Introducing the SteamSpeed STX 71 for Mitsubishi Evo X
You’ve asked, we listened. SteamSpeed now supplies turbos for the Evo X. To start with, we brought over our same proven 59 lbs/min STX 71 CHRA we have used since the beginning on the STI. On the STI, it typically puts down 400-450 whp and ft*lbs on pump gas. How do you recon it would perform on a Evo X? We set out to find out. More pictures here…..
SteamSpeed STX 71 for Evo X Specs
Make no mistake, the STX 71 is designed to be a 18k. How does it compare?
As you can see from the basic specs, the wheels are a somewhat smaller than the 18k; yet, the STX 71 flows 5.5 lbs/min, or about 10%. In simple terms, the STX 71 will be a more responsive than the 18k while being capable of making ~10% more power.
Initial Dyno Results:
We’ve had a few testers out there, and the intal results are looking good. It looks like they are getting a little more response with a little more power vs the 18k.
Here is some plots from data logs produced by Aaron at English Racing. this is the STX 71 vs the OEM turbo. As you can see, you gain +100 whp, and give up close to nothing. It feels the same as stock.
Here is the same car on their DynoJet dyno:
Here is the result from one of our customers in Florida.
[STX 71R for FA20 Performance Performance Hypothesis [Pre-Test]]
The OEM style twin scroll turbine housing is restrictive for turbos larger than the OEM unit and our STX 67 JB turbo.
This means for our big turbos, exhaust back pressure ratios can get well beyond 2:1 that is efficient for a JB CHRA.
If you are going 5:1 or 7:1 makes it hard to build power and it wears out the journal bearings and especially the thrust bearing.
Tuners that have a good strategy to manage this backpressure can make good power with the larger STX 67+ and 71 turbos, but if they didn’t, sometimes our customers would be disappointed.
The main point of that post was that a BB CHRA actually solves all of these problems:
The CHRA can stay efficient even if the pressure ratios are 5+:1
This means, it will be a lot easier for all tuners to build power with the BB version of our turbo.
The turbo will just make more power under the curve in general
The the thrust bearing is more durable, so the CHRA will stand up to more punishment.
[STX 71R for FA20 Test Results]
We set out to actually prove if the BB version of the STX 71 would perform as well as we had hypothesized, and solve the issues we had with the JB CHRA on the larger turbos. The short version is that yes, the SteamSpeed STX 71R BB Turbo for FA20 did exactly what we thought it would. It was a lot more efficient that the JB version of a similar size; therefore, it made more power everywhere. I suspect that tuners all over will be having an easier time getting results their customers want.
Here is the dyno result. 470 whp on E50 and 410 on 91 octane pump gas, and not measured on this chart, a ton more response everywhere. Note: this is at high altitude in Utah.
[Technical Notes From Jessie at FNP]
Jessie: “Hey, First let’s go over what we saw, liked and disliked with the unit.
It’s big, if the new unit has a clearance for the oil pan and obviously ships with hardware we are good. Obviously as the prototype it is going to have clearance issues, and fitment issues. There were literally no other issues noted from Luke on install.”
SteamSpeed: This will actually be a non-issue for retail units. We have actually already resolved all fitment issues on our production 71R. The production model has a modified turbine housing with a cutout to clear the OEM oil sump without modifying it. We also designed and manufactured custom studs that we include with the 71R install kit. This is how the retail unit will work:
Sounds epic. Do yourself a favor a crack open the boost nipple when running. The ball bearing turbo sounds incredibly mean at idle. With a catless exhaust it should sound great out the tail pipe. Think diesel turbo, screaming at idle.
Response, Response, Response. This turbo is incredibly responsive compared to the previous version. Transitions in and out of boost are much quicker.
More linear boost curve via WGDC input. What do I mean? Check out this boost profile compared to WGDC on the old vs new turbo. The new unit is much MUCH more linear with interrupt cycle. This tells us the effects of back-pressure are far less of an issue with this upgraded unit. You can also see the old turbo have more “Creep” under the curve. The new unit doesn’t not do this. The compare for RPM isn’t valid, as the previous tests were done in 4th, the current in 3rd.
67+ JB WGDC
71R BB WGDC
Makes more boost in the upper RPM’s. This also is a direct causation from the upgraded cartridge. It seems to be able to operate at higher levels of back-pressure with ease.
Red JB vs Yellow BB
Less oscillation of MRP than the outgoing cartridge. Just one of those anecdotal observations, normally we see much greater fluctuations in boost on the FA20 with our incredibly fast sample rates. This unit fluctuated much less, the average was 18% realized lower fluctuations. This is a great indication of how much more air is being delivered.
Much more efficient flow from the turbo. Check out the new vs old charge air temps!
New unit held much better boost. From 1.9bar avg on the old unit at redline on 100% interrupt, to 2.3bar avg.
