Piston RING GAP - HOW and WHEN to adjust it + GAP CHART - BOOST SCHOOL #6
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- Опубликовано: 6 мар 2021
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As you know the piston rings play an absolutely key part in your engine they hold combustion pressures in the combustion chamber. In other words they ensure that combustion pushes the piston downward instead of going past the piston. But the very construction of a piston ring is a compromise. Because we can't use rubber bands for piston rings, all piston rings must have a slit or gap in them so that they can be installed and removed from pistons. Of course this gap shouldn't be too large, because then it will let combustion pressures escape through the gap and reduce powder and efficiency. But being too small is an even worse scenario when it comes to piston ring gaps.
Other than holding combustion pressure in, piston rings have another key task, and that's to transfer heat from the piston to the cylinder, and then the cylinder transfers heat away to the coolant passing around it. As you know metal, like most things, expands under heat. This means that piston rings also expand under heat. If the ring gap is too small the ring will expand within the limited space of the cylinder, and the rings will eventually run into each other. When this happens the ring will have nowhere left to go and as more heat is introduced the pressure exerted by the ring on the cylinder will increase. This means that more friction will occur between the ring and the cylinder and this will produce even more heat. Eventually the amount of heat will become too high for the ring to transfer it away to the cylinder and coolant. Eventually the piston too will start overheating and by doing so it will start loosing it's structural integrity. This combined to added resistance between the ring and piston means that catastrophic failure is just a matter of time. The most common scenario is broken ring lands and loss of compression together with possible cylinder damage. In any case the engine needs to come out for inspection and likely a rebuild.
So what this tell you? Well it tells you that more heat means more ring expansion. If we're rebuilding our engine in it's stock form without significant modifications we don't need to touch the ring gap. But if we modify our engine to introduce more heat into the combustion chamber we need to increase the ring gap to account for this added expansion. Increasing the compression ratio of your engine increases the heat in the combustion chamber because the air and fuel mixture are compressed to a greater extent. The more you compress a gas the closer it's molecules come to each other, the closer they are the more they will contact each other and thus generate friction and heat. We can also add additional heat by significantly increasing the redline of our engine and spending prolonged periods of time at that redline. More engine revolutions means more friction between the rings and the cylinder over the same period of time and thus more heat.
But by far the greatest addition of heat into the engine is adding turbocharging or supercharging to a previously naturally aspirated engine or significantly increasing the boost levels in an already turbocharged or supercharged engine. Forced induction stuffs far more air molecules into the same space compared to natural aspiration, which means that it significantly increases the number of molecules in that same space which means that it increases the heat during compression and combustion and thus increases the amount of heat to which the piston rings will be exposed. To account for this, adding forced induction or significantly increasing boost often calls for an adjustment of the piston ring gap.
In this video you will find a detailed piston ring gap chart or piston ring gap calculator if you will as well as detailed and simple instructions on how to use a readily available piston ring filing tool.
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Thank you , but, what and where are the "T" and "R" marks for the oil rings at the 10:42 ? Thank you.
I just wanted to say, as a mechanical engineering student who is rebuilding his first engine, your content has been extremely valuable. Thanks a lot man.
I have rebuilt engines, and work for an automotive manufacturer… never in my life have I ever talked about ring ga with anyone. This man speaks needed knowledge! I totally agree with you.
@@StudlyDyl Okay, so, what and where are the "T" and "R" marks for the oil rings at the 10:41 ??
If you want it done properly, you should have all three oil rings separated by a little on a non thrust surface side of the pistons, and the oil rings should never be filed. Unless a specific manufacturer says to. These look like they are at about (if looking at the top of the piston), seems like 10 o clock, 8:30, and 6:30. But it’s hard to tell with that terrible picture. I would assume
Love the detail with the compression ratio equation.
So many misconceptions killed, in such a compact and understandable way.
I build cars for a living and I still love watching and learning from your videos. I may not learn a ton from each video, but typically you mention at least one thing I didn't know before watching the video.
If you build engines for a living do you mind if I ask for help/advice?
@@carsoncoopa well, you can ask, but I can't guarantee I have the answer.
I have 25+ years of experience in automotive technology and racing. Your video is the best teaching aid I have ever seen, well done!
I just bought piston rings today, perfect timing!
Pun intended?
