Club Cobra - LS3 bits and pieces

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Late model cats also clean up the mixtures with secondary combustion hence cleaning up older motors with overlap cams. If mixtures are out then your Nox goes up and so on. So an older motor that runs well with new Commo or Falcon cats should pass.

Quote:

Originally Posted by Gaz64 (Post 1342861)

Who tunes with a narrow band?

You can tune for any A/F ratio, stoich of 14.7:1, max power at 12.8-13.2:1, max economy at early 15s. You cannot do that with a narrow band.

Most cars these days have wide band O2 sensors ex factory. The ECM needs to know TRUE A/F ratio all the time. A narrow band cannot do that.

Actually, no they don't.

The reaction time isn't as quick with a wideband, and to get the low emissions requirements they don't get used.

If you go to 15's, your NOx spikes. If you go to 12's, your CO and THCs spike. You can't have both and you need a rapid flux from slightly rich to slightly lean to ensure the cats are able to process all of the gasses correctly.

the ECM needs to know when things are slightly rich or slightly lean and to react back the other way. MAF sensors and VE tables control how much fuel you need, with a 14.7:1 as the required emissions target for just about every car.

The only vehicle that comes from a mass manufacturer that has a narrowband O2 sensor other than 14.7:1 is the old fuel injected rover motors that needed more fuel, and hence ran a 13.2:1 O2 sensor.

the narrow band tuning that I'm talking about is to get people through the IM240 test in NSW - I know you can get heaps powah with a wideband - this aint my first rodeo. What I'm trying to do is prevent people from pissing a load of money up the wall tuning a car for power without being able to pass the emissions test. Pass the emissions test, get the car registered. After that it's up to you.

Treeve

if im using the cats and oxegen sensors and ecu that come off my donor engine a ve commy 6 litre one would think if those components are in good working order it should pass?i was going to use new oxegen sensors anyway as i get all my stuff at wholesale prices .i will try the cats and see what happens but if they need to be replaced then so be it .

You should be fine with that setup, just make sure you put a fresh tank of fuel in it before you test, and that your charcoal canister is fitted up properly.

So has anyone bought an engine from Preston Motors Surplus Parts Warehouse in Melb?

Bought my LS2 from Preston's back in 2008. No problem dealing with them. Dealt direct with Kevin Newell.

I did have a small leak on the fuel tank so raw fuel vapor was being sucked into the machine.....took a few attempts to work that out.

I would also trailer the car there and the guy would be waiting so had no time to warm it up, I even went 1 hour earlier once and he was still waiting.

the last time I drove it there went for a cruise up the freeway for a few ks and then straight for the test. Passed no worries.

Phil

I havnt seen the test procedure, but i would have assumed the test would be at operating temperature?

its a good thing to run it for a while to burn off any assembly lubes, sealants paint etc.

The test doesn't take long so to have it up to operating temp before they start is a good idea.

Zedn,

I think that your cats work better the hotter they are, so it is an advantage if you run the engine as hot as possible.

Cheers,

Ben

I run a LS3 and went through the testing procedure before it was slightly changed in Vic to follow the other states.

Used OE cats and full exhaust system with mufflers exiting the rear of the car. When I did the test that they were happy with I can'r recall if I had the supercharger on there or not. Did 4 tests 1st one came close with full set up, then changed a few things and took the s/c off but it still didn't pass.

LS3 is a great engine, mine stock except for the little thing bolted on tht op and has 400+kW at the wheels. I'm sure you can use LS7 heads and get better and then start doing rods etc.... but the LS3 stock parts are pretty good.