Output: Was increased by 12.35% over the older unit. This was also impressive as the turbo could have easily generated around 8% additional output, but the owner of the test vehicle was very specific to “Take it easy”. Based on the airflow averages and their changes, I’d say this observation is fairly precise.
Check out these airflow differences: Old Turbo 229 average max, New over 300! (it was 309 average when extrapolated up). That is an increase of 35%. Same intake, and injector scalings were used on both turbos. Compared to the stock turbo this is over 56% increase in flow!
Well, hope this helps you guys. I poured over all the data and these were the things that popped out at me.
In that iteration, it made ~360 whp at PRE facility on pump gas. For comparison, the SteamSpeed STX 71 on a 2015 STI made about 420 whp on the same day. With that turbo it was rewarding to push the car, and if you kept the revs up, you could keep it in boost, but realistically it was a 4.5k+ RPM turbo on a stock EJ207.
We would manufacture small batches of this turbo, and we would sell them all out before we could install one in Domino, but we able to finally get one installed. It has the smaller 67mm compressor which should make it more responsive, but the “+” means that it still has a GTX30 spec turbine which is a little better suited for a 2.5l. I think a GTX29 size wheel would be perfect for the EJ207. Next update to the turbo we can make the change. 🙂
The STX 67 wheel did get us close to 4k RPM, but it still feels big. In fact, doing pulls, it feels similar to the 71; however, everywhere else, it is night and day. The BB CHRA is super responsive. Going on and off the petal, the turbo is a lot more responsive. It could also be related to the fact that we went to speed density from a MAF based tune.
What is the final result? It made about 10 whp less with a 4 psi more boost. Not a bad trade off.
The turbo still feels a little big. Andy at FTW thought going to a top mount could give back about 500 RPM of spool. It would probably be best for our usage of the car, but for vanity reasons we like having the huge FMIC. We could just go to a 2.5l displacement, but it seems like it goes against the spirit of the ej207 swap.
Where do you think we should take the build next? Let us know what you think.
We’ve had customers constantly asking for this for at least a year. This post is going to make a lot of people happy 😁😁😁.
If you have been waiting for our ball bearing version of our 2015+ WRX turbo. The wait is over. Introducing to the world, the SteamSpeed STX 71R BB turbo for FA20.
Here are some pics:
What you are seeing here is the ball bearing version of our STX 71 turbo in our FA20 compressor and turbine housings in the flesh..ur…metal.
The tricky thing about making this BB product was adapting the Garrett GT cartridge to work seamlessly with the other OEM parts like the oil sump. For these, we will be sourcing the CHRAs from Garrett Japan, but we replace the compressor wheel with one of our own design.
What is the benefit of JB vs BB? This is the question we get asked all of the time along with, is it worth the extra cost? We use the same compressor wheel for both BB and JB. We recommend BB:
– In the cases where the customer intends to be more aggressive with the turbo and therefore demand more out of the CHRA. The BB CHRA will be more durable.
– Where the transient boost is a factor
– Where there are problems with backpressure
We have now had 100s of turbos installed in FA20 over the past 9 months or so. A picture has begun to emerge of how to make power with the FA motors, and the limitations are starting to be well understood. On e85, our turbos can make well over 400 whp using the 67 wheel, and over 550 using the 71. These results are much higher than the STI versions of the same turbo. However, on pump gas, they often make less power than the STI versions. Why? The FA20 responds great to octane, and really suffers with low octane. The EJ25 is less impacted by octane.
The other big factor that hampers power with the FA20 is backpressure in the exhaust system pre turbine wheel. The OEM manifold is really restrictive. The twin scroll turbine housing also doesn’t flow as well as and as efficiently say a T3 housing. All of this results high backpressure, and in some cases very high pressure ratios in the turbine section. A good manifold will unlock power in the mid and top ranges with our turbo. Cams are also an option, but backpressure is a real problem for the turbo to be efficient. As you may know, if the turbo isn’t being efficient, it isn’t making the power it could.
This is where the BB CHRA can provide a real boon for FA20 owners. A BB CHRA can stay efficient even when there is a ton of back pressure. JB turbos stay efficient only nearer to the idea ranges of backpressure. Also, if there is a lot of backpressure, like with the FA20, the BB CHRA will be more durable and last longer than a JB CHRA.
For EJ25s, back pressure and octane is isn’t such a big deal as it is with the FA20. It isn’t hard for most tuners to make great power with either our JB or BB turbos for STI. We expect that our BB FA20 turbos will make it so that customers will be able to get better dyno results with less effort from the tuners because they are more efficient against sub-optimal conditions. We expect to see higher average numbers with the BB version, and require our customers to have less supporting mods to get there. Imagine what your WRX will be like with one of these guys installed.
What do you what to know about these guys? What are your initial thoughts?
Here is a good dyno result of a SteamSpeed STX 67 on pump gas done at Bren Tuning with a before and after, green being before, and red being after. Obviously there are gains everywhere. You can see their post on NASIOC here. The short of it, the customer go a 85+ WHP and 70+ WTQ gain on pump gas!
