![Image](http://images.amain.com/images/large/blh/blh2500_2.jpg)
Devel V16 crankshaft:
![Image](http://roa.h-cdn.co/assets/15/50/768x1152/gallery-1449852806-sm2.jpg)
bound up with the already awkward question of crankshaft design ....Blaze1 wrote:The Devel V16 is a 90 degree engine and it's interesting to see that they have gone with an 8 arm (when viewed from head-on) crank design, which would make it equivalent to a cross-plane V8. From the video it appears to have a cross-plane like V8 rumble to it. I think they could have also used a four arm design (again when view from head-on. The other 4 arms would be in the 'shadow' of the first 4) ....
Devel V16 crankshaft:
http://roa.h-cdn.co/assets/15/50/768x11 ... 06-sm2.jpg
In terms of perfect balance and smoothness (firing order/angle), I think there are 4 possible bank angles, 45, 90, 135 and 180 degrees and 3 possible crankshaft designs (I think 1 of the 3 designs will result in unevenly spaced firing within each bank however). The 45, 90 and 135 degree bank angles can use 2 possible crank designs each and the 180 degree bank has only 1 crankshaft design for a perfect fit.Tommy Cookers wrote:bound up with the already awkward question of crankshaft design ....Blaze1 wrote:The Devel V16 is a 90 degree engine and it's interesting to see that they have gone with an 8 arm (when viewed from head-on) crank design, which would make it equivalent to a cross-plane V8. From the video it appears to have a cross-plane like V8 rumble to it. I think they could have also used a four arm design (again when view from head-on. The other 4 arms would be in the 'shadow' of the first 4) ....
Devel V16 crankshaft:
http://roa.h-cdn.co/assets/15/50/768x11 ... 06-sm2.jpg
one might think that one of the few attractions of the V16 eg relative to a V12 is the value of possible different bank angles
at or around 45 deg (more compact via width and simplification of valve gear etc)
or at or around 135 deg (allowing a 5 main bearing design for more compact length, less weight and friction)
btw
I once worked for someone who (I think) had use of a V16-powered MGB
a Motor Gun Boat with 3 diesel engines hurriedly developed (the crankshafts broke every week) from V12s
he was severely shot up (I think taking ammunition and demolition explosives to Sweden for the Danish resistance in late 1943 - when a Red Army breakthrough seemed possible and some in Sweden seemed to ignore their own neutrality)
the rumour mill said he earned a VC (apparently denied by the super secrecy remaining even today because of the neutrality aspect)
I think there was about 10 such MGBs with triple V16s (from an established engine V12 of around 750 hp)Blaze1 wrote: In terms of perfect balance ..... the 180 degree bank has only 1 crankshaft design for a perfect fit.
The idea you mentioned of having only 5 main bearings, if I understand you correctly this would mean only 4 crank journals, with each one occupied by 4 rods?
The gun boat you mentioned, was it a one off design. Triple V16s!
I'm going to looking into those engines you mentioned Tommy, as I've never seen a configuration with more than 2 rods per arm. As for the articulated rods, I've always liked the idea of the blade and fork style. I think the forks would have to absorb friction from 4 surfaces as opposed to 2 for the blades, perhaps this and structural issues is why the configuration isn't used for high revving application.Tommy Cookers wrote:Ferrari won WCCs WDCs and WECs ? with '180 deg V12s' with 4 main bearings (they were said to have tried 3 mains)
Alfa Romeo emulated this, as did Tecno with a 3 main '180 deg V' 8 cyl engine
something this should work with a 16 ie 5 mains and with maybe 150-135 deg, iirc I was guessing 8 throws
agreed you might use or be able to use 4 throws with a 180 deg angle
(the 1950s 180 deg F2 watercooled Andersen had 8 cyls and 2 mains, aircooled Porsche 8s had 9 mains and the 917 had 7 mains ??)
also this V16 seems a good application for articulated rods, giving a very worthwhile saving of engine length, weight and friction
the Life F1 car in 1990 raced with a 3 bank 12 cyl 'W' aka 'broad arrow' designed by Franco Rocchi (ex-Ferrari & MV flat 4 prototype)Blaze1 wrote: ..... as I've never seen a configuration with more than 2 rods per arm. As for the articulated rods, I've always liked the idea of the blade and fork style. I think the forks would have to absorb friction from 4 surfaces as opposed to 2 for the blades, perhaps this and structural issues is why the configuration isn't used for high revving application.
The bank angles are good in theory, but the theory assumes perfectly rigid crank and block. As the engine gets longer, the block and crank get more torsional compliance. This is a very long engine.Blaze1 wrote: In terms of perfect balance and smoothness (firing order/angle), I think there are 4 possible bank angles, 45, 90, 135 and 180 degrees and 3 possible crankshaft designs (I think 1 of the 3 designs will result in unevenly spaced firing within each bank however). The 45, 90 and 135 degree bank angles can use 2 possible crank designs each and the 180 degree bank has only 1 crankshaft design for a perfect fit.
It is strange they didn't opt for a central PTO, as the image shows that the central main bearing is longer than the others, however SME is a small company so perhaps they'd rather go with concepts they are more familiar with.bill shoe wrote: Typical tricks to reduce torsional compliance on long engines include taking the drive from the middle of the crank instead of the end, or using really really large diameter main journals. Don't see either happening on the Devel crank. The Bugatti Veyron used a really awkward W engine configuration to pump out 1200 hp with an acceptably short/stiff crank. The Devel is going to make much more power with a much longer crank? Skeptical, I am (Yoda tribute).
see this Paxman engine history linkTommy Cookers wrote:I think there was about 10 such Camper & Nicholson MGBs with triple V16sBlaze1 wrote: The gun boat you mentioned, was it a one off design. Triple V16s!
converted to cargo vessels for Operations 'Bridford' and 'Moonshine'
117' long and 28 kt
'Operation Bridford' was the 'ball bearing' runs to Sweden
the UK had a need for self-aligning bbs, but there was also some attempt to corner the market
'Operation Moonshine' was supply to the Danish resistance (via Sweden)