darkblueturbo

Now this may be a muppety thread, but I've been meaning to post this question for a while. Though I fear it may be REALLY stupid, cos if it was a workable plan, surely it would've been done by now by a lot of people BUT....

The lead in 4star petrol was an additive put in to protect against 'knock' or detonation as it's one of the most effective ways of protecting the engine.

The switch to all modern cars using unleaded fuel was due to the fact that the lead additives stripped and killed the catalytic converters that are now a requirement on all production cars.

Am I right so far??

Now most of us have the boost to higher levels so we have knocklinks to make sure nothing bads happening to the engine and use superplus or Optimax - sometimes even with Octane boosters - to give the best possible protection against knock.

As the cars that have done this usually have their cats removed first, can't we just use leaded petrol?? Or will it do other bad things to the engine...?

cmdcorrola

The lead in leaded pertol does not compensate for knock. It simply forms a protective coating on engine parts that are open to the fuel / air mixture.

This is why, when you have an old car - say a mk 2 escort, cylinder head work is required to install hardened valve seats to stop the valve seats wearing out prematurely.

darkblueturbo

o i c - thank you...

Leslie

The lead in leaded petrol does increase the octane rating, this was how they achieved the RON levels. Trouble with leaded petrol is that it leaves lead pollution in the air which is bad for health, this was why leaded petrol was done away with. It did also coat the exhaust valve seats and help to prevent them from burning away. Hardened valve seats are now fitted to guard against this as cmdcorrola says.

Engines now run much cleaner internally with unleaded fuel, decarbonisation is hardly ever thought of these days.

Les