HOW and WHY to EQUALIZE combustion chamber volumes CC - Project Underdog #10
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- Опубликовано: 30 июл 2024
- 00:00 How chamber volume affects the compression ratio
04:32 How to equalize chamber volumes
10:00 Benefits of polishing
What is up engine heads, today I'll show you how and why to equalize the volume of your combustion chambers. As you may know your engine's compression ratio is the relationship between the largest and smallest volume of your cylinder. The largest volume is achieved when your piston is at bottom dead center while the smallest volume is achieved when the piston is at top dead center.
This obviously means that your smallest volume practically equals the volume of your combustion chamber, which means that your compression ratio is strongly influenced by your combustion chamber volume.
When it comes to my build I have actually significantly modified my combustion chambers. My cylinder head is a 4AFE Toyota economy cylinder head which I'm planning to turbocharge. The valves were heavily shrouded so I had to remove a lot of material to enable better airflow. This meant that I increased the volume of my chambers significantly. Of course I was doing all of this modification by hand which dramatically increased the chances of the chambers having large volume inequalities. .
The first step is obviously to finalize the shape of your combustion chambers. The next step is getting a piece of thin transparent Plexiglas that is longer and wider than your cylinder head. Next we're going to install a set of dummy spark plugs and then we're going to overlay the Plexiglas over our chambers and mark the position right above the spark plug.
Now we're going to drill out the four holes that we marked. Now we're going to install all of our valves. We're going to smear the sealing surface on the back of each valve with vaseline or petroleum jelly. We're doing this because we need the valves to actually seal and not let water past them because we'll be later using water to measure the chamber volume.
Next we will need two syringes. A large and a small one. The large one must be larger than the volume of your combustion chamber. The small syringe must be able to measure 0.1 or one tenth of a millilitre.
Now we're going to smear a thin layer of vaseline around the outside of the combustion chamber. A little bit goes a long way. Wipe away any excess as there must not be any vaseline inside the chamber.
We'll first fill the chambers completely to see approximately how much volume they have. We will do this using only the large syringe as accuracy isn't paramount during this initial volume estimate.
Once we have done the initial estimate we will remove the plexiglass and restart the process. Because each chamber is around 35cc I will fill each chamber with exactly 34cc of water. This time around accuracy becomes paramount and your measurement will only be as good as your accuracy with the large syringe. Getting the exact amount of water into the syringe consistently requires a bit of patience but if you do it properly this process will have a pretty decent degree of accuracy.
Once you have the correct amount of water inside the syringe inject all of it evenly and carefully into the chamber. Now we're going to use the small syringe to fill the remaining volume of the chamber. As you can see here my last two chambers are the same but the first and second are not. This means that I must remove a bit more material from the first and second chamber to equalize them to my last two chambers. We will lift the plexiglass and evacuate the water from the chambers and get our air die grinder again.
Once all the chambers are equal you can finish things off by polishing the chambers. Obviously polishing removes an absolutely minimal amount of material that doesn't really affect the volume. Doing this before equalizing the volumes doesn't work because you'll ruin the polish each time you grind away material.
The logic behind the polishing is that it minimizes the chances of a hotspots but it also makes it harder for carbon to build up on the chamber surface. Less carbon buildup is always good because it ensures consistent performance and compression ratio and it also reduces the chances of a piece of carbon buildup falling off and acting as a hot spot for pre-ignition.
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There's a mistake in the compression ratio calculations when the volume increases by 5cc at 00:54. The total volume increases by 5 too so it becomes 505/55 and not 500/55 which means the result is 9.18 and not 9.01. The example obviously still works and the logic is the same but the number isn't correct. Thank you to @sagi fern for pointing this out.
No Bro... you were right. Sorry, and @sagi (sorry sagi) was wrong: the displacement of a cylinder is NOT the total volume of the cylinder/chamber system.
The displacement of an engine is the result of the volume determined by (bore x stroke). The displacement change only if you modify the cylinder bore or increasing the stroke by changing of crankshat.👍
@@chupachups6098 Total volume = (bore x stroke) + comb. chamber vol.
So if combustion chamber volume increases, total volume increases equally
... thickness of the head gasket my dude, adds to chamber volume as well as total volume.
Good save. When all else fails, check the math several times...
Proper Head Prep is really important. Not just in short term, but long term also. Some people think it's a waste of time, but there are lots of reasons to do it right from the start. Ever have to yank the heads off to correct a problem that should have been done before bolting everything together... oops.
Always amazes me that some people don't have the time to do these steps first, but have the time later to remove heads and do it anyway.
