Octane Ratings Explained – EricTheCarGuy

50 thoughts on “Octane Ratings Explained – EricTheCarGuy”

1. Who’s here from YourProudDad on tiktok!

2. “There is no succ”

3. If you haven't done it already you got to put that on a t-shirt. There is no suck.

4. Brilliant m8.

5. So only use higher octane with higher compression motors, right?

6. What about in 2 stroke engines, i put avgas 100LL in my 50CC 🤣 trust me i'm flying

7. in a turbo application you get richer as rpm and boost go up which lowers egt but that load and heat increase your egt so my question is… should your egt be the same temp throughout the whole driving range regaurdles of your AFR? or should your egt always change according to your AFR reguardles of rpm and boost?

8. too high octain with a rich mix will cause a miss ignition and cool down your plugs as its doing it which will cause a continuum of miss ignition untill you let off the throttle id predict..what i need is to read my egt

9. Eric whats up pal… question…… a miss fire sounds like a sputter and has a great power drop and cause a rich condition vs a knock or pre ignition will make a tiny ping sound and is harder to detect.. am i accurate on that? Im looking for answers to determine if Im blowing out my spark bcs i need a smaller gap and why I need a smaller gap, if Im pre ignighting and why, and if I need more fuel at higher rpm or just when boost builds depending on load vs rpm. I usually pull out my plugs and give them a good cleaning and it gives me the best results when my motor gets like this and brand new plugs completely fixes all that. I get new plugs once a year on this fully built 18psi turbo motor and have to clean them twice a year but Ive done the best i can do for the tune and its the best its ever run but Im trying to further educate myself.. what do you know or anyone watching knows?

10. Very well explained! Also great animations and like the matched pictures along the clip, like old gas station. Thx!

11. Get rid of that pcv to your intake as well. That will hurt the fuel ratio.

12. If the compression ratio is the difference between fully open and TDC … how do you adjust the ratio…? Isn't it a function of the fuel injected and the RELATIVE compression… irrespective of it's theoretical volume..?

    Air is NEVER combustable, whether you're at sea level or even in the deepest valley on the planet…. FUEL is, right..?

    At high altitude, the atmospheric pressure is lower than 14.7 PSI … and thus, you have a smaller difference between the VACUUM that opening your cylinder creates … and the maximum pressure of the environment — whether you have a Turbo or not. A turbo is even MORE hampered at high altitude unless there are changes to its profile.

    Lastly, Octane has NOTHING TO DO with the four phases of an engine. Only one of them; compression (if Eric feels it exists) … and, the one thing (importantly) that he got correct; that octane is a measure of a volatile fluid's resistance to spontaneously igniting without a spark.

13. Words are sounds we make to convey ideas, right..? At sea level our atmosphere is at 14.7 PSI, no..? When there's a PRESSURE DIFFERENTIAL of LESS than atmospheric pressure … if not VACUUM … what do YOU want to call it..??? Is "compression" fake too..?

14. So basically in a high compression engine if you run low octane fuel it may diesel itself but way too early

15. The intro music made me subscribe

16. Couple quick things,
    At several thousand rpm, 1 ATM of pressure is not enough to fill the combustion chamber, so the piston does create a vaccum.
    Octane does not dictate the compression ratio. The stroke does.

17. Hi eric, is a higher octane fuel good on an older car with new spark plugs, to make the timing of each cylinder a bit more accurate?

18. Amazing video, really love it. But if gasoline engines need a spark plug to ignite the mixture anyways, doesn't that make the octane rating irrelevant, because the mixture is only going to get ignited if we use the spark plug. I understand why this would be a problem in diesel engines, but I don't see how it could affect gasoline engines?

    I know it might be a stupid question, but I just cannot get my head around it.

    Great video btw!

19. Amazing video, really love it. But if gasoline engines need a spark plug to ignite the mixture anyways, doesn't that make the octane rating irrelevant, because the mixture is only going to get ignited if we use the spark plug. I understand why this would be a problem in diesel engines, but I don't see how it could affect gasoline engines?

    I know it might be a stupid question, but I just cannot get my head around it.

    Great video btw!

20. Excellent illustration. I now have a better understanding of octane ,it's purpose and effects. Great video keep up the good work.

21. Can i run a bigger spark plug gap with higher octane fuel and msd ignition? 9:1 comp

22. Nice video now i understand

23. so lame dude

24. As a car guy that already knows all this-
    That was a great video with killer graphics! Great job

25. I sniff differend gas types to obtain perfect octane level.

26. When he say there is no suction I exist out the video Common Cent when the engine running he put a napkin on the air filter he'll get sucked if the engine off can you put the napkin the napkin will not get sucked that till you right there the engine suck air while is running

27. Excellent video, your animation coupled with explanations are very good.

28. I am already sleepy…

29. Great casual style….. I vary the Octane with an upper cylinder lubricant since I've gone from lead fuel to unleaded and taking notice of any pinging in the past, I've learned just the right mix I feel…. The engine is a 'Million Miles +' (yes) old and runs even better now than 40yrs ago. Anyone still using lead fuel, my personal opinion is to ditch it and use unleaded with the added lubricant. Works for me anyway.

30. Intake : Suck
    Compression : Squeeze
    Power : Bang
    Exhaust : Blow
    Pretty much sums it up!!

31. Thanks!
    octane rating = resistance to burn.
    You the first I've heard to make it simple and clear (and I've been through many videos in the last hour).

32. If no suck, where does the vacuum come from? Thanks

33. In my country we only have 95 octane and 98 octane

34. These videos are older as you can see but you are packing some knowledge even then . Thank you and take care.

35. These videos are older as you can see but you are packing some knowledge even then . Thank you and take care.

36. Nice and clean and simple and clear. Thank you.

37. Yes correct. High octane fuel in a car that doesn't need it will just send unburned fuel out the exhuast, thus WASTING $$$ and robbing your engine of power.

38. the most informative video I've seen explaining octane/engine functioning – thnx' for upload – Philippines

39. The SUCC is strong within you

40. Oh man I stumbled upon a really old video love the pantera intro

41. What's the theoretical octane if my car runs the maximum ignition advance setting without any knock?

42. Woah indonesian octane ratong is the highest at 98, the name is pertamax turbo

43. I was wondering what Nux meant by "High Octane" in Mad Max Fury Road.

44. Obama was the first gay president.

45. Premium gas? Total hype. Hi octane gas is primarily used in hi compression, performance engines usually around 10 to 1 compression ratio to avoid pre-ignition, more commonly known as knocking. Probably 90% of today's cars can use regular gas.

46. When you hear Gnr in the background and start nutting

47. love your videos. cant believe this is from 2009. just browsing through my brake time lol..anyways its true about higher compression equals more hp. but its also more likely to blow up because of thermal heat. my dad and i built a 95 eclipse gsx 4g63t and instead of putting oe spec head gasket. we tried a thicker head gasket. lowering cp to 7 to 1. i know thats really low. but i also have big turbo. ball bearing. it made 440 to the wheels on 30lbs. low boost setting) now i can squeeze in say 60+ psi but im okay with it for now….what ive noticed is. between low and high compression engine. the high compression is more responsive but boost is more limited. lower compression paired with a good turbo (more boossstt you can throw at it), yes theres a little bit of lag but the top end makes up for it.. my buddies honda high compression started to leak while ive been beating on mine every chance i get 🙂 its so cool you mentioned thermal heat to the head cylinder. not a lot of people know of it, they just want horse power lol

48. excellent video!

49. Great video!

50. awesome

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