Cats for leaded engines

I’m sorry if you’ve already answered this in the past, but are you going to add cats for leaded engines? For it’s come to my attention lately that Holden engines from 1976 to 1985 had cats and ran on leaded fuel.

There is no point as the game does not even display emissions for leaded fuel. Assume that if leaded gas is used there is no emissions requirement.
Also the lead from the gas will bind to the converter, clog it, and turn it into a large, heavy, fire hazard.

It does show the emissions of leaded engines, just… not on the testing screen. Once you save a leaded engine and quit out, it will show the emissions on the sandbox engines screen. I’ve recreated many engines as well as made many of my own design and have found that leaded engines have emissions between 210,000 to 350,000 compared to 2,500 to 4,500 for (70s) not cat unleaded engines.

Which particular Holden models were these Corvette6317?

The reason I ask is because the lead in leaded petrol clogs up/poisons the catalytic convertors so they no longer function. Any engine fitted with a cat should be running unleaded only and since Australia didn’t ban the sale of new cars running leaded fuel until 1986, Holden would be extremely unlikely to invest in expensive cats when it didn’t need to. Indeed I believe this is why Holden had to buy Nissan RB30’s; the old 202 wasn’t good enough to spend heaps of money upgrading and the Buick V6 wasn’t ready yet…

Here is the link on the Leaded fuel story…

Australia may not have banned leaded fuel in new cars until 1986, but it did impose emissions requirements in 1976 which like other manufacturers at the time Holden would have had to follow. So if they didn’t have cats from 76 to 85, then what do you think they used?

This is what I know they used: Exhaust Gas Recirculation (EGR), Exhaust manifold air injection, Positive crankcase ventilation and miscellaneous timing and tuning improvements… But the best way to improve emissions was to ban leaded fuel and install EFI and cats! :smiley:

And how would EGR effect performance? It sounds like something that should be added to the game since I’ve read about many cars sold in America had EGR in the early 70s.

1976 saw a 10% drop in power for the Holden 308, was that because of the EGR?

It’s taken me a while to find anything on the subject, but it appears that there were new emissions requirements for the 1976 model year. From a perspective of hydrocarbons and CO, they were 4 times more stringent than the previous standards, and also had standards for NOx for the first time. The emissions equipment required for these standards could well have dropped power.


From 1971 to 1972, the US switched from SAE gross to SAE net horsepower ratings, but I can’t find out if/when Australia made a similar switch. But the gross/net change was a 10-15% drop in power ratings, depending on the engine.

Australia switched from SAE gross to SAE net in 1978.

Nope, it was from the reduced engine tune required to meet ADR 27A;-a-explained/

This was taken from a Torana Owners forum and there is no mention of catalytic convertors at all…

It is possible that you have seen a pre 1986 Holden with a catalytic convertor as modifying an older car with an engine that has to comply with a newer, more stringent, ADR requires the emissions controls to be installed as well. Another modification that can be mistaken for catalytic convertors is the installation of a “hotdog” muffler in the exhaust. These “hotdog” mufflers are a wider section of pipe installed in the exhaust (coincidentally where a cat sometimes resides) which deepens the exhaust note.

Automation doesn’t need to include cats for Leaded cars because Leaded fuel is incompatible with catalytic convertors. I cannot find ANY evidence that any manufacturer used Leaded fuel with catalytic convertors anywhere in the world. I’m not saying that it isn’t 100% possible that someone tried it but, since you cannot provide evidence of Holden using them Corvette6317, I strongly disbelieve that Holden, who was owned by GM in 1976, was the one who bucked the world trend.

If you can prove your claim Corvette6317 then I’ll be the first to admit I’m wrong but until then, please take the time to read the provided links and do some research of your own! :slight_smile:

BTW, I used to be a parts interpreter and I was burnt by making assumptions… I had a customer come in with an AMG tuned Mitsubishi Galant! I didn’t believe him so when I saw the car I was forced to eat some major humble pie… I looked on the Internet and confirmed the customers story. AMG (of Mercedes Benz fame) had built and tuned a number of Galants for the Japanese market! :open_mouth:

Well going by the specs of the Holden 202 according to my favorite site to get engine specs from, the Holden 202 most likely had lower quality valves based on how the rpm limit dropped from 4,900 to 4,400 in 1976. That site Automobile Catalog also states how the Tri-Matic version in particular had the torque peek come 100 rpm later than the pre-76 202 with power coming 400 rpm earlier, doesn’t look like it was so much detuned engine as downgraded engine. The version of the 202 which came with the manual 4 speed is a different story, it was detuned on top of the downgrade with compression dropping from 9.4 like on the pre-76 and Tri-Matic versions to 7.8.

If you’d like to look at Automobile Catalog, here’s the link:

The engine I was lead to believe had a cat was the HDT tuned Holden 308 for the 1980 model year, based on my friend’s research. It does now appear he was probably wrong and that I should just go ahead and recreate that engine with super unleaded unlike what me and my friend did in this video: … esjeBLCzaw

The 202 you’re referring to was just the Low Comp version. I knew a guy who had one, all noise, no go ( the car was the same), swore black and blue he could beat a 302 XC in his HQ wagon… he also thought the JD 1.8 Camira auto wagon with 60-ish hp could beat a 2.0 manual Escort.