Engine ECU Tuning a GTR to 400 Horse Power

(This is the continuation of my ongoing Build story) I dropped the car off at ACSP in Laval last night to give the tuner (Pat) enough time at his own pace to take care of the little things that needed to be done before we could tune, and he agreed to call me up when it was ready for the dyno so I could be there to setup the boost controller and watch the whole thing. Check out this video, its sort of an intro clip to the story:

During the day, Pat rewired my Fuel pump with a new relay to supply 13 Volts constantly to the pump. This helps to make sure fuel will always be where it needs to be, and helps to prevent against a short in the old wiring harness for the fuel pump.




Subscribe to our YouTube channel below for more great videos


Then he had to weld in a bung for his Wide-band O2 sensor, socket my ECU to accept the new tune and lastly install the bigger 660 cc Fuel Injectors, which were just cleaned and flow tested but were apparently quite difficult to get inside the oem fuel rail, but he managed.

Mustang Dynamometer Rolling Road

The Dyno at ACSP is a Mustang Dyno, one of the lowest reading dyno's on the market. This is because the power is recorded by whats being delivered through the tires, and onto the "rolling road". The Mustang Dyno gives the most accurate real world reading of power and torque but the downside is your numbers end up looking a little conservative compared to other dyno's that read at the hubs, which always read significantly higher because there is no rolling inertia from the wheels, and zero slipping.


On the Mustang Dyno there's the possibility that the wheels will slip sometimes on the rollers and you can see blips in the torque and power curve, but these are easy to spot as they will both dip sharply at the exact same time, and only for a brief second until the wheels get traction again.

Large cooling fan for Intercooler Radiator while Tuning the Engine

He put the car in position, and locked it down with chains and straps, put the giant blower fan in front of the car so that air would still be moving through the intercooler and radiator and got started with programming the ECU.

Chain lock and straps holding down car during engine dyno tuning

First thing to do was have a quick check through the systems and make sure everything was all good. Given the all clear from diagnostics he started by adjusting for the bigger fuel injectors, with a few light pulls at the lowest possible boost setting of 15 PSI the car was producing an astonishing 320 wheel horse power! (whp). He was a little shocked at how much power it could put down with so little tuning effort, so he got deeper into it, adjusting the fuel and timing maps from A to Z, he checked every cell and made sure it was a Super safe tune.

Remapping the ECU during Dyno Session

I made it clear from the beginning that my goal was not power out right, but more reliability. What good is power if you blow the engine in a week! So he continued to refine the maps and eventually got up to 360 whp in 3rd gear, we were all amazed that 15 PSI was able to hit such good power numbers, and the power curve was smooth as hell too! If you like the customer interior, take a look at this Article on how I swapped to R34 Racing Seats, Momo Racing Wheel, Defi Gauges and Controller, HKS Turbo Timer, Blitz Dual SBC Boost Controller and a unique Veilside 340 km/h speedo. He had tuned a stock GTR with mods similar to mine that morning, except running oem turbos and at the same boost level that car was making 20 whp less, so thats the difference the 2860R-5's make at 15 PSI, 20 whp.

He explained to me that we dyno tune in third gear because it provides the best resolution, he also explained a little bit about pulling the ignition timing some ten degrees or so, but a lot of the technical jargon is lost on me at this point.

Nissan Skyline GTR on Mustang Dyno 400 WHP

If you like the sound of that HKS Hi Power Exhaust system and wondered what it looks like underneath, have a look at this Article on Overhauling the Exhaust System, Turbo Outlets, Down-pipe, Decat, Cat-Back. So, with the low boost setting complete it was time to raise it up to the target max boost setting we planned of 18 PSI, after some fiddling around with the Blitz SBC-R we managed to land exactly at 18 pounds, he did a few pulls in third and ironed out the kinks in the maps, we then let the car cool down for a few minutes before seeing how much power it could put down.

Tuning the ECU on Laptop on the Rolling Road Dyno

We went up to fourth gear this time because fourth has a direct one to one (1:1) gearing ratio so it gives the most accurate power output readings, and since the tuning was essentially done, it was now time to see what this thing could really do! we watched the numbers climb just North of 400 whp before we maxed out the stock air flow meters at 6,750 RPM, damn we were all a little disappointed because this engine just wanted more! and it was willing to give us more too! we just ran out of room on the MAFs. Oh well the point was made, and the tuning complete. Pat figures that if we didn't hit the MAF limit so soon, we would have seen a max power output of 415 whp, which is an immense amount of power.
So, because I wanted a print out with a nice graph, we went back into third gear and he did one big easy pull and laid down 390 whp with 303 ft-lbs of torque on a relatively smooth curve, and he reminded me again that these numbers are really conservative and don't really mean a whole lot compared to other Dynos.

390 whp Dyno Chart Graph

He handed me the keys and my buddy Mitch (who'd stopped by to say hello) and I went for a few quick pulls up and down the street. Mitch's car develops north of 500 whp and is a monstrous machine so he was warning me about being careful when driving this car until I get used to the new power level. Essentially it's more than double the power I've been used to handling so far.


In first gear, I let out the clutch and we were away... boost comes in pretty early and hits full near 4,650 RPM. At 1.2 Bars (18 PSI) in first gear, theres not much of anything left in my brain, sheer and utter violence as the car accelerates into oblivion, its only describable as warp speed! before I knew it I was already at 7,600 RPM!! Time to shift, Drop it into to second and the madness begins all over again, all the way up to 7,800 RPM this time we're already doing well over 120 km/hr!! Into third gear now its just mind boggling, its so hard to process all the things around you at that kind of speed, the G-force from acceleration makes it feel like theres an elephant sitting on your chest, and I let off the throttle as we approached the end of the road.

Quickly turned the car around and went even harder back down the street, we stopped back at the shop and Mitch and I were both just sort of laughing nervously, its a Lot of power, and will definitely need some time and practice to get used to.
Feeling very satisfied that all our hard work had paid off, and the tune was perfect, I shook hands with Pat, thanked him for a job well done and parted ways.