ENGINE BALANCE: Inline 6 vs. Odd fire V6 vs. 90 degree V6 vs. 60 degree V6
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- Опубликовано: 6 фев 2021
- Secondary engine balance step by step explanation: • ENGINE BALANCE: Inline...
It's time for another video on engine balance and in this one we're doing a detailed comparison of the inline six with different versions of the V6 engine. The odd firing v6, the 90 degree v6 and the 60 degree v6. To see why the inline six is well balanced we're going to start by figuring out it's firing interval. We do this with a very simple formula. 720 divided by 6. The result is 120, this tells us that the inline six has an even firing interval of 120 degrees. If we deduct 120 from 180 (one stroke) we get -60, which tells us that there's 60 degrees of power stroke overlap in an inline six engine. The inline six has an even number of cylinders which means every pistons is canceled out by another piston, so perfect primary balance. It also has no rocking moment front to back like inline three and inline five cylinders. What about secondary balance. In an inline six cylinder engine the pistons move in pairs, and no two pairs are ever in the same part of the stroke. Which means that the forces associated with different piston speeds at different parts of the stroke cancel each other out. But there's a problem with the inline six. It's very long making it very difficult to package under the hood. So what do you do? Of course you split the inline six in two and separate the pairs of three cylinders into two banks and then you angle the banks in a V shape and voila the V6 is born. But because we separated the cylinders into two banks a question arises - what's the best angle between the two banks of the V? To figure that out we need to again employ our useful little formula for figuring out the firing interval, and because we again have six cylinders, we have the same formula and the same result. 120 degrees. The firing interval is also the perfect angle between the banks for a V-shaped engine. But there's a problem here. 120 degrees V6 engines are useless. Instead of being compact they are bulky! The whole reason a V6 was conceived is to make it more compact but you neuter all this compactness with 120 degrees between cylinder banks. This is why 120 degree V6 engines don't really exist in mass production, and can only be found in LeMans or F1. Although back in 2020 Aston Martin showed pics of it's new TM01 V6 engine, and although I couldn't find verifiable info from the photos it seems like it has a pretty wide angle between the banks, although it doesn't seem to be quite as a wide as a 120?
Ok so a 120 degree V6 is impractical. What do we do then? Of course we reduce the angle between the banks. How about 90 degrees like in a V8? You could even make it on the same production line as a v8, just chop off a bit of block and you got a v6? Well, that's exactly what buick did in 1961 for the very first generation of their Fireball V6. They derived it from their 215 cu in (3.5 L) V8 so it had the same 90 degree bank angle the only difference was the crankshaft. It Had shared crankpins just like a v8, but because it had only three, they were 120 degrees apart instead of 90 like in the v8. The result? A very rough engine with an odd firing interval. So why did it have an odd firing interval? Because it's bank angle is different from the natural even firing interval of the v6 and the crank pin separation angle the engine must adopt an odd firing interval.
And they were able to do create an even firing v6 while still keeping the 90 degree? How you ask? Well, let's think about it, what other part of the engine can you use to make up for the „incorrect“ bank angle? The crank pin of course. Split the pin in half and offset the pins from each other. This is called a splay angle, and your splay angle is going to equal whatever your bank angle is missing. But wait! Can we make a 60 degree V6 now? Sure you can. Just adapt the splay angle. 60 degree banks means you need 60 more to „fake“ 120, so you just make a 60 degree splay angle crankshaft. Done! But doesn't this small cross section make the crankshaft weak? Not necessarily, you can do what the Alfa Romeo Busso V6 did, and put flying arms between the offset pins.
What about primary and secondary balance of a V6 engine? Well a V6 is two inline threes in opposing banks and as such it has the same engine balance DNA, an imperfect primary and a perfect secondary engine balance. What about block rigidity and torsion or twisting forces of the crank? Well the v6 should be more rigid because it's more compact but we have plenty of modern proof (2jz, barra, s54, rb26, etc.) that with the right engineering block flexing or crank twisting really isn't an issue on inline six engines.
