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.
We have been asked many times by our customers, what is the difference between Blouch Turbo’s 20G-XT-R and our Steam STX 20-R. We put together this little table to help you know that the differences are. As far as we can tell, the biggest difference is that Blouch’s BB 20G costs almost $300 more than the Steam STX BB 20G. What do you get for paying $300 more? We can’t think of anything either.
Did you ever want to know how it’s possible for our Steam STX 71 turbocharger to make over 425+ WHP on your STI? It’s all about flow dynamics. We are not content with just having high-quality high-performance products so we decided to take the engineering to the next level.
Here is a dyno plot of our Steam STX 71 turbo in action. There is a whopping 140 WHP gain over the stock VF39 turbo with very little left on the table.
Other manufacturers, like Blouch and ForcedPerformance, can simply make claims to how much their products flow. But, how do they arrive at that number? Without compressor maps to demonstrate thorough testing, one can assume they are just guesstimating. Why make a guess? Because real engineering is expensive. Turbo testing is also very expensive, but that is what the big boys do to actually improve their products. You can’t get, what you don’t measure.
Garrett also makes claims to how much their turbos flow, but they actually provide detailed compressor maps. This is the result of rigorous engineering efforts.
When Garrett improved their ball bearing turbo line, they actually provided empirical data showing how their product has improved.
Although we have had great results with our STX 71 model, and lots of happy customers, we never stop thinking our products can be better. How do you make a great design better?
Steam STX 71 Performance Testing
First step, measure the performance of the current design. The way Garrett and other serious turbo companies make compressor maps is by testing it on a gas bench, so that is exactly what we are doing. The gas bench provides a super controlled environment to reliably test the turbocharger.
We measure a number of things on the gas bench: compressor wheel speed, pressures and temperatures before and after both housings, etc. With this data, we will be able to generate compressor maps similar to those of Garrett.
Checkout our current production STX 71 on a gas bench as we map out the performance and efficiency of the current design.
Here is a production turbo with the turbine housing all mounted up to the hot side of the gas bench. The yellow thing sticking out of the compressor housing is a speed sensor. It measure how fast the compressor wheel is spinning. The compressor wheel can spin in excesses of 150k RPM.