How to Compute Compression Ratio, Head Volume, Dish, etc.

I am planning a motor build for Project Domino. There is nothing worse than spending money on parts to only figure out you ordered the wrong thing. In this particular case, I wanted to make sure I ordered the right pistons the first time to achieve a reasonable compression ratio for pump gas.

Compression Ratio

I want to get to the basic math without going too deeply into how engines work, so I will provide a brief term overview. I will use Domino’s EJ207 for an example.

Computing Displacement Volume

Displacement/Swept Volume refers the volume displaced from the piston moving up (top dead center) and down (bottom dead center).

It is computed by the surface area of the piston times the stroke of the piston, times the number of cylinders.

displacement per cylinder = π * (bore / 2)² * stroke

total displacement = π * (bore / 2)² * stroke * num_pistons

eg. EJ207’s displacement = π * (92mm / 2 )² * 75mm * 4 = 1994cc

Computing Compressed Volume

Compressed/cleared volume refers to the volume between the surface of the top of the piston when at top dead center and the top of the cylinder head.

compressed_volume = piston_dish + ((bore / 2)² * (piston_deck + gasket_thickness)) * head_volume

eg. EJ207 compressed volume = 6cc + ((92mm / 2 )² * (1.42mm + 0.6mm)) + 50cc = 69.5cc

Computing Compression Ratio

Engine compression is essentially taking the displaced volume and squishing it into the cleared or compressed volume as the piston travels from bottom dead center to top dead center. Compression ratio is therefore:

compression_ratio = (cylinder_displacement + compressed_volume) / compressed_volume

eg. EJ207 compression ratio = (498.5cc + 69.5cc) / 69.5cc = 8.2

Now What?

Now that you have the basic idea of how the compression works, how is it useful?

Given some fixed variables, you can figure out how to adjust the others to achieve a reasonable compression ratio.

Note: if you are not increasing the head volume, then the only way to change the compressed volume is to modify either the piston dish, piston deck, or gasket thickness. Ideally, you modify it with the piston dish for reasons I will not go into. Rods length can change the piston deck, so consider it a factor when selecting the pistons.

The main way to change displacement is modifying the bore and stroke. For EJs, 2.1 stroker is *roughly* a 92mm piston with a 79mm crank, a 2.34l destroker is a 75mm crank with 99mm pistons, a 2.6 stroker is a 83mm stroke with a 99mm pistons…etc.

Applied Math

I wanted to build a 2.36l destroker with +2mm long rods. I won’t go into all of the reasons, but the thrust of it is that I wanted more displacement while keeping somewhat in the high-revving spirit of the EJ207.

Computing displacement is easy, we already have all of the variables:

displacement = π * (100mm / 2 )² * 75mm * 4 = 2356cc

I know I want to hit a target compression ratio of somewhere around 8.5-9.0, we don’t have the compressed volume yet.

We need: piston dish, compute piston deck, and factor in gasket thickness. We will keep the head volume at 50cc. I also don’t want to order custom internals, so we will stick with Manley’s catalog.

The long rods are +2mm longer or ~132.5mm center to center. Destroker pistons made for standard rods have a compression distance of 32.6mm. To keep piston deck constant, and not have the piston sticking out of the block, we need that to be 2mm less. Pistons for 79mm cranks are 30.7, and 83mm cranks are 28.7mm. So, the 79mm crank pistons are good, or ~1.9mm less, which makes sense. The stroke difference is 4mm / 2 = 2mm. So, the new piston deck is 1.53mm to account for the 0.1mm difference.

Manley’s piston has a -17cc dish.

compressed volume = 17cc + ((100mm / 2 )² * (1.53mm + 0.6mm)) + 50cc = 72.3cc

Compression Ratio = ((2356cc / 4) + 72.3cc) / 72.3cc = 9.15

That is a little on the high side, so how could we hit a lower target? Basically by increasing the compressed volume. If we wanted to hit say 8.5, what would it have to be?

((2356cc / 4) + X) / X = 8.5
=>(8.5 * X) – X = 589
=> X = 589 / 7.5 = 78.5cc

Or, we’d need 6.2cc more compression volume to achieve a compression ratio of 8.5. This can be done with the head gasket, or finding another piston with more dish, or increasing the head volume.


I found this helpful table on NASIOC for EJ motors. Hit the source link if you want to see it on that site.

Source: Titter

Dyno Time: SteamSpeed BMW N55 Stage 2.5 Turbo

We finally got some dyno time for the 335i at CarbConn in Kirkland WA.  The tune still isn’t done, but, it is the current state of where we are at.  There is still a problem with the knock pulling timing, so the timing and boost are set low for now.