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(Posting this here so that hopefully people will see it) I'd like to add a few extra points in addition to what you pointed out in the video:
Most people don't know this, but another reason that most V6's are 60° is because this V angle offers perfect primary balance while maintaining even firing intervals.
120° and 90° even fire V6 have bigger horizontal imbalances than vertical for each pair of cylinders resulting in a rocking moment. If the peak primary force of each piston is 1, the peak horizontal and vertical imbalances are 1.5 and 0.5 respectively for a 120° V6. The crank weights are sized to balance out the average of the imbalances so that the remaining imbalance is circular. In this case the remaining imbalance has magnitude 1, so a single balance shaft generating a force of 0.5 (with weights 180° out of phase) would have to be used. But as D4A mentions in the video, a 120° V angle is very wide, and you might as well use a boxer 6 at this point.
For a 90° odd-fire V6, primary balance is perfect as a 90° V-twin has perfect primary balance, and crankshaft weights can be used to balance out primary vibrations. The problem is that when you have non-split crankpins on a V engine, at least one of the firing intervals must be equal to the V-angle, and what happens in the case of an odd-fire V6 is that the engine's firing intervals alternate between 90° and 150°, as he explains in the video. (This is also why the 90° V10's used in the E60 M5, Viper, R8, and Huracan are odd-firing, as their use of a 90° V angle and non-split crankpins results in firing intervals alternating between 90° and 54°.)
For 90° even-fire V6, each crank pin has a -30° split to give 120° firing intervals. Vertical imbalance is 2 * cos(90° / 2) * cos((90° - (-30°)) / 2) = sqrt(2) / 2 = 0.7071 (again relative to a peak piston primary force of 1) and horizontal imbalance is 2 * sin(90° / 2) * sin((90° - (-30°)) / 2) = sqrt(6) / 2 = 1.2247. The average of the imbalances is cos(15°) = (sqrt(6) + sqrt(2)) / 4 = 0.965925, so the crank weights are sized to generate that force. The balance shaft weights are then sized to generate a force of (sqrt(6) - sqrt(2)) / 4 = 0.258819 and are again 180° out of phase with each other.
For a 60° V6 with -60° flying arms, both the horizontal and vertical imbalances are 2 * sin(60° / 2) * sin((60° - (-60°)) / 2) = 2 * cos(90° / 2) * cos((90° - (-30°)) / 2) = sqrt(3) / 2 = 0.866. This means that primary forces on a 60° V6 can be almost completely cancelled with crank weights without needing balance shafts.
All 3 configurations will also have a slight secondary rocking moment, but this does not appear to be an issue in V6's as the magnitude of the vibrations is normally pretty small.
In summary.. the FLAT 6 is the perfect engine.
I have a 4.0 straight-six and a 225 Buick V6 odd fire. Thank you so much for the information.
I would like to see you cover at this mess
ruclips.net/video/0_Kf-7kg6Ek/видео.html
Can you make a video about the Alfa Romeo 690T in the current guilia since it has a 90 degree v angle. Also the Ferarri 296 has a 120 degree v6, would be interesting to see what you opinion is
I wish there was a separate subject called "automotive engineering" in school and you were my teacher
There was at the school I went to
@@brentonellis213 👀 I want to go to your school
Could easily be covered in both math and physics courses, however the average student couldn't care less. Remember you are here because this is a subject that interests you, you are in a minority. There is a reason why there are more youtubers subscribed to make up tutorials than engine dynamic tutorials.
Mechanical engineering is the closest you'll find in most schools, there are specific automotive engineering programs but then you're limited on jobs
Sadly, The depth of the Auto Tech programs in Accessible High Schools has fallen by the wayside along with Numerous explorative arts, Social studies and extra curricular activities like Horticulture, Animal Husbandry, Industrial Mechanics, Drafting and Design as well as Carpentry, Masonry and Weapons education. Instead of learning how the world works and why, and being able to seek out the experience in a welcoming environment with their peers, they have been left to their own devices, thus staring into another device in their hands while being fed easily retained information that is in many ways absent of relativity. . I fear for our Kids Children.