I always found this debate interesting. I think it's useful to think in terms of swept volume and to keep in mind that static and dynamic compression ratios vary throughout the rpm range and are different and same based on the volumetric efficiency of your combo at any given rpm. Great vid as usual.
bro this is hands down THE best car channel on youtube
Facts!!!!
d4a is a more entertaining and not slow version of james may
Bump!
agreed. and I'm not even into cars!
trueeeee
Re: the large syringe at 34 cc initial fill. There are cheap digital scales easily available that can measure mass down to 0.01g (or even 0.001g). So it would be easy to use a scale to ensure that the 34 cc syringe initial fill is consistently identical across the four chambers. The point here is consistency, not anything directly related to accuracy (except the improved consistency). Cheers.
A slight improvement on his approach, but not quite perfect.
Follow all the steps up to filling the chambers with water. At that point, fill the large syringe with REFRIGERATED DISTILLED water and weigh it with a gram scale. Fill one chamber with water and then weigh the syringe again. The weight difference in grams is equal to the volume of the chamber in cubic centimeters. (well...technically 1cc of distilled water weighs 0.9982g, but that difference is too tiny to matter.) Refill the syringe, re-weigh it on the gram scale, fill the next chamber, and calculate the weight difference again. Repeat for all chambers.
smal digital cheap scales are wery dificult to use acuratly and consistently.
@@drajo123
No, they aren't.
Where exactly do you have problems?
Maybe I can help you out.
I routinely make perfectly repeatable measurements down to +/- 5mg, +/- 2mg if I take the time, that's the limit of the scale I'm using.
And as stated, they're repeatable even after weeks.
Having things more than accurate enough for measuring out your combustion chambers to 0.1cc in a rather short timeframe shouldn't be a problem at all.
I'm too lazy to calculate it rn, but I think even rather substantial temperature swings won't cause enough difference in density to actually matter much.
@@drajo123 bruh if i can use a mg scale drugged out of my mind to measure mg scale stuff then idk what to say about ur scales but maybe get better ones
@@deusexaethera . It is my recollection , that the Metric Weights and Volumes are thus .
One Cubic Centimetre of pure water , at 4 degrees C , the highest density point , is the DEFINITION of One Gram . 1.00000g
Ergo , One Litre = One Kilogram and 1000 Litres = One Metric Tonne . The Scale definitions based off the Standard Metre .
Always fun to discover a golden nugget like this channel. Your ingenuity and patience are truly impressive. Your explanations, clear and concise. Thank you.
The thing I love the most about this channel is the topics it covers.
You just don't think these as something you would do to your car, but after the video it's like a "totally obvious" thing to do.
Plus, it goes beyond the typical bolt-on turbo, catalog cams and such.
One of the best channels about cars, if not the best.
I enjoy your videos a lot. Over the past year or so you have enlightened me about a lot of things involving engines and the engineering behind them. At my age I am past doing this myself but when I was younger I would have killed for these types of videos. And we, your viewers, really appreciate all the time it takes to record these wonderful videos, so please keep up the good work and again thank you!
Be safe and stay well.
You definitely covered the basics nicely. Not too many people even think about cylinder heads other than how much they can flow. The one suggestion I have is that you can use the Vaseline after the valves are in and fill the largest volume combustion chamber with body filler ( or something else like it ) then you will have a template for the other chambers. I usually use differential gear marking paste on the template to see what needs work and where.
I'll never do this because I have no patience but your determination and passion shines through so this was good to watch and I hope you achieve your car dreams.
If you have enough money, you can pay someone to do this stuff. Some shops can even use a CNC machine for the best accuracy possible.
I purchased an '88 MR2 a few weeks ago that sat for a few years with a broken timing belt. Brought it back to life, now starting to work through the kinks that it has due to its age. Your videos are a godsend, and an inspiration for what I hope to do with mine in the future. Thanks!
Happy D4A Sunday to all! The best educational automotive channel on the interwebs! Very impressive work on your cylinder head. I can't wait for the test drive video of your MR2!!
Amazing DIY video, thank you for taking the time for making this tutorial. I had no idea that such small changes in cylinder head volume made such a great difference in compression ratio. Please continue with this series on your engine build :))
I know these videos don't always get as many views and such but, I'm so glad you make them. They are some of my favorite videos on your channel.
I've never heard about equalizing combustion chamber volumes! I just assumed they were precision made and would already be equalized. Good to know it's something worth checking on second hand engines you are building. TY!
All cast pieces; blocks, heads, intake manifolds, etc. are mass produced using sand molds. There is lots of variation between parts. You probably can custom order heads and blocks already prepped to your specifications. If not, some good old fashion elbow grease, knowledge gained from reputable web sites, and time can result in higher performance, better fuel economy, and a feeling of satisfaction.
