Triumph T-Plane Engine Explained and Compared with Yamaha's CP3 Crossplane Inline 3 engine
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Published 2022-11-20
The inline three is the new inline four. In the last few years we have seen this humble engine configuration become ever more widespread. A 1.0 liter inline three together with a turbocharger has replaced 1.6 or even 2.0 liter inline fours on many cars. An inline three has less cylinders therefore less friction and more efficiency. It’s also of course cheaper to manufacture and easier to package due to the reduced overall length. But when it comes to motorcycles an inline three of course isn’t considered downsizing, seeing that motorcycles on average have less cylinders than cars. Instead inline threes are a mix of luxury and oddity in the motorcycle word, and while there have been some very impressive and iconic motorcycles over the years, the configuration remains uncommon.
Now, one of the companies that has definitely done their part when it comes to contributing to increasing the percentage of inline threes is Triumph and in today’s video we will see how their T-plane inline 3 engine (Triumph Tiger 900 and Tiger 1200) abandons decades of established design logic to try and create an engine with a split personality, and we will also see how the T-plane compares to other inline three engines including Yamaha's “crossplane” inline three (aka CP3) engine (MT-09, Tracer, XSR900)
If we take a circle which is 360 degrees and divide it by three we will of course get 120. And this the crankshaft configuration that pretty much all inline three cylinder engines employ. We have the crank pins 120 degrees apart from each other which means that we have a piston reaching top dead center every 120 degrees of engine rotation. The result is of course an even firing interval. Now in a four stroke engine we need 720 degrees to complete a full combustion cycle. 180 for intake, 180 for compression, 180 for combustion and 180 for exhaust. To get the firing interval we simply divide 720 by the number of cylinders. The result is 240 and this tells us that the inline three engine fires every 240 degrees of engine rotation.
When we sum everything up the traditional inline three is a humble engine but it’s a good deal. It’s overall less smooth than an inline four thanks to a gap between power pulses and worse primary balance but it makes up for it by being more cost effective, more compact and more efficient.
But despite this Triumph rejected the traditional good deal offered by the inline three and chose to up-end the logic of this engine.
Instead of having of all the crank pins evenly spaced out and separated by 120 degrees they separated them by 90 degrees creating a configuration which looks like the letter T when viewed from the nose of the crankshaft – hence the name T-plane crankshaft.
Of course having the crank pins 90 degrees apart means that our even firing interval goes out the window. Instead of firing every 240 degrees of engine rotation the t-plane has an uneven firing interval where we fire cylinder 1 rotate 180 degrees and then fire cylinder 3 after which we rotate 270 degrees to fire cylinder 2 and then again 270 degrees to fire cylinder 1 again. So our firing interval is 180 270 270 and our firing order is 1 – 3 – 2.
So why would Triumph chose to take an engine that is barely smooth enough and make it less smooth by employing an uneven firing interval?
Well, there are two main reasons behind this. The first one is that an uneven firing interval creates a very distinguished sound character which sets the motorcycle apart from competitors.
A specific sound gives the engine a unique character and definitely helps sales. It definitely worked for Yamaha and their crossplane inline four which sounds completely different from any other mass produced inline four.
In fact the marketing worked so well for Yamaha that they tried to forcefully trickle down the word crossplane into their engine offerings with fewer cylinders, which is why their inline two and inline three cylinders are called CP2 and CP3….the cp being crossplane.
Now I completely understand the need for marketing, brand identity and so on but Yamaha’s CP3 engine is just a conventional inline 3 cylinder engine and it has the same crankshaft configuration as any other inline three. 120 degrees apart for the crank pins and an even firing interval.
Calling an inline four crossplane definitely makes sense because all the other inline fours are flatplane. All the crank pins lie in one single plane. But the inline three configuration is naturally crossplane, that’s at the core of the engine’s design. All the other inline 3 on the market are crossplane just like the CP3.
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#d4a #triumph #tplane
00:00 Conventional i3 firing interval
03:15 i3 Primary balance
07:13 i3 Secondary balance
09:09 T-plane interval and sound
17:26 T-plane primary and secondary
All Comments (21)
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Patreon: www.patreon.com/d4a Motivation: www.youtube.com/channel/UCt3YSIPcvJsYbwGCDLNiIKA 100 cars that changed the world: amzn.to/3DGXDf6 Stem engine model: amzn.to/3Y5iZLv 1-2-3 count with Car parts: amzn.to/3jxP7Z6 Patreon: www.patreon.com/d4a
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If I had a teacher like this I would definitely go for engineering school.
