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Post #1 Tue, Jun 20, 11:18 AM |
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BenFenner
Supercar Messiah - 2556
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A V-12 is desirable over a V-8 for many reasons.
A V-12 is more naturally balanced, producing (much) less vibration. (Without the use of balance shafts.)
A V-12 will have more cylinders firing per revolution, creating smoother torque delivery to the driveline (reducing the need for a flywheel, etc.).
What ging said about having more valves per cylinder is not correct. A naturally aspirated engine will draw the same amount of air, no matter how many cylinders/valves it has, as long as it is the same displacement. What you do get with more cylinders, and more valves, is the ability to suck in the same amount of air with less and less "pumping loss" (the power used by the engine to suck in its own air).
There are a few more reasons why a V-12 would be more desirable than a V-8.
This is not to say that V-8s do not have their advantages over a V-12. They do. It is generally accepted though, that a V-12 is, on the whole, a better engine design than a flat-plane V-8. A cross-plane V-8 (used for the most part, in American cars) on the other hand, is a pretty poor engine design, and I wouldn't begin to compare it to a typical V-12 engine. (See wikipedia for explanation of a flat-plane vs. cross-plane V-8).
http://en.wikipedia.org/wiki/V8
Ben Fenner is secure in his sexual orientation, which makes him a little bit better than most guys.
-CMG
I sincerely hope you're sitting back there saying, "Haha, look at all this wacky shit I'm saying! They really think I'm a pedophile!" rather than actually meaning it.
-bucknutz
Edited by BenFenner - Tue, Jun 20, 11:19 AM
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Post #2 Tue, Jul 11, 5:06 AM |
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platosbrainchild
New User - 4
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contrary to the facts stated by benfenner, you will not make the same amount of power with less valves
and its not pumping losses, its frictional losses
the reason the cylinder number is so high is so the stroke will be smaller, this is because for the most horse power w/o stressing the internals such as crank shaft, con rods and pistons
the reason for this is that if you have something travelling and stopping 200 times per second, something witha smaller path of travel will have less momentum, hence less g forces, hence less stress
remember that torque x rpm/5252 =horsepower, so;if i make my peak torque at a higher rpm, ill make more horsepower
another reason the number of cylinders is so high is for a smaller bore, because the smaller the bore, the shorter the flame front, the quicker the fuel/ air mixture burns, the less time it take to create torque, the more torque made, the more horsepwer made
current moto gp bikes are striking a balance between flame front travel and short stroke (you wouldnt want to decreasethe displacement because you will make less torque with a smaller displacement, although power could be the same with the same bore/shorter stroke, for additional rpm)because with excessively high bore to stroke ratios, the flame front travel is so high that the engine is not making enough torque
now for flow
engine designers have to strike a balance between cynder head flow and air speed going though the ports. the most efficient air speed is aproximately 350 feet per second for a 2 valve engine (chevy small block, things of that nature) and 400 feet per second for a 4 or 5 valve engine. one reason variable valve timing engine make more power everywhere is becuse they dont have to strike a balance, they just adjustvalve lift as rpm changes.
i hope i solved everyones questions
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Post #3 Sun, Sep 16, 4:46 PM |
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RedPower
Senior Member - 459
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I've got a few thoughts on this car and the question of its power. As it was a concept car, we have to remember the figures are very speculative, and usually optimistic. I think 400hp in 1992 with only 3.5 liters of displacement is pretty respectable, although does anyone know if the engine was actually dyno-tested? The reason Yamaha made a small V12 probably has something to do with their short-lived relationship as engine supplier to Tyrell F1. In fact, it wouldn't be surprising if the 0X-99's engine was related to the F1 unit, albeit in heavily detuned, rev-limited, and emission-controlled form. Well, it's in the history books now, and it's probably better Yamaha stuck to bikes.
It's going to be a long season.
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Post #4 Tue, May 20, 10:36 PM |
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petrolhead38
New User - 110
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Quote from BenFenner A V-12 is desirable over a V-8 for many reasons.
A V-12 is more naturally balanced, producing (much) less vibration. (Without the use of balance shafts.)
A V-12 will have more cylinders firing per revolution, creating smoother torque delivery to the driveline (reducing the need for a flywheel, etc.).
What ging said about having more valves per cylinder is not correct. A naturally aspirated engine will draw the same amount of air, no matter how many cylinders/valves it has, as long as it is the same displacement. What you do get with more cylinders, and more valves, is the ability to suck in the same amount of air with less and less "pumping loss" (the power used by the engine to suck in its own air).
There are a few more reasons why a V-12 would be more desirable than a V-8.
This is not to say that V-8s do not have their advantages over a V-12. They do. It is generally accepted though, that a V-12 is, on the whole, a better engine design than a flat-plane V-8. A cross-plane V-8 (used for the most part, in American cars) on the other hand, is a pretty poor engine design, and I wouldn't begin to compare it to a typical V-12 engine. (See wikipedia for explanation of a flat-plane vs. cross-plane V-8).
http://en.wikipedia.org/wiki/V8
you can get 1000hp out of a V6 for f*cks sake!
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