NSX Race Car Setup

I am going to take a different approach on my site for racing information and that is to go over some the challenges in the setup and it may help the community. This won’t be a full “How to” guide with step by step instructions. This is not my intent.

My goal is to answer some of issues that i couldn’t find answers to. Keep in mind this is a race car setup and your mileage will vary with your setup or purpose.

If you would like to read about the build jump to here (car porn):

ACURA NSX – The Everyday Super Car

Otherwise, prepare yourself for information overload.

1990 Technology

Old but I’m not that old. Young but I’m not that bold.

I guess to put it into perceptive I wasn’t even in my teens when the NSX came out and this technology is “old school” by today’s standards.

Grounds

Grounding on this vehicle is extremely important.  The engineers spent a lot in time trying to figure it out. Don’t reinvent. On the NSX it goes without saying to use the DARCO coated bolts to discourage corrosion. You don’t want to create structural weak points.

The resistant values outside the grounding locations are very ugly.

How ugly?

Fluke multi meter:

  • Factory mount points: less than 0.2 ohms
  • Mounting holes are equal greater than > 4.6 ohms through the body
    • Cleaning up for grounding will marginally improve signal
  • Roll Cage ~1.6 to  2.8 ohms

The take away is to use the grounding locations. I can hear the peanut gallery; “Aluminium is conductive”. That is correct, but not as good as, gold, copper, or silver. All it means to me is that the aluminium on the NSX is sealed very well.

FYI: There are also “special” ground bolts. These are tapered bolts that are designed to cut into metal.

EFI

AEM Series 1 V1.19

AEM Calibration File: 1042.v1.19

  •  Zero “0” values have weird consequences where values can cross over (eg. TPS , fuel table…); my guess is it floats the value or is undefined [IMO, It’s shame they did not work that closely with GEMS instead adapting]
  • use 0.1, 0.01 or something to that that effect to avoid issues; be wary of negative values as calculations are almost always based on a multiplier or a percentage value

What a quirky program. I played with the GEMS v3 version and I’m confused at the direction that AEM took. It should be no surprise to anyone that AEM series 1 is a rebadged GEMS with tweaks in the software and hardware. It lacks refinement in comparison to modern EFI solutions.

Use the NSX pre-configurations and adjust from there. I only used the settings and parameters as a starting point – it saved me hours of research and it cut dyno time.

MAP

The OMNI Power/ SOS map sensor:

  • Min Voltage:  0.00
  • Max Voltage: 5.00
  • MAP Filter:     5
  • Load Offset:  1.00
  • Load Scalar:   3.16
  • Freq #4 Div:   0
  • MAP Analog Input: MAP Voltage
  • MAP Period Input:  None

I’m really disappointed by the information I received and found – not even close.

  • MAP voltage you should test. In our case 5.00 is correct. If you are unsure ~ 4.90 or 4.95 would work
  • You can always cheat and look up the current atmospheric pressure via weather info (make sure it is absolute), and adjust before bringing it to the dyno; of course you should verify/synchronize off the dyno

Ignition Timing

Don’t forget even though this is a distributor-less ignition system (DIS) you should verify that timing is synchronized with the the ECU. A digital timing light is useful in this area.

Coil Number

Active: [F]1,2,3 [R]6,7,8

Injectors

ID Injectors comes with a table of the injectors tested so there’s really nothing to post. You will have to interpolate some of the values.

Injector Order:  [F] 1,2,3 (knock 1)   [R] 4,5,6 (knock 2)

Crank and Phase

Use the dyno and verify. Never trust the calibration.

Narrow band O2

Everyone says – what are you crazy? Hey, if you tell me the table is programmable I expect it programmable. It’s important having a working O2; even if it is a narrow band and even for a race car.  There is no reason to reinvent the wheel.

The main issue is that prevailing issue with zero ,”0″, values do bad things for the AEM series 1. How bad? the fuel tables change when you change the O2 settings, which is odd for me to see.  The second issue after playing with the O2 settings table is that it doesn’t plays nice with the narrow voltage range; there seems to be a disconnect between the software settings and what the hardware is outputting. At only key on I would consistently read a different stoich value. I’m sure if i think about it a bit longer I would find a solution.

Anyway, my curiosity stopped the moment I hooked up my old school LM1 to test my base map. I was being lazy and at the same time it was an academic challenge as I was told that this could not be done (it feels like this is something on the dyno I could figure out). Anyway, with all race projects I ran out of time and in the end it’s a moot point as we would be switching to wide band for logging and diagnostics.

Fuel

Injectors
Convert to high impedance injectors. The factory setup is peak and hold.

  • Remove the injector resistor box and bypass
    • Bypass: connect all wires together
  • Option 1: cut and solder all connectors together
  • Option 2: de pin and connect  together
  • Option 3:
    • cut resister plug box connector and use (this would make it messy to go back and test previous peak and hold injectors)
    • cut a plug from an OBD 1 distributor female plug and make your own connector
  • Option 4: SOS has a pre made plug

Fuel Pump Resister box

This is an interesting idea for fuel economy; I would say this is a pretty good cheat. You limit the fuel pump voltage delivery based on load. I can see the advantage (keep in mind everyday sports car) – easy diagnostics , less programming, less cpu cycles… The disadvantages are long, but it’s a compromise.

I took the resister box apart and from looking at the design a lot of effort was made to reduce noise. It kinda makes sense as it sits right beside the alternator.

Option 1: Cut and solder the connectors together
Option 2: Cut the fuel resister plug and loop
Option 3: Civic rear tail light plug and loop

Fuel Pump

Walbro 400 LPH

The factory fuel pump wiring is about 16ga from the main relay to the fuel pump. The distance is less than 5 meters (most likely closer  to 3 meters). Since we were changing the pump we might as well upgrade the wiring. There is a potential for overloading the circuit as the Walbro 400lph can draw around 19Amps of power (Factory is rated for 15A) .

De pin and replace the fuel pump wiring to a thicker gauge like 12ga (power and ground). De pin and replace the wiring from the the fuel relay. In this area you can improve the response from the pump as well by running power directly from the battery source.

Option 1: Run your own wiring (fuse, or fancy – fuse box +relay)
Option 2: SOS has a Kit that you can purchase

Collaboration with Kelsey B.

This ends part 1. Stay tuned for part 2

Part 2

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