Jacobs Nitrous Mastermind Install & Jetting Changes

150 Shot Without Nitrous Mastermind

Here was the result of the 150 shot jetting (63N/37G) prior to installing the Nitrous Master Mind. You can clearly see the large spike of torque as cylinder pressure goes way up when dropping all that nitrous into the cylinders at 3500 RPM. You can also see that since the amount of Nitrous being added stays constant, as RPMs rise, the torque gain falls off quickly. One of the goals of the installation of the NMM was to keep that torque gain flatter instead of just a large peak (that usually results in wheelspin).


150 Shot With Nitrous Master Mind

Here's the same 150 shot jetting now running the NMM. Bottle pressure may have been a little lower since this was run 8 or so of testing where to set the knobs on the NMM, but it's very representative of what I wanted to achieve. Notice the virtually flat torque curve. You can see that the system comes one at about 3200 RPM, then pulses the solenoids until around 5000, where it comes on 100%. The next task was to try to move the torque plateau up to the 550-575 lb-ft of torque range. That would be accomplished with larger jetting.


150 Shot vs. 200 Shot With Nitrous Mastermind

For the next several dyno graphs, we're not even going to look at peak numbers. For this exercise, we are mainly looking for an increase in power and air/fuel ratio. By air/fuel ratio, I mean I was using a prototype air/fuel ratio measurement device that Dynojet is now selling. This goes up the tailpipe and measures the air/fuel ratio of the vehicle. It was referred to as Lambda on the prototype unit. To get an air/fuel ratio from the Lambda reading, simply multiple the Lambda reading by 14.7.

For this graph, you can see that going from a 63/37 jetting to the 70/40 jetting (supposedly the 200hp jets), the air/fuel ratio got slightly leaner. This is still really safe, being that at 5800 RPM, the Lambda was still just less that .80, translating to an a/f ratio of 11.76:1 (quite rich).

You can clearly see here that going from the 63/37 jetting (blue graph) to the 70/40 jetting (red graph) made a difference in power output and air/fuel ratio.


Nitrous Runs Playing With Jetting

The blue graph is the 63/37 jetting (150 shot). The red graph is the 70/40 jetting (200 shot). The green graph was 73/40 jetting. You can see on the lambda that going up on nitrous jet, and not changing the fuel jet DID result in a slightly leaner mixture, and a little more power was achieved.


Nitrous Runs Playing With Jetting

Here the green graph was the result of moving the nitrous jet up another step to a 76. What I didn't undestand at this point is why the a/f ratio and power did not change. So I chose to experiment some more.


Nitrous Runs Playing With Jetting

This graph shows the 73/40 jetting (blue graph), the 76/40 jetting (red graph) and 78.5/40 jetting (green graph), with virtually NO change in a/f ratio or power. I was really starting to get concerned at this point, that I may have a restriction in the system.


Nitrous Runs Playing With Jetting

Just to prove myself right, I decided to up the nitrous jet to an 81. This would show me once and for all if the jet size changes were making any differences. As you can see, the green graph is with the 81/40 jetting. That this point, I am convinced that there is another limiting factor in the system.

After some consulting with my local speed shop, I decided to call CompuCar and find out what the orifice size of their Super Street solenoid was. They told me it was a .085 (or equivalent to an 85 jet) orifice. Despite their tale, I decided to go with a larger solenoid. In this case, I decided to go with a Nitrous Express solenoid. They were the only other manufacturer on the market that maintains that their solenoids will not be affected by pulsing (which is what the NMM does to achieve a progressive shot of nitrous).

I went with their .125" orifice solenoid, which they claim would support up to 300hp.


Nitrous Runs Playing With Jetting

Upon initial installation of the NX solenoid, I went back to the 70/40 jetting. It immediately made more power than even the largest jetting with the smaller CompuCar solenoid. A/F ratio started to get a little closer, and things were looking up.

This graph is with the NX solenoid. The blue graph is 70/40 jetting, the red is 73/42 and the green is 76/42. As you can see, even though I went up from 70 to 73 on the nitrous jet, going up from a 40 to a 42 fuel jet made the car get richer. Then, goin from a 73/42 to a 76/42, the green graph shows a slightly leaner mixture (and more power) than the red graph.


