Question about the cylinder angle.

[riff_raff]

As a race fan, the noise a race engine makes is very important- it's a huge part of the experience of seeing a race live!

Of all the types of racing I've seen live, top fuel drag racing provides the greatest tactile sensation. As the cars go by at over 300 mph, you can feel the heat from the exhaust (at 100 feet away) and your eyeballs literally rattle about in your skull!

As far as F1 is concerned, most engines for the last 20 years have had acoustically pleasing header designs. Whether they're V6 turbo's or N/A V8, V10 or V12's, they had even firing in each cylinder bank/header, so they sounded good. The only race engines that sound flat are NASCAR V8's (with a cruciform crank) or Superbike 45 deg V-twin Harley's and 90 deg V-twin Ducati's.

Also, remember when the IRL started, they used N/A 90 deg V8's. The engines sounded rather "un-race-like", so two years later they switched to a 180 deg (flat) crank configuration, to make the engines sound more "race-like".

As for the W12 engine proponent, Mr. Guy Negre, he is currently pimping for a company that is developing an "emission free" commuter car that runs on compressed air! http://www.theaircar.com/aboutmdi.html

Compressed air....Hydrogen fuel cell....Perpetual motion.....What's the difference? All of these concepts ignore the basic laws of economics, chemistry and physics. Is Mr. Negre any worse than Honda, GM or Toyota and their fuel cell B.S.?

I'll get off of my soap box now.......

[Reca]

Riff_raff : obviously the H16 is in my “crazy designs” chart, although I’ve to say that I do prefer the W12. Unfortunately I never had the chance to see and hear the H16 live, I was still in my parents’ dreams (should I say nightmares ?) when it was racing.

As for engine sounds, pretty much all the race engines I heard at the track are quite pleasant, the Ducati L-twin (known in Italy as “pompone”) is a matter of personal preference, some love it, some hate it, I’m definitively in the first group.

The worst engine sound I heard at the track has probably to be the one of the F.Renault V6, I was at the race a couple of years ago but I left after few laps for no other reason than the sound, 20 or so lawnmowers running on the track aren’t very exciting. I should say that it was 5 pm and the same day I did see also other races, including FIA GT so maybe the comparison increased my dislike... FIA GT sound great, also because many of them are V12 and certainly they do scream... these are probably the only cars, beside F1, that you can hear distinguishingly from the centre of Monza (about 2.5-3 km from the track). Most of the other engines’ sounds are “smoothed” by the trees of the park and then town noises do cover the rest, F1 and FIA GT on the contrary do want you to know they are there and then it’s hard to ignore the call...

Why would a W12 have less friction than a V10 with similar characteristics? Doesnt it have more moving parts (for instance multiple c-shafts and more cylinders)?

To make a long story short the friction losses in high revving engine depend mainly by the velocity of “crawling” (right term ?? I found it on the dictionary but I don’t know if it’s the right English term) between the parts and by the inertial loads. With more cylinders you have very likely smaller hence lighter pistons (smaller pins, lighter valves etc etc), all the parts have to complete a shorter path and all the parts are subjected to lower accelerations.

[...] it's difficult imagining anything but a crankshaft with just four throws, three rods on each throw [...]But it sure is a cool way to package twelve cylinders in such a short package.

To avoid the three rods per throw, in the Life W12 the con rods of the lateral cylinders weren’t connected directly to the crankshaft but to the con rod of the central cylinder, a solutions seen also on some aeronautical engines.
As for the length, according to the data I have the Life W12 was 530 mm long with a 85 mm bore, the same year a Ferrari V12 was 660 mm (bore = 84) an Honda V10 620 mm (91) and a Ford V8 595 mm (96). Obviously the W12 was also the widest, 704 mm compared with the 550-600 mm of the other V engines.

[DaveKillens]

Interesting observation, and I should have remembered, since I used to work on those very types of engines, aircraft radial engines.
http://science.howstuffworks.com/radial-engine2.htm
That would explain some packaging issues, but those master rods would be very massive for a racing application.
For me, one of the most inane racing engine sounds is the classic (and incredibly successful) Porshe flat six. Now that was a sound that failed to raise any excitement in me.
There are so many beautiful engines that make glorious sounds. Personally, any Ferrari V-12 for cars, and strangely, for motorcycles, the BSA Triple of the late 60's and early 70's. That 750 cc three cylinder going into a three-into-one megaphone sounded like music to my ears.

[manchild]

What about old 4 cyl. BMW M3 DTM?

[riff_raff]

Reca,

The noise you hear from an engine is mostly due to its exhaust. And an engine with even exhaust intervals always sounds most pleasant (ie. a 60deg V6, a 90deg V8 with a 180deg crank, a 72 degV10 or a 60deg V12).

