On the topic of large cy count flat motors. I knew about the Ferarri Testarossa having a flat 12 but after a short wikipedia search it turns out Subaru, Porche and Mercedes have all dabbled in the flat 12s too. Subaru actually built theirs for the wildly unsuccessful Scuderia Coloni F1 team in 1990. They never actually qualified for a race at all that year though.
The "Subaru" engine was designed by Carlo Chiti whilst he was at Motori Moderni; he also designed engines for Ferrari and Alfa Romeo (including a flat-12).
Porsche more than dabbled, they won WSC and CanAm titles with flat-12s! The CanAm boosted 12s were used instead of a planned flat-16:
They sure are, and we might see more them in the future. Diesel is nothing new. Increasing how well they spin up is an ongoing thing, I don't think they are going anywhere soon. Hybrid system to enhance the performance is kool. The market is still leaning on gas though, that's why we don't see as many popping up as we see more gas engings adopting KERS maybe TERS soon.
The problem is really the cost; a comparable petrol engine (turbo, electric-"hybrid", direct-injection) would still be cheaper to make.
V4 I think might shake itself to much (not absolutely) V6 are really smooooooth, more so than V8's. Didn't they do some I8's way back in the day. That would be a relatively looooong engine.
It depends on the crank configuration. A 90 degree V4 is actually smoother than any V6, both taken without a balance shaft (the V4 would be
uneven firing, though). A V8 can be smooth or not, depending on the crank configuration and whether it has additional balancing.
Straight-8s are inherently very smooth, except for the vibrations from the crank twisting and whipping; long cranks are a bit of a headache, part of the reason inline sixes have disappeared. Performance straight 8s from the 40s and 50s took power from the centre of the crankshaft to reduce the flex.
Really, this day and age, the lengths that manufacturers go to in the name of NVH, balance is not an issue, so any configuration deserves another look.
Now that sounds interesting.
Future tech
Imagine if you will, an engine with a variable compression ratio. It might be the next big thing like variable valve timing.
Continuously variable valve timing, variable compression ratio with a TERS Turbo and KERS drive line
Two strokes are unviable only because of fuel and oil consumption / emissions. With direct injection, that might be more controllable, especially with a blower (but both of those eat into the inherent simplicity and weight advantage of 2-strokes).
Variable valve timing effects a kind of variable compression ratio already, see
Atkinson cycle. The real benefits of variable (geometric) compression ratios would be in ultra-lean burn, compression ignition (as opposed to spark ignition) petrol engines, for fuel saving.
I think direct injection's success, combined with turbo-charging and downsizing, have pushed back the necessity a bit on that one for now. That said, I like the in-crank solution, if it can be proven to take the mileage and torque.
