How To Calculate Combustion Chamber Volume
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- Опубликовано: 14 окт 2024
- Check out Kalvinator Engines: www.kalvinatore...
If you want to figure out what your static compression ratio is, you're going to need to factor in combustion chamber volume or, CC the cylinder heads. In this video master machinist Kevin Frische shows us how this process is done. We also find out what the static compression ratio of #DarkMatterPikachu.
In addition to knowing cylinder head volume, you're also going to need to know the piston volume, bore, stroke, deck height, and head gasket thickness. With that information you can figure out static compression ratio using this website.
www.rbracing-r...
Thanks to Kevin Frische for his help in this video.
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This is one frickin cool series Eric. Because it's not about the nuts and bolts everyone knows, it's about the little things and tricks you never get to see. Great job!
Precisely.
This is the best video I have seen on this
You can definitely run higher comps on boosted engines as long as you have the proper engine management and tuning in place.
Probably, but the lower C/R means he can dial in more boost later and still be safe. This is intended to be used as a daily driver as well as some track use, so it needs to remain fairly reliable as well.
My Supercharged Corolla 1.8 has a compression ratio of 11.5:1, 220BHP, compressor is pushing about 8-10psi. Yes it uses super unleaded 98+ and yes it drinks about 25mpg! Hits redline at 8200rpm.
Some people love to hear big numbers when it comes to boost..
But you can get the same power with higher compression and less boost.
exactly. You can run a smaller turbo and hit the same power figures along with not completely destroying your out of boost transient response
Engines lose efficiency at higher rpm - the air has too much inertia to completely fill the cylinder before the valve closes. This is why boost will _always_ be capable of making make more power than n/a, especially at higher rpm (which is where max hp is measured, since it's a function of torque and rpm.) This is how the F1 teams managed to get 1300 hp out of a 1.5 litre V6 - with 80 psi boost. You'll never manage that with a 1.5 that's naturally aspirated, no matter how hard you try.
really enjoying this series
Me too, but it's almost over. :(
then we just move on to the next one. Its been amazing watching all your videos, even from the beginning, you always show the basics, the details, and never make us feel stupid. You are a master teacher. I feel i could become a master mechanic/tech just from watching your videos.
High complements indeed. Thank you very much. I've always worked hard at making the best videos I can. It's always great when those efforts are appreciated. Thanks again.
I'm liking the Kevin Frische/Kavinator Engines videos, as others have opined. I can tell Mr. Frische has spent some time in front of an audience (teaching). He has a very natural and comfortable presence in these pieces - as do you, Eric :-)
Any chance you'll help Kalvinator launch an affiliated RUclips channel? You could be like the Oprah to Kevin's Dr. Phil.
thanks Erik. great information.
way to support local business!
A meniscus is formed from the adhesion of the liquid to the side walls of the tube. You can also get a convex meniscus from the cohesion of the liquid to itself. If you put a bunch of drops on a coin, the cohesion would form a convex meniscus for example. In this case the liquid has stronger adhesion to the tube than cohesion to itself so it made a concave meniscus.
It's been too long, I have a mighty need to hear that engine roar.
ruclips.net/video/UADOHm6-BJc/видео.html
How on earth did I miss that? I watch your videos religiously
Listen to the outro as it is roaring on the dyno.
so I just went to their website... these guys are awesome!! they've been around the block a time or too...
that Buick grand national is beautiful..
Your videos are great Erick, keep up the good work brother
sweet, predicted 67 cc. Course helps I am familiar with the Cylinder heads.
its all about the details... good video Eric
thats cool..never would have thought it was done like that.
So you take the 67 ccs here plus the volume of the cylinder from TDC to deck height and divide that by the resulting ccs plus the volume of the bore and stroke from BDC to TDC?
That man is a mechanical genius!
I never would have ever thought of doing that.
Unless your piston sticks out of the hole, I assume your quench distance is less than optimal? Though I've seen the engine dyno videos and no doubt this engine makes good power, curious what the final quench height was in this setup?
"Just basic science, yo" - said jesse pinkman
He blinded me with"SCIENCE "!
Not to be confused with Turbo Yoda from other youtube channels.
Good info. Eric have you ever lived in Delaware? Just wondering for my own sanity
Nope.
+flyback 2me The First State. i swear i saw Erics twin brother, thats why i asked.
