Can someone explain the physics of why engines with the same sized cylinders but in differing amounts and arrangements have different compression ratio limits? E.g. V6 can run higher compression than I6 of identical capacity, and thus has higher power and better fuel efficiency. V6 also runs higher compression than V8 with the same cylinders.
Is it something to do with heat and the shape of the block, i.e. cylinders surrounded with a higher ratio of metal and coolant cool more effectively and so can deal with higher temperatures? This seems consistent with I4 running higher than I6 as well. If this is the case, will any engine planned for the game get higher compression than the V6? Maybe the boxer-4? Does a smaller angle between banks of the same length give better cooling?
Curiously, there is still a slight difference efficiency when fuel injection is used, where throttle-per-cylinder V engines have lower efficiency than inline.
A little necro to ask a related question: is it working as intended that I3, V6 and V12 (but not I6) equally get the best compression per carburettor? I guess all of this stuff is getting reworked in the future, but I don’t understand why V12 gets the same fuel delivery from a single carb as I3/V6.
More likely it has to do with manifold design. When dealing with carburetors and TBI systems, the routing of the manifold is designed not only to better atomize the air/fuel mixture, but also to provide consistent fuel delivery to each cylinder. This crude diagram should hopefully explain.
1 2
3 4
L R
5 6
7 8
I’m citing a 2 barrel carburetor as an example, the left side feeds cylinders 1,7,4,6 while the right side feeds cylinders 2,8,3,5. By staggering the pattern as such, the A/F mixture has to travel the same distance to each cylinder. Obviously multiple carb setups use different manifold designs, but to the same effect. When multiport fuel injection came into use, manifold designs could be changed so that rather than atomize fuel, they could instead provide optimal air flow to each cylinder as the injector sits above the intake valve.
I think you missed my necro post, I’m particularly trying to understand whether V12 is bugged because it has the same compression as I3/V6 despite being twice as long, and despite I6 having lower compression.
REQUIRE lower ratios, not have per se. V12 should have worse fuel distribution than I3/V6 with the same carb configuration (or single injector) and thus have higher required octane number and thus require lower compression with the same other engine settings.
Probably, I was just referring to how manifold design often determines fuel distribution to cylinders, I am not certain if the game takes that into account or if it’s even capable of doing so.
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