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Crossplane Crank Tuning

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Hello all,

I am a member on my schools FSAE team who is in charge of tuning the engine to its maximum performance! This upcoming year we are planning to run an engine that has a 270 degree crossplane crank which makes it a little more tedious to tune and I was hoping the awesome HP forums would help me with some advice. Specifically what things to consider with this engine that would not be normally considered with a regular 360 degree crank.

For those who want to know more about the engine, it is a Yamaha 2018 MT07. It displaces 689 cc and is in a vertical twin configuration.

Thanks a ton for all of your help!

If possible, I would try to install two O2 sensors so you can tune around whatever airflow imbalances you might encounter due to the odd firing order. That might not be a huge problem, but with only two cylinders it's not a huge cost difference to add a second wideband sensor and/or controller. Another common EFI-related problem I've heard from FSAE teams is in the intake manifold and fuel systems, since these are often replaced or customized to meet the rule requirements for throttle diameter. Make sure the fuel sprayed from the injectors has a good path to the intake valves, don't shoot it straight at the opposite wall of the intake runners.

If you don't already have access to them, order what back-order copies of RaceCar Engineering (published by Linc House, England, IIRC) you can get - they have had many articles and features on Formula Student and the prior Formula First.

http://www.racecar-engineering.com/ - you should be able to order from there and there is a link to Formula Student.

Oh, forgot, just treat it like a 90 degree V twin as far as ignition and fuelling is concerned - it will have the same firing, etc, intervals.

Not sure whether there would be an issue with balance/vibration if any internal balance shafts are removed.

I assume this was a development of the 4 cylinder crossplane crank and you may find the reasoning behind it of interest, I was doing some reading on it a few years back when it came up in a discussion in another forum.

If you have any issues, post the datalogs and we'll work from there.

We usually reply within 12hrs (often sooner)

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