Bru this is really a legit video, we the unwashed masses really appreciate it. ❤️
I'm not very washed myself
who the f is unwashed masses here? talk about lame self deprication humor attempt
Now you are washed with this videos knowledge.
@@lordjaashin its a term he uses in his videos get educated before you make stupid comments.
@@d4a question: couldnt you make a v6 without splay using a 60 degree angle? I was thinking you could use a firing order more similar to a v8? Just wondering since i dont have time or resources to figure this out myself.
It's an interesting way to explain stuff, by bringing up problems and explaining how to fix them, love these videos! If possible, throw in a rotary engine, when you'll talk about balancing again :D
I dont think rotary would have primary imbalance
Every Wankel engine is perfectly balanced.
@@andyharman3022 So they said: ruclips.net/video/ElkuWqhL9V8/видео.html
That is a cool engine! If you like rpms! Thats the engine for you!
O tom pochybuji. Není to klasická rotace, ale šmatlavý motor, který potřebuje vavážení. Proto se asi dělá min. dvourotorový.🤔
"he never talks about the strange Alfa v6..."
Oh shit, here it is!! 😂 Beautiful!
He has a special video dedicated to Busso's wonder ❤.
@@killerdinamo08 where??? :D
@@flaviopk50s Drat, I've mistaken him with an Italian guy who made a video about it, I beg your pardon ✌.
@@killerdinamo08 Confused him with Roadster Life eh ?
@@nvl2691 Right you are 😉.
This channel and engineering explained are really so valuable to people who actually care about this type of stuff. Explained perfectly and never boring while doing it
Looking forward to the flat-6 and VR6 videos. :)
Yup, I have 300ps 3.6L VR6 with 10,6° angle, so Im waiting with you :D
I almost commented that
If only nissan didn't suck hey
"Nobody really gets engine balance the first time."
You explained it well enough I got it the first time. 120° popping up again. Just so happens to be the natural angle of hexagons. Wich generally provide better balance and structure.
To quote CGP Gray "Hexagon is Bestagon!"
Further showing that indeed, hexagons are the bestagons.
🅱️exagon
I highly appreciate your effort in all those videos and that you smack so many informations that are pretty much well digestable inside em. Thats the stuff YT and the world needs (or at least i need it lol) keep em coming. I'm staying here... this stuff is pure gold
I had to stop in the middle of the video to write a comment because this is THE BEST video explanation of the said matter! Congratz!
Nobody:
Buick: let’s defy physics
Well, the latest Maserati V6 (the 'Nettuno' engine for their upcoming Maserati MC20) is a 90deg V6 without balance shafts, so maybe it can be done, contrary to what this video might want you to believe.
The old buick V6 and ecotec is one of the most reliable engines ever made.
@@raoulrr the original Chevy 90°V6 didn't have balance shafts either (the 200 and the 229). Once it went up to the 262/4.3, balance shafts were finally added
@@raoulrr interesting then how he literally says you don't need a balancing shaft.
One of the very best engines for a hot rod Willys Jeep is the old 225 Odd Fire. They fit well, are torquey, powerful, quick, run cool, and don't know how to stall.
When Buick's new manager sought to dump the Fireball 6 they sold it to Kaiser, who gave them heavier flywheels, dubbed them 'Dauntless', and mounted them in Jeeps and Jeepsters. When AMC bought Jeep from Kaiser they sold the V6 back to GM where it was eventually fitted with the split cranks, then increased to 231 cubic inches and built by the zillions.
You are such an incredibly good teacher.
Your videos keep oozing with Infos....keep it up bro!!!!
I've been trying to figure all this out for 30 years and never quite got there. THANK YOU!
I have a 225ci odd fire Buick in my old Willys Jeep, such a neat engine. One thing to mention, the flywheel is like +70 lbs. I’m not sure if this helps the off balance issues, but it does give it tractor-like torque. Great video, and great explanation!
A perfect video, right on time for the reveal of the McLaren Artura and it's hot-V 120 degree V6!
You are so incredibly talented plain and simple!!