In a stock engine it's close enough, but a modified engine is by definition not a stock engine. The modifications are what cause the problems in the first place, so more modifications are needed to fix the problems.
@@SJR_Media_Group does small varyations i chaimber shape not matter, as long as volyme is the same?
@@DaftFader it's almost impossible to get exact shapes of the combustion chambers , but today with special CNC (Computer numerical control), they can get really close. Old timers spent hours, even days to match combustion chambers, intake and exhaust ports. I would have taken mine to a speed shop and let them do it.
@@DaftFader
The approach (working assumption) is basically: those small variations in combustion chamber shape is too small and can be ignored.
Think in terms of “signal over noise”.
Whatever variations, if the “signal difference” between those variations is smaller than the “environmental noise”, then those tiny variations don’t matter.
Your videos are the most informative videos on automotive engineering I have seen. Congratulations and keep them coming.
really cool build. doing alot of stuff i have never heard of before. and doing it yourself to show how low budgets can be optimized. and this build verifies all your technical teaching videos, as in, proof you know what your talking about. have been a viewer maybe since the beginning, so keep up the good content. good luck with your build. from MD, USA
Wow just wow !!! You need time, patience, knowledge, patience and more patience to do something like this. This hands down is one of the best if not the best car performance channel in RUclips.
What a great video. You are one of the most informative car guys on you tube. I love your DIY approach.
Wow! So much dedication and hard work! Kudos! It shine's beautiful and must perform better now!
@ driving 4 answers . Love that you are doing it yourself & show good improvisation, thank you for sharing with us all. I always enjoy & look forward to all your uploads. I always learn something.
I know you wont see the polished surface once you assemble the engine but it sure looks nice! Seeing you grinding while the head is just wobbling around on the table without some kind of expensive equipment gives me encouragement to try doing more work on my vehicles with what meagre tools I have at home.
👌👍👌That's the absolutly best I've seen in 40 years about explanations how to make motors. I am car mechanic, have 60 years and made several engines. Your channel is very to recomand. 👌👍👌🙋🏼🐺i
Good stuff. I love your vocal delivery and emphasis on certain key words! Well done. I wish to channel and osmose your motor nerdness into my brain. 👍👍👍
Awesome video. It is extremely well explained as always. You should have at least 1M subscribers. Thank you for the video.
My 1st car is using the 4AFE engine. Super reliable and durable!!!
Beautiful end result, awesome walkthrough 🙏
Turned out waaaaaayyyy better than my attempt years ago. Guess my patience is much more limited. Good on you.
Amazing video as always but i would like to point out a couple things were missing
1- for diyers you could easily buy a burette sold on chemical supply stores for a fraction of professional kits
2- if you plan on getting your head decked do this before trying to equalize you combustion chamber volumes
3- generally is better to use a single piece of thicker glass with a hole could be bought cheaply at a glass store and make it a little more accurate
Great explanation!! So excited to see this project moving forward!!
My brother rebuilt a performance 202 holden for my Torana. He did similar things to this but high compression! Interesting video. I never knew the process. But it was very quick as he had it up to get Xu1 specs. Cheers
Nice work! You can also get 1cc medical syringes (usually used for insulin injections) to get that final fine tuning if you want. Thanks for breaking it down for us!
I absolutely love your content, dude. It's inKREdibly informative and educational.
Before saying this, I just thought to myself "Why haven't you liked and subscribed yet, then?"
so now I absolutely love your content and am a subscribed subscriber who liked the video 😁👍🏾👍🏾👍🏾👍🏾
Nice video! It's cool to see how sometimes we need to alter our approach in order to get the results we want, such as moving the holes for filling the chambers to a spot where it's easier to get air out of. A couple of things I'd like to mention as a former basic chemistry student: significant digits and margin of accuracy/error. The short version of both is that not every measuring device is truly accurate, and not every measurement can be correct to the smallest digit available by the measuring devices. That said, the measurements you were doing should be good enough for enthusiast work because you are chasing a power level easily obtainable by your overall setup and not making a 1K HP drag machine.
One of the best vids I've seen. Never thought about doing this myself. No I want to try this.
the head gasket thickness and evenness as well can contribute to compression ratio discrepancies. Cool video - enjoyed it.
7 hours of measurements and cutting now that's a super weekend
When I did a similar job without chamber volume correction on a small block chevy I was really surprised by how much good it did the engine. Even by eye it was possible in this case to make a smoother running engine. I don't know if it was the work on the gas passages or the cylinder head itself but the engine was significantly improved. This exercise was also very good for two-stroke engines, the passages between the crankcase and the combustion chamber were messy and of unequal volume, once more just cleaning up the mess made for a much more enjoyable ride.
