RE: Twin Spark heads

["Nick Koleszar" <npk@domain.elided>]

My understanding is that the 60s GTAs used a TS head so that they could fit
larger valves and that the FIAT block TS heads are primarily to improve
emissions levels. The PR value of the link to the GTA is not lost on FIAT,
however.

nk

> ------------------------------
>
> Date: Mon, 10 Jun 2002 07:54:28 -0600
> From: C M Smith <cmsmith@domain.elided>
> Subject: Twin Spark heads
>
> I thought the main advantage of twin spark heads was the ability
> to operate
> with higher compression without detonation. With single spark
> heads the end
> gas preignites if the compression ratio is too high. This results
> from the
> expanding flame front further compressing the mixture before it
> has time to
> ignite. The second plug ignites the end gas in a controlled fashion
> preventing this source of detonation.
>
> I also thought this technique had been refined to increase fuel
> efficiency
> and reduce emissions by delaying the second spark a little. It
> would still
> produce more power, but also burn cleaner and cooler.
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