Running lean or rich?

[306Puggy]

I know smoke on boost is a bad thing but what about the opposite, too much boost with too little fuel going in? I adjusted my MBC today on standard fuelling and found that I was able to make nearly 20psi at peak on standard fuelling. There wasn't that much more power but it was quite a nice setup is there any benefit to having more boost than you need to burn the extra fuel or should it be fine tuned into a tighter margin?

[bigcheez2k3]

I'm not sure you can run more fuel than the turbo can boost, hence why some limit their boost by fuelling.

[Toms306]

As I understand it, too lean a mixture causes high cylinder temps, will cause more NOx emissions but I don't expect you're bothered by that lol. I'm not sure whether it'll be hot enough to cause any engine damage though.

[londondan86]

I don't see why you would want to, man up and add more fuel! Lol

[Mattcheese31]

boost without fuel is a waste, you are creating higher temps by the turbo spinning faster for no good reason . .

[Tom]

But you need to fuel to make the boost in the first place... So without fuel there is no boost?

[Mattcheese31]

But you need to fuel to make the boost in the first place... So without fuel there is no boost?

true i guess, but you can run different amounts of boost with the same fuel . .

[chippyba]

what's the optimum smoke n colour a fine tuned engine should be ???

[silverzx]

what's the optimum smoke n colour a fine tuned engine should be ???

A light haze as you come on boost then clean burn whilst on full boost.

[chippyba]

clean burn ???

[silverzx]

clean burn ???

(No smoke).

[306Puggy]

Weird exchange just above me, moving swiftly on. I now have the pump maxed out and am making 19.5 psi except for higher up in the rev range where it reaches about 25 psi. The MBC is just a couple of turns in from the minimum yet I don't notice any smoke on boost so it's hard to tell. But then it is the case when you are making progress on full throttle plus trying to glance in the mirror at the same time!

Edit: The MBC is wound this much in: