Ahh... 50hp? That's quite aggressive. I'd recommend a piggy-back to the ECU to retard the timing. Without a timing retard and running fat on fuel, the max I would feed into the Smart would be 30hp -- maybe 35hp... I'd raise the RPM window to 3600 -- 4000 before starting the nitrous. A "sneeze" on the Smart intake manifold may not be pretty... It's a real long convoluted intake which might split. If you're using a fogger before the throttle-body, the fuel will probably puddle at the lower junction before the manifold separates into long separate runners -- so do read the O2. You might have to jet the fogger REAL fat to compensate -- and even then you might get a "sneeze" from the puddled fuel. The upstream O2 sensor used in the Smart is a wideband. You might be able to read the Smart's upstream O2 using a ScanGauge.
I'd do the conservative thing and start at 25hp with a fresh set of plugs. I'd read the plugs, check for fuel puddling if you're using a fogger and check into the behavior of the throttle-by-wire throttle body... The last thing you want is for the ECU to close down the throttle while you're still spraying. That's a recepie for a "sneeze" -- and as already mentioned, the Smart's intake manifold may not like it. My Smart will downshift when I press the pedal down all the way -- and the ECU automatically modulates the throttle during the downshift.
I've got a complete nitrous setup from a previous car -- but I went the turbo route on the Smart. Even with my preferred setup (nitrous/fuel direct port adapters on the injectors with high-pressure nitrous feed and separate jets -- not the NOS Nozzle crap) I didn't like the lack of control over the Smart ECU. I kept getting that bad feeling that it was going to do something I didn't want at exactly the wrong time.
Best of luck!
Linear Mode
