People ask me multiple times a week what upgrades they should do to their stock MR2. Let's break down in what order each stock item becomes a problem.
This is all for a 91-95 MR2 Gen2 3SGTE. In 1993, Toyota switched to slightly different electronics, but everything else is the same.
This guide is for people who want reliable power for street driving and the occasional track day. If you’re not sure where your car fits in this progression, we’re always happy to help you plan a setup that matches your goals and budget — even if you don’t buy everything from us.
A stock car makes about 170whp at 7psi.
The first upgrade is always a boost controller. A simple ball and spring manual boost controller will get you to about 15psi. The stock 91-92 fuel cuts at 12psi, and the 93+ at 16psi. You can simply unhook the vacuum hose to the MAP sensor to disable the fuel cut. The only adverse effect here is that the stock boost gauge will no longer work. You should also unplug the temp sensor at the engine lid so that the intercooler fan runs constantly. Most cars will make about 220whp at 15psi. This is assuming all the stock electronics are working right, which is increasingly rare nowadays.
At this point, the turbo will be working overtime. Be sure to run a high zinc oil, or your turbo is practically guaranteed to fail soon. Our favorite is 10w30 Valvoline VR1. Conventional or synthetic is up to you, we use conventional. The turbo will also be pumping out a ton of heat, and exhaust pressure will be up. It's time for an intercooler kit, downpipe, and exhaust. This will get you closer to 240whp at 15psi, still on the stock ECU.
The stock ECU is really not meant to run at this power level. Don't get me wrong, it will do it all day, and most of the time they're so rich that the only thing you're risking is fouled plugs. However, with proper tuning the engine could do a lot more. You can run a ROM tuned ECU, calibrated AFM, or piggyback ECU, but these options are obsolete and basically impossible to support remotely. Standalone ECUs have become so accessible and easy to install, that you're just wasting time on those other options. It's time for an ECUMaster Standalone ECU. Your car will run better and make more power. This does require fine tuning, but we include a really good base map that remote tunes easily on the street. Be mindful that most subsequent upgrades will require a tune touchup, so this is a good time to knock out multiple upgrades. You also get to delete the air flow meter, so get an intake. With proper control of the engine, you can expect around 260whp.
The limiting factor at this point is the turbo. The stock turbo is being pushed for everything it's worth, and the stock wastegate spring won't allow any more boost. The next upgrade is our CT27. This is a stock frame turbo, upgraded with a larger billet compressor wheel, ported turbine housing, and upgraded bearings for increased durability. You'll want the ported wastegate and billet actuator upgrades as well to maintain proper control of boost. This turbo upgrade should really come sooner than later. Many cars have badly worn stock turbos that will never last to the previously discussed options. This is a solid upgrade even for a bone stock car.
With the turbo upgraded, 300whp is right within reach! 300whp is a benchmark for many, and a significant one to surpass.
300whp is right at the limit of the stock turbo fuel pump. Losing fuel pressure can be detrimental to your motor. We include a fuel pressure sensor with our ECUMaster standalone package. This allows the ECU to detect a loss of fuel pressure during or after tuning, and prevent damage to the motor. However, it's likely worth the upgrade to a Walbro 255 fuel pump before you get to this point.
The stock fuel injectors are 440cc. At stock fuel pressure, these will be good for around 280whp when they are wide open. If you plan on pushing for 300whp, there are a few extra things to install when you install your standalone. A higher pressure fuel pressure regulator will provide the small boost in fuel flow needed to hit 300whp. At this fuel flow rate, the stock fuel rail has poor distribution of pressure due to small passages, so we offer a ported fuel rail. This is also a great time to install a set of cleaned and flow matched stock injectors. As you push your motor harder, especially at high boost, it's important to ensure each cylinder is getting the same amount of fuel.
300whp Gen2 3SGTE Combo
- ECUMaster PNP standalone ECU with ATS recommended sensors
- CT27 turbo upgrade with ported wastegate and 14psi billet actuator
- ATS intercooler kit
- ATS 3" downpipe
- Ported fuel rail
- 3.5 bar modified fuel pressure regulator
- Cleaned & flow matched set of stock 440cc injectors
- Walbro 255 fuel pump
- Braided AN fuel feed hose
- 170 degree thermostat
- 3 hours remote tuning
Your stock clutch is at its limit now. With electronic boost control, included with our ECUMaster standalone package, torque can be kept down. This means most stock clutches can make it to this point, but it's about to be time for a clutch upgrade.
