Two years ago I posted an initial appraisal of how the new rules would
affect engine power and this can be read here.
https://groups.google.com/forum/#!topic/rec.autos.sport.f1/_mAb0s-dZQY
I'm now going to look at the question of just how much power the engines
will actually need to be as fast as last year's ones. The minimum car weight
has increased from 645 kg to 690 kg but this is less important than it might
appear. The amount of fuel the cars can use is now limited to 100 kg whereas
last year a full race took about 160 kg. So in fact at the start of a race
the 2014 cars will actually be lighter, 790 kg compared to 805 kg. If we
make a rough assumption that fuel is burned off at a steady rate the average
race weight of this years cars will be (690 + 790) / 2 = 740 kg and last
year it would have been (645 + 805) / 2 = 725 kg so not really a big
difference. It will also make it easier for the designers to get the
suspension to cope with the difference between high and low fuel loads as
these are now much closer together.
The fuel flow limit increases linearly up to 10,500 rpm and then stays the
same all the way to the rev limit of 15,000 rpm. Power will therefore also
peak at 10,500 rpm and stay more or less constant until 15,000 rpm barring
gradually increasing frictional losses inside the engine which will steadily
reduce it a bit. Below 10,500 rpm the power will fall in a straight line
proportional to rpm. Torque will therefore stay more or less constant below
10,500 rpm because power = torque x rpm. So this will look nothing like a
conventional normally aspirated power curve which I hope most people are
familiar with. Plenty of examples on Google anyway if you aren't.
To obtain maximum acceleration from any engine it is desireable to hold rpm
as close as possible to that where peak power is obtained. In this case
power is constant all the way from 10,500 rpm to 15,000 so it makes little
difference where abouts in that range the engine is used. In practice there
will be no point revving it any higher than to ensure the revs drop back to
10,500 at each gearchange. With 8 gears the rev drop will be small enough
that there will be no point going past about 12,000 rpm.
In fact to rev any higher would increase unreliability and power would be
falling anyway due to frictional losses. So in effect these engines will
always be operating at a roughly constant peak power output, whatever that
turns out to be.
The 2103 engines were nothing like this. Previously allowed to rev to 19k
rpm, power would actually still have been climbing at the later 18k rev
limit and would drop markedly as revs dropped below that i.e. on each gear
change. With revs dropping to between 15,500 and 16,000 rpm at each gear
change, power would have fallen by over 100 bhp from the peak at 18k of
about 750 bhp. So the average power being delivered would have been much
lower than the actual peak of 750 bhp. This gives an immediate advantage of
50 bhp or more to the new engines operating at a single constant peak output
all the time.
Factoring in all these things to a detailed computer simulation program I
compared the acceleration of the old cars at an average weight of 725 kg
with the new ones at 740 kg. To obtain equivalent acceleration all the way
to about 190 mph it turns out that the new engines only need to produce
about 515 bhp from the base engine, plus the 160 bhp from ERS for a total of
675 bhp to be fully competitive with the old engines at 750 bhp but only
actually producing that briefly at every red line.
That 515 bhp is almost exactly what I calculated the new engines might be
able to produce two years ago from the fuel flow limits.
It is likely that other factors such as drag and downforce have also changed
but there is not enough information yet to estimate these. Given that both
have probably fallen somewhat the new cars may even be a tad faster in a
straight line than the simulation predicts.
One thing that immediately showed up was how pointless it is to have an 8
speed gearbox with engines that have a totally flat power delivery. In fact
I tried restricting them to only 5 gears and it made hardly any difference
to acceleration. It just meant they had to be revved a bit higher so the rpm
still fell back to 10,500 at each gear change with the larger rev drop. Yet
another pointless FIA complication when they keep saying how they are trying
to restrict costs but never do.
The other thing the drivers will immediately notice is that there is no rev
limiter to bounce off any more and choosing the exact gearing will be very
uncritical compared to last year. With most gear changes at about 12k rpm
but with another 3k left over to be used if necessary the cars will continue
to be able to accelerate right up to every braking point regardless of DRS
use, slipstreaming, tail winds and weight falling as the fuel burns off.
So this is a pretty bizarre set of technical regulations. A gearbox that no
one needs and a 15,000 rpm limit that no one will ever use. I wonder how
long it will take them to change these.
--
Dave Baker