v12 or v10

[Greg Locock]

In some respects V angle doesn't matter for a V12 because it is essentially two I6s welded together. But that's not really the case. Fo F1, aero is a consideration, but more important is charge robbing and exhaust pulses.

If there is no gas crosstalk between each bank then you are still left with torsional vibrations, which can and do break crankshafts and camshafts.

[Zynerji]

In some respects V angle doesn't matter for a V12 because it is essentially two I6s welded together. But that's not really the case. Fo F1, aero is a consideration, but more important is charge robbing and exhaust pulses.

If there is no gas crosstalk between each bank then you are still left with torsional vibrations, which can and do break crankshafts and camshafts.

These are the nuggets of gold I come here to find!

Care to elaborate on your last paragraph, Greg?

[Greg Locock]

How do you mean? TVs are why your engine has a harmonic damper, and why some camshafts run a metal rubber metal drive cog.

As you change the v angle you'll change the phase relationship between left and right hand banks. I've never done TVs while varying V angle. So, supposing you had zero degrees, you've got a big I6, explosions and inertial forces from each bank are in phase, or 180 degrees you've got a boxer and the forces are 180 degrees out of phase (probably wrong in detail).

I've just found this paper, which looks like a great start. https://www.enginehistory.org/Piston/Be ... nalVib.pdf

He mentions Ker Wilson, a beautiful set of books that we had at Lotus (we had a great library), and which I devoured.

[echedey]

so was the ferrari v12 engine at 75º a good or bad idea that ferrari had, was it worth it or should it have been left at 60º?

[Greg Locock]

Engineering is about compromises. They got lower frontal area, better cooling, more space to put stuff in the valley.

[saviour stivala]

''FERRARI V12 engine at 75 degree'' was the tipo 043 of 1994 (Claudio Lombardi/Osamu Goto) it produced 830 bhp and by the end of 1994 was producing 850 bhp@15800 rpm, This is said to have been the most powerful NA V12 to race in F1. The next FERRARI F1 engine was a V10.

[J.A.W.]

How do you mean? TVs are why your engine has a harmonic damper, and why some camshafts run a metal rubber metal drive cog.

As you change the v angle you'll change the phase relationship between left and right hand banks. I've never done TVs while varying V angle. So, supposing you had zero degrees, you've got a big I6, explosions and inertial forces from each bank are in phase, or 180 degrees you've got a boxer and the forces are 180 degrees out of phase (probably wrong in detail).

I've just found this paper, which looks like a great start. https://www.enginehistory.org/Piston/Be ... nalVib.pdf

He mentions Ker Wilson, a beautiful set of books that we had at Lotus (we had a great library), and which I devoured.

Also on the site you linked Greg: http://www.enginehistory.org/Piston/fo/FO.shtml
V12 firing order arrangements can be viewed, & in a fair number of variations, allowing
comparisons between engines, such as for example the differences between two large
R/R V12 types flown in Spitfires; Merlin/Griffon (which, with individual ejector exhaust
stub-pipes, can clearly be audibly distinguished on vid, for those who may care to check).

Another look at the illustrations in this article shows crankshaft torsional vibration/harmonics
amelioration/suppression palliatives employed by R/R for the Griffon, in addition to F.O. change.

http://spitfireperformance.com/griffon-65.pdf


Also worth noting - is a fundamental difference between 180 degree (horizontally opposed/flat)
12cyl engines though.

Almost all of them are not of "boxer" type featuring a crank-throw per con-rod (the Subaru 12cyl F1
attempt is one example, though) - even the Porsche 917 flat 12 was not a pair of their "boxer" flat
sixes joined in tandem, just a typical rod-pair shared-journal V12 crank - albeit mounted in a crank-
case opened out to a 180 degree angle, as the Ferrari BB 512 was too, (so despite any badging or
not, the "Boxer" nomenclature was applied - but the "boxer" claim was pure bullshit 'ad-speak')...

(A bit like 'quad-cam' but worse IMO, for being wrong technically & not simply being used as an
obvious 'dumb-down' hype-term).

[saviour stivala]

''FERRARI 'boxer claim'' revolves around the 312p which had a bore and stroke of 78.5 and 51.5mm,a compression ratio of 11.5:1 and used a firing order of 1-10-5-7-3-11-6-9-2-12-4-8, with 12 units having been build. This FERRARI engine was not a 'boxer - opposed piston' configuration. It was called 312PB ('B' for boxer) only because the the 'B' was added by publications, but never senctioned by FERRARI. If anybody kowns of any 12 cylinder engine having been build in 'boxer - opposed pistones' configuration I would be very interesested to know about.

