NOS Question?

[malexie]

Will the Merc 280 or 300x ecu adjust fuel for a Dry shot of NOS?
If so, I would guess the Air Temp sensor tells the ECU its cold air correct?

[108]

No,

[malexie]

Well wet shot it is. Thanks

[CI STV]

Not sure about the 280 or 300X, but on the older 2.5 EFI motors, you can probably get way with a 50-75hp dry shot, since the air temp sensor will sense the significantly colder IAT created by the nitrous in the crankcase and add fuel to compensate. You would probably want to either increase fuel pressure a bit and/or richen the overall mixture just to be safe, and read plugs and monitor EGTs to dial it in.

We’ve done that on a friend’s 2.5 1/4master drag setup and it works.

BUT, without the ability to tune the amount of fuel that is delivered for cold air compensation (there’s no graph for that in any of the ECU tuning software that I’ve seen) there’s no way you can safely add a large(100+) dry shot and the ECM will automatically add the correct fuel augmentation, like on most of the aftermarket automotive ECUs out there (Holley,etc).

Pretty sure that the unlimited guys with the fancy aftermarket ECU’s have that figured out…