Stupid engine question

More than likely packaging. A flat 12 is a very wide engine but has a low center of gravity . The problem is you dont have the flexibility it terms of suspension design etc. with a flat 12.

 

A V12 and a flat 12 or boxer are different configurations of cylinder arrangements. A flat arrangement is at 180 degrees apposed typical in old VW's Porsche's Subaru's BMW motorcycles etc. and a V is at 90, 72 or 60 degrees typically to each bank. There are others like inline, radial or the W engines and others, but a flat V12 is not possible. The flat engine was used typically to lower the cg of a vehicle or to allow for better cooling as in BMW or VW and Porsche. Or to allow for a more space efficient vehicle. A flat or boxer also allows for a natural dynamic balance like an inline or a V12. As for why Ferrari stopped, perhaps it was do to complexity or the difficulty in using this in their traditional front engine V12 car.

 

They are talking about cylinder positions. Flat is flat --. V is V. There is no flat V.

 

The Ferrari 12 from F1, the Boxer and the TR is a 180 degree V engine.

 

Yep there is that. crank pin sharing, not cylinder arrangement.

 

A V 12 is a 12 cyclinder engine with a pair of connecting rods on a single crankshaft throw. Thus, a V12 has 6 throws on the crankshaft.

A Flat 12 is a 12 cylinder engine with a single connecting rod per crankshaft throw and two throws between a pair of journal bearings. This is also known as horizontally opposed.

A V12 can have any angle between the banks. 60 degrees is the natural engine architecture for a longitudinally narrow V12, 180 degrees is the natural engine architecture for an engine that is vertically short. It is possible to build a prfectly balanced V12 with a 120 degree bank angle (although I am yet to see one.)

One might note that the Inline 6 has excellent engine balance, better than either the flat plane V8 or the cross plane V8. An horizontally opposed flat 6 engine is just as well balanced as an inline 6 engine. This is why Prosches have used this arhitecture.

The Berlinetta Boxer and Testarossa used the flat V12 engine architecture, and placed the vertically compact engine above the transmission. This lead to great mass centralization, but a higher center of gravity than desired. The F1 flat V12s hat the transmission out back and a very good center of gravity. This architecture was the pinacle of F1 until ventrui cars (ground effects) came around and the space occupied by the cyclinder banks became needed for the ventruies.

In my opinion, the proper andgel for a mid engine V12 is 120 degrees, with the transmisson hanging out the back. This would give a shallow deck height for the rear bonnet, and a very good center of gravity. If the engine were not just too long for a decent wheel base.....perhaps it the 12 cylinder only displaced 3 litres.....

 

I stand corrected. Thank you for the clarification.

 

And just to make it more confusing, modern Ferrari V12s have been opened up to 65 degrees to make more room for intake ducting. So I had a 60 deg V12 and have a 65 degree V12, but never had a 180 deg V12.

Taz
Terry Phillips

 

Since a V12 is simply 2 I6 engines on a common crankshaft, and the I6 is a perfectly balanced engine, any bank angle is acceptable for balance. The only sour point is that if the angles are not a multiple of 60 degrees (720/12) then the power pulses to the crankshaft will not be even.

So the 65 degree bank angle V12 has power pulses at 65 and 55 degree intervals.

 

I think you're confusing the definition of "boxer" in the mix here. A boxer engine is 180* opposed with pistons on their own crankshaft pin, a non-boxer's opposing pistons share a crank pin. Wether a Vee can be 180* or not is a different discussion.

 

............... you can combine a V with an opposed piston

....... the result is an amazing engine

http://en.wikipedia.org/wiki/Napier_Deltic

the interesting bit is no cylinder heads or valves.

 

Ferrari has never made a production flat 12 engine...only 180 degree V-12s in the Boxer and TR series...

 

Can't agree with you guys. On what sacred temple wall is it carved that a "flat 12" means only a "horizontally-opposed flat 12"? IMO, "flat 12" includes both horizontally-opposed and non-horivontally-opposed 12 cylinder engines -- i.e. "flat" refers only to the angle (180 deg) between the banks and "12" to the number of cylinders.

 

And here I thought this was a question about a "stupid engine"...I was about ready to get out my answer book on the 1942 Lincoln V12, 1950s Saab two-stroke/three-cylinder plant...

Thank you -- I'll be here all week. Try the veal and tip your server.

 

It gets very difficult to fit a flat twelve in between the front wheels when they are in the fully turned position in a front engine application. It would be tough to do with overhead valves, with overhead cams even more so. If you are going with a mid-engine layout it can readily be done, but, as mentioned earlier it messes up the airflow under the car if you have tunnels for getting the air out from under the car and that is the issue for a racing car. For a street car it can be done.

 

I disagree. They have made flat production engines. All 180* opposed engines are flat. 180* is as flat as they get. Ferrari hasn't made a production boxer engine, no matter what any of the Bs may or may not stand for in BBi.

 

"Design and Tuning of Competition Engines" Robert Bentley: There is one multi-cylinder engine that combines almost unsurpassed balance and even firing. It is the horizontally opposed ... with a two throw crankshaft--popularly known ad the Flat-..., pancake ..., or boxer.

The Berlinetta Boxer did not have a boxer engine, it had a 180 degree V12.

 

So your definition of a boxer engine is a horizontal flat engine with a single plane (two throw) crank?

In other words a boxer does not include a multi-plane crank? If that's what you're suggesting, who's the authoritative source that says that's the case?

For clarity, the Bentley quote merely indicates that a two throw crank in a horizontally opposed engine is a boxer, not that such a crankshaft configuration is the only boxer configuration.