I was just watching the GP bike qualifying at Laguna Seca, the 4-stroke V4's sounded odd. The only explanation I could think of is that they were firing 2 of the 4 cylinders simultaneously. Thus making it sound like a V-twin.

Ultimately though, sound-wise, there's nothing that compares to a top fuel dragster. It's indescribable! If you ever get out here to southern California, give me a call. I'd be more than happy to take you out to the NHRA Winternationals at Pomona. It's something you have to experience at least once in your life!

Good Luck.
Terry

[manchild]

...Ultimately though, sound-wise, there's nothing that compares to a top fuel dragster. It's indescribable! ...

Do you perhaps have some links to high quality sound file of dragster engine?

[Reca]

The noise you hear from an engine is mostly due to its exhaust. And an engine with even exhaust intervals always sounds most pleasant (ie. a 60deg V6, a 90deg V8 with a 180deg crank, a 72 degV10 or a 60deg V12).

Yes I know that, nevertheless the Ferrari V12 of 90s don’t have an even fire interval (V was 65° and then 75° the last two years) and I like the sound very much anyway

I was just watching the GP bike qualifying at Laguna Seca, the 4-stroke V4's sounded odd. The only explanation I could think of is that they were firing 2 of the 4 cylinders simultaneously. Thus making it sound like a V-twin.

Yep, the Ducati Desmosedici is a “Twin Pulse” as Ducati call it. That was the idea since the start of the design (I spoke with a Ducati engineer in November 2001 when the bike was still in design phase and he told me “not a twin but sort of...”), although for the first season they used a standard firing order because of reliability issues, IIRC only since 2004 they are using the “Twin Pulse”.
Anyway almost all the engines in MotoGp have an uneven firing interval or are “big bang”, also the Yamaha and Kawasaki 4 in line. Apparently it’s a big advantage in bikes rideability (spelling ?), according to a Kawa engineer : “That’s the modification that allowed the biggest jump in the performance of the bike”. A couple of months ago I read that also a team in Supersport or maybe Superstock, was planning to modify a Yamaha production engine to have the “big bang” and there were plans to change the rules to avoid it since obviously it’s against the spirit of the category.

Still talking about MotoGp engines, the reporters of the Italian tv have lot of freedom in the pits (one of Ducati’s engineer is a cousin of the journalist...) and during the qualifying usually show part of the bikes, a few races ago they did show the Ducati engine, the KTM one, and the following race the Kawasaki engine, all disassembled from the bike. The Kawa engine is enormous compared with the other two, particularly with the Desmosedici that is very small and also quite light (60 kg). The journalist put his hand over the Ducati’s head and it was about as wide as his span, say 24-25 cm.

Ultimately though, sound-wise, there's nothing that compares to a top fuel dragster. It's indescribable! If you ever get out here to southern California, give me a call. I'd be more than happy to take you out to the NHRA Winternationals at Pomona.

Well, until now the thing that impressed me the most was a Tornado taking off no more than 20-25 meters from me, if you promise me that the dragster is just half as impressive then it goes straight in the list of “things to see” !

[riff_raff]

Reca,

(sorry, but it's a bit off-topic)

Ahhhh....Ducati bikes! You Italians seem to have such a great eye for aesthetics. The 749 and 999 are both very elegant designs.

I also like that Ducati goes their own way with mechanical design. They still use use steel tube space frames instead of the typical (Japanese) aluminum twin spar. And Ducati still sticks to their trademark desmo valve train, even though it's hard to justify on a cost-versus-performance basis. Good for them!

And by the way Reca, your member info says you're located in Monza, Italy. If you're native Italian, I must compliment you on your English. It's quite good!

Regards,
Terry

[DaveKillens]

Wow, the "big bang" theory. I think it was first discovered on the Harley oval dirt racers of the 60's, and on. The theory was to give multiple cylinder engines a single firing pulse, as much as practical. From what I heard, such a drivetrain gives a very pronounced torque spike. On a limited traction situation, the rider/driver can sense oncoming loss of traction. Of course, such a design places brutal loads on the entire drivetrain. I think Honda gave it a try on the CART Honda that Bobby Rahal drove in the last few years of his career. I was at the Toronto Indy, and Rahal's car sounded very different than the rest.

[riff_raff]

Dave Killens,

Maybe I'm wrong, but I think the "Big Bang" firing order (multiple cylinders firing simultaneously) originated with the Honda 500cc 2-stroke GP bikes. The way I understand the theory is as follows (and I've never ridden a 500cc GP bike so I may be wrong): the fast riders of the time figured out that sliding the rear end through a turn was the fastest way to go. This was courtesy of ex-flat-trackers like Kenny Roberts. To get the rear end sliding, you had to use the throttle. An engine that had two cylinders firing simultaneously produced a bigger peak torque at the rear wheel, and thus spun the rear tire more readily and made it easier to slide the bike thru the turns under control, resulting in faster lap times.