BMW N55 STX 78R vs Stage 1
BMW N55 STX 78R vs Stage 1

Stage 2.5 Setup:
– FBO 2011 BMW 335i manual
SteamSpeed STX 78R BB Turbo
– Single port meth
– Only 21 psi, 9 degrees of timing

– 456 whp, 518 ft*lbs torque

Here is stage 2.5 vs SteamSpeed STX 67 (aka stage 1)

VS Stage 1 Setup:
Stage 1 SteamSpeed STX 67 Turbo
–  Single port meth
– 21 psi, 14 degrees of timing


Stage 2.5 vs Stage 1 vs FBO:

The SteamSpeed STX 78R Turbo for BMW N55

 BMW N55 Stage 2.5 Turbo Install

Here are some action shots of the new SteamSpeed STX 78R Turbocharger being installed into a N55 equipped BMW 335i.  This car has successfully been running our STX 67 (aka stage 1) turbo for about a year now.  The owner was able to put down 400 whp with the 67 on pump gas + meth.

We’ll see what he can do with the STX 78R.  As you can see it is quite a bit larger than the STX 67, about +11mm on the exducer side.  Based strictly on the comp wheel, this turbo should be able to make between 500-600 whp, but the OEM turbine housing should limit that to some degree.  Initial dyno testing will show to what degree.

Base purely on inductive reasoning, this turbo should perform somewhat better than the currently popular Pure Stage 2 turbo: their turbo has wheels somewhat larger than a GTX3076R, our 78R is somewhat larger than a GTX3076R, they remachine the OEM housings, so do we, but the main difference is that our turbo has a BB center section, and Pure reuses the OEM JB CHRA.  Given that the only main difference that impacts performance is that our has a BB CHRA, what does that impact?

BB CHRAs have some standard advantages over JB: it is more responsive especially with transient boost, it is more efficient, it is more durable, etc.  In this case, the biggest difference, I think, will be the fact that BB CHRAs can be stay efficient in spite of backpressure much better that a JB CHRA.  Normally JB is fine up to 2:1, but BB can still be efficient at much higher ratios.  This matters a lot in this case, because the OEM manifold/turbine housing is going to generate a lot of backpressure when you try to make over 500 whp.

The BMW N55 STX 78R turbo going in.

BMW N55 STX 78R turbo Install
BMW N55 STX 78R turbo Install

This is what SteamSpeed STX 67 “stage 1” looks like next to the STX 78R “stage 2.5.”

BMW N55 STX 78R vs Stage 1
BMW N55 STX 78R vs Stage 1

BMW N55 STX 78R vs Stage 1
BMW N55 STX 78R vs Stage 1

SteamSpeed STX 67 “Stage 1” for BMW N55 installed.

SteamSpeed STX 67 "Stage 1" for BMW N55 installed
SteamSpeed STX 67 “Stage 1” for BMW N55 installed

Stock vs PS2 vs SS2.5
Stock vs PS2 vs SS2.5

SteamSpeed STX 78R “Stage 2.5” for BMW N55 installed.

SteamSpeed STX 78R "Stage 2.5" for BMW N55 installed
SteamSpeed STX 78R “Stage 2.5” for BMW N55 installed

SteamSpeed STX 67 "Stage 1" for BMW N55 installed
SteamSpeed STX 67 “Stage 1” for BMW N55 installed

Here are some initial results:
v3 – 16 psi
v4 – 18 psi
v5 – 19 psi

BMW N55 STX 78R v3,4,5 Tunes
BMW N55 STX 78R v3,4,5 Tunes

Update 2

We finally got some dyno time for the 335i.  The tune still isn’t done, but, it is the current state of where we are at.  There is still a problem with the knock pulling timing, so the timing and boost are set low for now.

Stage 2.5 Setup:
-FBO 2011 BMW 335i manual
– SteamSpeed STX 78R BB Turbo
– Single port meth
– Only 21 psi, 9 degrees of timing

– 456 whp, 518 ft*lbs torque

Here is stage 2.5 vs SteamSpeed STX 67 (aka stage 1)

VS Stage 1 Setup:
– Stage 1 SteamSpeed STX 67 Turbo
–  Single port meth
– 21 psi, 14 degrees of timing


Stage 2.5 vs Stage 1 vs FBO:

Update 1

The car has had some more tuning.  The red lines are where we left off last time. Looks like it is hitting peak torque around 4k fairly consistently. It looks like we were able to pick up another 50 ft*lbs and 50 whp comparatively. Version 9 has new colder plugs, so the tune is backed off.

