Isuzu G-series Twin Cam

G'day,
I know this may change state to state... but in fitting a dohc to my TE, do I have to fit a catalytic converter?

From what I remember, if the car the engine came from had a cat, then you have to... so, I think my engine came out of a ZZ/Z or ZZ/R or ZZ/T (did they all have dohc's?), did they have to fit a cat to be registered in Australia?

I've also heard I have to modify the fuel neck to only accept unleaded fuel...

What ever requirements the law makes, it is desirable to run a catalytic converter on an engine that operates on ULP. It can't do any damage and in many ways it's probably a good thing. It does reduce certain emissions. You might expect someone inspecting the car to look a little more favourably if they see it has a cat fitted. as for loss of performance, not if you use a cat designed for high flow applications and there are many of these in service now.

Fork lifts that can run only on LPG must still use a catalytic converter if used in confined spaces. It's law. Even the cleanest of fuels (LPG) can still be scrubbed to a safer level of emissions with a cat.

Depending on the engine you are using. If the engine was designed and approved at manufacture only to run on ULP then the fuel filler neck must not accept any larger filler like those for dispensing petrol that used to contain lead. In all probability you won't need that using a G series twin cam engine becuase it's probably not going to come under the same laws BUT on the same token there is no longer lead in any pump petrol so is it still relevant?


Hmmm... G180W twin cam Hyster....!

Actually Robbo, you have made an interesting point bringing up your question about filler restrictors.

I wouldn't mind researching the available fuels to see what the consequences would be if you were to run a late model ULP car on the current blend of LRP. Because it no longer contains any lead compounds it shouldn't by rights poison the catalytic converter like lead addative fuels did. That was the reason restrictors were made so people could not mistakenly fill up with 'super' grade fuel.

If the lead issue is no longer a problem then why do we have to still fit restrictive devices to a modified car?


On a slightly different angle, while travelling outback some time ago, I was surprised to find remote areas only serving up one choice of petrol. AvGas 100. That was all you could find. Everything ran it. Imagine the late model cars filling up with green petrol laced with lead! You need to run it in aircraft so it was the fuel that was supplied. Cost of bringing in petrol as well would have been around the same per litre in the end so just take one and don't bother with the other. Of course the EPA side of things out there is no issue. No one buys a car, takes it out there and expects to bring it back to the city to resell. They die out there and the morning smog report is always the same... no big deal. There isn't a need to be concerned with lead poisoning the kids by driving the car. It's petrol inhalation that kills them out there.

all good points Poida...

As for the lead petrol issue with the LRP and restrictors.... I can't even get LRP around my place, its only ULP or PULP at the servos and has been for a while.

When I get a bit closer to finishing the project I'll talk to my engineer and see what he says, if I need a restrictor or not.

Well I haven't really looked hard around my place because I have always run ULP in any petrol powered Gemini's I've owned anyway. I don't think LRP is still available here. As far as I know it was destined to be phased out so it may already have happened. I suppose the bureaucrats stubbornly keep on with the same old law because no one wants to make a change. It does prevents people accidently filling up with diesel though.

My ZZ/R has a normal fuel filler neck, does this mean I have to change it or can I leave it as is

If it was produced that way and it passes the requirements to register then you shouldn't need to change it. I'd double chack that with the authority in your state.

well if its any help my TE passed in WA without a CAT cause i didn't think the ZZR's Had them to begin with.

Cars manufactured prior to 1986 do not need to comply with ULP laws regardless of donor vehicle. Irrespective; all Japanese vehicles produced for the japanese market since 1968 are designed for unleaded petrol only. As such a catalytic converter should accompany any donor vehicle. If the engine is the only item you have then I would suggest that you do not worry about it until the engineer or EPA tell you to do so.

PF60ZZR wrote:My ZZ/R has a normal fuel filler neck, does this mean I have to change it or can I leave it as is

Can you buy leaded petrol in australia? Why would you bother???

in posts just above it was stated that LRP (lead replacement petrol, actual leaded petrol hasn't been available for a few years) is being phased out, I cannot get it anywhere near my place at all, only ULP or PULP.

Apparently catalytic converters stop working after 30,000km. They restrict the system slightly, too. I'm not sure about the legalities.

Are the G180s and G200s leaded as standard? My G161Z runs perfectly fine on Unleaded stock... Or am I missing the point? I'm lost...

As Denny said, the reason G series engines run on ULP without a drama [with the exception of ignition timing that is] is because they were built to run on it. We got the G161/180/200 as per Japan specs, and seeing as they had ULP for ages it means that Leaded didnt really affect the engine much other then octane.

From what i know, the reason its possible is because of the alloy head already having hardened valve seats, thus not needed to be lubricated.

Nick-

the original question wasn't if I could run ULP or PULP, I've run my G200z on PULP for years... it was if legally I had to fit a catalytic converter with a G180W. I'll just ask my engineer before I get the exhaust made.

Do you want to fit one or not? I mean enviromentally speaking it can only be useful and they are not exactly restrictive on the whole.

I'd say fit one if you are concerned they will make you do it. They won't knock you back for having one but may if you don't. Chances are they will say do it anyway if you ask.

The G180W may have been fitted with a cat and if it was then you have to also fit one but if it wasn't then you won't. Not having the original exhaust the engineer may opt that you should just in case.

Those members owning a genuine PF50 or PF60 ZZ model, have yours had a cat from factory?

Yes a Cat is fitted from factory - funnily enough my car was engineered last week and I was told I didnt need it as its an 81

When I present my twin cam for rego I'm going to do so with a cat fitted. I don't see how it can do any harm to have it there. It's not exactly restrictive in comparison to a lot of mufflers. Even using a larger pipe core cat than the system in the car, tapering in and out of the cat and you reduce the chances of restriction even more. I have a 2.25" system on my twin and a high flow 2.5" cat from a VT Commodore.

That's good advice. I suppose you could weld a cat in yourself if you really wanted to. How much did that high flow Commie cat set you back, Poida?

Free to good home!

I rescued it from "tha crusha".

Hahah, that's a good find! (nice pic too) I guess they'd be fairly cheap at wreckers, etc.

If you need a cat or not will depend on the ADR's that apply to the engine your fitting. Seeing as the "w" motors were not offered in any new car sold here its becomes complicated. The ADR applies to Passenger cars from 1986 and commercials came later, not sure when. I have an 89 shuttle bus here and its got no cat and no ULP filler.

It would be at the engineers discresion.

Bob.