So we have reached another stopping point in the build. I picked up the FX on the 6th and have driven daily without punishing her too much. I've done a few pulls... with caution.
The tuner was going through increasing boost levels when around the 430whp mark, coolant started spewing from the overflow reservoir vent. On the dyno in a 105 degree shop, the OEM temp gauge started to rise so we backed off the boost and held the power to 400whp. On checking the injectors, we found they were running at 85% duty cycle at full boost. Intake temperatures are 20 degrees over ambient. All in all it looked to me like we were riding the hairy edge of cooling failure. Granted this was on a dyno with a fan pointed at the radiator, but I want more of a safety margin than that. Since I have driven the car now for a little over a week, the temperature gauge has never risen much above the half-way mark, but twice I have ejected coolant. I can stop it from happening if I drive easily for the last 15 minutes or so of my drive. But if I do a hard pull within 10 minutes of shutting down the car, heat continues to rise for a few minutes after the car is off and coolant overflows. If I do a hard pull and shut down immediately, coolant will eject violently.
So the shop is recommending a larger core radiator paired with a lower temperature (Nismo) thermostat. I have followed up on a couple cousin forums and even the G and Z guys say the stock radiator is pretty inadequate after going forced induction. I also have my intercooler and two oil coolers in front of the radiator, making it less efficient. Instead of moving everything around and trying to make it work, a 36mm core Koyo R is now on order.
The tune will continue after the new parts are installed and we are going to maximize the injector duty cycles without getting too aggressive. Don't want to max them out and run lean in colder weather. I've decided to draw the line here (at whatever power level the injectors can give me). At some point in the future if I want more, a larger turbine housing, 800cc injectors and a new tune will be all I need for a nice bump. That probably won't happen unless I burn up this transmission and am forced to go for something that can handle upwards of 500whp.
Short list of items for the next shop visit:
Engine oil will be sent to a lab for analysis and we will most likely try a second interval on the Rotella T5. Goal for the analysis is to see how long I can run this oil between changes - could be as many as 10K miles depending on the analysis results.
The oil filter - removable cartridge style - has no bypass and a high flow capacity will be installed as well - a little fabrication is required to get it to mount properly. Right now I'm using a Nissan Titan OEM filter.
We're also going to re-work the oil catch can system - probably going to a two can setup.
Will be installing some fresh NKG copper spark plugs.
Installing the Nismo thermostat and Koyo Radiator - fabrication required for radiator hardpipe.
As soon as all of the ordered parts have arrived, the FX goes back down for one last wrench session and a solid few days with the tuner. When she comes back, I can FINALLY turn my attention to some nice wheels.
