Re: Twinspark Spark

["Sasha Nackovski" <snackov@domain.elided>]

Lawrence,

I can only really answer one part of your question. Yes there is a delay
between the firing of the first and second plug. But this is where it starts
becoming interesting. The old 1980's Twinspark (proper Alfa block with
t-spark head) had two identical plugs for each cylinder, designed to achieve
complete combustion efficiency while allowing ideal valve angles in the head
and so on. On the new T-spark (Fiat block with Alfa head), there is one
small plug and one large plug per cylinder. The small plug fires a fraction
of a second before the large plug fires. Apparently by firing the small plug
first, not only will combustion efficiency be improved, but a much smoother
engine will result. The reason for this is that the smaller spark removes
the natural mechanical slack from the engines bottom end on the combustion
stroke before it gets hits by the larger spark. In other words the larger
spark does not need to contend with the small amount of slack in the
Pistons/rods/crankshaft assembly, thus theoretically allowing the engine to
be smoother and more refined. Hopefully this non-technical explanation makes
some sense to you!

Whether this theory works or not is debatable (the t-spark also has
counter-balance shafts to improve smoothness), but anyone having driven the
new t-spark engined cars would tell you that they have an extremely smooth
and refined character about them all through the rev-range, so the engineers
have obviously done something good with the engine.

Regards,

Sasha

Sasha Nackovski- Whittlesea, Victoria, Australia.

> Date: Mon, 3 Jun 2002 08:17:28 -0600
> From: Lawrence.Gowin@domain.elided
> Subject: Twinspark Spark
>
> On a modern twinspark engine, is there a delay between firing the first
and
> second plug?  If so, how much of a delay?  Does the delay stay the same
> throughout the rev range?  Just curious.
>
> Cheers,
> Lawrence
> '71 GTV
>
> Lawrence Gowin
> Level (3) Communications
> lawrence.gowin@domain.elided
> Office: (720) 888-1234
--
to be removed from alfa, see /bin/digest-subs.cgi
or email "unsubscribe alfa" to majordomo@domain.elided