Why no 5 Valve Engines?

[uzael]

I've seen in the technical regulations that the engines are allowed to use up to 5 fuel valves per cylinder, but as far as I know no manufacturer use that setup. Is there some technical reason why it's not feasbile or is anyone afraid to branch out into a new area of engine development?

[rodlamas]

Simply because this is an FIA restriction.

Engines can have no more than 4 valves per cylinder.

Cheers

[uzael]

ARTICLE 5: ENGINE
5.1 Engine specification:
5.1.1 Only 4-stroke engines with reciprocating pistons are permitted.
5.1.2 Engine capacity must not exceed 3000 cc.
5.1.3 Supercharging is forbidden.
5.1.4 All engines must have 10 cylinders and the normal section of each cylinder must be circular.
5.1.5 Engines may have no more than 5 valves per cylinder.


seems to me the FIA allows it.

[Guest]

I think the weight savings of a 4-valve is superior to the increase in surface area of the 5-valve.. especially at the rpm's they're turning.

[West]

Could be less complexity in the engine or fuel economy.

[Reca]

In early ‘90s 5 valves per cylinder was present in F1 engines (Yamaha, Ferrari and also Peugeot IIRC) but then the solution was discarded. Currently an example of engine designed solely for race purpose and still using 5 valves is the unit of the Yamaha M1, the MotoGp contender.
The main advantage of the solution (beside the total intake area a bit larger) is that each valve is lighter and so this allows to increment the revs still using metal springs. That’s no more an issue for F1 because of pneumatic springs but it’s the first reason for the choice in the M1 revving up to 15-16k rpm. Anyway, according to Mr. Yoda (Yamaha engineer) over a certain value of bore also this advantage is nullified and 4 valves becomes the best choice (M1’s engine is a 4 cylinder and B is probably under 85 mm, for an F1 engine it’s 96-98 mm). That’s because with larger bore it’s difficult to keep a good combustion efficiency, the design of the combustion chamber is very critical, 5 valves just make it even more complicated. Another problem is that then you have also to control the interaction between 3 different flows at the intake instead of two and often the bad interaction reduces the mass flow in spite of the larger area.

[Senna Fan]

In the early 90's Ferrar had a 5 valve/cylinder setup, but after Osamu Gotto moved to Ferrari (Former Honda engine designer, is an exhaust specialist, now is the Head of the Petronas Engine program), he changed all of that and was responsible for Ferrari moving to a 4 valve design.

[Reca]

The Ferrari V12 with 4 valves/cyl debuted on the F-93A at the qualifying of the Germany GP in July 1993. The race debut was here in Monza in September.
According to the biography on grandprix.com in 1993 Goto was still working for McLaren.

An update to my previous post. According to latest reports the new version of the Yamaha M1 engine for 2004 will have 4 valves per cylinder. At the moment I don’t know if the new version will be adopted only by the official team (Valentino Rossi and Carlos Checa) or it will be also at the disposal of the other “a bit less official”, team (Abe and Melandri).

[proengineer]

the most important reason why not 5 Valves is, that 5 valves are very
bad to steer, you nead a very complicated system to trigger the 5th valve,
the diameters of the valveplates are smaller, and the positioning of the
spark plug is most difficulter in the combustion chamber, as with 4 valves... the valves have bigger dihedral angles!!! (bigger cyl.head!!!)

another reason why they dont use 5 valve technology, is the weight, you
have more moved components, you need a bit bigger cylinder head and
the advantage you´ve won with the 5´th valve is lost...

so i hope that helps you a little bit...

Kind regard´s

ROBs ;o)

engineering@gmx.at

[Silver-Arrowz]

In the early 90's Ferrar had a 5 valve/cylinder setup, but after Osamu Gotto moved to Ferrari (Former Honda engine designer, is an exhaust specialist, now is the Head of the Petronas Engine program), he changed all of that and was responsible for Ferrari moving to a 4 valve design.

I read something about this too. It was all mathematical but apparently 5 valves had little or no advantage over 4, and also it was less fuel efficient.

[Monstrobolaxa]

Humm having 5 valves....will lead to extra losses due to friction, which would lead to a need of extra energy to work the acutating system (probably increasing the fuel consumption)....cause you'll need a actuating system for this extra valve....the other thing would be....the weight....the other thing I see is.....would it be used as an intake valve? or a exhaust?

[Rogue230]

Intake or exhaust would seem to be arbitrary or predicated on the placement of the spark plug and other comonents.

I would suspect intake though becuase engines, at least ones I've dealt with tend to maintain an an area ratio where total exaust area is about 85% of total intake area.

This would make the intake valves very large relative to the exhaust valves were three exhaust valve to be used.

With three intake valves and two exhaust valves the valves would be closer to the same size allowing more concentric positioning.

[pyry]

5 valve engines are actually more fuel efficient, but more complicated. the air intake and outtake are more precise, but im under the impression that its not an f1 thing due to the high rev. we have an Audi a4 2001 with an 4 cylinder 20v 1.8l turbocharged engine, having 163hp, 220nm torque, yet the consumption is 6.2/8.0/9.8

[mep]

It would be used as an intake valve because the presure different of the exaust gases is much bigger than the intake air.
With pneumatic valves it is easy to steer five valves and it is possible to make an burning chamber witch looks a litle bit like a ball, so the burning of the petrol is ideal. This would made an average.
In this case the third valve wouldn't lie in a line with the two other intake valves. It's tourned a litle bit off with a special degree.
The five valves engine comes from motorcycles because with only one or
two cylinders it's not important how big your cylinder head is.
But in a ten cylinder f1 engine the size of the cylinder head is important.

[Monstrobolaxa]

Osamu Goto

worked for Honda - from 1970 to 1991
worked for Mclaren - executive Engineer - 92 and 93
in 1994 he went to work in Tokyo
at the end of 1994 he went to Ferrari and left in 1996
1997 - untill today - Petronas engines