Future of V12 Engines - Discussion

Roughly speaking, the friction of the combustion cycle is proportional to the length of the rings. A 1.5 litre 4-banger has a lot less friction than a 1.5 litre 12-banger, and it (the 4-banger) also has lower weight, and occupies a smaller volume.

Assuming the same bore stroke ratio = 1.2 (~= F355 bore/stroke) we get tables that look like:

DISP Cyl per/cyl B/S Bore Stroke red line ring
4000 1 4000.00 1.2 182.83 152.36 4065 574
4000 2 2000.00 1.2 145.11 120.93 5122 912
4000 3 1333.33 1.2 126.77 105.64 5863 1195
4000 4 1000.00 1.2 115.18 95.98 6453 1447
4000 6 666.67 1.2 100.62 83.85 7387 1897
4000 8 500.00 1.2 91.42 76.18 8130 2298
4000 10 400.00 1.2 84.86 70.72 8758 2666
4000 12 333.33 1.2 79.86 66.55 9307 3011

Where I arbitrarily set the redline RPMs to a constant divided by the stroke and made this constant give 8500 RPMs for the 3.5 litre F355.

Looking closely, we see that the 12 cylinder makes 14% more power than the 8 cyclinder, 26% more than the 6 cylinder, and 45% more power than the 4 cylinder. So there is NOT a big gain in power for the high cylinder count engines when comparing the V8 with the V12. There is a lot of power when comparing the V12 to the I4.But you get most of it by the V8 stge anyways.

You can also see that friction increases with cylinder count, so you will have more trouble achieving good fuel economy numbers.

Personally, I think there should be 3 Litre V8s and 4 litre V12s, but i doubt I will see any in cars I can afford to buy.

 

and on the other side of the coin the more cylinders the more piston area that the combustion pressure is acting on and thus more power generated. The 4l V12 in your table has 60,000mm² of piston area vs the 4cyl with less than 42,000mm² (the V8 is 52,500mm²). So the V12 has 45% greater piston area than the 4 - which is why V12s produce more power than 4s... if all else is equal.

I would love to see more 3.0l and 4.0l V8s and V12s out there.




PS: based on this great theory BRM built a V16 for their F1 programme

 

besides the stated above, the ever increasing CAFE and emissions regs hinder the idea, even if would be cool
increased RPMs to make up for displacement, increases fuel consumption, which increases emissions, etc.
for example, the area between the piston crown and first piston ring typically traps unburned hydrocarbons, and reason piston lands are kept as small as possible, multiply that area by 12, and it adds up, etc.

 

Gov regs will put a stop to the big motors very soon IMO.

 

I just dont see it happening. New generation of car guys(Gen X and after) are simply interested in power and tech, and they dont really care how it comes to them(T4, TT6, 8, Etc.).

Factor in government regs and cost of manufacturing, etc, it makes sense for car companies to go with smaller and tech cool motors.....

 

Koenigsegg has been working on camless engines. He says he's getting close with a pneumatic system that actuates each valve separately and can run up to 20Krpm:

[ame]http://www.youtube.com/watch?v=Bch5B23_pu0&list=UU5rBpVgv83gYPZ593XwQUsA&index=1[/ame]

He's also said repeatedly that a camless engine could be up to a third more efficient and far less polluting than today's average ICE.

With such possibilities around every other corner it's hard to know where we might end up in, say, ten years time. (One odd Supreme Court ruling - did anyone think this Supreme Court would allow CO2 to be labelled he sort of pollutant the EPA can regulate with near zero accountability? - or a new battery tech, and the whole game changes overnight.)

 

Can't fault him for doing the "Elon Musk Salesmanship Dance", but, when he was talking about how much engine space was saved, he didn't seem to include the now-needed (large) air compressor + air tank + air plumbing + new (and large) ECU + bigger electrical system needed. Then, when he waived his hands at the end, and said it could all be powered by regenerative braking, no mention of the cost of that additional complexity.

I've no quibble with the argument that, if you had complete and "free" control of the valves, the engine's average efficiency could be improved 30% by optimizing the valve motion at each operating condition, but the tricky bit is actually saving lifetime net energy overall (and not blow up too often ) -- i.e., paying $15K more to "save" $5~10K worth of gasoline over the life of the car = NET ENERGY LOSER! So it really gets down to overall lifetime cost for such a system to achieve widespread adoption -- which doesn't apply to K-egg anyway ...

 

I am glad Lamborghini is still sticking with V-10 and V-12's...they make their V-12 meet regs and costs, there is no reason others cant as well..

 

Isn't the whole point of wanting a V12 car that the driver wants to feel and hear a big, naturally-aspirated engine? (I'm asking, maybe I'm wrong!)

The V12 Astons, Ferraris and Lamborginis sound absolutely amazing, yet even though the Huayra has a 6L V12, it's twin turbos ruin its sound completely. That's why the 458 is better than the MP4 in my book (from a V8 point of view).

Just my 2 cents.

 

The new ferrari enzo or whatever its going to be called will be a V12 with electric assist to the motor. The Idea according tot ferrari is the V12 can be optomised for top revs and power with the electric motor filling in the torque deficit at lower revs. So you get the joy of a V12 with great power emission fuel economy. Of course they are talking over 700BHP.

But the same can be applied to a much smaller V12 say a 2 liter or 3 liter. You optomise for High HP and revs, using electric assist instead of a turbo or supercharger to fill in the lower rev power/torque deficits. This way you cover all fuel economy and emission regs which really only apply at lower power settings and revs, with electric assist to the V12, and you maintain goode driveability without the prasistic drag of a SC or lag of a Tc.

Back in the 50's ferrri made 4 cycl engines because they best met formulas for power and fuel economy in racing, apprently they were even experimenting with twins. More cylinders can give you more power, but more friction, somewhere there is a happy medium. In any event nothing is as smooth or sonorous as a V12, so in premium products it will probably survive with all manner of trickery to bring aboiut the necessary power and efficienby.

Hopefully we will not see turbos, however you slice it a turbo motor has lag, and lacks that instantaneous response of a NA motor.

 

I would hope that he's not exaggerating by much and that he's factored in the perfectly valid points you've made above; if only because it's counterproductive in the longterm. (Personally, it's hard to look at all he's achieved and think he hasn't thought this out. Time will tell, I guess.)

 

From the CvK interview in evo #180:

Koenigsegg are working with a bus company that will use this system first. He also doesn't anticipate this tech leading to an engine downsizing, as demand is for more and more power.