Excellent!!!. Like always. Thank you Eric
Question, when you bore a engine do you replace the piston or rings and how do you know what size to get??? please do a video showing it. thanks
See the previous videos in the series. The 2 before this were about pistons and rings. Link in the description.
I did but don't remember hearing the answer to my questions but I'll go back an look again.. thanks I never miss a video
Pistons are built with a certain oversize in mind. Most common are .030, .040, .060 then in mm you have .25, .5, and 1mm oversized. Each has it's own corresponding ring set
The machine shop will measure the bores and determine how much needs to be taken off to repair any issues. Then you or they order oversize pistons and rings - for example .030 or .040 larger. Once the machine shop receives the pistons, the documentation will include the actual acceptable bore tolerance for that piston set and the machine shop will cut the bore accordingly. The bore is slightly larger than the piston because the pistons will expand under heat. Different materials have different tolerances. This is where an experienced machinist is worth $$.
nice vid, simple and direct
Fantastic insight and video as always 🙌🏻
adn again, great and informative video, i like it. I wonder how to measure CC in top dead center on cylinder whith a piston that have displacer on top of it isntead of a dish? This combo might be useful for more static compression in n/a build
I believe that info should be found in the print up for the pistons you're using. Otherwise, I think they use a special clay for that.
For flat top and dished pistons we place the piston at top dead center, then using a larger acrylic plate and burette similar to the ones shown in the video to measure the complete volume.
If wanting only the piston dish volume we use a similar setup on the bare uninstalled piston. These methods are extremely accurate, fast and account for the additional volume of our custom shop machined fly-cut valve reliefs.
Nice! Thanks for the info.
i think he meant, if the piston has a dome and stands pride of the deck!
Carl Benz
Then that is a slightly more complicated procedure to measure and calculate.
With domed pistons, we rotate the crank to place the piston about 1 inch down the bore, place a light coating of Vaseline on the bore, rotate the crank to place the top of the piston dome flush with the block deck against a straight edge, gently wipe off any excess vaseline from the bore and top of piston without altering its position, this seals the rings and prevents loss of the measurement fluid past the rings and ring gap, carefully measure the distance from the block deck to the top of the piston crown (not the top of the dome, not the valve relief) and record the distance, secure and seal the acrylic plate over the bore. then using the burette completely fill and note the volume of the fluid to fill.
Then calculate using the formula
[pi * (r-squared) * height * 16.387064] - measured burette volume = dome volume
V = 3.14159 * r-squared * height * 16.387064
Where:
V = Cylinder Volume for measured height
pi = 3.14159
r = radius or 1/2 cylinder diameter
square the radius
h = height or measured distance from piston crown to block deck
16.387064 is the multiplier to covert cubic inch to cubic centimeter or milliliter
1 cubic inch = 16.387064 milliliter
1 milliliter (ml) = 1 cubic centimeter (cc)
Example:
4.125 inch bore
2.0625 radius
4.2539 radius squared
0.375 inch measured distance from piston crown to block deck
V = 3.14159 * 4.2539 * 0.375
V = 5.0115 Cubic inch
V = 5.0115 * 16.387064 = 82.1237 ml
The measured burette volume was 49.2 ml
82.1237 - 49.2 = 32.9237 ml
The piston dome volume is 32.9237 ml
Bigger gaskets!? I wouldn’t want this guy building my engines talking like that 😆
Did you CC all the combustion chambers to see if they are equalized?
Hi Eric is there any chance you could do a video on how to work out the Cubic Capacity of an engine, its pretty complicated to me....involves squaring numbers, radius and Pi from Fred in England.
Bore x Bore x Stroke x .7854 x # of Cylinders is a simple formula I use.
Why the copper over like a mls style gasket? Just thickness or is there some other advantage?
brilliant video
That was awesome. I dig it.
