Anyone install a ZEX nitrous controller in their 2015? I have a complete wet system going in and need to find out which wire is the output wire on the TPS for the ZEX box. This box is used for triggering the nitrous at Wide open throttle, in case you didn't know. ZEX made a kit for the 07-13, but won't answer questions about the 15, as they haven't tested it.

Any info is appreciated.


Mike

 

I can't answer your question at the moment, but I will advise you NOT to use the T-Tap connector to patch into the TPS. Long story short, it ended up cutting through mine. I'm going to solder it tonight.

I think what you need to do is find a service manual for the GK5 and look at the wiring diagrams. You MIGHT be able to find the right cable with a multimeter. I don't know if this will work with a dbw tps, but you could possible unplug the connector from the throttle body, set the multimeter to DC and have it grounded then have someone move the gas pedal up and down while you check each pin. The key should be on but NOT running.

 

Mike,

I can not answer your question but I am very, Very, VERY interested in your nitrous setup. I did not pursue this route because I couldn't find out where you would tap into for fuel. The fuel system is a 'high pressure' system since the vehicle is direct injected. The only way I knew you could use nitrous on this car is to use a totally separate fuel container for the wet system to utilize, to supply fuel through the intake manifold.

Any thoughts on this?

 

There's no fuel rail with a quick disconnect on the GK5?

 

It's not that it doesn't have a fuel rail but the fuel is supplied directly into the cylinders. The fuel rail pressure is post 1000psi vs 35-50psi for an MPFI engine. Tapping into that high of fuel pressure can cause issues. I'm trying to find documentation on exactly how high this fuel pressure is in the 2015+ Honda Fit.

In the meantime, you can see why I'm interested in this nitrous setup as it seems the OP has this figured out.

 

I would buy the Nitrous Express dry kit for about $300. Uses stock injector system and adds 25 plus howsepower. Activate it with a pushbutton built in the shifter handle or a hurst shifter mounted switch part number 2483875. You can also mount a switch that activates by accellerator pedal position. I would put in a series safety lockout switch to prevent it from engaging unless wanted.


James

 

Don't you need to tell the ECU to apply more fuel with a dry kit?

 

arrow runner :

You are correct. If you add nitrous which is really adding more oxygen it takes more fuel to go with it to prevent leaning out the motor and causing problems. However the ECU monitors the air fuel ratio to adjust how much fuel it puts in the car. The limit of fuel is when the injectors are at their maximum. That's why dry system run with small horsepower gains only. The jets in the Nitrous express kit are for 10,15, or 25 HP boost. Check with them about campatability with the Fit or look on their site for their recommndations. Others also make "DRY" nitrous systems for small boost levels. If you want 50 to 150 HP boost you will have to figure out a way to use a "WET" system. Hope that helps .

James

 

Here is a link that explains how it works. The cold NOS spray tricks the MAF sensor into thinking extra air is coming in and adjust for extra fuel through its injectors. That makes the limit the maximum flow of the injectors on the car. Here is the site.

https://www.dynotunenitrous.com/stor...?idproduct=117


James

 

Here ls link for the 18 page PDF install manual.

http://www.dynotunenitrous.com/store...RSAL%20DRY.pdf


James

 

Everything I read said to put the nozzle AFTER the MAF to avoid damaging it from the freezing temps. Clearly it must be possible to put it in front after all otherwise I'd doubt this company would still be selling this product.

 

They do say in the manual to get the nozzle at least 1 foot upstream from MAF. This insure the gas is dispersed and just looks like really cold air to the MAF. They also say that this is the way most "DRY" systems get the extra fuel to go with the nitrous.

 

WTF! James is right! I had a LONG post before this but then went to the link he provided and this nitrous system does in fact spray through the maf sensor to let the maf sensor determine how much fuel to add. Very interesting!

My old dry system raised the fuel pressure to the injectors itself rather than hoping the maf sensor measuring the intake of nitrous. Interesting indeed. I will have to look more into this.

Of course the tracks will be closing soon so no point and rushing through this now. I'm sure with this though, our cars would be at least in the 14 second range in the 1/4 mile.

 

The line pressure is not 1000LB, the injectors jack the pressure thats why they are
so bloody expensive in direct injected cars (Work like diesel injectors) the line feed
pressure is 60 to 80 lbs on most cars. Add a T and a slosh box with pump and your GTG..

Worst case tap the line with the proper fittings and buy a regulator to drop the
pressure to what your spray system needs..

 

Kevin :

That is strange they did it that way. They say the plume of cold NO2 gas on the MAF is what triggers the injectors to send more fuel. They also say to inject after the filter and 1 foot away from MAF. To do it right would reqiuire an aftermarket intake to get enough piping between the filter and MAF. With this installed along with your other mods you will get in the 14s.

James

 

Ok, you know more about this than I. I was looking into it heavily a year ago after I purchased the Fit. There were no takers (Zex, NitrouXpress, NOS, etc).

I also went on several forums to see if any other make/model of vehicle had nitrous installed on a direct injected engine. None of them had anyone that was successful doing it. There were rumors of a Vette that had it on one of the Vette forums but after chasing that down, it was all he-say/she-say. Would you mind pointing/linking to a direct injected car that has nitrous on it? Again, I could not find any, anywhere.

I also was talking to First State Motorsports, here in DE, about installing nitrous while they were installing my Deltacams. Again, the same thing. They couldn't find a place to tap into the fuel pressure line, that wasn't high pressure.

This is why I'm really interested in seeing how this turns out.

 

Is there no worry of blowing a rod or a ring or a gasket pushing 50% more power through the stock motor?

 

Maxswisher:

You are correct. Too much horse power increase and the engine or drivetrain will fail. On the fit I would not be scared to add a 15 to 20 HP increase. Remember The Fit adjusts to conditions. On a mountain top with less oxygen in the air the Fit lowers fuel delivery to keep air fuel ratio correct. Of course that means a drop of up to 20 HP because of lack of oxygen. As you go down the mountain to sea level you get that 20 HP back because you have more oxygen in the air. The Fit just adds more fuel to keep the air/fuel ratio constant. Adding a little extra oxygen by uing nitrous means the Fit will add fuel to compensate to a point. The bad news is past that the engine will lean out too much and cause damage. Thats why dry systems cannot support high HP boost like wet system can. If I wanted to install Nitrous on the Fit I would buy a cheap dry system and buy a few blank nitrous jets. Drill out at 1/3 the size of the smallest jet you get with the kit for absolute minimum injection. Monitor Air/fuel ratio when running the nitrous to make sure you do not go too lean. keep drilling ut the jet ot a slightly larger size each time and try again. That will give you a baeline on the Fit for how it responds to nitrous without leaning out to much. Off course this does not add massive power gains everyone looks for but may be safer.


James

 

James,

Would you please be more specific as to which nitrous express dry kit you're talking about? That link is just the nozzle.

 

maxswisher :

The link for a cheapest dry system I have found with a full size tank is

https://www.dynotunenitrous.com/stor...?idproduct=117

The main thing is to start out small. With a jet drilled extra small you may only get 5 HP increase. When experimenting work up slowly. Companies sell blank jets you drill out yourself.

James