We’ve been manufacturing Subaru-only turbochargers for some time now. That is mostly because we started doing this because we are Subaru enthusiasts. That being said, our capabilities stretch to other brands. Now we are offering a twin turbo upgrade kit for both prospective stage 1 or stage 2 applications.
This is a legitimate turbo upgrade; meaning, it is designed for the factory location. We supply a new balanced CHRA, complete with new turbine wheel and billet compressor wheel in 62mm or 67mm, depending on what your goals are, and you install that CHRA in your existing turbine housing, attach the compressor housing and all other factory accessories, such as the blow off valve and the wastegate actuator.
With supporting mods, this kit is 600whp capable (stage 2). Because we are using our 9-blade technology, the spool is still quick and peak flow is there for high rpm performance.
As one might expect, these are manufactured with the same strict attention to detail that we have exhibited in the past with all of our Subaru turbochargers. They have superior internals and excellent balance characteristics; everything one needs for high octane, high RPM enjoyment.
Want more information? Give us a call at +1 (206) 607-9149 or visit our site.
Occasionally, we have the opportunity to help our customer troubleshoot situations where their expectations are not being met after installing one of our turbochargers. This sounds bad initially, but hear me out.
For a moment, consider that a turbocharger is a lot like a big barrel of water. At the top, there is an inlet where water can fill the barrel. At the bottom there is an outlet where water can exit the barrel. If the inlet at the top of the barrel is closed, it will be impossible to achieve constant, high volume flow out the exit. Now consider the opposite, where the exit is barely open but the inlet is entirely open and a hose is pouring water in the opening. It won’t take long before water is overflowing out the opening and there is still very little water coming out the exit.
Turbochargers work on similar principles, only more complex. Their ability to flow is dependent on the engines ability to move the gasses that are injected into the cylinder for combustion. For example, if one were to use our Steam STX 71 with a factory exhaust, it is likely that they would be disappointed on the dyno. The factory exhaust is simply not capable of moving exhaust fast enough for the turbo to spool quickly or make power because the engine can only combust as fast as it can evacuate the exhaust gasses. Therefore, the more gasses you can create, the more horsepower and torque you will make. This process is contingent on the ability to move gasses through the system and out the tailpipes.
Sometimes when a customer might state that a turbo is spooling slower than expected, we discover later that there is an exhaust leak somewhere. Since a turbocharger’s job is to leverage wasted heat from the engine by means of capturing it in the exhaust path, it makes sense that if that heat is leaking off before it reaches the turbo, the turbo will spool slower and produce less power overall. This one takes us back to our early days in school where we learn about the Law of Conservation of Energy.
Another culprit of a let-down on the dyno can be the wastegate. The wastegate is called that for a reason. It’s sole purpose is to waste energy. This is a good thing when it is tuned properly, and a very bad thing when it is not. The wastegate’s job is to open when the turbocharger has pressurized the intake manifold to the proper pressure (usually measured in psi). Let’s assume you are striving to reach 20psi with your tune. When the turbocharger achieves this, the wastegate on the hotside of the turbo opens up to let exhaust gasses that would normally drive the turbine, escape around the turbine instead of passing through it. This makes it possible for the turbo to flow at a desired rate without overboosting the engine. If the wastegate is opening to early, or the spring is insufficient for the tune, exhaust gases that are necessary to make power will be lost along with the power they would have supplied to the engine.
Intercoolers. We love them and we hate them. We love them because they cool the air charge going to our engine, lowering the risk of detonation, and giving us much more power than we would have if they were hotter. Hot intake gasses are less dense, and because of this, supply less oxygen per cubic liter than colder intake gasses. A warmer intake charge also means that your tuner will have to compensate for those temperatures in power-robbing timing settings. A good top-mount intercooler will be sufficient for most, however many opt for a front mount intercooler. There are advantages and disadvantages to both. Your build and your pocketbook will largely determine what works best for you. A front mount intercooler means a lot more air is necessary to pressurize the intake system. This results in power later, but it usually results in lower intake temperatures too. Also, more piping, means more connections and more connections means more opportunity for leaks. If you find that your intake is leaking, you’ll know it by a massive loss in power and it taking longer to reach boost. The air that would have been used to combust a greater amount of fuel is being dumped to atmosphere. That means less power to the wheels.
