[Diy_efi] RE: Timing and dyno pulls

[Andris Skulte]

Hotter coolant will have a greater temperature difference between coolant
and the ambient air, so a higher rate of heat transfer
(i.e. better). Think of it this way - a hot
cup of coffee cools down much faster to luke warm (120 deg to 80 deg) than
a luke warm cup to room temperature.

Andris/SPD

On Mon, 23 Dec 2002, Grant Beaty wrote:

> So higher cooling system temp helps heat transfer from coolant -> radiator
> as well as engine -> coolant? I thought only the latter was true.
> 
> Grant Beaty
> 
> ----- Original Message -----
> From: "M. Claywell" <clay0052 at umn.edu>
> To: <diy_efi at diy-efi.org>; <diy_efi at diy-efi.org>
> Sent: Monday, December 23, 2002 2:02 AM
> Subject: Re: [Diy_efi] RE: Timing and dyno pulls
> 
> 
> > Hello,
> >
> > In regards to F1 guys running high water temps (~ 125 Celsius), one of the
> > main reasons they do it is to reduce aero drag. They are likely down on
> > power (from what they could make if they ran a lower water temp), but are
> > also saving on aero drag. The higher temp differential between the air and
> > water temperature will allow higher heat transfer rate, thus require
> > smaller radiator, thus lower drag. I think it was two years ago or so,
> that
> > the FIA limited the maximum pressure that F1 cars could pressurize their
> > cooling systems to. I believe it is around 50 psi. Running higher
> pressures
> > would allow even higher water temps if they desired, and if it proved
> > useable, as far as the trade off between aero drag and power goes.
> >
> > Cheers,
> > Mark
> >
> >
> >
> > On 20 Dec 2002, Dave Dahlgren wrote:
> > > The Beemer I am sure is tuned for emissions and mileage not peak power..
> > The
> > > compression ratio is probably a little on the high side for 87 octane as
> > well
> > > but that will make for a greater efficiency at part throttle.. Emission
> > and
> > > fleet mileage.. They have lots of compromises that race engines never
> > see. If
> > > you build an engine with too much compression for the fuel available you
> > can
> > > pull timing out at WOT to stay out of trouble but it will never run as
> > well
> > > as
> > > if it had the right fuel. For all you know the BMW might run best on 98
> > > octane
> > > that is not available in the USA at the pump.. Easiest test would be to
> > add
> > > some
> > > 103 octane unleaded race gas and see how she goes..
> > >
> > > As far as head temp goes I never suggested a heat riser in the way of
> > sharp
> > > edges was ok. It will always be a problem, 40 degrress of coolant temp
> > will
> > > not
> > > make the sharp edge show up though. A long pull on the dyno sure will
> > though.
> > > You can not find it in 1 second on a dyno jet though might take about 3
> > or 4
> > > seconds under full load..
> > >
> > > If the F1 guys needed to have the engine run cooler do you really think
> > they
> > > would say nope can't do it guess we will just be 30 hp down.. Face a
> > couple
> > > of
> > > million to solve the problem is pocket change to them..
> > >
> > > Why not beryllium.. It makes real good valve seats.
> > >
> > > Dave
> > >
> > > William Shurvinton wrote:
> > >
> > > > No: dave's point: Best power is way off detonation in a race engine.
> My
> > > > question, why does a modern road car gain 10HP when run on high octane
> > > (real
> > > > test, think it was a BMW) when all it has to go on is the knock
> sensor.
> > > > Inference: it must be running close to knock all the time.
> > > >
> > > > > > and race cars (F1 in particular) only ran so hot
> > > > > > because the aero package demanded a limited rad area
> > > > > > and air flow. Hotter was more efficient.
> > > > >
> > > > > With the engine components themselves, you are limited
> > > > > by how much heat the materials involved can withstand
> > > > > before weakening.  With highly-stressed engine parts
> > > > > that are built to JUST withstand the stresses of a
> > > > > race and be as light as possible, managing temperature
> > > > > is CRITICAL.  So there are conflicting needs; the need
> > > > > to keep the engine structurally sound, and the
> > > > > "desire" to have it as hot as possible in the
> > > > > combustion chamber.
> > > >
> > > >  I quoted F1 because it is an extreme case. The engines are run at
> > > > riduculous coolant temps and revs and until recently were billet
> > > unobtanium.
> > > > I like beryllium in space apps, but not sure I want it in my car.
> > However
> > > > the coolant temp in this case is due to not being able to get the heat
> > out,
> > > > not because the engine liked the heat.
> > > >
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> > >
> > >
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> >
> >
> >
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> 
> 
> 
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------------------
Andris Skulte
Skulte Performance Designs
http://www.skulte.com  
Z28tt-89 IROC T56 DFI Twin Turbo


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