Re: hopping up an '84 Spider

[jonesy@xxxxxxxxxxx]

Bill Bain wrote:
>Assuming that your lust for increased HP isn't satiated,
>it's time to go to higher compression pistons.  Later Spiders
>using the Motronic engine management system used higher
>compression pistons than their earlier Jetronic sisters, and
>there are plenty of aftermarket choices too. Again, getting
>the guidance of an experienced Alfa mechanic would be a good
>idea.  Higher compression means more octane needed in the
>gas and it also can effect emissions in ways that might be
>problematic for the Jetronic to deal with (can anybody
>elaborate on this?).

The Motronic computer has a knock sensor input, whereas the
L-Jetronic computers do not. The knock sensor tells the
Motronic computer to retard the ignition - when necessary,
to avoid pinging. I believe the compression ratio for a
Motronic equipped Spider/Alfetta is around 10:1.

Did the Motronic Alfetta have a knock sensor? I would guess
not, as it was designed a few years prior to them
becoming commonplace.

Regards,
Robert Jones,
1979 Alfetta GTV 2000

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