@@Jesus_Christ_loves_you_alot I don't think timing and piston rings are really related 👀
@@Minekeek Still engine related lol
@@Jesus_Christ_loves_you_alot I'll admit it I asked myself the same question as you 😂
I am not an engineer, just love learning about the engine. I had absolutely no idea how critical the ring gap is. Especially when boosted! Thank you for your work!
Love the boost school series! I currently drive a factory Boosted car that has been turned for double+ psi and with over 150K miles it's in need of a rebuild plus I think my head gasket is going out. Needless to say the information in this series will definitely help me out along the way.
Digging the intro
"What is up, ENGINE-HEADS?!"
Always a great channel to watch. Thanks for all of the hard work helping educate people.
The best series on RUclips
Literally never appreciated a channel more than this one. Love it.
100% Straight forward, well organized information.
0% bullshit! Please keep at it.
The smaller gap on the top ring is interesting. On big marine diesels they have grooves in the top ring to have a controlled pressure leakage so the load is more evenly spread between the two rings
Yeah, that's gas porting, which is supposed to prevent combustion pressure from leaking past the rings and diluting the oil. The absolute worst thing to do to an engine is pressurize the crankcase, especially on boost. Diesels are terrible on oil dilution since all the hydrocarbons get past the rings, so gas ported or gapless rings are a good idea for clean engine oil, which also prolongs the life of the turbos if they share the same oil.
You do a great job of explaining these engine concepts!
Thank you so much for this video! Because I decided to only mildly turbocharged my engine I left it stock but still I wondered about ring gapping should I ever decide to build it and go high boost. This video saves me tons of time on tedious research because I know I can trust your information. Thanks again D4A for another high quality video!
It is great that you surprise us with your beautiful and useful videos every time. In fact, I do not have the expressive words in which to thank you for this wonderful amount of information about engineering and mechanics. Thank you very much for all that you provide.
Fantastic content! Thank you for all the work and research you put into your videos!
Thank you very mutch it went from a boring sunday to a interesting day there is always something to learn.
you explain complicated concepts simply, your the best by far at what you do, well done !!!
Wake up kids... IT'S TIME FOR BOOST SCHOOL!!!
I see your tiktok comments everywhere now on RUclips too?
@@magicstew45 Been in the RUclips comments since years before TikTok existed. :D
These series of videos are really very good and well produced. Ive learnt so much !!
i cant wait for u to get to 1 million subs
I wish I could subscribe a million times.
I appreciate the insight into how careful one must be when filing and fitting. Great vid.
Thank you for create a detailed vídeo about ring gap, You are the only one that did it at this professional level!!!!! Great content on yout channel
I bought and used that exact ring file tool to file fit the rings in my Supercharged 5.8L(355ci) V8!
This is one of the best video intros i have seen in a long time ;_;
keep up the great content
Great video as always. I recently came across gapless rings, still researching them.
It’s nice to hear everything over again
I really want to do this all ways dreaming about this
thank you, I was thinking about piston rings gap for a while and now youtube throws me solution, thank you, very detailed video
I just mounted a grinder with a cutoff wheel on my bench and used that. I also gapped my rings slightly loose for NA and slightly tight for low-boost turbo application. From what I've heard we are still using very conservative values to determine ring gap when most modern engines are pretty happy to run much tighter.
One thing I felt could've been touched on, which you may have covered in a different video (correct me if you have done it in another video) is the role of each ring. Top ring is the fire control ring, this is designed to stop the flame front during the combustion process from getting between the piston and the cylinder walls. The middle ring is the compression ring, as the name suggests this is responsible for the majority of the actual compression process. The bottom ring stack is the oil control ring, these are only to control oil. and don't add anything to the compression/combustion process.
Traditionally, before boosted engines were so common, the compression (second) ring had a smaller gap because it was believed that the gap in that was the most critical to how the car runs. Nowadays, they have since discovered about the combustion pressures being trapped between the two, mostly due to forced induction aggravating a problem that manufacturers weren't aware of.
New intro? My boys moving up in the world
Awesome awesome video, explained in simple English so easy to understand from video and narrative, no plans to do this but always wonder how to do it. Now mechanic's cant bullshit me.
We always use an electric bench grinder with the smoothest stone we have. works great but opposite of the manual cranking grinder, you need to be extremely light and careful you don't remove too much, as it goes fast. I've done this on all my Honda Jseries Performance engines whether our builds (daily driver j35a7 400-600whp Nitrous Turbo builds) or customers 400-1000hp engine builds. HalferLand Performance
Interesting you say to push the rings in with a piston that has no rings. I used a piston with only the 2nd ring on it to make sure the ring was square in the bore because the 2nd ring will prevent the piston from further going down into the cylinder, and it will be perfectly even on all sides.