Above 300whp, the stock composite head gasket becomes a problem. It will need to be replaced with an MLS head gasket in order to push harder. This here is the reason why the Gen3/4/5 options are so great. They will go beyond this point without opening up the motor.
While you have the head off, a couple more upgrades to do. Install a phenolic spacer. This deletes the restrictive and clunky TVIS system, and lowers charge temps by preventing heat soak. This is a convenient time to install a high volume oil pump, to make sure every engine component has the best oil cushion possible at high RPM and high boost.
High Volume Oil Pump
You'll be out of fuel flow with the stock 440cc injectors and increased fuel pressure around 320whp. The stock fuel rail uses side feed injectors, which is fairly uncommon. Stock Gen3 or Supra 550cc injectors are a popular upgrade. However, we need E85 capability soon, and that requires a lot more injector than 550cc.
On most cars, the octane limit of 93 octane will be around 330whp. This varies based on engine condition and intercooler performance. Your turbo is a heat pump, and the engine will detonate sooner with more heat. At this point, the stock pistons are also seeing way more pressure and temperature than a stock car. I don't recommend pushing past about 320whp on 93 octane without special considerations.
On the other hand, E85 is like, the best thing ever. It has much higher octane, allowing more boost and timing. It also requires 30% more fuel for the same mixture. This lowers charge temps and cylinder temps significantly. It also creates around 18% more air out for the same amount of air in, spooling the turbo significantly quicker. Modern standalone ECUs and available sensors have made E85 super accessible. No measuring at the pump or switching maps. With flex fuel, you can just dump however much E85 or 93 in the tank, and the ECU will adjust fueling, boost, and timing accordingly.
If you intend to push higher than 320whp, you should go to a top feed fuel system and flex fuel. The standard 980cc injectors we include with our top feed fuel system will support 450whp on E85. It's a whole 'nother can of worms to get past that point, so that will be plenty for most.
If you want the most out of your build, you should install a set of GSC S1 cams, valve springs, and cam gears. This is best done while doing the head gasket upgrade. This is also a good time to install an ATS intake manifold.
ATS Intake Manifold
Top Feed Fuel System
With a simple head gasket replacement, cam install, clutch upgrade, fuel pump change, a top feed fuel system, and flex fuel, you're ready for a new dyno tune. You should be running 20w50 VR1 at this point. You can expect about 360whp on E85. The CT27 will be near its absolute limit and pumping out a ton of heat. The intercooler is likely to heat soak with extended use at this level. This is a great setup for a street car, but it should be turned down on track. With a better intercooler, more power is possible and for longer periods of time, but your stock pistons may not be long for this world if pushed for extended periods of time at this level.
Next up is a forged motor. A forged 3SGTE short block will make the 360whp setup reliable for years to come.
Now you have head room for more power! Our Garrett GT3071 turbo kit bolts onto the stock exhaust manifold, and is 500whp capable with really good spool. That intercooler upgrade will be mandatory now. Our top mount intercooler is huge, larger than you'll see on many front engine cars. This will do a great job of keeping intake air temps down, even on track cars. With these items, your setup will be good for 450whp.
3S blocks crack around this point. For this reason we keep torque down and stop at around 430whp on 3S blocks. If you intend to push this far, you should really go for a 5SGTE instead of the forged 3SGTE. The 5SFE block has much thicker cylinder walls that take a lot more to crack. Check out the linked page for more details on this upgrade. If you're going this route for 500whp, get the 1300cc injectors instead of the 980cc, and go for S2 cams instead of the S1.
Above 500whp, you need a turbo 2GR. If we're doing the work here, we are already well past the cost of the turbo 2GR swap, which makes 600whp, drives way nicer, and is more reliable and serviceable.
Shockingly, the stock transmission and drivetrain has no problem with anything discussed here. The stock cooling system will work great too, although a radiator upgrade may be in order for track cars. The MR2 fuel system is E85 friendly. The stock ignition system is good beyond 800whp. Thank you Toyota, for overbuilding.