Of course you have the same bore and stroke in each cylinder...
Back when my cousin was working his way through an automotive tech school he bought as a project a 1962 car from my father. It had a straight six chevy 261 (like the truck motor, but canadian so it had hydraulic lifters) which ran, but was burning oil almost as fast as it streamed out past the rear main seal. Being a student with limited means, he ended up rebuilding that straight six with new rings for all six cylinders, three original pistons, but one cylinder needed bored 0.040 over and two were okay with 0.020 over and those three needed new pistons.
Obviously not built for performance, but it ran great with the expected straight-six smoothness. That car became a daily driver for a few years plus we put thousands of miles with multiple 1000+ mile road trips driving at high speeds while burning multiple tanks of fuel to reach our destination. We'd leave after school on Friday needing to be back on Monday or Tuesday at the latest.
Amazing bit of information great work 👏 👍 and very informative keep it coming 👍
Nice to see it progressing.
I remember when I had to do this for my Malaguti Fifty TOP equipped with a 75cc aftermarket Morini cylinder... I was 15 and I not only had to check the compression ratio, but also the squish area which is paramount in a 2T high performance engine. For that I was pouring candle melted wax into the spark plug hole with the engine mounted and piston at TDC, then remove everything again to check the squish area was effective and finally re-melt the wax into a siringe in order to get its amount and get the volume of the combustion chamber. Such a tedious job, considering that every time the squish wasn't what I expected I also had to re-do all after having lowered the cylinder base gasket (if not put it in the machine to cut away few 1/10s of mm to get it right)...
I don't even change my own oil, yet I watch these videos.
This will be like the most sophisticated home made build on the planet. Everything is so accurate and beautifully done. Can't wait for the end result
You should see some of the stuff people do on the DIY.. I'm a joke compared to some of that.
@@d4a dude you're like an A grade full on engineer. Most diy RUclipsrs that build cars don't have nearly as much knowledge as you do. Every video i learn something new. Amazing stuff
This is what I’ve been struggling with! Thank you!
Awesome video as always! I'm always surprised I don't see a lot of people do this with their builds. I guess they assume whoever refreshes their heads does it, but I'm betting that's a faulty assumption. Others probably don't know they should do it. I supposed in a completely unmodified head other than being resurfaced you shouldn't need to, but still, I'd wanna know. I like the syringe idea over the burette! Feels like it would give more control. My excitement over this engine keeps building!
The syringe method is pretty good. I've used it when cc'ing ACVW heads.
Thank you soo much for this, I've been meaning to purchase the CC kit but shipping cost a fortune, I'm surely gonna try this syringe method for my motobikes
P. S
Superb video, salute
You make the best videos! Great work👍
My only comment is i respect your detailing, toward blueprinting, which is what you need to be the winner at the end, nothing you do is wasted, Thank you.
Great video, reminds me of when i did the same when i was 13 on a lawnmower engine, if anyone is considering this its a great place to start with an engine build, cause your guarunteed to make mistakes and its cheaper if you do it on a lawnmower
Love this channel! Hey btw if you decide to port and polish. Leave the intake sides semi rough like 400 grit and smoother on the exhaust ports like 800-1200 grit. Then polishing slightly but not like your combustion chambers are. Sure CNC porting is best. But unless your building a completion engine? There is no need. 👍😊
I'm building a bmw m20b25 stroker engine, your videos have been a great benefit to me, thank you
e30?
@@wackydriver yep
Great explanation of port and polish!
Nice video as always, cheers from Chile mate!!
I couldnt wait to the end of the vid to tell you mate you’re absolute genius. This is the shit little kids dreams are made of! I had no idea of this just wow!
Wow! That's a lot of work but very rewarding. I guess you really want to look after that engine now so you don't destroy the head and have to do all that again!
this was actually really informative and useful video. thank you!
This is proper craftsmanship.
Great video. Thanks for showing us this.
just want to applaud your dedication, one day I'll do this!
Great video, keep it up, let your videos guide the younger generation
I lowkey want this channel to stay underrated so no one else gets smart and i can continue to grow my knowledge, lol but fr tho this guy deserves an award
A digital postal weight scale can help a lot with measuring the combustion chamber volume. If you weighed your water container first, then fill the CC to the brim, then weigh the water you have left, the difference is weight of the water in the CC ( assuming you didn't drip or spill ). Then convert that weight to volume ( adjusting for temperature, too if you want SUPER accurate ) .
Awesome video. It was very informative.
Love your approach!! Double the work for a V8!! Now I HAVE to do it!!
