68 replies to this topic

[HartleyHare]

A W12 can be a set of four banks of three cylinders, but is more likely to be similar to a pair of Volkswagen VR6 type engine blocks on a shared crank: Each block is a pseudo V6 but the narrow angle of the vee means they can shared the same head.

As I posted on the desert that is the 'Rumour and Gossip' topic, I suspect that the effort expended by McLAren and Ferrari in getting their respective cars' weight as low as possible might be because a heavier motor is waiting in the wings....

Also the matter of efficiency of a 12 versus 10 cyl motor, there are other factors which are important - such as the ease of charging the cylinder with gas. The 12 will have a smaller volume (each cyl 16.7% smaller) required to be filled but at a higher rate, due to higher revs. But the airflow pressure into the engine is independant of the engine itself - it is determined by the aerodynamics of the airbox of the car. This should mean that revs can be extended upwards whilst maintaining an efficient burn, providing greater peak power and a broader powerband.

[IndyIan]

PDA, Hartley Hare,
A problem with 12 cyl. compared to 10 cyl. is oiling the engine. I doubt that because each cylinder is slightly smaller in a 12 cyl than a 10 that each cylinder would need less oil so even if a 12 cyl revved at the same rpm it would lose some hp just pumping more oil around.

Then when a 12 cyl revs higher it becomes less efficient again and requires more fuel because it has to pump more oil faster. A 12 cyl engine may make 5% more hp but could need 10% more fuel to do it, making the car heavier and slower. I think this is why ferrari went to a 10 cyl in the first place.

I do hope ferrari or honda figure out ways to get around this as the last ferrari V12 sounded awesome!
Cheers!

[tak]

Tony-
great derivation--makes much more sense now. As for dT/dt, I have no idea! BTW, I did not mean my earlier remarks to be critical--please don't take them that way!

On the W12, If I remember correctly, that engine was put together by an organization dubbed "Life", and run by the Osella team before they bankrupted (hence, Osella Life team). The basic configuration was 3 banks of 4 cylinders each, forming a "W". I believe it was 120 degrees total included angle, meaning 3 banks separted by 60 degrees. It was a miserable failure. One of the big problems cited was the exhaust pipes out of the center bank heated the intake of one adjacent bank. That was the public reasoning. In reality, I think they had huge crank vibration and bearing problems. In almost all "V" type engines, two connecting rods share a common crank journal. For example, a V8 has 5 main bearings that support the crank, with 1 journal hosting 2 connecting rods between each main. A V12 has 7 mains, with each journal between mains supporting 2 connecting rods. In inline 4 typically has 5 mains, with each journal between suporting 1 connecting rod. In the case of the W12 engine, IF they went with a 5 bearing main, each journal between mains would have to support 3 connecting rods (very strange). The other alternative is to do 7 mains, with each journal between mains carrying 2 connecting rods. Problem here is that you are back to the length of a V12, but with a higher center of gravity.

One more note on Boost figure between F1 and CART. I believe The numbers quoted by PDA are "absolute" measures--they include atmospheric pressure (1 bar or 14.7 psi or 30 in of mercury). The numbers I quoted in my earlier post are "guage" readings, and do not include atmospheric pressure. (For example, if you measure the pressure in a car tire with a gauge, and it reads 30 psi--this is the "gauge" pressure. In reality, the tire has 44.7 psi "absolute". There are of course 14.7 psi outside the tire as well(unless you are at altitude, but that's a different story!).

[PDA]

Tak - correct, the 40 in Hg is absolute, so the engines have in fact very low turbo boost.

On the subject of W12 emgines - There is a splendid 30's special that runs in UK vintage/historic events called the Napier Railton special. It was built for the Brooklands outer circuit, and is quite a handful on road circuits. It has a Napier Sea Lion aero engine, which is 24 litres, with three banks of 4 cylinders with, I think, a 60degree included angle. Each cylinder has its own exhaust pipe, with no linking down to a common pipe. Each is like a drain pipe, and the noise it makes is incredible.

Equally interesting, and almost as bad, was the H 16 3 litre BRM engine of 1996.

[Yelnats]

Christiann, Your comments about the 3 litre V12 only recently becoming feasible is not born out by history. I recall watching a very succesfull 3.o litre v12 Ferrari race in the World Sports Cars in the late fifties and early sixties and it won Le Mans and numerous other races. Racing V12's have been built as small as 1.5 litres but this is generally agreed to be overkill for such a small displacment.

Until the introduction of the V10, tradition had dictated that only 4, 6, 8 and 12 cylinder engines were sufficiently balanced to survive in a high reving racing environment. But recent experience has proved this incorrect and the V12 has fallen into disfavour as offering very little power advantage for the additional length and complexity. F1 packaging has become so tight in the last ten years that few designers can be bothered accomodating the extra length of a V12 and the major redesigns of suspension and chassis involved.

The fuel consumption disadvantage of a V12 commes from a complicated mix of greater mechanical losses due to more ring area cylinder and crankcase drag, greater heat loss due to larger combustion wall area, more valves to open and close and the fact that a more powerfull v12 engine pushes more air/fuel mixture through in a given time period.

The main advantage a V12 has over a V10 is a shorter stroke for a given bore/stroke ratio which allows more RPM for a given piston speed. This shorter stroke also means it has a larger piston area for a given displacement gives more room for larger valves and better breathing.