Nitrous Runs Playing With Jetting

At this point, going from the 73/42 (blue graph) to the 76/42 (red graph) had made quite a difference. I then decided to go up to a 78.5/42 jetting (green graph). You can see that it made a big difference in the power and a/f ratio. That's about where I wanted to see the a/f ratio be.


Nitrous Runs Playing With Jetting

I then went from the 78.5/42 (red graph) to an 82/43 (green graph) and you can see that the car got quite rich again.


Nitrous Runs Playing With Jetting

By going up to from the 82/43 (red graph) to the 86/43 (green graph) the a/f ratio came up and so did the power. What did confuse me a little is that the 78.5/42 jetting was making more power, and was slightly leaner, so I knew the car wanted to be leaner than where it was.


Nitrous Runs Playing With Jetting

I continued to go up on the nitrous jet to an 86/43 (red graph), then went to 89/.46.5 (green graph). I figured this would make the car go lean, and so it did, yet power was still good.


Nitrous Runs Playing With Jetting

With a 46.5 jet for fuel, I then went up from the 89 (red graph) to a 93.5 (green graph) with no appreciable difference in a/f ratio or power. At this point I started to wonder if pulsing the solenoids means that I won't get full use of the orifice size of the solenoid, meaning that a 93.5 may be the limitation for this solenoid as well. Just to ease my own mind, I went ahead with one larger jet size.


Nitrous Runs Playing With Jetting

And I thought I was right. Going from the 93.5/46.5 (red graph) to 96/46.5 (green graph) yielded no difference either. This told me that around a 90 jet was the biggest this solenoid would support.


150 Shot With NMM vs. 89/42 Jetting With NMM

In the end, I ended up with 89/43 jetting (red graph), which yielded a virtually flat torque curve at around 500 lb-ft of torque (not quite as much as I had hoped for, but good nonetheless). As you can see, the blue graph (70/40 jetting) and the red graph (final 89/43 jetting) were very close on a/f ratio. The final jetting resulted in a peak of 497 lb-ft of torque pretty much flat from 3500 to 5200 RPM, and a peak of 463.8 horsepower at 5800 RPM. This is an increase of 177hp at the wheels from the baseline motor pulls.


Before NMM With 150 Shot vs. NMM Run with 89/42 Jetting

On this graph, the light blue represents the horsepower achieved with the 150 jetting (63/37) without the NMM. The bright red graph is the horsepower of the 89/43 jetting with the NMM. While the horsepower is down a little below 4900 RPM, when shifting through the gears, you never fall that far back anyway. Above 4900 RPM, the NMM jetting is considerably higher in output, where you really want it.

The dark blue graph represents the torque output of the 150 jetting without the NMM. Again, the torque is quite a bit higher below 4900 RPM, which results in more wheelspin, but look at 5600 RPM, the NMM torque curve is up 50 lb-ft more! That's going to translate to much better performance.


150 Shot Without NMM vs. 89/42 Jetting With NMM Horsepower All Gear Run

Here's a comparison of the horsepower on the bottle through the gears. The first hump is second gear, then third and finally fourth. As you can see, in third and fourth gear, the car is making considerably more power now (red graph) than before the NMM (blue graph).


150 Shot Without NMM vs. 89/42 Jetting With NMM Torque All Gear Run

Here is the same dyno runs, just displaying torque instead of horsepower. As you can see, the red graph (NMM and bigger jets) provides much more torque than the 150 jetting and non-NMM runs. Look at the difference in torque at 120 mph in fourth gear...that's about a 100 lb-ft of torque difference. I can't wait to see what it does at the strip!


The installation of the Jacobs Nitrous Master Mind was fairly simple. Most of the wiring is straight forward, other than knowing which wire goes to the ignition system. I'm running the Accel 300+ digital ignition system, so it has a white wire that plugs into the stock harness's pink wire, which is the trigger for the coil. This is the wire to splice into.

Since the NMM wants control of the spark, it has to go inline BEFORE the ignition box. That means that the proper installation requires cutting that white wire leading to the Accel box before the box. The white wire coming from the stock plug goes to the green wire on the NMM, and the yellow wire on the NMM goes to the Accel side of that white wire. This allows the NMM to have rev limiter and retard control of the vehicles' ignition system.

