[Kinetic Research]

The donor car was taken for it's last drive today, as I need the axles from it for my daily driver. After a proper warmup captured a range of ballpark datapoints for setting up the speeduino on the test engine, which will use a Spartan 3 wideband O2 to refine the fueling.

Sliced into the ignition signal wire to get a contact for the oscilloscope probe. Coil on plug dwell is 2.5ms at idle, around 3ms at higher loads.

The ECU grounds the injector coil (11.6 ohms cold so expecting around 1.2A when running) so intercepted the wiring on the injector coil ground side to analyse the injector pulsewidth across a range of engine loads. Car in drive and brakes fully on, holding throttle at the desired MAP values that the speeduino will use as the engine load axis. Transmission oil got very hot but as it's off the road now not an issue.

DPscope capture of full throttle injector pulsewidth - leads are set to 1:10 so that the voltage level was captured properly, however not sure they were correctly attenuated, but was really only interested in the pulsewidth anyway.

[Kinetic Research]

The laptop is running the DPscope software, works good enough for my budget/purposes. 16 quid plus shipping.
https://www.picaxestore.com/catalogsear ... q=+dpscope

3D printed a housing and soldered leads to the 2 BNC connectors.

[AlainNotHere]

Might be late to the party, but what prevents you from mechanically syncing the engines, say using a gear between the flywheels to force sync, you could that way use a single efi controller in a 3 cylinder configuration, wired to two pairs of injectors.

at some point I thought hey... what prevents one from put one crankshaft pulley side connected to the flywheel of the previous one to configure a v12?

the j30 also has the advantage of low compression in case you want to throw some psi at them.

[PSIG]

Been there, done that, and suggesting to try providing old system values is a lot more work than finding the new values. While certain readings are of use for initial settings (IAC frequency, general MAP at x-load or speed range, etc), most of the fuel and ignition tuning will be to max efficiency (power, economy, drivability, etc), rather than factory goals (emissions, NVH, etc).

Likewise, the factory ECM has different function results, so will produce a bit different fueling or timing at an indicated PW for different reasons. It won't be spot-on and only a place to begin, while tuning will be necessary in any case, so don't spend too much time there - but have fun!

[Kinetic Research]

What prevents you from mechanically syncing the engines, say using a gear between the flywheels to force sync, you could that way use a single efi controller in a 3 cylinder configuration, wired to two pairs of injectors.

What prevents one from put one crankshaft pulley side connected to the flywheel of the previous one to configure a v12?

Could be done simply but then cannot suspend one motor. The original NSX got around just fine on one V6 of similar output as the J35. I do not think this car will be driven in full 7L configuration during the daily commute, but early mornings on the weekends certainly! The twin clutch allows proper VCM.

Sire customs did that with their V16 "hot rod", inline twin engines are probably the most common method of tandem power units, however longevity can be an issue as crankshafts are getting all the torque focused on the last journal, tapping the power away at the center means both cranks are "OEM" torque rating. The J series cranks are durable with boost, but extra stress on the crank will somewhat shorten it's life. By how much depends on your driving style.
https://www.youtube.com/watch?v=VfswVtaZJHU

Others have tried the tractor pull setup, I would not like to see the reliabilty factors at the pitch line velocity on those gears at max revs.....
https://www.youtube.com/shorts/xiFiu1XX-HA?

[Kinetic Research]

Been there, done that, and suggesting to try providing old system values is a lot more work than finding the new values. While certain readings are of use for initial settings (IAC frequency, general MAP at x-load or speed range, etc), most of the fuel and ignition tuning will be to max efficiency (power, economy, drivability, etc), rather than factory goals (emissions, NVH, etc).

Likewise, the factory ECM has different function results, so will produce a bit different fueling or timing at an indicated PW for different reasons. It won't be spot-on and only a place to begin, while tuning will be necessary in any case, so don't spend too much time there - but have fun!

My Tuning experience = 0. My results from internet searches to find baseline data for the components = 0. PSIG's advice and wisdom =1. It is an important point that the values posted are only to establish a rough baseline so that engine can be started and tuning can be carried out. Intake and exhaust system are different to OEM so factory settings are not valid. I am sure the fun is on the downward slope of the learning curve.

What has been fun is working on the spaceframe model, there is nothing like tactile 1/6th scale feedback;

[PSIG]

No problem. It's exploring, and just looking to save some time or frustration for you. Some other useful data while you're running the engine could be recording 'normal' warmed temperature and operating range; injector open-close latency (dead time) at two voltages to start an injector correction curve; coil dwell and correction; fuel pressure; and any other basic TunerStudio setting (or info to create a setting) you may be scratching your head about for initial set-up.