Unnecessary arguments that creeps-up on a subject being discussed are easily avoidable if one keeps to the subject under discussion. Why push-in different configurations than that the one under discussion such as different number of cylinders/Vee angles as well as two stroke?.
Why not?
But while queries are being made...
Why is it s-s - that you C & P blocs of text seemingly sourced elsewhere - sans acknowledgement/links?
''Why not?'' Because it greats unnecessary confusion in a discussion. Who on here including you does not C&P blocs of text sourced elsewhere?.
As regards the simple copy/paste of information; please either attribute within your post or paste the link to source. Other posters can then refer to it directly. Not all sources of information are correct (either deliberately or in error).
Why is it s-s - that you C & P blocs of text seemingly sourced elsewhere - sans acknowledgement/links?
''Why not?'' Because it greats unnecessary confusion in a discussion. Who on here including you does not C&P blocs of text sourced elsewhere?.
As regards the simple copy/paste of information; please either attribute within your post or paste the link to source. Other posters can then refer to it directly. Not all sources of information are correct (either deliberately or in error).
As regards the 'simple' copy & paste of information - link/source was already given in my answer to the ''1949 Cisitalia 1.5-litre flat-12'' question to the same gentelman some pages back.
''Why not?'' Because it greats unnecessary confusion in a discussion. Who on here including you does not C&P blocs of text sourced elsewhere?.
As regards the simple copy/paste of information; please either attribute within your post or paste the link to source. Other posters can then refer to it directly. Not all sources of information are correct (either deliberately or in error).
As regards the 'simple' copy & paste of information - link/source was already given in my answer to the ''1949 Cisitalia 1.5-litre flat-12'' question to the same gentelman some pages back.
I'd suggest if you'd go back,& check your post at the top of page #9, its an example of your C & P,
again presented with no source/link - which pretty much amounts to plagiarism - its poor form...
Best not to that claim others do it, (esp' sans evidence) as if that somehow excuses the impropriety.
(In fact, I did provide a link to the Porsche-Cisitalia, within the post, not a vague pseudo-reference).
Re: v12 or v10
Posted: 29 Jan 2022, 09:16
by Bandit1216
I was thinking. Will there always be an equilibrium given a certain volume? Early 21st, 20000 rpm seemed to be better than 18000 with 3 liter, but it can’t be without limits.
Imagine a bore of 100 with a stoke of 10. At one point the torque will get too low to overcome losses and you will not reach the rpm to compensate for it. You would need a 50mm bearing for a stroke of 10. I think at one point bore-stroke ratio will reach a breakeven point and that in turn will dictate the best cylinder number for a certain volume. For a racing engine without fuel restriction that is.
It might be 2,5 liter V8 is best, 3 liter V10 and 3,5 V12.
I was thinking. Will there always be an equilibrium given a certain volume? Early 21st, 20000 rpm seemed to be better than 18000 with 3 liter, but it can’t be without limits.
Imagine a bore of 100 with a stoke of 10. At one point the torque will get too low to overcome losses and you will not reach the rpm to compensate for it. You would need a 50mm bearing for a stroke of 10. I think at one point bore-stroke ratio will reach a breakeven point and that in turn will dictate the best cylinder number for a certain volume. For a racing engine without fuel restriction that is.
It might be 2,5 liter V8 is best, 3 liter V10 and 3,5 V12.
Keith Duckworth used to claim that a 400cc cylinder is the best compromise.
A ‘super-short’ stroke such as you mention would require a non-normal engine architecture (the crank would operate more as a cam), this methodology is used in A/C pumps (there are a couple of videos on YouTube where these have been converted to 2-stroke engines - interesting!!).
The other architecture that springs to mind with a very short stroke is the Wankel Rotary.
( good job I re-read before posting, auto-correct almost got me there )
Imagine a bore of 100 with a stoke of 10. At one point the torque will get too low to overcome losses and you will not reach the rpm to compensate for it.
Torque is not a function of stroke length, capacity is.
That being said, extreme values of stroke, such as your 10 mm, are very likely to create odd effects that limit power. One thing that immediately springs to mind is with such a short stroke not being able to open the valves enough as the piston doesn't move far enough down the bore.
Re: v12 or v10
Posted: 30 Jan 2022, 01:34
by gruntguru
And the bigger valves need more lift to reach their potential flow.
Re: v12 or v10
Posted: 30 Jan 2022, 04:21
by J.A.W.
As a topic curiosity, here's an article inc' an experimental 10cyl variant of the Chev Corvair flat 6 (boxer).
It'd be interesting to see this engine opened up, given the 6cyl ran a 4 main-bearing crank, but the
10cyl appears to have larger spacing between the cylinders, indicative of a main between each pair?
And the bigger valves need more lift to reach their potential flow.
Or use all the poppets as exhaust valves, as in a Detroit Diesel 2-stroke, & a short-stroke high-rpm
(for a diesel) 10cyl might bring back that Audi Quattro-type of howl* that some fans still mourn...
NL_fer found a Y-T site that gives an idea:
*If you want more of an F1 scream, play it at 1.5x speed..
And the bigger valves need more lift to reach their potential flow.
Or use all the poppets as exhaust valves, as in a Detroit Diesel 2-stroke
lots of tiny valves wouldn't need more lift
poppets & ports is limited by the brevity of the 2 stroke exhaust period
extreme bore:stroke ratio allowing more rpm is helped by .....
Al/Be MMC (banned) and NR 500 or novel architecture (banned)
(relatively) friction reduces as stroke and displacement are downsized - and bearing losses aren't increased
extreme bore:stroke ratio is hindered by.....
(relatively) more heat taken to coolant via 'piston area' than saved by displacement downsizing
so it's heat loss vs package benefits of downsizing
Re: v12 or v10
Posted: 13 Feb 2022, 22:26
by echedey
well here are the first parameters of my engine, if there is something I can modify to get more performance, please let me know so I can take it into account and continue improving. https://drive.google.com/file/d/1JwjlD2 ... sp=sharing
Re: v12 or v10
Posted: 14 Feb 2022, 11:15
by Greg Locock
Here's a V8 crank I'm looking at, I think the setting on mesh density is called unfeas!
good job I re-read before posting, auto-correct almost got me there 
