed 6500# with 1400HP and a Me109G weighed 7000# with a 1475HP engine.

Nice shout out to Greg's Airplanes and Automobiles. These videos remind me of his. He's all about getting into the technical details of WW2 aircraft engines.

Interesting mention towards the end regarding squish/quench not being properly utilized for increased anti-knock capability. From my experience with high-performance automotive engines, for squish to be used effectively there must be a portion of the piston head's surface that comes within roughly .045" or less of the combustion chamber surface when the piston is at TDC. My guess is this was hard to implement without a complex piston dome/dish shape because if it was simply flat then the volume at TDC would have been small and compression ratio likely would have been much too high to be suitable for the intended manifold pressures. Just a thought, makes me want to read that Horsepower Race book even more now...

Enjoying your videos very much thank you for your research and detail please keep them coming

Really well done and informative. Thank you.

I have a fantasy plane, it's a de Havilland Mosquito airframe built-in carbon fibre. In my fantasy I'm always looking for more power than the Merlins it was originally given. This is an interesting part of the dream!

From an engineering standpoint, the nuclear bombs were a terrible move, yet they really saved a lot of American soilders, and more than some Japanese civilians. Still the death knell of the piston engine.

A great overview and very well poresented. By the way, I see the book on the Rolls-Royce Crecy over your shoulder: designed just a few miles form where I live!

Did you know that the V-1710 was almost considered to be a tank engine? It was tested on the T29 heavy tank prototype, probably influenced by the Rolls-Royce Meteor.

Excellent, thanks!

Realy like new format. Looking forward for new vids!

@6:10 look at the valve seats😎 3 angle form on the intake. 5 angle on the exhaust. That’s Race Car Stuff

the size, complexity, and raw HP of these monsters is incredible just to be flown directly into German flak by 18-25 year olds. Such a crazy period in history

Very interesting video on the Allison V-1710 engines also because I know very little about the history of the Allison factory. I always understood that the Allison V-1710 was easier to maintain compared to the Rolls-Royce Merlin and had better performance at low altitude. Regarding the issue of the P-38 that had issues over the cold and damp weather it seems to be controversial: years ago I bought a very interesting series of booklets, in this case the two parts on the P-38 variants. It emphatically stated that, here is the following excerpt: "the digestive problems with the engines that occurred at high altitude was argued, by other authors, was due to the cold and damp European weather. The booklet argued that temperatures and humidity are generally the same around the world at altitudes greater than 25,000 feet where those problems occurred when in the Pacific the Lightnings established a great record for reliability regardless of altitude and temperatures. Based on all the facts, it is evident that the poor quality of the British fuel is to blame, because they proved unsuitable for use in turbocharged in-line engines. Powerplants with two-speed, two-stage, mechanical superchargers and even radial engines with turbo superchargers did not have the same ingestive problems with the British fuel but the combination of an inline engine and a turbocharger always did." Mind you that those are not my words as I merely copied it but who wrote this seems to know the facts. That said I didn't know that the Army didn't let the Allison company to develop their own mechanical turbocharger that would have permitted to develop better high altitude engines without needing to use Packard made engines. Good job again 👍👍👍