Mitsubishi Evo 8 FQ400 Development
The FQ-400 is somewhere near to the pinnacle of factory-tuned Evo’s, but can the best of the breed be made even better? One of our clients believed it to be so and with some patience and cash to hand, he pursued what had been little more than a theory.
There are many stars in the Mitsubishi galaxy but the one which claims to shine among the brightest is the Evo 8 FQ-400. With a tasty 400bhp output from its HKS-tweaked 2.0-litre 4G63 engine, a sub-4.0second 0-60mph sprint and a reported 175mph top speed, the FQ400 offered among the ultimate figures of factory-tuned Evolutions, complete with a three years/36,000 miles factory warranty. Yet, there was always a nagging doubt that the headline-grabbing power figure hid even more potential than Mitsubishi itself realised? Although very rare 430 and 450 versions were produced as The Colt Car Company explored the outer edges with HKS, the FQ-400 was more readily available.
Desiring to improve the performance of the standard-spec FQ400, Torque Developments International (TDI) was approached to investigate exactly how much more the already stretched Evo had to offer. “This was the first FQ400 we had got our hands on,” stated Mark Catchpole of TDI“so, before doing anything else, we decided to carry out a performance audit, which included a dyno test and data logging on the standard car to evaluate the power, torque and other essential characteristics. With the baseline figures established, we could then construct an effective tuning path, rather than throwing parts at the engine blindly in the hope they might work” said Mark. By carrying out this audit of the standard car, We wer able to learn how best to modify similar examples in the future. The Rototest dyno is well known to be the most accurate and reputable machine in existence, which is why it is the weapon of choice of many Tier 1 manufacturers and race teams. The initial dyno test revealed some interesting and, quite frankly, surprising points. Firstly, the power is significantly short of the claimed 400bhp, a moderate disappointment for a car with such a lofty reputation. On our Rototest chassis dyno, the results came out at 308.7hp and 299.5 lbs/ft at the hubs, which allowing for estimated transmission losses equates to approximately 385hp at the flywheel.
Naturally, some of this may be due to intrinsic wear and tear, although ‘rounding-up’ does seem to be the likely culprit.
Secondly, the power graphs illustrated that the torque curve was far from ideal. Many readers may remember a Top Gear episode, from a couple of years ago, where Jeremy Clarkson demonstrated the off-boost lethargy and massive turbo lag in a 5th gear acceleration test against a Fiat rental car with a 1.6 litre petrol engine. Mark commented “We found that the torque rose slowly to a point just below 5000 rpm then climbed up rapidly to its peak before diminishing substantially once again just prior to hitting the rev-limiter. This suggested that there was a mismatch of airflow characteristics among some critical components.”
Having provided us with the go-ahead for a two-stage modification process, the first step was to get as much performance from the standard 2.0-litre unit without increasing the boost pressure or changing the turbocharger altogether. Once this had been stretched as far as possible, then the next step would be to increase the engine capacity with a stroker kit, fit a more appropriate turbocharger and to raise the boost pressure above the standard offering. Further evaluation of the potential issues needing to be resolved resulted in TDI suggesting the initial round of modifications. A Cosworth CNC ported cylinder head was fitted to increase airflow, along with a pair of HKS camshafts with HKS cam pulleys to increase cylinder filling at high speed. The Cosworth cylinder head is a brand new casting, precision machined by a CNC robot to modify each valve throat and port accurately and consistently. This increases the efficiency of the intake and exhaust air flow significantlyy. The cylinder head is provided complete with larger stainless steel racing valves and uprated valve springs.
This shows the Cosworth CNC machined exhaust ports.
Polished combustion chambers and larger Cosworth stainless steel valves.
CNC Cosworth machined intake ports
Pre-fitted with Cosworth racing valve springs
The Cosworth cylinder head can be purchased at http://www.tdi-plc.com/catalog/index.php?cPath=107_439_495_496
We took the standard engine apart for inspection, the team was surprised to note that the FQ400 retains the same camshafts as the standard 280bhp output engine. We selected a pair of HKS 264 degree camshaftswith 10.3mm lift, which have greater valve acceleration and deceleration rates to increase their open area, thereby providing more opportunity for power and torque to be developed. HKS adjustable camshaft pulleys were employed to enable accurately optimized timing.
Upon removing the standard cylinder head during the course of the exercise, we also surprised to find that the forged pistons used had an unusually high amount of clearance. This had led to a case of bore wear, as shown in the pictures. This can demonstrate several unpleasant characteristics, such as excessive engine noise and heavier than usual levels of oil consumption. We knew that we would be turning our attention to the cylinder block as a separate evaluation, so did not deal with this issue at this time.