I use gas to check valve sealing on heads that I'm not sure about. I don't think I ever thought of using alcohol for the same thing, though I supposed the surface tension would be similar and give the same result.
can i put 2, 3 ,4 or more head gasket to reduce the compression ratio? will this easy cause a leakage? i really need to know, thanks guys
i may tell you the full story of my case, i have a nissan figaro, i am about to change the cylinder head, and i bought a nissan micra cylinder head from ebay, because it look the same, but unfortunately i found that it is actually different, Nissan figaro cylinder head has a step inside as figaro has turbo but micra doesn’t have turbo, so the figaro cylinder head designed with a step to reduce the compression ratio, but now i bought a Micra cylinder head which without a step so if i install it, my figaro is gonna have much higher compression ratio and will hurt the pistons i believe, so now i am thinking to get 3 - 4 more head gasket to increase the gap in order to lower the compression ratio, but in the market there is no any super thick head gasket, so i am thinking to put more head gasket together, do u think it will works? thanks
Very good video! :D
Interesting video's Eric ! Great job.
What a nice way to measure the volume, i bet he unscrewed the sparkplug to drain it :-D
Basic measurements and methods appeal to me for some reason.
I think we just flipped it over and drained it out.
How messy lol, i like the father/son companys, i think they care more about the customers.
Just my view.
Classic method has been used forever. The next step is to get the compressed thickness of the gasket and calculate the area of a circle with a diameter of the bore. Then calculate the area of a circle the diameter of the bore with a thickness of the distance of the top of the piston to the deck. Add them up and you have the total area of the compustion chamber at TDC. Then just calculate the compression ratio. If you want to get anal about it you can add the volume of the valve reliefs in the top of the pistons. But only engineers like me do that kind of stuff.
Collab with Engine Yoda and Turbo Yoda
Something's Frische.
My physics is quite rusty, but if he moved the tip of that biuret a littttle bit closer to where the hole end, when the water level would have reached the tip, wouldn't the fluid stop running ? I think I'll try that when I have some time ...
there would have to be a decent enough seal between the biuret and the Plexiglas otherwise it would just seep out between the two, but I like were you are going with this. you could also just use a syringe...
Vary cool guy a pleasant video
For colored liquids you are supposed to measure at the top of the meniscus, both at the start and at the end (not that it makes much of a difference). Pharmaceutics student here!
There have been many scholarly discussions regarding properly reading the fluid meniscus and it really does not matter as long as the starting and ending readings are consistently top and top or bottom and bottom.
There is an introduced error discrepancy if mixing top/bottom or vice versa readings.
Totally agree, that is what the parenthesis is for! It is all relative but in the case of colored liquids sometimes you just can't see the bottom of the meniscus due to their high opacity. In this specific case, there are probably more significant errors derived from the thickness of the vaseline on the cylinder head, the fact that the acrylic might not be completely flat and the tapered opening should not have been filled (or should have been accounted for). In the end, it probably does not matter though.
as an engineer, that has to do with the surface tensions depending if the fluid is concave up or down. But as mentions the difference should only matter between start and end for the reading position
another way is using the weight of the fluid and knowing the liquids density. water is the simplest (approx 1000kg/m3) and solving for volume
are you always walking one time around your house before you open the front door?
not sure what you're trying to say..?
Nik Trp doing it that way is adding an unnecessary step.
That's for those who don't have a fancy burette.. chances are more would have a kitchen scale
Thought I would add for those that do not have a burette = (me), then a syringe and accurate scales (.01g) can be a sub. 1gram of water is 1cc. So get a large syringe weigh it with your water in it and then fill your chamber and calculate how much water has gone in. Can even check your calibration of your syringe if you are sad:-) Mine worked out ie weighed my syringe filled to 100ml and it got 100grams heaver. comments?
He sound like Ross from Ross garage from motorweek
how to measure pistons valve pockets cc...please give a solution sir
OK Veri good
cant we use watet sir??
that is cool
20 years ago I watched a show where Ferrari was doing this oh their engines
I use the same buret in my lab lol
How much does the gasket compress?
Advertised gasket thickness is the compressed thickness. How much it will compress when torqued depends on the material.
The published thickness spec for SCE ICS Titan brand copper head gaskets is the compressed thickness at the specified torque.
That spec can be different for different manufacturers and different products.
I have another way . I’ll send it to you and I’ll happy to know comment about
What happened to the mess that was supposed to be made? Did he get really lucky?
what causes errarte idle my chevy impala raming up between 2&3 rpm while car is running
probably a vacuum leak somewhere, check for cracked hoses or leaks in the vacuum system. could even be an intake manifold gasket.
