The problem is that the majority of dry systems simply run an FMU: They just up the fuel pressure to compensate for the nitrous. Obviously, EMS tuning is a better option, but it is hard to beat the simple reliability of wet systems (so long as you design the system to avoid fuel puddling, which is not all that hard on a rotary).

 

Also, if your running a 3rd gen or a TII with an aftermarket ecu then you have a speed density car and the computer wont see the extra oxygen. The only extra fuel or timing changes you'd get is from the air temp sensor and thats not even close to enough fuel or retart. Even if it was enough the air temp sensors are so slow to react that it wouldnt make the changes in time.

This means if you were wanting to control it with the ecu then either you need an ecu designed to control nitrous (which not all of them do). If you have a ecu that does NOT control like the Power FC for a 3rd gen, piggyback, or upgraded ecu then you'd have to swap out the map before spraying to add the fuel.

Its all to much hassle, I'd rather run a wet kit that mixes in the right amount of fuel for the nitrous that its given. I'm not as concerned about the timing, I already run a real retarted timing.

BTW - a MAP sensor doesnt see an increase in flow, it only reads pressure. A nitrous system doesnt create positive manifold pressure. The MAF (mass air flow) meter on a TII is what would see an increase in flow but I dont know how well that would work for nitrous, and like mentioned before 3rd gens and TII with aftermarket ecu's dont have a MAF.

STEPHEN

 

I have never seen a system in which the nitrous is measured as airflow by the ECU; the fogger is almost always plumbed after the AFM.

Dry systems typically do not alter the injector duty cycles, they merely up the fuel pressure. Its one of the reasons they are limited in their maximum horsepower values. This is another reason why the typical dry kit is not so hot for turbos... at 15 psi of boost, the fuel pressure is already around 55 psi. Add a 75 horsepower shot trough it, and the fuel pressure will increaser an extra ~10 psi. The fuel pump is now working at 65 psi, which decreases fuel pump flow. A wet system does not increase fuel pressure, so fuel pump low is limited only by the maximum manifold pressure.

 

Here's an idea.....

Placing a fogger nozzle in a PP arrangement in the housing. COMPLETELY seperate from the rest of the FI gubbins

 

Hmm? I am a little confused as to what you are suggesting?

ALL wet foggers are completely separate from the fuel injectors.

If you are thinking about putting the wet foggers in the rotor housings... bad idea. You want them at LEAST 6" from the entrance to the engine.

For a PP, you best bet would be to install one wet fogger in each runner just a little bit behind each carburator.

 

I meant that it would never come into contact with any of the inlet tract (reducing the amount of airspace available for the fuel/air mixture)

So why place them 6" away from the housings?

 

Appreciate the explanation guys.

 

for one burning hot rotor and liquid gas are not a good thing to mix

 

Needs some room to atomize. As a general rule, the longer the length, the more power you will make.

 

But what about direct nitrous injection? You can can get stupid amounts of power from that, and that injects directly into the combustion chamber (on piston engines anyway)

What about injecting nearer the spark plugs?

I'm messing about with my engine, and I'm going to try and squeeze out as much power as possible from it, whilst retaining streetability

 

I am familiar with direct injection as a form of fuel injection but not nitrous. Are you sure you are not just confusing this with direct port nitrous?

Direct port nitrous puts one fogger per intake runner; it does not put fogger IN the combustion chamber.

A non-direct port system will either (typically) use a spray bars mounted after the carburator or a single nitrous fogger mounted bore the throttle body. Direct port is several nitrous foggers mounted in each individual runner after the throttle body.