[Diy_efi] ideas for ignition solutions?

[Joe Doty]

Greetings all,

I have just finished assembling and testing a megasquirt EFI system, and
am looking for ideas for an ignition system.  I'm not sure exactly what
I'm looking for, but the concerns are definitely tunability and street
driveability characteristics.  I would most definitely want it have have
knock sensing capability.

I have a 1.8 16v VW scirocco with 9.2:1 compression, with an "h-trim"
t3/t4, using a small spearco FMIC.  The car is primarily driven on 91
octane gasoline, and runs anywhere from 12-15 psi of boost currently.
The engine is equipped a hall sender distributor.

The options I have right now as far as factory systems are (a) the
current digifant I (a VW cousin to Bosch motronic) and (b) the factory
system that came with the car (electronic, used with CIS).  The digifant
I system has a 2 bar MAP sensor, and I can get chips for this system but
I can't tune it myself.  The other system has a 1 bar MAP sensor.

There is a programmable ignition kit I've seen out there (from
autospeed.com) but I can't tell if it uses a MAP sensor or not, and
there would be no coolant temp retard/advance.

There are vacuum advance distributors available that will fit this
engine.

Any ideas?  I'm just brainstorming at this point...maybe a certain GM
setup would work?

Thank you for your input.

Joe Doty
IT/Development
joe at lcnetwork.com=20

-----Original Message-----
From: M. Claywell [mailto:clay0052 at umn.edu]=20
Sent: Monday, December 23, 2002 1:03 AM
To: diy_efi at diy-efi.org; diy_efi at diy-efi.org
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..
>=20
> 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..
>=20
> 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..
>=20
> Why not beryllium.. It makes real good valve seats.
>=20
> Dave
>=20
> William Shurvinton wrote:
>=20
> > 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.
> >=20
> > > > 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.
> >=20
> >  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.
> >=20
> > _______________________________________________
> > Diy_efi mailing list
> > Diy_efi at diy-efi.org
> > http://www.diy-efi.org/mailman/listinfo/diy_efi
>=20
>=20
> _______________________________________________
> Diy_efi mailing list
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>=20



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