Supporting modifications influence your turbocharger’s efficiency. The fewer you have, the less power you will make. It is important to consider what other items will be necessary for you to achieve your goals when bolting on a device that is intended to push your vehicles power well beyond what the factory intended.
How does one correctlypreload a turbocharger’s waste actuator?
We get asked this question often, so here is a little guide on how to correctly preload a turbo’s wastegate actuator. In general, you adjust the preload according to the pressure of the spring that is in the actuator. Most aftermarket turbos are set to 1.0 bar. Actuators can be adjusted up or down ~+/- 0.1 bar of their spring pressure. Our turbos come preloaded with 0.9-1.2 bar depending on the application.
2. Attach the actuator to the arm of the turbine housing’s flapper arm. Note: do not insert the cotter pin yet to the flapper arm.
3. Attach a boost source to the barb on the waste gate actuator. Pictured below is a custom made apparatus that connects to an air compressor. We also sometimes use a reversible vacuum pump (one that can be reversed to make pressure as well as vacuum) and use that to apply the target pressure.
4. Apply the target pressure which should match the spring that is inside. Then, apply 0.1 bar of pressure more than the target.
5. Check the flapper’s gap. It should be open around 0.10mm at 0.1 bar beyond the target preload. We are using a 0.10mm gap feeler to check. If you do not have a gap checker, you can get close by watching the flapper to move ever so slightly.
6. If the gap was correct in step 5, go to step 7. If the gap is not correct, you fine tune by adjusting the actuator rod. Shorten the rod to add more preolad. Lengthen the rod to decrease the preolad. Repeat steps 2-6 until the preload is correct.
7. Reattach the cotter pin. You turbo is now correctly adjusted.
We would like to introduce you to our newest turbo to our lineup, the Steam STX 67 Plus Turbocharger aka STX 67+.
Best on our gas bench testing of our Steam STX 71 compressor wheel, we were able to estimate that our STX 67+ compressor wheel will flow 0.38 Kg/s or over 51 lbs/min. That is a huge increase power producing flow vs stock, while still maintaining the quick response of a stock turbo.
STX 67 (estimated) vs GTX2067R Compressor Map
Our gas bench testing on the turbine section illustrates how our turbos are able to both spool quickly, and flow very well even at high RPMs. This is how we are able to achieve both a quick response and keep building power up top. This was measured with the STX 67+’s turbine and our 8cm^2 single scroll WRX/STI turbine housing.
Do you have a JDM STI style twin scroll turbo setup and exhaust? We have you covered with our STX STX 67+ Twinscroll. Still with our up 400 WHP STX 67 compressor wheel, but now with our larger high flowing low-inertia 9-blade turbine.
We often get asked questions about shaft play. The concern is valid. Before leaving the factory, all Steam STX turbochargers are inspected and validated to not have shaft movement beyond 0.09mm in any direction as part of our QA process. Without precise measuring equipment, it would be hard for a person to detect that tiny amount of deflection.
Here is an example test where the max deviation was 0.027mm.
Typically shaft play implies bearing failure and damage. Side to side movement implies damage to the main bearings. In and out moment implies damage to the thrust bearing. Once the shaft play is too extreme and the turbo’s wheels touch the housings, the whole turbo is ruined.
The most common reason to bearing failure is lack of lubrication, meaning not enough oil getting to the bearings, or the oil is old or contaminated such that it can’t protect the bearings. Also, if a turbo is not primed before staring your car, the bearings will experience a sever lack of lubrication. It will cause bearing damage and premature turbo failure. FYI: The stand procedure is to crank your engine for at least 30 sec without starting it to get the oil throughout the turbo CHRA.
Poor lubrication is the 90%+ failure case. Upon disassemble of the CHRA, it is very easy for us to detect oil related failures.
The other failures are due to customers just pushing their turbos hard. Pushing your engine components hard isn’t a problem; you just need to be aware, it makes them wear out faster. If you push your turbo to very high shaft speeds for long periods of time, it won’t last as long. Turbochargers are normally balanced on a VSR (vibration sort rig) up to 100,000 RPM; however, pushing a turbo to high pressure ratios will exceed 100k shaft speeds. Customers may run at higher pressure ratios, just like they can also have a 12k RPM readline, but it does impact durability.