Love your videos!!!!
Your videos are awesome and very helpful thank you for sharing this knowledge
What a good video!!!!
i am building an engine and i just have the service manual and not too much idea of what im doing !!
Thank!!!!
This video helped explain why there are multiple rings on piston. thank you.
Muito obrigado, ótimas explicações, continue compartilhando seu conhecimento. Deus abençoe
Nice love that you can learn so much on youtube, haven't done an engine rebuild yet, but I want to, by buying some junker. I have done a top end rebuild after blowing my timing belt going 70 mph down the hwy.🤬
Thank you for sharing your expertise
You sir are The Lord of the Rings.
i had to make a ring squarer on the lathe because the top of my pistons had a step
best day ever ! ! !
Love the info! Thanks.
damn really cool video man, everything very well explained
Great video as always,
if I could suggest one, I think a really in depth analysis of the changes Mazda made with their 1.6, 1.8 and 1.8vvt found in the first 2 generations of Miata. would be highly appreciated.
in the Miata community there is a large misconception the differences are minimal, but they are certainly not, and it irritates me slightly when people dismiss the engineering that went into the later year engines.
Mazda also used these engines in a number of other platforms, including collaborations with ford and Kia.
I do like to add that the failures of a to tight piston ring can vary from piston/ring to piston/ring.
Some rings snap into pieces.
Some butt up together and one part will press inn to the piston and the other will press out to the cylinder wall and you will have a deep score inside the cylinder which usually end up with a trashed block that no longer can be rebored and require sleeves.
Sometimes if the fitment it just right it will just cause a insane amount of heat and eventually faliure.
and the best case scenario when the fitment is loose then the ring can jump on top of itself.
Okay wow this video was very educational thank you
Great information thank you so much
a good example to show compression adding heat is those compression fire pistons used in survival packs to start a fire just by smacking a piston in a tube with something flamable like cloth inside the tube.they have glass ones great for showing compression creating heat
Tolerance philosophy I was taught was to shoot for the middle of the spec. The smaller the difference in the spec the more critical it is. IE spec= .017-.026 shoot for .0215.
Thank you !! very informative !
Muito boa essas tabela.
Very informative sir
Super informative.
感恩了解，謝謝分享！
Perfect
Good job
🇧🇷
You're doing a great job.
May I ask you if you think that a turbo chared engine or rings would have higher heat under sustained loads like a boat?
i think another key is to install piston ring gaps in opposite directions to increase distance of gas escape route at lower temps. make them longer by the time the gas tries to escape so when the piston is receiving pressure from the gas till the bottom dead end the gas is still trying its way put of the piston rings. helps pistons achieve working temp earlier and keeps dirts out longer too, no?
Good ol thermodynamics causing heat expansion... Not only is ring gap important but so is quench area (steel vs aluminum rods), piston to wall clearance, and piston to valve clearance
You explain very calm and nicely good mech guy I wish you could help me boost my nissan L28
Which way do you turn the handle on the tool? Do you make the disk go upwards or downwards? It makes more sense to me to turn downwards so you're not holding the ring down while the disk is rotating upwards like in the video. Which side of the piston ring faces up while on the tool?
Thank you sir for the informations
What about gas ported rings? Gapless rings? Different ring materials? If you're going to turbocharge, then it's a good idea to replace not just the rings for performance ones, but the pistons themselves as well. Having the pistons matched to the cylinders guarantees a good fit, while also boring the cylinder out square to fit it.
You should make an explanation to how to clock rings on the piston ;)
Good info
I enjoy your voice. Reminds me of the dude from Django.
a couple things i wish you would have covered here is the orientation the 1st and 2nd rings
1st ring gap at 12 o clock and the 2nd ring gap at 6 o clock so you less compression losses
and are some rings direction specific, like can they go in any way or is upside down a thing or no?
if im not mistaken the oil scraper ring for example, part of its job is to help clean the oil off the cylinder walls so you face less oil consumption
im not an expert by any means and these are just a couple things ive heard/read somewhere before and wasnt 100% sure if it was accurate or not
please correct me if im wrong
Bravo majstore
Order them ten thousand over
Four thousands per inch of bore.