Early Pierce Spray brake cleaner around the intake manifold mating surfaces and check if the rpms fluctuate
try soapy water instead
Ok with da soap & water what im lookin for
Vaccum leak if old imp, sensor if newer one.
so how long till u the engine in the car
iirc, the engine is in the car already, he is just releasing the build videos over time
I've already test fitted the engine. It still needs to come back out so I can swap the front suspension. I also still need to rewire the car and figure out the fuel system. Still some time yet before it's on the road.
Only ccing one chamber?
For finding C/R that's good enough but if you were blueprinting the engine wouldn't you want to do them all? Thanks for responding by the way.
Why no skippable ads? FeelsBadMan
I don't control the ads, RUclips does.
Well,I wasn't aware of that,thanks for clarifying
Did not know the valve pistion is that big xD
Can someone explain what the point of that was?
If you're combining off the shelf parts and you have machined them, this is how you would figure out your compression ratio.
EricTheCarGuy thanks
How to compute??
Your gut seems to be getting bigger... (like I'm one to "talk")... Cool vid Eric! Maybe consume more salads? ;) #leangut
This was shot back in May. I've lost 15lbs since then.
Right on! I like your videos, and want to see you around for a long time!
how can i tell if its intake gasket
Go on the forums dude, a lot more people will help and it will be better overall
IIGrayfoxII yea just google it and put in the symptoms your car is having or whatever and your type of car it will be easy to find your problem
"If you have automotive questions, ericthecarguy.com, that will be listed in the description"
No reason you can't have higher compression than that , even with boost. I know many boosted cars with 10:1 - 11.5:1 on boost... Tuned on 93 octane for the street.
It's much easier to increase boost. ;)
more efficient, more responsive with higher cpr. But I dont think youll be track racing it on the limit so who cares.
In terms of simplicity, yes it's much easier to just turn up the boost. However, boost and compression are actually different in the way they affect performance and the reliability of the engine. For street applications with moderate boost, it is always preferred to have the highest (dynamic) compression possible. This way the turbo will be spooling much quicker, and off-boost applications will feel better, more torquey and improve MPG.
In addition, putting a thicker head gasket with the aim to reduce compression is not ideal as it increases the quench areas in the combustion chamber, which in turn makes it more prone to knock. Personally I have some experience with this and was actually quite surprised with the results. My car comes turbocharged with 8.5:1 comp. pistons, but the engine suffered critical failure and I had to change out the pistons. The only ones I could find at the time were 10:1 comp. and the car runs just as good and feels much better in lower RPMs, boost is about 0.6 bar (~9 psi). This is all stock, used parts. I know it's not the best way to go about fixing an engine, but it was all I could do at the time.
My point is, Eric, a lot of times people in the engine-building business are somewhat afraid of compression and try to avoid it at all costs (when it comes to forced induction). In my personal opinion, it is best to tune around compression :)!
I got tired of having a low compression (8.5:1) boosted motor, after I swap in a 6 speed for better MPG. If I ever get the time I'm throwing in a motor with 10.8:1 , with the same turbo setup.
575hp @ 7.8psi of boost on this engine. Also 640lbft @4500 of torque with a very flat curve starting at over 400lbft off idle. This engine turned out exactly how I wanted it to. Those numbers do not use a generous inertia calculation either, .06. It'll be just about immortal and will run on pump gas. No need to stray into the danger zone and the possibility of it not working or premature failure.
Engine yoda (he's the engine yoda)
but..but.. there was 2 air pockets left..
With under 9:1 I hope to see this thing pushing 18psi 😈
it's hard to modifi engine
am I tripping or did subscriptions grow over night?
one of these days I will get a first comment.
Eric get some sleep!
I just wanted to be the first to comment shittttt
Looking for help. Anyone in the comments here please reply. I replaced the front drivers caliper 2005 Outback because pistons were seized. Now on the passenger side front the pistons(dual pistons) retracted fine but when you press on the brake the one piston comes out faster and further than the other. I was testing it with the caliper off the bracket. Should this be replaced? Or can i get away using it?
I would not believe the two piston's will ever come out exactly the same. Fluid is getting to one before the other and the other starts to move after the pressure build's Drive it.. I have been fixing cars for 50 year's. A master tech. I have never seen them move the same.
ah too late i already replaced it. The one piston would barely come out at all while the other was almost all the way out. I don't think that would be good for the pad.
plus not my car so if there was a problem with it they would have to come back to me so might aswell. Although it sucks paying another 100 odd dollars.