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As a guy who's ridden for >50yrs and has only the most basic understanding of engineering, I absolutely love this channel, and am so glad I discovered it recently. Brilliantly clear and fascinating explanations, matched by equally brilliant graphics. Keep up the amazingly great work, and thank you!
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Hey! Daytona 675 owner here, although it sounds like the tripple would be a not so smooth engine it actually is one of the smoothest bikes I’ve ridden, vibrates a lot less than a few of my mates bikes. Sounds nicer stock than any other bike and honestly the power delivery after 4k makes it feel like it’s got a vtech engine in it, highly recommend any bikers to have a go on a triumph because the engine is amazing and their bikes amazing handling, 10/10 hit the spot for what I wanted in a sports bike
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I'm an engineer, and you gave me some insight into the finer details of a 3 cylinder engineer, plus a Triumph fan & rider.. 👍
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Excellently explained. I've got the T-plane engine on my Tiger 900 and it really does have a split personality. Above about 4500 rpm it acts like a four, under that it's more like a V-twin, and sounds great at any revs.
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Just when you thought 3-cylinder engines were really straightforward :D I kinda envy early engine guys when they started experimenting with all these geometries! And now I have a craving for some CP Chocolate Pudding :D
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I'm a new powersports mechanic, 7 months into it now. This channel teaches me so much about the concepts and functions of engines, etc. I can repair and rebuild all day, but learning and understanding the theory and concepts of operation helps so damned much. Thank you for doing what ya do man!
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I wanted to thank you from the bottom of my heart for the knowledge you share. I'm a ship engineer and you helped me understand my profession even better than the best teacher I had till now. Best of wishes.
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I am no way major in engineering and all other stuff but this guy makes it easier for a dummy like me to even understand a fraction of it. Now this is what you call born to be a teacher! PLEASE KEEP THE VIDEOS COMING!!!
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I have a Tiger 900 and when I knew my motorcycle has such a strange engine configuration I thought this was stupid. Now I do not think it is stupid anymore. Thank you. Keep beeing probably the best channel on mechanical engineering ever.
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The Petronas FP1 did use a 180 degree flat plane crank in some of their race bikes during their final season in WSBK. It was never homologated and yes it would have sounded different to the 120 degree but they were desperate for power during that last season and the other teams knew it would never be a title contender due to being a smaller capacity engine compared to the 1000cc 4 cylinder bikes being used after the change from 750cc 4 cylinder to 1000cc 4 cylinder. The petronas FP1 was never going to be a bike that got sold even though rumours that the full homologation numbers were not met, Petronas did actually build the number of bikes needed to homologate them for racing even though they never passed homologation for the road at the time. Riccardo engineering did run a number of them to try to homologate them but due to over heating of the rear facing cylinder heads and the issues the race bikes had with cylinders becoming oval due to massive heat behind the cylinders and colder air on the forward facing intake side Petronas decided it was too much of a risk for them to sell due to the liability claims they could face.. But they did use flat plane cranks in a number of bikes. How do I know?? I worked for the company that made them..
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My Daytona 675r might have some fuelling issues atm but the sound when she's right is just the most beautiful thing. Knowing a bit more about it from this makes it even more special. Nothing like a triumph triple
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The 'flat plane', 180° Laverda triple was known for being better able to withstand race tuning than the 120°, a lot of racers continued using it long after the introduction of the latter. I think this was because the pressed-up crank was less prone to twisting its crank pins/webs out of alignment at high RPM and outputs with the 180° layout.
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Man, this is becoming the engine balance channel
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Best teacher on youtube, teaching me about things i didn't even think i needed to know
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Just commented after the brake video. I would absolutely love a master cylinder video to help understand how you can actually brake faster (and almost more importantly, more consistently). Some guys deleted the booster but install a larger master cylinder. Chasebays make great kits, especially their dual piston master cylinder with a 6:1 pedal ratio. Thanks for these video, Mark
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your teaching ability deserves MONEY...
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Thank you for this explanation. As an owner of both a Tiger 1200 and Street Triple, I was not really understanding the difference between these two engines, particularly where off-road traction is concerned. Now I see how the T-plane assists traction, and also it’s distinctive sound.
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Wow, came to learn about the difference between I3 engines and learned a concept about motorcycle traction I have never heard anyone explain before. Great video!
