Compression Ratio Explained - Roadkill Extra

This installment of the Roadkill Extra engine-building series gets a bit theoretical: What is compression ratio, how does it affect engine performance, and how can it be altered? But it’s also very practical, as David Freiburger explains every detail you need to understand in order to use a compression-ratio calculator. Tune in and tune up!

[motorolaphone]

It is outstanding how today you can learn more effectively from 14 minute video on YouTube than from many classes on an 4 year engineer at University. Freiburger communication skills are flawless. If only half the professors had the natural talent he was gifted.

[moparedtn]

Ladies and gents, I give you David "One Take" Freiburger.
Damn impressive performance right there, sir.

[mac]

This guy teaches from the heart.very enriching lecture

[inkontrolmtb]

Learnt more about c/r in 13 minutes than i have in my whole life... keep up the how too's, love em 💪

[WilliamITA]

In 13 minutes you've been able to explain this subject much much better than my professor did in 1, 5 hours of lesson at the university (I'm studying mechanical engineering)! Totally in love with this kind of videos! \m/

[robertwest]

I've been a big fan of David Freiburger since his articles in Car Craft. I was subscribed from 1987 until 2009. It got to where they had done everything there was to be done and just rehashing the same old stuff.

[loweredlifestyle]

im impressed on how good of a teacher he is very easy to follow

[ericw]

You are my hero! We love you here in the DRC! Thank you so much for the many years of knowledge you have given us!

[benjaminbohan]

Freiburger just explained compression ratios far better than my engineering instructors... I'd be down to get some more educationally focused videos from him! He knows his stuff and, more importantly, knows how to explain it.

[the_gilligan]

Rip headphone users who turned up the volume in the beginning..

[jasonwynn]

That was fantastic. Straight to the point, easy to understand. Cheers from Queensland Australia. 👌

[drewbarker]

One of the best explanations of static compression ratio I’ve ever heard.

[daddynichol]

Great explanation. I'm sending this to my grandson since he's a budding gearhead.

[wirenutt]

What a great explanation on compression ratio calculations. Kudos to the writer(s) for doing such a fantastic job in 13 minutes. And kudos to Freiburger for spitting it out so clearly and quickly. People don't realize how difficult it is to convey so much information is such a short time and be thorough and accurate. I knew how much info needed to be communicated and I was thinking, "There's no way he can do it justice in 13 minutes and change." I stand corrected.

[hanablemoore]

I love this dude. I wish my shop teacher was this good.

[NathanJones-lzgh]

David is the best automotive teacher I’ve ever heard.

[ben]

Extremely thorough and accurate explanation! Thanks!

[drnoodle]

After all the year at school i did, Roadkill are the best professor i had yet :D

[harmanklop]

please do more of these engine explain videos on youtube

[SealofPerfection]

Good explanation. The visuals will really help those folks who don't understand this topic fully. Reminded me a bit of how I learned it in school xx years ago.
A suggestion for a follow-up: So you have your pic with the volume of the cylinder and the gas molecules, right?
What else is in there? Heat. What else happens when you compress it? Friction...that's why you need higher octane so it won't "diesel" and fire on its own. Tighter you compress it, the more heat it creates from friction and if it gets too hot, that heat will ignite the mixture before you want it to. Plus, why cooler, more dense air makes more power. All of it goes hand-in-hand.

I bet you could do another complete video with all the rabbit holes that would lead to.