BMW N55 STX 78R tuning in 3rd 2011 335i
BMW N55 STX 78R tuning in 3rd 2011 335i

BMW N55 STX 78R EWG Version

Newer BMW N55′ have an electronic wastegate vs the older pneumatic style wastegate.   The turbine housing is also a little larger, so we think it should also help make some more peak power to some degree.

We’ve made a few for some customers, and this is what they look like:

SteamSpeed STX 78R for N55 EWG
SteamSpeed STX 78R for N55 EWG

SteamSpeed STX 78R for N55 EWG
SteamSpeed STX 78R for N55 EWG


Dyno Results: SteamSpeed STX 71 for Mitsubishi Evo X

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?

Model: SteamSpeed STX 71 MHI TD06-18K
Compressor Wheel: STX 71 (11 blade): 54.1mm/71.4mm 18K (7/7 blade): 55.1mm/75.0mm
Turbine Wheel: TD06SL2  (9-blade): 54.1mm/61.0mm TD06 (9-blade): 54.0mm/61.5mm
Flow: 59.5 lbs/min (tested) 54.0 lbs/min (est)
Install Kit Included: Yes No
Price: $1499 $1699

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.

SteamSpeed STX 71R BB Prototype Tested: 470 WHP

Hey guys,

Sam here from SteamSpeed.  We super happy to get back to you with the results of our SteamSpeed STX 71R ball bearing turbo for FA20 applications, ie. the 2015+ WRX.  The basic specs are:

  • Stock frame meaning it just bolts up in place of the OEM turbo
  • Utilizes a Garrett GT ball bearing CHRA (center housing rotating assymbly) sourced from Garrett Japan
  • It is GTX2971R spec meaning the we make our own compressor wheel of that size, and reuse the Garrett GTX29 turbine wheel.

[STX 71R for FA20 Prototype Pre-Test Recap]

Several months ago, I wrote a longish article discussing challenges with the JB CHRA and how the new BB CHRA.  It is a great read, and I highly recommend that you read it, but it lays out why we think the BB version of the 71 will be a superior turbo to our JB version.  The next section outlines, the basic points.

[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.

SteamSpeed STX 71R for FA20 Dyno Plot. Green – E50, Black – 91 pump gas

[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:

Notice we modified the turbine housing to work with the OEM oil pan without modification. We also include custom studs with the install kit.

Notice we modified the turbine housing to work with the OEM oil pan without modification. We also include custom studs with the install kit.



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.



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.

Jesse @ FNP Tuned”

SteamSpeed Focus RS Intercooler Upgrade: Final Design Approved!

We are excited to announce our final revision to our Focus RS intercooler! We’ve gone through three design revisions and this is the perfect design.

[Mounting & Fitment Improvements]

The first prototype core design showed huge efficiency gains vs the OEM unit; however, we saw room for improvement.  In the next two prototypes we iterated and improved the end tanks and mounting tabs to further increase the efficiency of the core and ease of install.

After the intercooler had been mounted and driven nearly 1000 miles of road conditions including freeway cruising, data log pulls, dyno time, and spirited drives, we found ways to improve its mounting to the chassis vs the OE.  In our final version, we increased the thickness of the mounting tab material from 3mm to 5mm and adding a perpendicular support to the lower tabs for greater strength and durability.  This insures a rigid mount to radiator chassis.  We also found that utilizing openings in the bumper frame to support the intercooler from the top was much more effective then the OE mounting points; the factory cooler is only suspended from the lower tabs and held vertical by the upper tabs that engage hooks into the casting of the cooler tanks.  Due to the increase in weight of our cooler we knew the lower supports would never be sufficient without the extra bracing.  To utilize the bumper frame, we installed a bolt and nut through the opening. This was fine for our final prototype but we look forward to using a plastic insert and screw to secure the upper mounts. This will ensure ease of installation with minimal effort.

Here you can see just how massive this thing is. There’s also a good view of the upper bumper frame mounts. This holds the weight nicely and gives great support for the cooler.

[Intercooler Performance Testing]

Our upgraded Focus RS intercooler, uses quite a bit more heat removing aluminum vs the OE unit.  It is about 30-40% larger by volume and more than 50% larger by mass and surface area vs the OE unit.   The performance of the intercooler core of our first prototype was stellar, so final prototype’s core remains the same.