Here is a standard STX 67 for 2015+ WRX tune at COBB Surgeline. Unfortunately it does not have the before plot, but it was a 60 whp gain on pump gas. This car had a 3″ turbo back, intake, and front mount intercooler. It was tuned at COBB Surgeline. We have to give these guys at COBB Surgeline props. This customer was initially impacted by the wastegate flapper defect a few units had from the first production batch. The guys at COBB took the time to correctly diagnose the wastegate problem.
SteamSpeed STX 67+ for 2015+ WRX
Here is a nice dyno plot comparing a fully modified 2015 WRX without the SteamSpeed turbo [green], then with the SteamSpeed STX 67+ [red]. This with some ethanol blend, around 50%. This was tuned in Utah at FNP by Jessie. It looks like about a 100+ WHP gain and 65 WTQ.
If you are anything like us, you are always looking to make your car a little better: make more power, handle better, etc. Since we got our hands on our 2016 Focus RS, we’ve been looking for ways to make it better. Case in point, we’ve been hard at work developing our new front mount intercooler kit for the 2016 Focus RS.
Intercoolers are an integral element to the whole turbocharger system. The basic laws of thermal dynamics tell us that that when you compress air from the intake with a turbocharger, the compressed air coming out of it will be hotter. The purpose of the intercooler then is to lower the charge temperature back down to a cooler denser charge. Simply put, a better intercooler will cool the temperatures more effectively, and your car will make more power.
How can you measure how “great” an intercooler is? There are two main factors that really determine how effective an intercooler is at making more power: efficiency, and pressure drop.
Efficiency basically measures how much colder the air is coming out of the intercooler vs the air coming in. It is a direct factor to your engine’s power output. There are diminishing returns, but generally, the larger the core is, the more efficiently it can remove heat from the charged air. In this case, bigger is better; the more surface area an intercooler exposes for cooling the more efficiently it can cool.
Pressure drop impacts power as well, but indirectly. All intercoolers will provide some restriction to air flow. The harder it is for the air to get through the intercooler, the greater the pressure drop will be. This in a real sense robs some of the hard work the turbocharger is doing to create boost and flow air in the first place. If the intercooler has a high pressure drop, the entire system will make less power. Why? Your turbo will have to work harder and spin faster to hit your boost targets. For example, if you goal is to hit 20 psi post throttle body, your turbo might have to generate 24 psi instead of 21 psi. Pushing your turbo harder to make more boost pressure to make up for your intercooler’s pressure drop is counter productive. As the turbo works harder. it is most likely becoming less efficient and generating more heat. This is an important factor to consider when deciding how big to make the intercooler, and what type core you want use.
How did we SteamSpeed make a great intercooler? First we packaged the largest possible core into the OEM location without having to hack up your car. Our analytically estimates put our upgraded intercooler core to be around 30-40% more efficient than the OEM unit. To tackle pressure drop, we utilized the best possible flowing bar and plate cores, and custom-designed high-flowing cast aluminum tanks. It is easier and cheaper to just bend plate aluminum and weld it up, but it worth it to us to spend the time an money to make the best possible end tank designs. Next we made new silicone hoses and mandrel bent stainless steel piping which flows better than the OEM parts, and causes less pressure drop.
Before we get too crazy making parts for the Focus RS, we wanted to get a good baseline to measure the improvement.
According to Ford, the 2016 Focus RS makes 350 HP. If there is a 20% drivetrain loss from the crank to the wheels, that would be around 280 whp. How did she do?
Red [stock]: 289.6 WHP, 309.48 ft*lbs, 24.4 PSI
Blue [Cobb Stage 1]: 311.12 WHP, 342.83 ft*lbs, ~25 PSI
Afterwards, we threw it up on the rack over at Nameless Performance to see what parts we could develop for it. The over all consensus was that most of the OEM parts for the RS were really nice to begin with; never the less, there is always room for improvement. Look for product updates from SteamSpeed and our partner Nameless Performance.
PRE recently did a test that pitted lots of Subaru stock location turbos against one another. This is what the plot of our smaller Steam STX 67 looked like against a Forced Performance HTA 71. The STX 67 basically made power sooner, had better low down power, and made 10-25 whp across the entire rev band.
Here are some unboxing pictures of our new Steam STX 67 turbo for FA20 (eg. 2015 WRX). This is our design validation (DV) prototype turbo. It doesn’t have as perfect machining as the final retail version will, but I think it does give you a much clear picture of what will be included in the box.
This is a design validation (DV) prototype, so it does represent a final retail product. For example the housings aren’t fully machined in these pictures, and they are just showing OEM accessories to illustrate that this turbo is a direct replacement for the OEM turbo. The retail version will have custom fittings. The final turbo will just reuse the stock turbo oil pan.