I knew pistons werent perfectly round all the way through their height these days, but didnt realise just how different the geometry is, very cool man :) always learning, and knowledge is POWER
Looks like himself again, back in the days I'd watched him make poly mounts... Super smart dude, I've actually made my own mounts not long after you made your video. Keep on keeping on.
Im an a apperentice engine builder by trade and dude I CANNOT GET ENOUGH OF YOUR CONTENT its super informative and intriguing and watch every video that you put up as soon as you do please keep up the amazing work so i can keep learning and to keep enjoying your videos
I simply love learning the details of the basic parts of the engine and how complex they really are! Without you not sure I ever would learn these details.
You should have mentioned Honda's attempts at trying to make squarish oval pistons work in a desperate attempt to maximize bore area for a given sized block. That went well...
Very detailed and informative video. Could you please answer the question: why is it that the main bearing axis is symmetrical below the cylinder bore axis. Couldn't you counteract the main thrusts loadings on the pistons through a asymmetrical design or a flat mounted engine?
I'm sure you've thought about it, but I'd love a video on wrist pin height as well. Also, do any pistons have a pin offset from the center? Towards the major thrust side for example? Great vid as always!
That's a great topic suggestion! Thank you. There's definitely offset pins out there, many new engines have them. It reduces friction, reduces NVH too. I'll definitely cover it in the future.
Great content and superb video. A lot of engine builder rotate the piston in the bore because of the pin offset, what does this do to the major and minor thrust surfaces? And wear and tear?
Thanks for another great video. I have thought about the things you covered but have a hard time finding good sources of accurate information online. Do you have any books or other sources you would recommend that goes into depth on cylinder and piston geometries as well as the combustion chamber and valve configurations?
A piston is a very complicated object: not only like explained here, but the pin bore from the piston is not cylindrical : it as special forms (double cone like+ oval) , to compensate the flex from the pin and from the piston+ lubrication...and much more hidden secrets...(i had work by Mahle and Kolbenschmitt...)
0:35 is not the taper (a cone shape would have flat sides and not let light through). This effect is because of the "barrel" shape (barreling). This allows the piston to better handle the side loads from the connecting rod. Pistons are pushed sideways into the bore by the connecting rod, and the barrel shape helps with this so the top and bottom edges don't dig in.
Hi guy. Offset pistons can equalize major and minor thrust, reducing total friction while increasing power, efficiency, and torque. My guess is that they aren't universally used because offset pistons complicate balancing. And adding a thermal break while using the appropriate metal for each sub-part of a piston is far superior to the kluge that is currently standard in obsolete designs. This sort of design also simplifies each part, which makes forged parts practical, greatly improving all aspects of performance without breaking the bank. The above improvements make your engine wayyyy more efficient. They are also some of the several improvements by which a truly modern engine protects its oil from heat and blowby. Oil changes ought to be very, very infrequent. They are needed so often because of contamination and degradation, both of which are glaring indicators of poor design. All in all, a fun little video. Thanks and have a good one. :-)
If your solution weren't far more difficult than the current one, it would already be used. If you believe that to be untrue, start a piston company, and make the automotive world a better place! :)
I feel like Western English even though not the most efficient language, is able to convey the most acute, detailed and understandable level of communication between people trying to explain things to each other.
Thank you for the Piston explanation I always thought it was a little simpler than that but apparently there's a lot of math in it, congratulations on your haircut signs of growing up There's Hope for you yet.....lol
It also makes it harder to measure the piston to wall clearance accurately especially when the piston manufacturer doesn't provide a gauge point. Sure the piston alloy must also effect these geometries. Another show of the engineering marvel that is the 4 stroke ICE
How long does it take that the Piston cools down while a brake with shout of engine and how long does it take to get again to perfect expansion when you start the engine again? Does a 15 min break with 1 minute time to warm up again before full load (on the highway for example) means a lot of stress for the piston and the cylinder bore?
do you know that the hole for the pin is usually not in the center but slightly offset (we're talking 1mm max) toward the exhaust? i don't remember why tho!
The pin is slightly offset, so when the full force hits the piston at Top Dead Center, the rod isn't standing straight on the crankshaft, but rather starting to go down, thus converting more force into rotary motion, rather than just smacking your crankshaft
It can be done on some engines, but on many engines the mains overlap the bore bottom or there's simply some sort of lip or something in the block. But even when you can remove them from the bottom there's no benefit to it, because you can't install them from the bottom.
You are wrong about the reason for the shape it is narrower across that section because of thermal expansion, it expands more across that area because it has more mass under operating conditions the piston is infact round
Damn what I've done I've put a piston inside the engine cylinder without a piston ring, to check the bore, cause i dont i have a tools try to rotate it and got stuck all of four cylinder and i think the problem is a bore so i go to the machine 😞 Co'z i thought a piston is rounded
Most measure it 90 degrees from the pin at a predetermined height from the bottom of the skirt. The height depends on the piston and manufacturer, but it's usually close to the bottom.
I did too. But not when they got in my eyes, and needed an eternity to dry, and annoyed me in my sleep. This was my second time with long hair, I lasted half a year longer this time 😂
@@d4a pros still outweigh the cons haha. Will stay with your content till your third time.. Looking forward to new episodes of boost school. Keep it up man. :)
I'm a huge fan of your job but today I disagree with some explanations you give. I'm pretty sure that the barrel shape is done due the fluidynamics of the oil in the cylinder wall, in particular to have a meatus of olil and an oleohydraulic lift that keep the skirt apart from the cylinder wall and avoid metal to metal contact
That's pretty much what I said, I just didn't use the words "meatus" and "oleohydraulic". Friction reduction is basically what it's about. By the way, Google "meatus", I'm afraid it's a bit out of place here 😉
@@d4a I traslate italian meato in meatus, I agree with you that's not used in the same way I use it. I'm sorry. btw if you know it's a pity that you don't explain deeply like you have get used us. But don't worry man it's only a whim of mine