Man, I’m 1.29 minutes in the video, and I just understood secondary inbalances even tho I had already watch other videos since many time and never understood it. Thanks man, I’m pretty sure the rest of the video will be as interesting !
I love this video! Your explanation helps me better understand the imbalance in the Buick 231. I was working on these things in my younger years, knew they were rough running, even knew they were the offspring of their v8 cousins (evident in the distributor cap), I just never saw an explanation as detailed as yours, thanks!
As a kid my buddy had a 231v6 In a jeep commando pickup, and I did really know about V° or anything, I just remember it had a distinct sound idling
This is my new favorite car youtube channel. Your voice is so calming I literally started falling asleep.
I could never get my head around why the v angle made any difference. You've just answered that brilliantly. Thanks.
This is the first explanation of odd firing vs even firing that I’ve actually understood! Thanks :-)
As usual, my daily goal of learning something new is fulfilled by watching your videos. Thanks :)
I still find it amazing how much I learn about the basics of engines from you! The simple stuff like this make a huge difference in engineering an engine. We all appreciate your knowledge and thank you for sharing!
We really need teachers like you. Presents the data effectively and clearly. Kudos !
i've not found anyone (professional or otherwise) that does a better job explaining this concept with more passion that you have. You're amazing and i can't wait to see what other content you come up with. Great job.... just amazing!
I Love These Engine Balance Videos I Really Do.
One or the best divulgative channel on piston engines, great job.
Another spectacularly detailed explanation of a complex subject that we (the learning laymans) can wrap our heads around. Love it! And thank you as always for taking the time to educate us!
You're the best presenter/teacher on RUclips....seriously you are brilliant. I will watch all this series for sure.
The RUclips gods just recently started putting some of your videos in my recommended section and it has been a great experience. Thank you for the many great informative videos
I can't believe the depth you bring. Thanks for the great content!
These videos really are great, thank you for having such a concise explanation of all this that's actually easy to understand.
EXCELLENT VIDEO AS ALWAYS PLEASE DO A VIDEO ABOUT THE TYPES VALVE LIFTERS HYDRAULIC ETC...
THANK YOU
Truly the best explanation for a common man to understand.. You are a gem of value to the engineering students. What made it simple for us to understand was the pictures and animations which made us relate to your explanation. thank you
Man, this video is just God´s blessing. I have an exam in 10 days on this exact topic. Now I have a deeper understanding. THANKS!!!
i think this is one of the best series you did so far!
Amazing work ! Your videos never disappoints !
I love these videos! I always wondered the differences between odd and even-fire V6s. Thank you!
Just descovered your channel. I am studying different automotive engineering books, and I must say you really explain these subjects in an extreamly interesting way, and all in an easy to understasnd way. Love it!
Always seem to know how to make education videos entertaining and interesting. Really enjoy the content, love from NZ :)
Awesome video D4A! I'm super impressed with your ability to explain and educate.
Thanks my man!
Great, great video series. Being a petrolhead for more than 50 years, I finally got to understand the concept of secondary balance/imbalance. Thanks again, and keep these videos comming (-:
Damn, these videos are my go-to when I need to understand anything related to cars. I've spent many years modding engines, but I never really knew about why the engines were built like they were. Excellent videos that you make =)
This guy makes great videos. I am sharing them with my motorhead friends. These make you think and realize stuff never thought of before.
Beauty, nice focus on important aspects. I don't know what a dialect that is, but it's well pronounced and understandable. I think some teachers of technically focused high schools can highly benefit from using your videos even directly in classes. Technical part nicely graphicaly explained with nice english training involved. I'm glad to be subscribed. Keep it up.
Great video man, a lot of time went into putting that together I'm sure! You've made some complex subjects super digestible and I appreciate it very much! 👍
Very nice video, glad to see you are continuing the engine balance videos. Will be interesting to see the big boys like v8 vs v12 and even the i8. Keep the good work and stay safe 🙂
Math test belike: name the offset between pistons of a 2-stroke inline 7
I think its about 51.4 degrees
discovered your channel yesterda, massive fan, thankyou for all you do, i appreciate it, love from australia
I really love your engine balance video's they made me fall in love with the inline six design. I have a request though, can you please make a video comparing the inline six with the v12 engine configuration, explaining why the added cillinders help the smoothness of the engine. I really hope you cover that one day.
