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filler@godaddy.com
Tuning since 2012
2004-2020 STI
The first thing I always have my customers buy for an STI or any EJ-platform car is an AFR gauge. If you care about your motor, you need to pay attention to AFR. We’ll get more into that below. Although the STI comes with a factory AFR sensor, it becomes inaccurate under boost because rising exhaust pressure affects the sensor. It reads correctly in vacuum, but once in boost, the numbers can’t be trusted.
Second, you will need an air-oil separator to remove excess pressure from the crankcase. The OEM STI crankcase pressure rises above 5 psi when adding power or running more boost. That pressure needs to be evacuated, and that’s exactly what an air-oil separator does—while also preventing oil from entering the intake. Oil ingestion lowers your fuel’s octane rating and can cause knock.
If you wish to keep the factory downpipe, an external wastegate will be very beneficial. An aftermarket downpipe increases exhaust flow from the turbo, allowing pressure to escape and more air to enter the engine. This results in quicker spool and more torque.
Once you have a good air-oil separator and AFR gauge, the next best mod for power is an upgraded fuel system with a flex-fuel kit. This will also require an AEM 340 fuel pump or larger, which is recommended for any power-related modifications. An intake is helpful but not necessary until you’re over 400 whp; the stock turbo will not max out the factory intake before that.
If you want more than a basic build, I recommend the BCP X500+ or X500R. Both bolt up to a factory car with no additional modifications and clear the OEM TGV housings, unlike many other aftermarket turbos. The X500R is capable of over 500 whp, and the X500+ can get you close to that.
For these turbos, you will need either Injector Dynamics 1300cc or 1700cc injectors. A dual fuel pump hanger is recommended but not required. The X500 turbos can outflow a single AEM 340 pump. You can use stock fuel rails, though upgrading them isn’t a bad idea.
At this level, you will also need an intake, and either an upgraded top-mount intercooler or a front-mount intercooler, as well as a fuel pressure regulator. The OEM STI regulator (2008+) is not suitable for larger injectors. You may have heard of the “STI stumble,” which refers to the inconsistent fuel pulse in the lines caused by the design of the OEM regulator.
08+ STI/WRX EJ25 Stumble
When upgrading the intake, downpipe, injectors, or turbo, you may notice a hesitation between 2,000–3,000 RPM. This is known as the 08+ stumble. It is caused by the OEM fuel pressure regulator. As the injectors open and close, they create turbulence or pulses in the fuel system that stall fuel flow momentarily. When the injector opens again, that delay causes the hesitation.
This issue is resolved with an upgraded fuel pressure regulator, and it’s recommended on all 2008+ EJ models.
Air Fuel Ratios
AFR are important to engine health
Learning these values can save your engine one day
AFR main purpose is thermal efficiency as you will generally make withing 10% of power from 14.7 to 10.2, the richer the afr the higher cooling effects, however running too rich can raise EGT. For most turbo cars on pump gas the target at full boost is around 11.7 to 10.8, anything past 12.6 is considered over fueling and turbo cars require over fueling in boost to keep the cylinder from overheating causing per-ignition and detonation.
The most important thing to remember is that at full boost you should see an AFR near 11.7 or lower depending on fuel, higher AFR at full boost can cause damage. 91-93 pump gas 11.0 at full boost is prefered
Air Fuel Ratio, or AFR is referring to the amount of unburnt fuel in the exhaust. A complete burn is called Stoichiometric, for pump gas this is 14.7 or 1.0 Lambda. You will see this AFR at idle cruise and low loads. Since most cars use a pump gas conversion no matter what the fuel if reading in afr it will display a value of stoichiometric as 14.7 and full power afr between 12-10.8.
Overrun Fuel Cut Off
Upon decelerating the ECU will turn off the fuel injectors or reduce the duty cycle to 0%. This results in pure oxygen passing through the engine and you will see AFR values of 18-22+ until the rpm where fueling is restored this is normal and for fuel efficiency.
Fuels like Ethanol or E85 have a greater cooling effect and prefer a leaner afr, near 12:1 Gasoline AFR conversion, or .82 Lambda. At 85% Ethanol or Alcohol using the Alcohol conversion that's a AFR of 8:1 or a stoich of 9.7:1 this large quantity of fuel is in part why ethanol can run leaner as well as a lower in cylinder and exhaust gas temperature.