Oil rings are directional, butt the ends and see where they point , that will be facing to the top, and don't forget smooth out the ends or they will score the cylinders.Your videos are great, always find something useful.
that why overbore stroke and bore ratio need wide ring gap to prevent engine failure. But if block and from aluminium with ceramic liner is not too problem because aluminium can be expanding more if piston ring made from ductile iron.
u can turn the handle faster on the ring filer, his point was the heat will mess with the rings temper, but as long as u keep the ring cool itll b fine it would go real fast in running water
Any idea what the top ring gap should be on a 2" bore, air cooled engine, spinning upward of around 9000 revs! With higher than stock compression, and a ported head, I also added a performance cam, it may spend most it's time above 7000 rpm, and possibly as much as 9500, unless it's ideling it's probably not going to see below 5000, and being air-cooled, I'm thinking it can get a bit on the hot side, I went with . 008" and . 009" about . 002-.003" more than stock, if you can call a 50mm bug bore kit made in China, or some place in Asia, if I skrooed up, I can replace the whole Piston and jug for about $35 and about 30 minutes,. But it does. Have a good amount of compression! I'm concerned with the old starter even starting the thing! But I'll know tomorrow, I didn't want to anoy the neighborhood by firing the thing open header, I'm not accustomed to such a small engine!
When I was 18-19 years old I have rebuilt my father's VW Sharan's VR6. Piston ring gap? RAZOR BALDE! He scrapped the car half year later :-D . The cause were valve lifters that were starting to seize...
Would adding a higher lift camshaft warrant a ring gap change? Probably a dumb question but I want to know for my rebuild, boring the engine .030" over and porting/polishing the heads as well if that makes any difference for a Ford 4.0 OHV v6 engine
always check the engine manufacturer's specifications if possible, but these are good guidelines
U are the best👌
What if we machine the grove in the piston large enough to except both compression rings & in that way eliminate the end gap by having both rings in the same grove?
Hey man I love your videos a lot, I've been subbed for some time now and because of your videos I've felt confident enough to buy my first motor for a rebuild (b18b). I just got the engine and even though I felt confident before I'm getting cold feet because I don't even really know what to do, my question is what should I do. I know what I want to build (maxpeeding turbo hoping for 250-300hp) but I don't know what I should do to make it happen. I want to build it right but at the same time I don't want to gap rings and tear apart my entire engine because I'm scared I'm not ready for that yet. If anyone out there has any suggestions please I'd love to hear them it's a 300k kms junkyard Honda b18 from a 01 integra and I have very little knowledge about engine rebuilding. Should I leave the head on and just turbo? Should I inspect connecting rods? I don't know and I'm searching for help. Thank you to anyone in advance.
Merci beaucoup ♥️
So here's a question, I'm building an Audi 1.8 with a gtx3071r turbo and I have a compression lowering head gasket which .05 taller so if I run the oem ring gap will I see any issues? It'll be seeing about 20lbs of boost
rings are there to transfer heat away from the piston to the cylinder?????? thats a first time ive heard that. thought they were for compression and to prevent oil from getting into the combustion chamber ( along with the oil rings ) i know the rings themselves produce a damn lot of heat just threw friction with the cylinder walls. i tought the heat got transferred directly from the burning fuel into the cylinder walls. and oil squirters under the piston also used oil to cool the piston from underneath
Dje se moze raditi honovanje bloka i ima li potrebe provjeravati prstenove koji su namijenjeni za motor kojem se radi generalno, nema nikakvih izmjena ?
Odlican video inace 👌
the rings have a second gap aswell. it is the ring groove gap. cause if that gap is too small then you could have ring expand so much that it gets stuck on piston thus not sealing properly anymore
New piston rings for the rotary engine! 😏 Just legends are gonna understand !✌🏼 Great video! 💯🔥
Can we please have a video talking about engine idling?
One many millions of people would have the time ,knowledge and money to do this in their own .
what is your opinion on gapless piston rings ?
Great information here +++++
How good are the gap here for turbo psi if its a daily driven ?
Thanks
I have situations were the oil spacer on the third ring is too long and buts together before fitting snugly in the groove. This requires cutting 1 or 2 segments off the spacer so that the 2 rails can be correctly fitted
Awesome!
Please make a video about pushing rods gap adjsutment 👩🏭
The first 2 minutes sound very familiar in the Subaru EJ257 engine family 👀
I like to put the old oil scraper rings on my Pistons to make them square in the bore when I set ring Gap