what CO setting to aim for on a turbo setup?
Turbo Mini Forums

When setting up a base tune with a gas analyser what should I aim for CO wise? I looked at the Metro turbo spec and it says between 0.5 -1.0 CO. Seems a bit lean to me, what do you turbo peeps recommend or are running In your cars? Using a BDD needle.

What year is your car?

Yes i moved to the darkside

Instagram @jdm_brett

W reg 1980.

For MOT purposes your car only needs to be below 4.5% CO and 1200ppm HCC

And I'm sure it will idle much happier richer than it will around 0.5-1.0% CO

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

I noticed when I adjusted the CO it seems to stumble and possibly pink too on load, wich it didn't before I adjusted it. Was at 2.5 - 3 when checked it. Wernt a bad guess when set it up from sound and smell lol
Think I should go bsck to that.

0.5 - 1% doesn't sound like the recommended CO. I'm sure it is more like 3%

Sure my standard 998 was about 2.5-3.5% on the last MOT which is a 79/80 mini. If you want an exact figure (well what mines running at now) I can borrow a gas analyser from work and stick it up my zorst for you tomorrow

Edited by Shauna on 23rd Nov, 2014.

They don't die, they just get faster!

i think 2.5 3.5 % sounds more realistic than what the book says, richer the better on a turbo motor i guess? is the Standard needle only rated to 7 psi boost, or can you run a little more before a needle change?

CO at idle is CO at IDLE, it is no indication of the fueling for the rest of the needle you seem to be confusing this with running

Edited by Brett on 23rd Nov, 2014.

Yes i moved to the darkside

Instagram @jdm_brett

surely if the CO is 3.5% at idle, you would have a slightly richer mixture throughout the rev range regardless of the needle profile, than what you would if the CO was set a lot less like 0.5% because the jet is physically sat lower in the carb and thus further down the needle to start with to get 3.5%.

on my set up, it pinged at actuator boost pressure when it was set at 1-1.5% CO. i've wound it back up to where it was before i adjusted it, so now roughly 2.5-3.5 % CO and it does not ping any more.

on a turbo motor under boost safe AFR is 12-13:1, yes running richer can be wasting fuel, but in high boost it also helps cool the valves and pistons from what ive read and been told. id rather run richer and cooler than leaner and hotter.

at 4 psi i don't think that really applies until i get into higher boost pressure as a standard needle would surely over fuel on 4 psi.

im not running an intercooler at present but intend to do this.

if i wanted to run 10 psi with an intercooler at 8.8:1 CR what needle would i need to start with?

would i expect with the lower CR than the standard metro turbo lump i would need a little more boost to get the same power but would have increase the torque over standard?

i've seen "high boost" needles on ebay but they don't say what boost they're good for.

I'm confused! Why are you trying to tune your car by co? Surely you should be looking at the aft gauge just to get you going before the rolling road like Brett has said? Mines got the bdd needle and runs okay on boost at 8psi, it's just too rich off it.

Edited by Shauna on 23rd Nov, 2014.

They don't die, they just get faster!

In the not too distant past, you tuned the fueling using an exhaust gas analyser. Tuning for full power you would aim for around 6% CO at full load full throttle (obviously on a dyno) with ~3% at idle.

Edited by Sprocket on 23rd Nov, 2014.

Makes sense back in the day where nobody had afr gauges . I'd be willing to stick one in to see the idle but I'm not driving around with a probe stuck in there haha!

They don't die, they just get faster!

Edited by stevieturbo on 24th Nov, 2014.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will