Our Focus RS intercooler upgrade brings intake temps well below 100 degrees F.  It doesn’t get terribly hot here in Washington State but we did manage to have a day with an ambient temp of 80 degrees F and a resting 101.9 degrees F. You can see in the graph how the Charge Air Temp (white line) drops rapidly when the throttle body opens. And makes its way back down to 86.7 degrees F when grabbing 3rd gear.  That’s great!  Many tuners are happy with and consider an intercooler “good” if it can manage to get below 100.  The temp does start to climb as expected in the longer gears but as shown in the second graph the charge air temp only climbs 5 degrees to 92 degrees before lifting off the throttle.  In comparison, the OE core is much less efficient.  We’ve recorded increased charge temps of around 30 degrees F.  That means our upgraded Focus RS intercooler around 25 degrees (6x) cooler than the OE intercooler!

If you have any more questions please let us know!

[Testing Data]

Above is the data log of a 1st through 3rd and into 4th gear acceleration. The white line shows Charge Air Temp. The Charge Air Temp is around 100 degrees F when the throttle plate is closed.  The induction air is moving slowly and heat from the engine heats the air.  When the throttle plate opens is when the largest drop in Charge Air Temp occurs.  Lots of fresh air is let in and the heated induction air passes through quickly.  As the vehicle hits 3rd gear it is apparent the turbocharger is now working very hard. There is a slight increase in Charge Air Temp towards the end of 3rd gear. If this data was done without the cooler we would see.
Data log continued (same log as previous graph)

#ford #focus #rs #turbo #intercooler #prototype #presale #keepitcool #steamspeed

Project Domino: A New Turbo and a New Tune

It has been over a year since we’ve done anything with the old girl.

As a refresher, our 2001 Impreza RS had(power wise):

  • a full version 8 JDM WRX STI swap
    •  The the version 8 EJ207 engine is still stock; it didn’t seem right break down a perfectly health motor at the time
    • Version 8 STI 6-speed
    • We did the 5×114 conversion from a 07 STI
  • Custom 3″ catless turbo back
  • Custom FMIC with a ridiculously large IC core
  • Big MAF intake
  • SteamSpeed silicone inlet
  • ID1000 injectors + a Walbro 255 lph pump
  • SteamSpeed STX 71 JB turbo for JDM STI twin scroll

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.

[Domnio V3]

We wanted to do something a little more responsive.  Enter the SteamSpeed STX 67R+ BB turbo for JDM STI.

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.

[Dyno Plot]

[Next Steps]

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.

Installation Guide for EJ fitment Steam Speed Turbochargers.

We are proud to announce  a simple installation guide that can be used on all EJ fitment vehicle.  We kept most of the description as generic as possible and high lighted the key steps in replacing your turbo. As stated in the video there may be differences in your exact application.  Below the video is the full transcript of the narration.

Full Transcript

Welcome to the installation video for EJ fitment steam speed turbo chargers.

  • Today we will be installing a steam speed stx67r-10 twin scroll on our version 8 ej207. This process can be applied to any EJ fitment vehicle or to these listed part numbers.
