Warning: engineering content: Also, the rotating assembly will have natural harmonic frequency as elastic systems do. The force on the turbine will also add additional vibrations at different harmonics depending on the design of the aero. Basically the natural harmonics + forced vibrations can also damage the bearings. Most of this is mitigated though, by the design of the turbine aero, and using the VSR to remove extra vibrations due to imbalance. In other words, this type of failure can be avoided before you get your turbo through proper design and manufacturing.
Compressor surge can be destroy bearings as well, but can generally be avoided by designing your turbo system correctly. If you don’t actually want to figure it out, the I would recommend getting some good advice on what you need. Ask your tuner, or give us a call if in doubt.
For journal bearing turbos, damaged bearings are easy to replace assuming the wheels have not touched the housings. It is possible for a normal person to replace them in their home garage if they are careful. We however, resubmit the turbo through our entire QA process including a re-balance on a VSR.
Garrett ball bearing turbos are more resilient to abuse, but when they break, they are very hard to repair, well at least for any one other than Garrett. Essentially they are designed such that the whole bearing assembly has to be replaced. Garret does not sell then to the public. The ones you see on ebay are fakes, FYI.
To recap, you can avoid most turbo failures by: following correct turbo install procedures, providing a sufficient and clean oil supply, and having the car properly tuned. If followed, your turbo will last for years reliably.
Great news, our production Steam STX 67+ turbos for Subaru WRX STI are in stock! The preorders have already started shipping, so you should see your turbos soon.
In case you were wondering, they are similar to our standard Steam STX 67 turbos, except the plus model has the next larger turbine. The should both be 350-400 whp turbos. The plus model might be a better fit for your car than the standard 67 if your car is more built, has a 2.5l motor, or otherwise is higher flowing.
Tuners strongly recommend them; we recommend them. Now we make them: Introducing the SteamSpeed BCS (boost control solenoid aka EBCS) plug and play for all turbocharged Subaru models.
Our 3-port boost control solenoid provides super high resolution boost control to dial in much more accurate tunes vs. the old OEM 2-port solenoid. Our BCS provides your tuner the tool need to safely dial in the correct boost levels, and achieve the best results possible. At the heart of our BCS is a super reliable industrial valve that is more responsive, higher flowing, more durable than stock. With our high performance BCS valve, your turbo will spool quicker, and maintain the tightest possible boost curve.
We include everything you need in the box for plug and play install. It mounts right to the stock location without modification with our custom made brackets, and clips right into the wiring harness. We even include new silicon vacuum lines and bolts so no extra trips to the parts store is needed.
Installation is a snap. Our BCS can be installed in 15 min with basic tools by most everyone.
We have used the GrimmSpeed BCS on our cars in the past, and they have worked great. Tuners we have worked with in the past recommend them, so we used their product as a measuring stick.
For our test, we simply swapped out the GrimmSpeed BCS and hooked in the vacuum lines in the exact same ports and swapped their connector for ours into the wiring harness.
How did it work out? Not surprisingly, they worked basically the same since they both are based off of nearly identical MAC industrial valves. In our testing, our higher flow barb option did out flow the GrimmSpeed BCS by about 20%. Our standard barb option flowed exactly the same. In fact, in our testing, the boost curves were identical with both BCS.
This is how our EBCS was hooked up to the waste gate.
We have been able to compile our initial flow testing on our Steam STX 71 turbocharger, and we have to admit, our expectations have been exceeded. We didn’t expect the STX 71 design to out flow the Garrett GTX3071R, but that is just what happened. It turns out the original STX 71 design was actually quite good from the get go. Don’t worry. This testing is just a baseline. We intend to make it even better.
Just as a refresher, this is what the compressor map lines mean.
Here is the Steam STX 71’s compressor map. As yo can see, it has a max flow of a whopping 59.5 lbs/min.
How does the Steam STX 71 compare to the Garrett GTX3071R? See for your self. The STX 71 actually out flows the GTX3071R by at least a few lbs/min.
Here is the turbine section map for our Steam STX 71 turbocharger in our version Subaru WRX STI single scroll turbine housing. It is mildly ported and 8 cm^2 in Mitsubishi speak or 0.55 A/R in Garrett speak. The both measure the “size” of the scroll. Bigger means the housing can flow more generally speaking.
How does our Subaru turbine housing flow compared to the Garrett T3 housing for a GT30 turbo? It actually flows quite well for being “smaller” than a 0.63 A/R T3 housing. We attribute this to our signature 9-blade high flow turbine design.