History of Aus Petrol octane

[mick taylor]

Originally Posted by Dr Terry

During the 60s it we often added Avgas to super for high comp engines, but factory motors with anything more than 10:1 weren't commonplace. GT-HOs & XU1s were the ones we saw. US imports were less common. During the early 70s we had a company called Fleetwing ??. They sold 100 octane at the pump, that made life easy.

No Kingswood 308 had anywhere here the power of a stock VN 304. The best leaded 308 carby motor (not counting L34) was the HJ which was listed at 250 bhp & the VN 304 EFI was 165 kW.

250 bhp equates to 186 kW but this is Gross power, not Net. While there is no direct conversion factor 186 kw Gross would be around 120-130 kw Net. You can't compare power numbers from the 60s & early 70s to today's.

The Holden EFI V8 was a very good engine for its day, especially compared to the EB Ford 5.0. Modern engines rely less on compression & octane, with most improvements seen in camshaft profile, head flow & electronic management of fuel & ignition.

Dr Terry

Look at the advancement's from the first Holden in 1949 and the compression jumping up from 6.5:1 to 6.8:1 and then to 7.0:1 and then topping off with a whopping 7.25:1 on Standard fuel of the days, now apart from advancement in the grey engine camshaft and all, I am sure that the Standard fuel Octane rating went up during them years, not to mention more again we can see with the Holden red motor, look at the jump to 7.7:1 in a 1963 low compression 149ci and then a whooping 8.3:1 in the 1971 173ci low compression. with 89 octane Standard in 1971 I remember a 87 octane as before that and what ever it was before that ?

Look at the new engines now VF V6 with 10.2:1 running on 95 octane, sure they can run on crap like 91 octane but the computed is retarding the spark timing to do so and all.

They have alloy heads and all mind, but look at the VS V6 with a iron head running 9.35:1 on crap like 91 octane, sure I heard my wife's VS V6 ping like a bastard directly when I would overtake on the highway but then it was fine until I hit 5000rpm then pinged to 5500 on Caltex 91 right from new, but it was a real good performing VS V6 fastest I have ever driven and I drove some that were ok and some were gutless crap right from new.