Technical and Performance > Engine Management Forum

Nitrous on an NA

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toplessFC3Sman:
You absolutely want to do a wet shot, since our motors are very sensitive to detonation - adding nitrous is analogous to forcing more air into the engine, and if you don't increase the fuel (wet shot), you'll end up with a high-load lean condition, which is what pops turbo motors all the time.  Especially with a stock ECU, the ECU won't detect that its too lean & correct enough for it until you're already detonating, causing damage over time if not immediately

~Groll69~:
That is true, the computer system and sensors associated with it are slightly primative in the fact that they can not adjust the air fuel ratio fast enough to accomadte the increase or decrease in the air flow. 

That would explain why at low compression I flood out with the current stock injector setup.  If the computer was able to adjust for those conditions on a quick and consistent basis, then a dry shot would work in my opinion.

Looks like i am looking into getting a wetshot nitrous setup for the NA.

toplessFC3Sman:
Well, I don't think any stock engine management system could handle that sudden of a change in O2 without any warning (such as intake P or mass flow going up) - its just that some engines are naturally more resistant to or tolerant of detonation so it doesn't matter as much.

Usually, stock ECU's of the late 80s thru 90's could only adjust fueling 15 - 20%; if you're running a 50 hp shot on a 150 hp engine, you'd need roughly 33% more fuel (more if you want it slightly richer for more cooling & detonation protection), which the ECU couldn't provide anyway.  Plus, there's always a couple-cycle delay for the exhaust to reach the O2 sensor, for the sensor to react & tell the ECU, and for the ECU to start correcting.  Plus, the knock sensor & circuit is almost worthless, so that can't even act as a band-aid until the ECU catches up.

It's not really a fault of the ECU, a 50 hp shot of nitrous is a bit more than it's been designed to take.

~Groll69~:
So your saying that i should look into getting a new ECU in order to support a small nitrous shot?

ITSWILL:
You just need a wet shot. Your ecu is fine.

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