Newsgroup: it.sport.formula1.moderato
Titolo: [ENG] Theissen explains difference between V10 and V8

Source: pitpass
http://www.pitpass.com/fes_php/pitpass_news_item.php?fes_art_id=27227
The decision to switch from V10 to V8 engines in Formula One was
made at the end of 2004, leaving the engine specialists to focus their
efforts over 2005 on the new regulations. 2006 sees the culmination of
the switch-over phase. As BMW Motorsport Director Mario Theissen
explains: "The development of a V8 powerplant for Formula One represented
a huge challenge for our engineers - especially given the relatively
short amount of time at their disposal. The V8 is a totally different
concept to the V10. The drop in output is roughly proportional to the 20
percent reduction in displacement. I would therefore expect lap times to
climb by an average of one to two seconds. The reduced output on tap for
the drivers means the cars will spend significantly more time per lap
under peak loads. Reliability is top priority. We can't wait for the
serious action to get under way in Bahrain on 12th March. Only then will
we get an impression of who's really been doing their homework."
Differences Although the V8 with the now compulsory cylinder angle of 90
degrees may look like a sawn-off V10, technically it is an entirely
separate concept with its own specific requirements. The V8 has a
distinct firing sequence and demands a fundamentally different crankshaft
design. Whereas a 72-degree offset crankshaft was used in BMW's V10
Formula One engine, V8 powerplants can feature crankshafts with either
four throws spaced at 90 degrees or four throws spaced at 180 degrees.
Standard production engines are fitted with 90-degree crankshaft variants
due to their better dynamic attributes, but a 180-degree crankshaft is
favoured in racing car engine design. The improved performance this
allows offsets the disadvantages in terms of dynamics.Indeed, mechanical
dynamics and vibrations represent a particularly critical area of
development for the new generation of Formula One engines. The V8 units
have different firing sequences and intervals from their V10
predecessors, which leads to a totally different situation in terms of
vibrations. The V10 entered a critical area in terms of vibrations
between 12,000 rpm and 14,000 rpm. However, this was not an issue as the
engine did not spend much time in this rev band and smoothed itself out
again once the driver stepped up the revs. And, since that was where it
spent the majority of its time, vibrations were not a worry. A V8, on the
other hand, is not so well off. Its vibration curve enters critical
territory later than the V10 - from approximately 16,000 rpm - and
continues to climb from there. It is therefore no longer possible to
think in terms of getting through a difficult patch and everything will
be all right. Now, the problem of constantly increasing vibrations has to
be confronted head on. If you don't get a handle on vibrations, they will
eat into the service life of the engine and multiply the loads exerted on
chassis components. In order to get on top of this problem, the
calculation and analysis of each individual engine component has to be
totally reliable. However, analysis of the individual components is only
part of a bigger challenge. Determining how they work with and against
each other in simulations of the overall system is the main task.
Restrictions Reduced mass should mean less in the way of "bad
vibrations". However, the regulations have sensibly nipped any natural
tendency among the teams to reach straight for exotic - and expensive -
ultra-light materials in the bud. The engineers work with conventional
titanium and aluminium alloys, as stipulated in the regulations. The new
V8 has to be heavier than its predecessor, even though the 2005 engine
had two extra cylinders. This season's powerplants must tip the scales at
no less than 95 kilograms. This should include the intake system up to
and including the air filter, fuel rail and injectors, ignition coils,
sensors and wiring, alternator, coolant pumps and oil pumps. It does not
include liquids, exhaust manifolds, heat protection shields, oil tanks,
accumulators, heat exchangers and the hydraulic pump. Added to which, the
new regulations stipulate that the engine's centre of gravity must be at
least 165 millimetres above the lower edge of the oil sump. The experts
had previously managed to lower the ten-cylinder engine's centre of
gravity to the benefit of the car's handling. However, the longitudinal
and lateral position of the V8's centre of gravity has to be in the
geometric centre of the engine (+/-50 millimetres). For the technical
commission, checking that everything is in order no longer consists of a
simple weighing process. Now, making sure that the rules have been
observed involves weighing on two levels and making calculations
according to the lever principle. Previously a closely guarded secret,
the dimensions of the cylinder bore are now limited to a maximum 98
millimetres. The gap between the cylinders is also set out in the
rulebook - at 106.5 millimetres (+/- 0.2 mm). The central axis of the
crankshaft must not lie any less than 58 millimetres above the reference
plane.Another critical change in the regulations is the ban on variable
intake systems. Known as "trumpets", these systems could previously be
used to optimise the car's torque curve. The fixed duct lengths will now
make achieving good engine driveability a more exacting challenge. The
teams will have to strike a compromise between maximum power and good
driveability. Where the best compromise for the pipe lengths is to be
found depends on various factors. The track layout and the weather, for
example, both play a role. The teams will favour one set of intake pipe
lengths for circuits with long straights - like Monza , Indianapolis and
Spa - where power is critical, and a different selection for twistier
grand prix tracks such as Budapest and Monaco , where driveability
relegates raw power to the back seat. The same applies in wet weather.
The air intakes are, by definition, part of the engine and are included
in its 95-kilogram maximum overall weight, but they can also be changed
up to qualifying.Joining variable intake systems on the black list are
variable exhaust systems and variable valve control systems. The power
supply to the engine electrics and electronics is limited to a maximum 17
volts and the fuel pump now has to be mechanically operated. Only an
actuator may now be used to activate the throttle valve system. With the
exception of the electric auxiliary pumps in the petrol tank, all
sub-components must now be driven mechanically and directly via the
engine. The story in numbers
  *  It takes 3 men 3 days to put together an engine
  *  200 engines are used for trials, tests and grands prix
  *  8 million ignitions per race
  *  1,500 CAD drawings before the engine's GP debut
  *  Maximum piston acceleration: 10,000 g
  *  Maximum piston speed: 40 metres per second
  *  Average piston speed: 26 metres per second
  *  A piston accelerates from 0 to 100 km/h in 0.3 thousandths of a
    second
  *  3 tonnes of force is exerted on the connecting rod
  *  Maximum temperature at exhaust: 950 degrees
  *  Maximum air temperature in pneumatic system: 250 degrees
Copyright 2006 Pitpass.com
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 different crankshaft design. []
Gran post!!
Thx...
mrlc
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