Another benefit of "Big Bang" engines is that when you fire two cylinders at opposite ends of the crankshaft, simultaneously, it reduces the torsional moment applied to the crank. Thus extending the fatigue life of said crank.

[Reca]

Ahhhh....Ducati bikes! You Italians seem to have such a great eye for aesthetics. The 749 and 999 are both very elegant designs.

Actually the responsible of the design of 999 and also of the Multistrada is a French man, Pierre Terblanche... to tell the truth, at the launch of both these bikes many Ducati purists weren’t very happy. The 999 front end, especially in the first version with the now fortunately gone “cuts” at the side of the glass, looked at first sight too much “jap” (as you can imagine Japanese bikes are, for Ducati fans, the “enemy”) and the exhaust at the rear end isn’t as good looking as the twin tubes of the previous model, then there’s a double arm fork at the rear instead of the mono, many saw it as a betrayal.
Obviously most of the criticism was also a consequence of the love for the previous series, the 916->998, designed by Massimo Tamburini; the man just has It, each bike from his pen is a masterpiece, and it’s normal to expect criticism for the bike having to replace a masterpiece... Terblanche worked for years as Tamburini subordinate and I’m sure he learned a lot from him but there are things you just can’t learn.

To see a few pics of Tamburini’s work, go to http://www.mvagusta.com and then click on the right on the CRC logo under “Design”, there’s a pics gallery of the F4 Tamburini a special edition of the, already wonderful, F4.

BTW, you said you’ll take me to a dragster race, well in the same way, when you come to Italy, give me a call, I’ll take you to Borgo Panigale to visit both Ducati’s Museum and Factory (and since we are there, also Galleria Ferrari since Maranello isn’t too distant...).
Since I visited it in 1999, I never looked at a Ducati bike the same way as before, trust me, if you see how these bikes are made you easily understand why they aren’t cheap.

And by the way Reca, your member info says you're located in Monza, Italy. If you're native Italian, I must compliment you on your English. It's quite good!

member info is correct so I can accept your compliment, Thank you ! Although I’m afraid after few seconds talking, in person, with me you would very likely change opinion, I do little conversation exercise in English and since I learned French at school I got no education on pronunciation... while writing at least I can take my time, then the dictionary, Word orthographic control...

[Reca]

Wow, the "big bang" theory. [...]

I don’t know when it first was “discovered” but it became famous worldwide, as Terry said in 500cc GP, mainly during the Doohan era. At the time many thought it was mainly a psychological thing, Doohan was doing the winning with it and other drivers wanted it too, but then some of them didn’t notice the performance difference they were expecting; furthermore when Doohan switched back to the “screamer” (standard firing order) he continued to win anyway so the unconvinced people considered it as a confirmation of their doubts and “big bang” became for many people synonymous of placebo.
Now it looks like there’s some truth in it, at least, that’s what one would assume when almost all the MotoGp manufacturer adopt it... To explain the effect there are slightly different theories, from the most simple explanations like “the longer interval between ignitions gives to the tyre more time to recover” or “the tyre rotates more so most of the contact patch changes between two ignitions” up to the more complicate “it’s related with tyre vibration modes and frequency of the ignitions”; what all explanations have in common is that “big bang” makes the rear tyre work better, fundamental in bikes given the excess of power in relation to the contact patch area and the lack of downforce, so the rider can open the gas with more confidence being more in control of the bike.
In term of effect on engine characteristics, when Ducati finally introduced the Twin pulse (I verified, it was Assen 2004) they said that it caused a little loss of power, but I think it’s mainly related with exhaust tuning than with the firing order per se (and anyway Ducati Desmosedici problem isn’t certainly lack of power...).
Some people also say that the “big bang” gives more torque at low rpm, don’t know if it’s the case but I suspect it could also be a recollection of the Ducati dominance in SBK. Since one of the reasons was arguably the low end torque, they associate that with the lower frequency of ignitions of the twin (sort of “natural big bang”) compared with the 4 cyl. But one shouldn’t forget that these years the Ducati twins in SBK were 1000 cc while the 4 cyl were 750 so any torque advantage was most probably coming from the displacement.

[riff_raff]

Reca,

The Ducati 916, in my opinion (with its single-sided swing arm), is one of the most beautiful bikes ever produced. The only other bike that even comes close is the Honda NR750 Oval Piston bike. Of course, the NR750 costs about $10,000 more than the Ducati (If you could get one!).

Regards,
Terry