Because of some of the horror stories I have heard about the Jacobs' products, I decided that it would be better to cut their wiring harness and use a 9-pin molex plastic connector. This has two benefits. First, removal of the NMM for any reason is made much easier. Second, since the NMM had the igntion signal routed through it, I simply built a second plug that passed the ignition signal straight through and voila, the car still runs. Below is a complete listing of the wires used in the NMM, and what they connect to:

NMM Wire Color:

Connects to:


+12v Keyed


Out To Accel Box


In From Stock Coil Trigger




Not Used


Not Used




Out To N2O Solenoid or Relay (ground)


Hobbs Switch In (ground)


N2O Trigger (ON) (+12v)


Out To Fuel Solenoid or Relay (ground)

In my installation, I decided not to use the Brown wire on the NMM. My Hobbs switch was already wired to the negative side of my main relay, so if the pressure dropped, I don't need the NMM to kill the nitrous, it will happen already. The NMM requires a ground on that wire, indicating good fuel pressure, so if you choose not to use the Hobbs switch wired to the NMM, simply ground the brown wire.

Installation was fairly straight forward. I mounted mine in the glove box, upside-down, so that the knobs were easily accessible. I put two small pieces of velcro on the bottom of the glove box, and the top of the NMM (facing down) to hold it in place. The wiring also has two LED's wired into it. This is so if I needed two, I could monitor the outgoing signal to the solenoid relays. Here's a picture of it's final resting place:

The first unit I received had a problem. After getting it in the car, I noticed that it worked fine, as long as the car was cool inside. I installed it one evening, and it ran flawlessly on the RPM side. At this point, I had not tried to activate the nitrous. The next morning on the way to work it worked fine; however, that afternoon on the way home from work it didn't work fine. The problem I experienced was much like the rev limiter was kicking in. No matter where I set the rev limiter, it would limit me to about 3,200 RPM. When I got home, I was confused. Everything was hooked up correctly. I called Jacobs the next day and sent the unit back UPS next day delivery for quick turn-around. A week later I received a new one and wired it in.

The drive home was perfect. I played with it and set the rev limiter just below the 6000 RPM limiter I have in the stock ECU. The next morning was also fine, but I figured the real test would be the drive home from work after the car sat in the sun all day. On the way home, it too exhibited the false rev limiting that the first one had. At this point, I was patting my self on the back about using a plug instead of wiring it in directly.

I let the car sit for a few hours, then took it out for another test drive. By this time, the temperature outside had dropped to around 85 from the 110+ during the day. This time the car would pull to approximately 5000 before cutting out. I started to get the idea that this problem was heat related. The hotter the NMM was, the less RPM it would allow.

I called Jacobs back again and this time told them that they should test this unit so that I didn't receive a third broken one. They told me that normally there is a $25 test fee, but in this case they would waive the fee. They were also going to issue me a UPS call tag for the unit, so that I would not have to pay for it's shipping back to them.

Five weeks and MANY phone calls later, the call tag finally arrived. The unit was sent back and supposedly tested. They found no problems with it at all, and sent a third unit out to me. For whatever reason, that one worked fine, and is the one currently in the car.

Talking with some of my electrical engineer buddies, they seem to think that the NMM uses its own trigger coil to fire the ignition. This means that they read the incoming spark signal, then generate their own. If a cheap trigger coil driver was used, it would be influenced by heat, and would not be able to send enough signal's to support the engine. They figure that's the case of the NMM. Had this one not worked, I would have pulled it apart and started looking for this trigger coil myself. I'm glad it didn't have to come to that.

The NMM itself does do a good job. One thing that I will warn any potential user about is that the knobs are WAAAY off. If you can see it in my picture, the second knob from the right is the N2O on RPM. Their dial goes from 1000 to 6000, and where it is set corresponds to 3200 RPM. Looking at it, you'd think it was more like 4500 RPM. Now look at the third knob from the right...that's the full-on RPM. For a knob that goes from 1000 to 10,000, it's set at around 8000 to bring the N2O full on at 5000 RPM. Had I not had the dyno to do testing, I'd never have gotten it right. The left-most knob is the rev limiter. As you can see, it's set pretty close to 8000 RPM, where it actually comes in around 6100. Just be aware if you too pick up one of these units.

Once we got it working, it's a great unit. As you can see above, it has helped out considerable. Hopefully that will also show up at the drag strip. I plan to go there in the next few weeks to see if I gained anything. It may be hard to judge though, since I've also changed wheels and tires since my last outing. We'll see if the MPH goes up any.