[Greg Locock]

Oh yes, you can definitely hear firing order. Toyota Landcruiser I6 uses the other obvious firing order to us, so for grins we built an engine in their configuration. Different, not better.

[Tommy Cookers]

''FERRARI 'boxer claim'' revolves around the 312p which had a bore and stroke of 78.5 and 51.5mm ....

this supposedly ordinary example of a quite ordinary type ..... remarkably .... had 'only' .....

4 main bearings
(they tried 3)

don't know about those inspired thereby .....
Alfa Romeo etc
Tecno - a 4 crankpin flat-8 2 litre (3 main bearings ? - and what crankshaftwise & vibrationwise ?

[J.A.W.]

''FERRARI 'boxer claim'' revolves around the 312p which had a bore and stroke of 78.5 and 51.5mm ....

this supposedly ordinary example of a quite ordinary type ..... remarkably .... had 'only' .....

4 main bearings
(they tried 3)

don't know about those inspired thereby .....
Alfa Romeo etc
Tecno - a 4 crankpin flat-8 2 litre (3 main bearings ? - and what crankshaftwise & vibrationwise ?

Could it be - the Ferrari engineer had lately read a W.O. Bentley treatise on short-crank/main-bearing
minimalism - or had taken inspiration from Chrysler's 4-main bearing 'slant-six' reliability?

[J.A.W.]

''FERRARI 'boxer claim'' revolves around the 312p which had a bore and stroke of 78.5 and 51.5mm,a compression ratio of 11.5:1 and used a firing order of 1-10-5-7-3-11-6-9-2-12-4-8, with 12 units having been build. This FERRARI engine was not a 'boxer - opposed piston' configuration. It was called 312PB ('B' for boxer) only because the the 'B' was added by publications, but never senctioned by FERRARI. If anybody kowns of any 12 cylinder engine having been build in 'boxer - opposed pistones' configuration I would be very interesested to know about.

The mid `70s Ferrari 365 GTB Boxer/BB512 was an 'economy' replacement for their famed 'Daytona',
& as a 1st 'full-size' Ferrari mid-engine road car, sought to ride on Nikki Lauda's F1 successes,
so the bogus "boxer" claim was part of the hype used to hide the fact that it was a lesser machine...

By all means look up the (as previously noted) Subaru true 'boxer' flat 12 F1 engine, if it is of interest.

[saviour stivala]

The FERRARI produced 'flat' 12 engines as well as the Subaru 'flat 12 engine were not a 'boxer - opposed piston' engines but a 180 degree flat 12.

[Stu]

The FERRARI produced 'flat' 12 engines as well as the Subaru 'flat 12 engine were not a 'boxer - opposed piston' engines but a 180 degree flat 12.

And the early/mid-nineties 3.5l Group C Mercedes was a 180 degree V12.
A ‘flat-12’ has a different firing order to a V12.

[Tommy Cookers]

The FERRARI produced 'flat' 12 engines as well as the Subaru 'flat 12 engine were not a 'boxer - opposed piston' engines but a 180 degree flat 12.

And the early/mid-nineties 3.5l Group C Mercedes was a 180 degree V12.
A ‘flat-12’ has a different firing order to a V12.

IMO and all that ....
180 degree V12 is just a name for a flat 12 - because every flat 12 every made had 6 crank throws (like a V12)
people started calling it a 180 degree V12 when Lauda won everything

a flat twin has 2 crank throws
a flat 4 has 4 crank throws
a flat 6 has 6 crank throws
a flat 8 has 8 crank throws (unless it's a Tecno)
the above if having respectively 1, 2, 3 or 4 throws would have eg a vibration issue
a flat 12 with 6 throws doesn't

a fellow worker said that horizontally-opposed meant 2 crankshafts and 2 pistons h-o in each cylinder
he having driven such (a 32000 hp Doxford)

hey - how to get on with the new mod !!


I was about to say that a heat-dilution NA engine seems unwise ... but ....
a heat-dilution NA V10 seems less unwise that a heat-dilution NA V12
(h-d meaning design around running always on extreme lean mixture)