2015+ WRX Fa20Dit
For a Fa20Dit WRX I suggest the following:
Ethanol! These cars respond extremely well to E50 or a fuel mixture of 50% ethanol and 50% pump gas. A Flex-Fuel kit, or E50 Tune on average will make 50-100 horsepower more! That means a stock 2015+ WRX on E50 can make a
320+whp or as much power as a full bolt on WRX, or STI on pump gas, with only a Tune, Flex-Fuel kit, and/or AEM 340 fuel pump. A in tank fuel pump is the only required part to run ethanol, a HPFP will allow for slight more power but will not make any more on its own. I suggest a Catted J Pipe & TMIC or FMIC will help with intake temps.
Pure E85 will not work due to the design of direct injection. With direct injection you only have a small window of time to fuel. the only time DI systems can fuel is between the time the intake valve closes and the spark plug fires during the compression stroke, if you are using E85 the car requires 43% more fuel than pump gas. This ends up taking so long to spray the required amount of fuel that you end up spraying fuel while the spark plug Is firing, this ends up not giving the required fuel needed for a safe controlled combustion, since it’s not running out of fuel in the same way a port injection car will, it not rise in afr as the car is leaning out, it will simply breakup, buck and misfire, this is dangerous and the only way to run full e85 is with port injection or methanol injection, m5 is a great power adder
With Ecutek multiple maps are can be chosen on the fly via cruise controller
Rolling anti lag
boost off the line launch control with true anti lag
Don't forget to get a walnut blast every 30K miles
Do not remove any emissions related devices. I will not tune catless vehicles, or delete emissions related ecu fault codes.
GT86/GR86
The GT86 is a great chassis, unfortunately it feels very sluggish from the factory. The best and most noticeable mod for the non turbo Fa20dit is once again Ethanol! You will notice a night and day difference. A Flex-Fuel kit or E85 and E50 Map settings programed via the cruise controller stalk will be the most noticeable difference besides going forced induction. A full bolt on GT86 will make the similar power to a Bone stock GT86 on E85
For the GT86 only a tune is needed to run E85 the stock fuel system has more than enough to run E85+ but a E85 safe pump is never a bad idea
With EcuTek's Race Rom features from PROecu
Multiple maps can be programmed into one tune
1 to 4 Maps can be selected via the cruise controller.
This can be done with the engine running .
To convert to E85 or E54 from Pump gas, simply run your gas tank empty or until at least the low gas light comes on, then fill the tank with completely with E85 or E54. Once full start the car let it run for a moment until you hear the idle change, then pull the cruise stalk towards you, and select the map mode for E85 or E54. If you DO NOT have a flex fuel sensor you can still run E85 or E54 but you will need to test the fuel to verify the mixtures before you fill. If you have a preferred station and no flex sensor, your car can be tuned for that mixture of Ethanol specifically.
TURBO SUPERCHARGER
When boosting a GT86 its import to get a good tune, these cars are designed without a turbo in mind. Since the GT86 uses a direct and port injection system designed for only vacuum, and having no boost reference will not add the required fuel for boost. To correctly increase fueling you need a larger than oem Map sensor the go to for the 86 platform is the omni 3 bar
A catch can is important to keep oil from ent the intake manifold and going through the combustion chamber, this is a must on all turbo cars that see abuse
If you get larger injectors, though most kits do not require them 1050cc injector dynamics are the go to. When it comes to the GR86 1050cc is need for turbo and E85 you can turbo with oem injectors at 300-350 whp. The GT86 has 350 whp worth of fuel on e85 with a drop in fuel pump only and 320 whp complete oem fuel system. The gt86 fa is only safe up to 350 whp. The GR86 can do 500+ whp with the supporting mods.
Why boost leaks are bad
Boost leaks can happen to anyone, but not a lot of people fully understand what’s going on. Yes, you lose boost but if you have a high flowing turbo you may still hit the same psi, only your turbo is going to work harder now in order for that to happen you have to have more exhaust gas pressure so by having a boost leak this raises exhaust manifold pressure, raising exhaust gas manifold pressure can cause more back pressure to the engine. This will cause more blow by or higher crank case pressure than normal leading to more stress on your engine.
aside from that a mass air flow based car will run rich or stall due to air entering the intake and leaving before it reach the engine. Speed density cars are less affected by this, but it will still have a harmful effect on the engine if you ignore it