DIY: Nitrous oxide setup for ~$100

[7milesout]

I figured there was other basic stuff like making sure your plumbing is good and probably having a controller of sort, but it sounds like really just watching your sensors and not starting with a 200hp shot is the key. I imagine things you need to watch would be the AFR, Timing, Fuel Trim, and Duty Cycle?

Mainly (I think) would just be AFR and Timing. It would be awesome if one could determine if their engines knock sensor picked up of any pre-ignition during a time span that NX was being sprayed. I'm probably going to have to look into running a "window switch." Which in this case, means there is a sensor that monitors rpm, and even with an active NX system ready to spray, even with the solenoid button in the active spray position, that solenoid is not triggered until a certain rpm. A window of rpm. Say, like spray between 2,500 rpm and 6,000 rpm. Something like that. Because, my Scamp is on little bitty tires (original size for the car). And if I just whomp the pedal to the floor, it's just a tire smoke show (all show, no go). The Scamp had an open diff and would smoke the RR tire when whomping the throttle. I installed a True-Trac diff. Which in a straight line locks both rear tires equally. And now when I whomp the throttle, the Scamp smokes both tires and frequently changes direction. I can leave the line much harder with the True-Trac, but still not full throttle, gotta get about 40 feet out before I can go WOT. So, NX at any rpm at full throttle would probably be a bad thing in the Scamp. So yes … controls, are a good thing.

Works exactly as you expect, spits out a decimal number (14.7, 13.5, etc). Thank god for standards.

OMG, you guys are so lucky. I would imagine that my Lexus has the same wideband sensor. But I don't know how to get a reading from it. Ever since having the AFR sensor on the Scamp, I wanted to see AFR readings from my Lexus. Why? Because I think that if I could tailor my carb settings to have the Scamp V8 run at the same or similar AFR readings as the Lexus V8 (385 hp), the driveability of the Scamp would be that much better . It's been a fun journey learning this. Luckily WOT is fairly easy to hit a certain (12.2) AFR. Its other throttle positions which are more challenging.

[phaux]

It would be awesome if one could determine if their engines knock sensor picked up of any pre-ignition during a time span that NX was being sprayed. I'm probably going to have to look into running a "window switch." Which in this case, means there is a sensor that monitors rpm, and even with an active NX system ready to spray, even with the solenoid button in the active spray position, that solenoid is not triggered until a certain rpm. A window of rpm. Say, like spray between 2,500 rpm and 6,000 rpm.

Well, the car DOES have a knock sensor onboard. I imagine if you had a way to build a custom NX controller (Arduino anyone?), you could define the exact conditions that had to be met for NX to be sprayed. Maybe even watching the MAF/MAP to make sure there's lots of airflow to carry the shot down the intake.

Its other throttle positions which are more challenging.

That's why (custom) ECUs are much fun, you can dictate the fuel and spark at any load and rpm combination to get the exact AFR you want anytime

[Daox]

So, its getting warmer, and this means we're moving closer to getting this thing installed on the Mirage! I'm hoping to get some time this weekend to look at where and how I'll mount this setup in the car. I'm thinking it'll go right beside the radiator in the open area in front of the engine. I'm also thinking that I'll 3d print up some hinged bracket to hold and clamp it in place. That bracket will be bolted to the car somehow. I think I've even stated designing it already. I'll post pictures when I get a chance.

I do still have to get the smaller jets drilled as well. Still working on that...

[Eggman]

Sounds like you need a fire extinguisher bracket for your nitrous bottle. There should be one ready made somewhere. Maybe at Northern Tool?

[Daox]

Yeah, there are definitely similar items. I'm not sure for the size of tank I'm using though. Its only about 3.25" in diameter? I don't see too many 3" fire extinguishers mounted to walls. It also has to be mounted upside down in the car so it sucks up the liquid nitrous instead of the gaseous nitrous. I'll take a look though. No use reinventing the wheel.

[7milesout]

Daox - As I understand, NX bottles have dip tubes to get to the liquid. I might have missed something, maybe your bottle is more home-made with no dip tube though.

[Daox]

Correct, there is no tube on the inside. I will be mounting the bottle upside down to get the fluid out. Alternatively, I could modify the tank cap to have a tube in it. But, I think mounting it upside down will be easier.

[Wubbalubbadubdub]

You're already a good ways in so I can't stop you I guess. 3 cylinder 72cu engine with itty bitty ringlands = cracked piston very easily. What happens is this, at x amount of heat, the piston ring will expand and butt together and push (up usually) into the itty bitty ringland and crack the piston. This happens with power adders and even some NA engines.

So, here is my advice. Do not spray in lower rev range. 4k+. I had an 02 camaro with an LS1 and I used a progressive lsx controller that pulled x amount of timing when engaged, 8 degrees for 250. For a 1 The window was set for 3600 rpm for 150 shot and 4k for 250. On a stock engine, mind you. I was spraying a wet shot, with an external fuel system with a low pressure carb style electric pump. The supplemental underhood tank got unleaded race gas. I never blew my engine and that poor ******* went through life as a state trooper car for 80k miles then I beat it to hell for another 100k and I probably refilled my 15lb bottles every other week in the summer (never in winter). People who sprayed lower, or who didn't utilize a progressive controller, did. A progressive controller just pulses the solenoids at varying rates.

Dry shots always go in front of the MAF. Wet are post. A lot of vehicles don't have a MAF. Also, some factory ECUs/programming are better suited for dry shots than others. The enrichment fueling might not be quick enough to safely utilize a dry shot. All unknowns in Mirage-land. You're not going to be able to pull timing, and considering how torquey little 1.2 engine is, hp and tq are equal, I suspect the factory tune has quite a bit of timing. When I was spraying my wet shot, I didn't purge my lines very much because I really liked making sure the fuel got to the combustion chamber ever so slightly before the nitrous did.

I'm a gearhead, your money is better spent on a ****ty project car if you rely on your Mirage for daily transportation. I love my slow and ****ty mirage but I can't imagine trying power adders other than some tiny turbo. But, that's why I have a 79 camaro in my garage with a lq4/4l80 and a 78mm turbo.

[Daox]

Thanks for the info and warning Wubbalubbadubdub. I agree with pretty much everything you said. If I wanted a fun car, spending a few thousand on a different car is definitely a better way to go. I also agree about only spraying at higher rpms. It totally makes sense and is much safer. I could probably make my own progressive controller with an arduino, but I just don't see that being worth it. I also doubt the solenoid I chose will open and shut fast enough to do so smoothly.

As for how much power increase the 3A92 can handle, we have yet to see. Nobody has really pushed this thing that much from what I've seen. There are a few turbo and supercharged Mirages out there, but not a ton of info on them. The SpeedLab supercharger is putting down 104hp? Not sure if guys are blowing engines with it, but that is really impressive considering its a supercharger and not a turbo. That engine is pumping out a lot more than 104hp to spin up that supercharger. Of course, I won't be retarding timing like you mentioned, but I will have a lot colder charge air, so that hopefully makes up for something...

I am hoping that I will not do any damage to the engine. If I do, we will all learn something. But it will not be the end of the world. I am prepared to deal with the consequences.

[Loren]

Used Mirage engines are cheap. I know a guy who swapped one in a weekend.