unleaded fuel

An interesting piece of information I discovered while reading the parts catalogue over a light lunch today.

I know this was discussed somewhere before but I always assumed that when the Z7U 734 engine was introduced for unleaded petrol that along with Lambda sensor and new ECU that new heads would be added with harder seatings along with valves made of harder material to counter act the lack of lubrication etc

But no! All the same part numbers! And since the ignition is fully electronic with knock sensors theres no way or need for that matter to alter the advance.

Surely then the Z7U 730 engine of the early turbo models can run on unleaded without care or worry for mileage in a year etc as was previously advised?

Any thoughts?

I don't know the answer but I've always run my '86 turbo on Shell Optimax unleaded.

[Alpineandy]

The engine was always intended to be unleaded.
I usually use Optimax or a 'super plus' as unleaded/super unleaded makes it run hot.

Gta turbos will run quite happily on 95 Octane fuel. You might find a small difference i.e. barely noticeable from Optimax or the other higher octane fuels around but they certainly aren't necessary. I would advise if you are running more boost than standard to go for the 97/98 Octane fuel as it gives a bigger safety margin before the engine det's. In Japan they get 102 RON fuel! Thats why alot of the japanese imports here run well below their quoted power outputs here as they have to majorly retard their ignition timing for the poor fuel.

An interesting piece of information I discovered while reading the parts catalogue over a light lunch today.

I know this was discussed somewhere before but I always assumed that when the Z7U 734 engine was introduced for unleaded petrol that along with Lambda sensor and new ECU that new heads would be added with harder seatings along with valves made of harder material to counter act the lack of lubrication etc

But no! All the same part numbers! And since the ignition is fully electronic with knock sensors theres no way or need for that matter to alter the advance.

Surely then the Z7U 730 engine of the early turbo models can run on unleaded without care or worry for mileage in a year etc as was previously advised?

Any thoughts?

The only way they would have altered the advance was through the new ECU, and the lower compression ratio would have helped too.

Alpines for Germany had a different TDC sensor (offset 4 degree) to work with their better fuel rating, but ours is as it is now. This is why you can get away with advancing the timing at the TDC sensor.


The handbook recommends 98 octane for 730s, 95 octane for 734s and 95 octane for A610s

When i first bought my car, at first i ran in on ordinary 95 unleaded. But after a spell of the engine coughing and sluttering for no apparent reason, i switched to 98 optimax, the spluttering vanished and I've always maintained it runs better on 98 optmax ever since.