I hope you had a good vacation with your family! Glad you are back! Thank you for the great DIY tip to save money and be accurate. I want to take my engine apart simply to improve airflow! I also want to increase the compression ratio. Any good tips to do so on a naturally aspirated engine?
thats cool and awesome, give you alot of credit in taking the time and patience to do each cylinder. what do performance shops do to ensure piston dome masss are equals well? as that could throw off your ratio also. my guess is building a tesybe and placing each piston into it to a specified depth and monitor the increase of water levels or displacement
Now that I know this kinda stuff exists I wanna do it myself. I could even do the measuring very precise at work!
Good one, I admire your patience :)
great video! Can't wait for more videos as this engine comes together.
what a perfectionist! impressive channel! just wanted to say that watching your videos is a lot of fun. maybe weighting the syringes with a precise scale can be better than eyeballing IDK
Very satisfying, thanks!
I really like your videos... so thorough... However, in this one, why did you not deck/clean the head surface first?? So you had a truly flat surface for the plexiglass to sit on when taking the measurements.
Yes, that would be the typical approach, but when you're grinding the bit can sometimes skip and you can accidentally gouge the deck. The old gasket material remains are incredibly thin but are a great layer of protection and I feel more comfortable with them because I'm a bit clumsy sometimes. Petroleum jelly will seal even against dirt and debris and the difference in chamber volume after decking will likely be minimal.
@@d4a sorry need to disagree with this , yes i wouldn't deck the head but you really do need to scrap all the gasket material off. you can see a big clump of gasket which could be 1mm which would make a difference. also we use a thicker bit of perspex so to not have any sag. P.s, great videos
This will likely come down to "how well I want it done", if you want absolute accuracy, you can resurface the head, but like it's said in video, this is enthusiast home build, you ideally wanna save some money, especially with the grinder that hes using
A god and fast way to clean the head for this kind of work is a fresh knife honing stone and wd40. if its a cast deck you use atf instead of wd40.
There is so much wrong with this video it is comedy for anyone who knows what they are doing.
Loved the vid, super informative! :)
Good shit my guy, super informative and entertaining
Thanks.😁👌 For your experience and videos .very helpful. 🙏🙏🙏👍
Wicked stuff! Was wire tucking my g5 cleaning it all up and now might go and equalize the head 😂😂
Awesome project! 👌
Amazing video, as always !
Great video. I think I first do a "simple" head gasket replacement. So, I wouldn't end up in such a pickle a many others at my DIY car repair shop. Who did bite of more then they could chew.
Sometimes you can buy a used head, do the work to it, then install it when you are ready. Later, you can sell your original head to someone else. Either that, or you can buy an "As-cast" rebuilt head from your local auto parts store and work that over, then turn in your existing head for the core charge. However, you only get about 30 days to return your existing head as a core. That method may actually be better, since the valves and valve seats have already been reground or replaced, and the deck has already been milled.
You just could’ve bought a titration Burette, they are way cheaper than the Kits from the US and More precise
Around 10 quid for a 150ml and 9 quid for the stand.
What is a titration Burette ?
@@brendanjones3395 A Burette that is used for titration.
It’s laboratory equipment which is used to dose a certain liquid (mostly acidic or Bases)
Thank you for the explanation I never heard of this tool I will research more into it.
Great description!
Thanks, good info, well explained
This is really useful. I will do this on my classic Mustang
Really like the content helps a lot. Thnaks
Thank you, Verry good explanation!
Very cool to see how its done i think it consume a lot of time. Thanks for learn us this.
I would add to get the rough chamber work as close as possible between each chamber. Then get the cylinder head resurfaced before finishing the chambers and getting everything dialed in and equal. The removal of material from the head gasket surface on the cylinder head will reduce the volume in the chambers, so it's good to do it prior to the finished work.
Thanks for the explanation.
Wow just amazing thank you 🙏 I’m just stunned
Great video..... I'm tried this myself. I used Wintergreen Alcohol instead of water
That's a real labor of love :)
Great stuff.
I've found using laboratory digital balance (0.01g) to weigh by large syringe before and after complete filling the chambers is simpler and quicker. (1gram=1cc)
Damn your smart ! The idea was great 👍🏻
Great job! Next, the runners!
Great video. Thanks
DIY quite informative video 👍👍
Plz make videos on new tech and startup of ic engines, like earlier the one you found alfdan. There are many startup and technology to improve efficiency with different fuels. Thank for sharing video....🤗
Nice work. Wish I had the space and tools to do this. Still gonna need hot tanked and machine work.
Another good one.
Love your channel ❤
Keep them coming I am curious how it will turn out