Rotational Inertia - Effects on Horsepower

What effects does rotational inertia have on acceleration? Low moment of inertia components lead to more available horsepower. An explanation of rotational inertia, and why it's best to use low moment of inertia components in your drivetrain.

The next video will include additional information on rotational inertia.

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[TheMotownhustler]

Thanks Professor. I'm 66 retired and drag racing for a hobby. I appreciate the information. 👍🏾😎

[IsmaelMartinezPR]

Another example is an ice skater doing circles as the move their arms in the spin faster. Great series you have a great future as a teacher any day.

[EngineeringExplained]

Thanks! I certainly will. The next two videos are basically math based (the next one mainly just words). Basically I just teach myself what I'm interested in, and then relay what I learn on my channel. Glad you guys enjoy it!

[MercedesAMGsRULE]

I love this video. I have a Mini Cooper with the 'run flat' tyres on. I changed the tyres and weighed the old ones Vrs the new Non runflats. There is a huge 3.6kg per tyre difference due to the stiff tyre wall that the runflat has. Of course then I had it on the dyno, and the difference was 1.9 horsepower, (obviously it was dynoed on the front wheels so if I include the rear wheels I can double this figure) so the total Hp increase is 3.8. Also helps handing, it's comfort, quieter and more fuel efficient. The tyres are cheaper too! It was the Pirelli Runflats Vrs Continental Premium contact 2. I just carry an inflation kit in the boot if required.

[n.s]

its important to know that flywheel mass is calculated in ic engines to store
kinetic energy permanently during combution strok and giving it back in the following stroks to give the engine smoth tourqe curve between stroks

[EngineeringExplained]

A heavier flywheel will not improve acceleration at higher vehicle speeds; it would however reduce engine braking, so you'd have more inertia to overcome when stopping the vehicle, while in gear.

[EngineeringExplained]

Thanks, glad to hear this! And I have no plans of stopping!

[EngineeringExplained]

You simply have to provide enough power to power the engine continuously, this likely wouldn't change much with a different flywheel. Worse mileage in the city, roughly equivalent on the highway. A heavier flywheel could potentially provide a small benefit in drag racing, storing more "free" (doesn't take up time) energy to use once the light turns green.

[mackchannel]

Old content is still good content. This helped me understand much about my vehicle that I did not know. Thank you for taking the time to put out this video!

[EngineeringExplained]

Well if off-road vehicles never planned on going over 10 mph or so, ever, then 1 gear may be acceptable. But it's always nice to have a low gear set also for moving very slowly with maximum torque. You just want the versatility of multiple gears, in part so that it can also be used on the road or anywhere.

[francisgaliegue]

This video does not have enough views.

I have never figured out what inertia really was until I saw this video...

Excellent job. Congratulations!

[williamdutoit]

This explains well why cars tend to spin their front wheels when shifting from 1st to 2nd, It's all that inertia that is "stored" in the engines high speed. when shifting to second the engine has to rotate slower but it doesn't want to causing a peak in torque at the wheels resulting in loss of traction. This also explains why my motorcycle doesn't wheelie in 1st but shifting fast to 2nd lifts the front wheel momentarily.

[EngineeringExplained]

No worries, the formulas and technical aspects certainly aren't for everyone. I will have plenty more videos which are more "traditional" and simply explain how things work. That said, I like to be thorough, and topics like these are needed to tell the whole story. In a few weeks I'll have a detailed exhaust story (basics, catalytic converters, mufflers, o2 sensors) and shortly after I hope to start getting into hybrids/electrics. The math will be minimal!

[MisterBinx]

About 4:10 is where it really clicked for me. Great explanation thanks.

[Irish]

This is the first time the concept has been made clear to me. The explanation was great and I really understood it since being aware of it for 3 years now. 5 STARS!! Thank you. :)

[EngineeringExplained]

There are no simple disciplines of engineering, your knowledge is sound. :)

[EngineeringExplained]

Lifetime eh?? Sounds good to me! As long as you're out there I'll keep making videos.

[TilakRajVerma]

Thank you Mr. Professor. Such a great insight and so simply explained 👋👏

[EngineeringExplained]

That's a great question, and something I try to discuss with professionals when I get the chance. I believe it does mean this, but I'm not certain the effects it may have on stability at higher speeds. Also, it depends what your pivot point is. If I had a track at my disposal I would play around with weight locations to see the effects. Abandoned airports are a tad pricey these days.

[shananagans]

Great vid. Many people discount the importance of rotational inertia.They understand weight overall but they don't really understand how you are kind of doubly penalized by weight that also spins. One time I was buying lighter wheels & tires for my buggy (1, 200lbs) & I said "this should make a huge difference." The guy said "it's only 40lbs you won't notice it" I said it's 40 less lbs of unsprung weight & 40lbs less rotating weight. He didn't understand & looked at me like I was a crazy woman