924Board.org

doug60 · Joined: 24 Jan 2012 Posts: 11 Location: england

Hi,

The 924 1984, should run on 98 octane, Now you can't get this, I've been running on 95. Should you advance the timing to compensate for this ? and by how much. I put the lead additive in.

Thanks

DB

Horizonblue · Posted: Mon Feb 06, 2012 3:55 am Post subject:

You should not advance the timing, but retard to approx 5° BTDC.

I did that on mine, and it cured a lot of engine noise under acceleration (ignition knock)

Power loss; maybe it can be measured, but I can't feel it.

You can also just retard the timing, until there is no ignition knock, then it should be fine to run the car. It will take some test-rides and adjusting.
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Euro 924, 1976

"If you can't fix it, don't break it"

/P.G. Andersen

ptheskil · Joined: 03 Aug 2004 Posts: 128 Location: Essex, UK

You don't need lead additive for valve seat protection on the 924 engines. It will help with the octane problem though. But...did you know that the so-called "super unleaded" fuel in the UK is around 98RON - it varies a little from supplier to supplier but Shell Vpower and Sainbury's own brand super unleaded are 99RON IIRC. I run Sainsbury's and Vpower in my turbo without any trouble.

The extra money you spend on fuel will be partly compensated for by not needing to use an (expensive) additive and the improved fuel consumption you will get by not running with retarded ignition. Spend the cash on a dose of fuel injection system cleaner from time to time which is very worthwhile for engines with K-Jetronic.
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1981 931 series2 Euro spec

Cedric · Joined: 27 Aug 2004 Posts: 2750 Location: Sweden

When i drove my 79 n/a i never noticed any difference when i switched from 95 to 98 or the opposite. Did drive on 98 on the track most of the times though just for the extra margin. The ignition was regulary checked and adjusted to specifications.
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1980 924 Turbo
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scm924s · Joined: 22 Oct 2010 Posts: 283 Location: Gloucester UK

The 924n/a and the early 924S are designed to run 95 octane in UK, the only one requiring 98 octane is the last 924S with the 160BHP motor. No fuel additives are required.

Horizonblue · Posted: Tue Feb 07, 2012 2:42 am Post subject:

doug60 · Joined: 24 Jan 2012 Posts: 11 Location: england

Thanks for the replies and info.

Why don't you need a lead additive ?, did the 924n/a come with hardened valve seats as standard !!

DB

Ozzie · Posted: Wed Feb 08, 2012 6:14 am Post subject:

yep
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

!tom · Posted: Wed Feb 08, 2012 9:39 am Post subject:

Especially considering the North American market cars at least had catalytic converters, which are destroyed by lead in fuels and hence require unleaded.
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78 924 NA
5-lug