  • Notice our vehicle is far from stock and what you see in the video may not match your vehicle. However, the key points of the process will be the same.
  • We begin by gaining clear access to the turbo. We removed the air filter and Mass Air Flow sensor housing and charge pipe at the turbo.
  • If you have a top mount inter cooler remove that from the throttle body and compressor outlet.
  • The silicon or plastic hoses may be stuck. Use brake clean to break the adhesion and carefully work the sealing edge with a hose pick. Take caution not to puncture or tare the hoses as this will lead to a boost leak later.
  • Next remove any heat shielding you may have installed. Whether that’s a turbo blanket such as the steam speed titanium or carbon fiver turbo blankets or bolted on stamped steel heat shields.
  • Next use a rust penetrator such as “wd40”, or “pb blaster” and soak the turbine housing bolts on the up and down pipe flanges. Allow them to soak for at least 15 to 20 minutes.
  • While the bolts soak, place a collection pan underneath the vehicle directly below the turbo and remove the coolant and oil lines connected to the CHRA portion of the turbo.
  • I suggest using hose clamps to minimize the amount of spilled coolant and coolant unnecessarily draining from the engine.
  • I also cap the coolant lines on the turbo to also minimize the mess.
  • Next you can begin to loosen and remove all the up and down pipe flange bolts.
  • Caution, these bolts can break if too rusted together. If this happens you will need to replace them.
  • When the flange bolts and nuts are removed disconnect the down pipe from its solid mounts on the side of the transmission. Up plug any oxygen sensors and move the down pipe from the vehicle.
  • Once the down pipe is clear loosen the compressor inlet pipe and maneuver it toward the front of the vehicle underneath the intake manifold until it is clear of the compressor housing.
  • Then you should be able to lift the turbo off the up pipe flange and oil drain tube.
  • Take caution with the oil drain tube as the hoses can stick and tension clamps can lose their tension over time and fall off while removing. The open oil drain will be exposed and can risk material falling into it.
  • Place the new and old turbo chargers on a work bench and note any comparable differences that may cause fitment issue or parts that may need to be transferred such as coolant lines or the oil drain tube.
  • Next you will see there are 3 studs provided with your new turbo. Place these in the corresponding locations compared to your previously removed turbo. Then tighten these studs with a 7mm open end wrench.
  • Apply thread sealant or thread tape to the oil feed line fitting on the back side of the cylinder head. This will be a hard line on AVCS equipped engines.
  • Then install the oil feed line.
  • Prep the up and down pipe flanges for new gaskets, remove any surface rust or grease and oil with a fine grade abrasive pad. Then place your new up pipe gasket on the flange.
  • Place your new steam speed STX turbo charger on to your up pipe flange. Remain aware of the oil drain tube alignment. If the drain tube is new it may be more difficult to slide onto the metal portion connected to the CHRA (center housing rotation assembly). You can apply a thin film of engine oil to the rubber drain tube to ease its fitment on to the metal portion. Then Place the tension clamps back into place.
  • Carefully guide your turbo inlet pipe onto the inlet of the compressor housing. On larger turbo’s this may be more difficult as the compressor inlet diameter may be larger than the diameter of your inlet pipe. Tighten the clamp, securing it to the compressor housing.
  • Begin to reinstall all the nuts and bolts securing the turbo to the up pipe. Be sure all nuts and bolts are in place before tightening all the way. Place your down pipe gasket on to the outlet flange and studs on the turbine housing. And guide the down pipe into place.
  • Then install the down pipe flange nuts and bolts. Again do not tighten until all bolts are in place.
  • Torque all up and down pipe bolts to 26 ft/lbs
  • Next apply thread sealant or tread tape to the oil feed line fitting on the top side of the CHRA.
  • Reconnect the coolant hoses and vacuum lines.
  • Carefully check each step on the installation to be sure nothing was missed or any hoses moved out of place.
  • Reinstall the charge pipe and air filter housing.
  • The most important step is priming the oil system. If this step is not performed eruptible damage will be done to the CHRA.
  • Disable the ignition system but either removing the crank sensor signal.
  • Crank the vehicle over for a minimum of 30 seconds.
  • Re connect the ignition system and start the car.
  • Allow the vehicle to idle for 15 to 20 minutes and reach operating temp slowly. Do not rev the engine.
  • Inspect your work for coolant or oil leaks at the fittings and hoses.
  • Be observant for a hiss noise of possible vacuum or intake leaks.
  • Once the vehicle has been thoroughly checked, let it cool and reinstall your heat shielding.
  • It is now imperative your vehicle is tuned by a trusted tuner using a chassis dynamometer.


The SteamSpeed STX 71R BB Turbo for FA20 (2015+ WRX) Is Here!

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?

Dyno Testing: SteamSpeed STX 67 Turbo for Ford Focus RS Prototype

STX 67 Turbo for Focus RS Prototype Dyno’ed!

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.

Mod List:
– Stock 2016 Focus RS
– SteamSpeed STX 67 turbo prototype
– SteamSpeed front mount intercooler kit prototype
– 92 octane WA pump gas

Here are the dyno results from our car at English Racing.

Green: Baseline, Stock RS with Stock Tune – 92 octane
Red: Cobb Stage 1 Base Map – 92 octane
Blue: SteamSpeed STX 67 turbo + SteamSpeed FMIC

SteamSpeed STX 67 Turbo for Ford Focus RS Prototype
SteamSpeed Focus RS STX 67 Turbo Upgrade

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.

SteamSpeed Focus RS STX 67 Turbo vs Stg 2
SteamSpeed Focus RS STX 67 Turbo vs Stg 2

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.

E-mail for Focus RS product inquires.

Next steps:

It would be interesting to see how this turbo would do with more bolt ons like a turbo back and upgraded intake.  Our car was mostly stock otherwise.  I think we see some modest gains.

The wastegate duty cycle was about maxed out, so that could improved with a different waste spring preload or changing out the boost controller.

I think we could make the compressor somewhat larger without overpowering the turbine section.  That might net another 10% more power.

Other notes:

And the car still got 28 average mpg on the way back.