Keep up the good work man. Cheers!
The v12 will definitely be covered eventually
Absolutely incredible video. I could watch these for days
Fantastic video, and absolutely fantastic teacher. So glad I found this channel.
Thanks for this excellent video, supporting animations and dialogue. You have put a lot of time and effort into this very professional presentation, well done. Am looking forward to the next instalment.
Love how you did the recap instead of just saying to watch your other video 💕💕
Phenomenal! The best video in your series on engine configuration (6cyl engines) fundamentals.
My favorite series! Can't wait for the next episode!
Excellent technical explanations. I will follow with great interesr this series of videos
Awesome explanation for begginers like me!!Thanks for sharing!!
What an awesome upload. Great explanation of the odd fire v6 and why it was necessary to split the crankpin on the crankshaft. Great job. This is the video yet - just because I didn't understand what it meant by odd fire v6 and I didn't understand why the splitting of the crankpins was necessary.
Great work putting it all together AND EXPLAINING IT ! That's the hard part, explaining it in a way everyone gets it. 😎👍
Bro you are the best channel to watch you teach me a lot about how to fix my car thanks you keep on doing the good work my brother blessing
This video alone was why I subscribed, my little chevy s10 has the 2.8 v6 and it's 60° . I never really understood why until this video! Thank you for sharing your wonderful knowledge and wisdom with everyone on here :)
Great video! 👍
Awesome explanation ! 💪
It’s a pleasure to watch and listen! 👌
👌👍✌️
Nice work. I watched your entire balancing series to help clear up the confusion I ran into researching balancing solutions for aircraft radial engines. I'm looking forward to doing the same w inline and v aircraft engines, and thanks to you I anticipate understanding the various crankshaft configurations I'm likely to observe.
man i admit that you're super underrated
I love the sound of the odd fires, great video 👍
Bro, another great video! Really good explanation and use of animations. Great job! 👍
Great explanations, and your animations are great !!!!
Ma boy D4A KILLIN the game
Fantastic video, great explanations. 100 thumbs up !
Excellent explanation - greatly appreciated.
u know this was the kind of stuff that kept me up at night so thanks for making a video about it
Great material and better explanation. Thanks
Thank you for this great educating video! As you mentioned in the video, I look forward to see the comparison with the VR6 engine.
I second this
bruh that tata nano bit cracked me up, thank you for the great content
Great video! Cant wait for the rest of series
Very concise and well explained.
Good stuff!
Thanks, been waiting for this one and also looking forward to the other two videos on the topic
This really explains why the Buick V6 was such an odd duck. 😀🤓
You are a genius!! You make explaining this look easy, which it is not
That made it completely clear for me. Thanks for the great video
This is extremely interesting! I wish some day you'll make a video about a V8 - e.g. crossplane / flat plane
Well-made,informative video that is easy to understand! Thank You Sir !🌞
beautiful explanations. thank you. loving your videos.
Mate. That was an excellent educational video. Thanks for posting this.
Good to see you're feeling better!
Was about to ask you about vr6 and flat 6 but you answered it in the end hehe
Thank you for watching until the end. Everyone's asking without watching.
You just made it so I can teach this to kids and I thank you
Wow, this channel is really, really well done.
Great explanations and a great video!!! Love it!!!
Great vid! Makes me appreciate this j30a5 that im dailying that much more!
Excellent video, kudos!
He's the Antov of cars! Amazing info!
Very interesting as allways i just love these videos.
Great video, fantastic explanation 👍
Loving your videos. Cant wait for V6 vs VR6 and V6 vs V8 and different types of V8!
Shyt, this is so damn comprehensive, oh my, time well spent! Thanx!
Awesome video mate.
I was going to ask you to make a VR6 video but I waited to the end and sure enough you're already on it awesome content keep it up
great skill at explaining! awsome informative video ;)