Whilst on holidays in my home town of newcastle(NSW) over christmas, i noticed that service stations are phasing out leaded petrol instead, every time you fill up you can buy an additive to add with the unleaded fuel,
I thought i would start a thread to expand on this idea,
What would happen if you ran unleaded in a car without using the additive?
What difference would premium unleaded make?
And, is it possible to make a leaded motor into an unleaded motor? does the head have to be modified and the carby?

Any thoughts on this?

on my first ute i had an a14 i ran that on premium unleaded and as far as i am aware it had no mods to the engine. my second ute had an A15 i used the additive once and it never ever ran the same again. third ute with the A15 im planning to run premium again but this time i will put hardened valve seats n stuff in. im not really sure what i would have to do but i recon i could do it if somebody told me.

I have never run additive or leaded in any of the A series motors I have owned. Never had a problem with recession etc. and I did over 160 000 k's on my most recent A14 and it was already a high km engine when I got it. Only problem I ever had was letting Converted drive it at an Autokhana.

which was driven to class honours I might add....
plus it blew the cobwebs out of it...

and the fan belt too... And blew out coolant and did you stop??? Car had to go to the Crusher after that. Broke my heart and I had to leave the country. Feral flamin' Aussies.

was engine ok??? It still took class honours...

talk about feral ...how bout the 10 year olds who tried to execute you with a BB gun???

A series engines are ok because they have an alloy head which means they already have to have hardend valeseats so unleadeded wont hurt them. If you run unleaded on a cast iron head which hasn't had hardened valveseats inserted the old soft ones will wear out very quickly.

THe only difference premium will make is that it is 95-98 octane which is close to leadeds 96 which means you wont have to retard timing to stop pinging.

I didnt know that freak. good info. isnt there a problem with unleaded fuel burning hotter or something?

Not that I am aware of. The only difference is the obvious. One used to have lead/now lead replacement and one has no lead. The lead in the fuel acts as a lubricant. Without hardend valeseats and no lubricant they wear very quickly. To have a leaded car converted to run uleaded only requires changing of the valveseats to harder ones which will be able to take unlubricated punishment.

So, is there any difference in performance? better or worse?