I can't envision the V12 revolutionizing F1 soon as the V10's in use now are not showing any signs of peaking in output and each year show impressive HP gains.

[HartleyHare]

The interesting thing about the configurations is that so many people assume that the V10 is the optimum. I'm not convinced - I think a lot of teams operate by the 'purple pole principle'. If they see a purple pole in the winning car, they'll put it their for the next race. The Ferrari V12 was pretty close to the pace in the early to mid '90's, and I still wish they'd persevered with it. But it was one area of 'doubt' (like the drivers) that Ferarri felt they needed to eliminate.

The odd thing is that you could use (almost) all the arguments that indicate a 10 cyl motor is better than a 12 cyl to 'prove' that an 8 cyl is better than either!

I just wish we had the variety. At some tracks the 12 cyl motor would shine, at others the 8 cyl's packaging advantages might be crucial. Perhaps if we had the same tracks we had 10 years ago we'd still have V12's running. But with the current proliferation of go-kart track circuits in the F1 calendar, the absence of even one V8 (the last non-V10 format to win the title) is a little surprising.

[Yelnats]

HarleyHare, I aggree that imitation is easier than inovation and the V10 could be one of these cases. But nothing succeeds like sucess and the V10 has had plenty of that. We shouldn't forget the reign of the V8 for 1o or more years in the sixties and seventies. Could the V10 last as long? Sure, why not?

But I still would like to see a V12 in F1. With Ferrari being run by a commitee I see no more reason for them to commit to the V12 than Mercedes or Ford. Perhaps BMW will try but this is a big step for a new entrant.

[ket]

When turbo was banned, Ferrari was actually planning to adopt the V10 configuration as research has shown that V10 offer a good compromise between torque, power, consumption and packaging. Renault, Honda and Alfa-Romeo were going for V10. However Enzo Ferrari was still around and he always hold the view that a proper racing engine must have 12 cylinders. The post-turbo V12 was a result of deference to the Old Man's wishes.

[Christiaan]

Yelnats, I am sure you can appreciatte that the v12 i the 60's revved a lot lower and had less power than that of the 90s. this means that the inherent problems with lubrication and stresses were not there in the 60s

[tony]

I was in a hobby store the other day and they had some old F1 models. One that I found interesting was a 6 wheeled Tyrell. I have never heard of or seen this thing before. Does anyone no about it? Was it just a test, a joke, or did Tyrell actually use it in races? Did other teams has 6 wheeled cars?

[DangerMouse]

The Tyrrell was banned very quickly (I can't remember exactly) but I believe it got banned even before it turned a wheel in a race.

Williams were also working on a six wheeler at the same time.

[IndyIan]

tony,
I've seen race footage of the 6 wheeled tyrell on speed vision so I think it got into a few races, I don't think it was doing very well or they would have shown more of it. The idea behind it was to reduce aerodynamic drag with the shorter tires so they needed 2 more to maintain traction.

[SlowDrivr]

In case anyone hasn't noticed, there's now a technical forum!

[PDA]

The six wheel Tyrell ran for two seasons and won one race, and second and third in a number of others. It was not banned: the ban on more than 4 wheel vehicles came later. The reason it was dropped was that Goodyear were unable/unwilling to continue special development of a tyre only used by one team.

The Williams 6 wheeler only tested. March also showed a six wheeler to the press, but it naver actually ran. Many think it was just a publicity stunt and March had no intention of ever running it. It had the close coupled wheels at the back, and it would have been near impossible to make the three differentials work in any meaningfull manner.

[baddog]

The tyrrell P34 was anything but a dog. raced for several races including winning the swedish grand prix of 1976 the car had significant technical advantages, but was dropped, allegedly due to problems with tyre support.

Shaun

[Megatron]

The 6 wheeled Tyrrell actually had a purpose behind it. In the 1970's, serious work was starting to be down the the aerodynamics and it was learned that the tires creat nearly 60% of the drag across the car.

Someone thought that if you have four really small front tires instead of two very large ones, you could considerably cut the aero drag without effecting downforce.

Thus, the 6 wheeled car became a reality. People considered it a joke, but really it was a great idea.

As stated earlier, however, the main problem with the car was tire devolopment. Tyrrell depended heavily on Goodyear to keep devolopment of the small front tires on a par with their larger counterparts, and for a while, Goodyear did a decent job of it.

However, with only one team running them, devolopment was nearly certain to fall behind, and after 1977, the Tyrrell went back to just four tires.

Williams and Brabham also built "prototype" six wheeled cars, but never decided to race them after Tyrrell pulled out. Brabham actually constructed two different cars for consideration.

Aside from tire devolopment, other problems with the car were weight distribution, drivability, and suspenion.

The idea would have to be eventully abondened anyway, as this was just before the introdution of ground effects, and with such little air flow to the undertray, it would be difficult at best to build an effective ground effects car with 6 wheels.

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Death through Tyranny - Megatron



[This message has been edited by Megatron (edited 08-10-1999).]

[tak]

I don't remember where I read it, but while the six wheeled Tyrell was designed for low drag, it's real strength was that it turned into corners better than any other car of it's time...

[Christiaan]

OKAY ALL YOU TECH BUFFS
We have a new playground. Check out the new forum and give all credit to Bira!

Imagine a modern day pitstop with that Tyrell

[tony]

Thanks all for the info on the 6 wheeled machines.

I am switching to the Technical Forum.