At the front, a larger HKS intercooler was fitted to provide reduced air-charge temperatures. While the standard intercooler is reasonably large, we considered that its thermal efficiency was compromised for the needs of such a high output engine, so it was binned and replaced with the HKS item.
The HKS intercooler kit can be purchased at http://www.tdi-plc.com/catalog/index.php?cPath=107_439_495_496
Turning attention to the inlet side of the engine, we discovered that the standard induction pipe between the air filter and turbo had a severe internal restriction. We dealt with this by designing and fabricating a brand new, bespoke induction pipe, completely free of any restrictions that might slow down the air-flow. At the same time, the standard air box was replaced with the HKS Super Powerflow Reloaded induction kit. The standard factory fit recirculating dump valve was replaced with a vent to atmosphere HKS SSQV dump valve.
The standard FQ400 is equipped with an Ecutek engine management system, which in the majority of applications proves reasonably effective. Yet, something with the untapped potential of this project warranted a greater level of fine-tuning. We wanted greater engine control and functionality so we selected the HKS F-CON V Pro along with a MAP sensor, temperature sensor and harnesses. The ECU is a standalone engine management system, with a 32×32 resolution, providing highly detailed adjustment for fuel and timing, along with full data logging capabilities including readings for speed, RPM, water and intake temperatures, timing, boost and injector duty. The new ECU was paired with an HKS EV6 boost controller, which had been chosen for its superior boost control characteristics.
After running and calibrating the FCON V Pro ECU, the final results were 370.9bhp and 339 lbs/ft at the hubs, an increase of 62bhp and 40 lbs/ft. This equates to an approximate gain of 77bhp at the flywheel, giving a new flywheel figure of 462bhp.
It is important to note that this increase has been obtained, without raising the boost pressure, and it demonstrates that the gains have arisen purely from increasing the efficiency of the engine, along with accurate mapping of the new HKS ECU. The new graphs provide a much healthier curve and the added flexibility and overall usability provides a brisker on-road performance, even without the intended increases in peak power and torque levels.
We have already achieved some impressive early results and, as you will see in a forthcoming instalment, there is much more to come courtesy of a stroker kit that will increase the engine’s capacity allied to a larger turbocharger that should exploit more comprehensively the greater airflow capabilities.
We saw previously that we were able to yield a very impressive almot 80hp just by improving the engine breathing and careful ECU tuning. This is actually quite difficult to achieve without increasing the boost pressure but it is what the “science” of tuning is all about.
The FQ400 owner decided that a more substantial performance upgrade was required so we were commissioned to undertake the installation of a Toda Racing 2.3 litre 4G63 stroker kit, HKS Full Turbine set up kit, custom GT Turbine, HKS fuel injectors and delivery kit, and a high flow throttle body and intake plenum.
Toda Racing are one of Japans foremost racing component manufacture. Here we see their 2.3 litre stroker kit which comprises of a 100mm stroke crankshaft, Toda Racing 86mm or 86.5mm pistons, and Toda Racing High Power connecting rods. The crankshaft stroke is increased from the standard 88mm to 100mm which has a positive benefit to engine output torque.
The Toda racing forged alloy pistons are available in 86mm and 86.5mm. They are of extremely high quaility which means that they use exceptionally low clearances to reduce piston noise and oil consumption. They feature a Defric coating to reduce friction and aid initial running in. They also feature high strength piston pins, improved oil return and are balanced to within 0.25g.
The Toda Racing High Power connecting rods combine light weight with exceptional strength.
The Toda Racing stoker kit can be purchased at http://www.tdi-plc.com/catalog/index.php?cPath=107_439_495_496
This is the cylinder block after boring, honing and preparation.
Here’s the cylinder block assembled with the Toda racing 2.3 litre 4G63 stroker kit.
Here’s the high capacity plenum with HKS fuel rail.
Inside the plenum.
Here’s the high flow plenum compared to the standard Mitsubishi plenum.
Here’s the standard throttle body compared to the high flow throttle body.
HKS fuel rail and 1000cc fuel injectors.
Some images of the engine built and components installed.
We designed the turbocharger specification based around a Garrett GT30 to achieve our objectives.
The HKS set up kit required modifications to suit the GT30 turbocharger.
The Toda Racing / Cosworth 2.3 litre stroker engine finally gets re-fitted.
All of the above parts can be purchased at http://www.tdi-plc.com/catalog/index.php?cPath=107_439_495_496
After running in, the engine goes back on the Rototest dyno to have the FCON V Pro calibrated.
After increasing the boost pressure to 2.1 bar, we finally saw a yield of 466hp and 425 ft/lbs at the hubs (approximately 500hp and 500 ft/lbs at the flywheel) at a relatively low boost pressure.
Further performance enhancements are in the pipeline.