Racecar Engineering - Crankshaft Trigger Wheels

Today we go into details and explain how different crank wheel geometry affects the reliability of your engine.
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[@BigRingStumpy]

I installed a 60-2 Fab9 wheel on my fresh build. The teeth looked janky to me and the wheel oscillated a tiny bit. I'm new to this so I did not know any better and installed it. When I went to check my car's timing it was off by 6 degrees at idle. So my hall sensor was not reading one of the teeth. I cannot imagine what would happen at 7k rpm. I just received a 36-2 from 949 and it looks much better.
Thank you for sharing this information. Well done!

[@patrickcowanjr1]

Glad this was helpful!

[@AR3n3gad3]

Super informative! Thank you!

[@patrickcowanjr1]

Glad it was helpful! Something I wanted to share.

[@miatafan]

"boom, fuck you, turn faster"
best line to explain Piston engines lol
6:20

[@patrickcowanjr1]

:)

[@fabianamok872]

thanks for the very informative video

[@patrickcowanjr1]

Thanks for the positive feedback!

[@UnsponsoredBuilds]

Awesome video! Shared!!

[@patrickcowanjr1]

Glad you liked it! I want to start doing these with higher effort put into them. Just so busy but I can think of 100 different topics I think would be really interesting and having good visuals and clear explanations would be really helpful and easier to watch. I have noticed my Racecar Engineering videos have done better than average. Funny enough, lightweighting videos do better than average too.

[@skymit5519]

so with the 36-2, you kind of get a reading every 5 degrees. as you get the rising edge and falling edge? As the gap would be 5 degrees of rotation then the tooth itself would be 5 degrees(assuming tooth and gap are even)

[@patrickcowanjr1]

They do 36 teeth spaced 10 degrees apart. But my ecu only looks at one edge, so it uses 10 degree info not 5.

[@miatafan]

great video, sucks the Fab9 part is junk.
Ive always wondered about applying this idea to the VVT cam Reluctor wheel as well, seems to me it would be another case of more teeth being better, as long as the ecu can be told theres more to count

[@patrickcowanjr1]

That's a good point, I've never considered if it would help or not. I suppose knowing what duty cycle you are PWMing the valve would kind of answer that. If the frequency is too low, then you would already have up to date info after a certain RPM so having more up-to-date data would be of more limited use. But then again, if you had more data, perhaps a valve with a higher PWM could then be implemented. Something tells me more modern cars probably have more teeth and high control frequencies.

[@billwilner1839]

Why do you say that the Fab9 wheel is "junk"?

[@miatafan]

​@@billwilner1839 rough edges on the tooth profile that can lead to inaccurate readings

[@patx35]

For awhile, Nissan ran a 360 "teeth" trigger system. While it's a high quality part, they have a fatal flaw where the trigger disk is driven by a timing belt. At high RPMs, especially with aggressive valvetrain mods, the cams would start oscillating in respect to the crank. That would cause the crank sensor to double read several teeth, causing a noisy crank signal. People would either swap out the trigger disk for a 36 tooth, or switch over to a crank driven trigger system.

[@patrickcowanjr1]

That is really interesting! Makes perfect sense. I've actually spent many hours thinking about implementing a 360* tooth wheel on the crank.

[@vg23air]

why go 36-2 instead of 36-1 ?

[@patrickcowanjr1]

36-2 is worse to me. But flyin miata had a very high quality part so I used it anyway.