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.
Have you been wondering what our stock turbo STX 67 upgrade could do, the Results are in!!!
For this unit, we started with an OEM unit and increased the compressor wheel around 3mm on the inducer and 4mm on the exducer. The turbine section remained the same for this prototype. It is not clear if the OEM turbine housing can support a larger turbine wheel; there is not much room in there.
Our N55 turbo with similar enhancements on the cold side, and is able to make about 60-70 whp more power than the stock unit + stage 2. Lets see how our Focus RS prototype does.
We couldn’t be more pleased with the initial performance gains of our STX 67 prototype for the Ford Focus RS. Our friends at English Racing in Camas, Washington helped us reached 345 WHP and 383 wft*lbs @ 22psi (recorded with map sensor). That’s 55hp & 77 ft*lbs over the factory tune.
– Stock 2016 Focus RS
– SteamSpeed STX 67 turbo prototype
– SteamSpeed front mount intercooler kit prototype
– COBB AccessPORT
– 92 octane WA pump gas
Here are the dyno results from our car at English Racing.
What does our turbo look like vs a full “stage 2” car (FMIC, turbo-back, intake, etc.) on the same dyno? There was still the same ~40 ft*lbs torque gains, and about 11 whp on top.
Some initial thoughts:
We saw some solid gains on our mostly stock car. It was in fact the most power and torque a Focus RS has put down at English Racing on pump gas.
Since we left the turbine section as is, we didn’t expect to see huge gains on the top-end that one could probably be achieved with a larger A/R turbine housing. Accordingly 11-33 whp gains on the top end are not huge, but still a significant improvement. 40 ft*lbs on the low end is a good result. That is something you’d feel daily driving. It is clear that Ford really wanted to optimize for low end torque with this design, so it may be a challenge to overcome that housing’s limitations without replacing it all together.
All in all, there were gains around 5-15% across the entire rev band, so we are pleased with the result. It really doesn’t lose any of the benefits of the stock unit in terms of responsiveness and so on while making solid gains everywhere vs the OEM unit. As is, it is a no-downside upgrade vs the stock unit.
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.