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More Cylinders, More Power?


johnc

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Another thing that I don't think has been brought up is that for a given engine size, more cylinders = smaller CCs, which promote more complete combustion, and can be cooled more effectively which also allows for more timing advance (or higher compression), both of which can lead to higher power outputs.

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The distance between the centre of the piston and the bore wall is shorter in a v12 this allows the piston to cool quicker and means engine is less prone to detonation

This allows a higher static compression ratio

Also as has been mentioned before there is more avaliable port area for a given displacement the more cylinders you put on

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.............I think the friction is irrelevant, maybe a loss of a few hp.

You can't say more cilinders is more power. Because the bore and stroke can variate.

You can have 4 liter V12 engines, and 11 liter V8 engines.

 

 

Very true what I was trying to say.

 

As for the SIZE we are talking about equal liter engines. so a 3L V12 against a 3L V8 ect.

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One thing that I just thought of...... Are we just limited to V blocks??? Or straight, or both??

 

Because there is more rotating mass with the longer cranks.

 

So far as I can tell the only set variables would be:

 

1. Same over all capacity

2. Valves per cylinder

3. Fuel octane

4. Compression ratio

 

To keep a good comparison I think these would need to be kept.

 

Flexible variables

 

1. RPM

 

This is as I see it. I know my views are my own, I am Trying to keep it to some set parameters to help the discussion as a whole. If you see an error in my logic please speak up.

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Seriously, beyond eight cylinders, how many engines do you know of that don't have a massive amount of R&D to squeeze power out of them? Four cylinders are the land of econo-boxes for economy (power and torque are not usually a high priority). Sixes are cheap "mid-size" power (get something that runs for 60~80k and then it needs parts) and eights for torquey big vehicles (again, power not high on the list). But we get to V10's and V12's and they are usually exotic engines where power is high on the list.

We would need Ferrari/BMW/Merc/etc./etc. to design a 3L V6 and a 3L V12 of similar build quality to compare. I honestly think you guys hit on it, however. More valves, better rod/stroke, etc. until you get into too much friction from more cam lobes, rings, etc.

Maybe one should compare relatively similar engines that have a variation in valves/cylinder for a portion of the idea, such as Modular Fords, etc.

Neotech; if the bigger-cylinder engine can sustain higher rpm due to it's better rod/stroke ratio, then that should be an advantage that it can exploit for comparative purposes.

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We would need Ferrari/BMW/Merc/etc./etc. to design a 3L V6 and a 3L V12 of similar build quality to compare.

 

Investigate the M111, M104, M119, and M120.

 

These are the Mercedes Benz 4cy, I6, V8, and V12. They use practically the same dimensions for everything (rods, throws, etc.) Even the cams use similar duration. You can compare hp/Liter at your own will, though using the 500e M119 would be a joke unless you compared it with the Kompressor M111, C36 M104, and AMG (7.3) M120, since it was built and tested by Porsche ;)

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Neotech; if the bigger-cylinder engine can sustain higher rpm due to it's better rod/stroke ratio, then that should be an advantage that it can exploit for comparative purposes.

 

That is why RPM would NOT be a set variable. :burnout:

 

I think that my list would prove to be a great way to compare two setups.

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