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Old 06-16-2018, 11:19 PM   #1
sponaugle
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Default 2018 STI RA Engine Block Teardown

With the release of the 2018 STI RA, I was curious what changes were made to the internals of the engine. Subaru had indicated that new pistons were used, but didn’t specific much else in terms of internals.

I ordered a 2018 RA engine block about 2 months ago, and at that time there were no spare engine blocks in the US. It was eventually ordered from Japan and arrive at the end of last week. The price was the same as the regular STI short block.

On first glance, the block looks almost identical to the existing EJ257 motor. The cases is the newest 705 case, the crankshaft has the nitride black finish, and the piston tops look very familiar.





I disassembled the engine and first took a look at the pistons, since that is something documented as being ‘improved’.



RA piston on the left (BV), 2004-2006 STI piston on the right (A5)/

The pistons are very similar, and both appear to be machined cast parts.





The most obvious difference is the construction of the bottom of the piston. The older EJ257 piston does not fully enclose the pin boss, while the new construction has significantly more material around both of the pin sides of the piston. RA piston on the left above, STI on the right.



From the side, you can see the difference in material around the pin area. Construction and dimensions of the ring and ring area looks the same, with the exception that the upper ring area is fully coated on the older ones.

While not easy to see in these pictures, on the bottom side the depression right at the center of the piston is less, and the material is thicker. I would estimate the piston is between 1 and 2mm thicker going from the top to the bottom surface.

Other dimensions appear to be the same. Compression height, ring position, etc are all the same.

The new piston is heavier - 424 vs 414 grams (10 grams heavier).

I did a quick CC measurement and they appear to be pretty close. I’ll do a more complete measurement in the next few days.





The crankshaft appears identical to the 2016/2017 crankshaft, with no special oil modifications.



The rod also looks to be the standard previous year EJ257 rod. You can see the slight difference in design between the original EJ207 rod, the early EJ257 (2004), later EJ257 (2008), and the 2018 STI/RA rod.

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Old 06-16-2018, 11:19 PM   #2
sponaugle
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One interesting difference in the piston is the presence of a ‘Hitachi’ logo in the casting. This did not appear in previous pistons (which has a small Subaru mark in that location).



I will measure all of the factory bearing clearances to see if there is any difference there.
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Old 06-16-2018, 11:20 PM   #3
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And no difference in the wrist pins...

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Old 06-16-2018, 11:59 PM   #4
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Nice work, do you think the new block will be able to support more power? Or still have ring land issues?
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Old 06-17-2018, 08:37 AM   #5
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How dare you! That's Restricted Access! Lol

Interesting.....
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Old 06-17-2018, 10:45 AM   #6
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Quote:
Originally Posted by Specgtr View Post
Nice work, do you think the new block will be able to support more power? Or still have ring land issues?
I was wondering this too. With the limited number of these things produced, it's possible we may not find out for a while since, I imagine, most guys my only bring these things out on a sunny Sunday drive. At least, I know I would if I was privileged enough to own one.
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Old 06-17-2018, 11:48 AM   #7
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Quote:
Originally Posted by viper_crazy View Post
I was wondering this too. With the limited number of these things produced, it's possible we may not find out for a while since, I imagine, most guys my only bring these things out on a sunny Sunday drive. At least, I know I would if I was privileged enough to own one.
From the literature of the 2019 STi, it appears it's getting the same block and pistons as the RA so there should be a lot more examples available for reliability.
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Old 06-17-2018, 11:54 AM   #8
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Oh, interesting.
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Old 06-17-2018, 01:53 PM   #9
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Interesting. Thanks for doing this, I was curious what the differences where.

Any idea why the case halves have a different part number if they are the same as the previous 705 castings?

I have to say, so far the "new" EJ is a bit underwhelming.
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Old 06-17-2018, 03:35 PM   #10
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Might want to proof-read a few of the left/right notes, as a few are flipped on images where you cannot see RA vs. earlier markings. Some are obvious to readers, but a few others are not.

As I expected ever since the first images of the cast valve reliefs were shown, Subaru talked up the new parts as if we were being given something amazing, assigned a price tag to the spares equivalent to older GDB-A/B forged parts, yet they went cheap in the end.

Just like the 2008+ 6MT oiling.
Just like the 2018 gutted DCCD.

Subaru USA is now a company that completely preys on ignorant buyers. Downgraded or side-graded parts while marketing them as upgrades and charging people out the ass. Pretty sad to see when the economy in both the USA and Japan aren't the driving factor for behavior like this at the moment...
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Old 06-18-2018, 10:29 AM   #11
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Default 2018 STI RA Engine Block Teardown

once again you have done the subaru community a great service. thank you for this.

i should mention your pics got reversed. you say left (bv) is the RA piston but the pic has it on the right.

were they mis-labeled? or is it just the camera flipping the image?

just though i would point it out to avoid confusion.
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Old 06-20-2018, 03:07 AM   #12
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WOW . Hitachi makes piston die cast aluminum at Mexico ,not sure if its the same for the sti
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Old 06-20-2018, 10:42 AM   #13
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It is possible that Subaru added something to the casting process to make this "new" piston stronger. If you know about how they make cast pistons then you probably know that you can add elements in the casting process that can make a cast piston significantly stronger while keeping the same characteristics of a cast piston vs forged. You would not be able to see this as it is the material itself that is stronger.
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Old 06-20-2018, 11:05 AM   #14
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Sponaugle FTW!

Quote:
Originally Posted by mrsaturn7085 View Post
As I expected ever since the first images of the cast valve reliefs were shown, Subaru talked up the new parts as if we were being given something amazing, assigned a price tag to the spares equivalent to older GDB-A/B forged parts, yet they went cheap in the end.

Just like the 2008+ 6MT oiling.
Just like the 2018 gutted DCCD.

Subaru USA is now a company that completely preys on ignorant buyers. Downgraded or side-graded parts while marketing them as upgrades and charging people out the ass. Pretty sad to see when the economy in both the USA and Japan aren't the driving factor for behavior like this at the moment...
Yeah I quit drinking this company's Kool-Aid quite some years ago. Like the older platforms but no more new Subies for me.
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Old 06-20-2018, 11:33 AM   #15
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still prefer my ej22's
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Old 06-20-2018, 01:19 PM   #16
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Quote:
Originally Posted by mrsaturn7085 View Post
Might want to proof-read a few of the left/right notes, as a few are flipped on images where you cannot see RA vs. earlier markings. Some are obvious to readers, but a few others are not.

As I expected ever since the first images of the cast valve reliefs were shown, Subaru talked up the new parts as if we were being given something amazing, assigned a price tag to the spares equivalent to older GDB-A/B forged parts, yet they went cheap in the end.

Just like the 2008+ 6MT oiling.
Just like the 2018 gutted DCCD.

Subaru USA is now a company that completely preys on ignorant buyers. Downgraded or side-graded parts while marketing them as upgrades and charging people out the ass. Pretty sad to see when the economy in both the USA and Japan aren't the driving factor for behavior like this at the moment...
Yea, I'll fix that.. a couple of them are incorrect. I fixed in on the original facebook post, but forgot to come here and fix it.

Thanks!

Jeff
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Old 06-20-2018, 02:48 PM   #17
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Quote:
Originally Posted by A-man07 View Post
Yeah I quit drinking this company's Kool-Aid quite some years ago. Like the older platforms but no more new Subies for me.
Yeah... it's really sad to see the other Japanese marques bouncing back with newer, better cars while Subaru (formerly FHI) took the low road and absorbed all the benefits of the better economy into the bottom line. It's like they learned in 2007(ish) that they could cut costs/performance in the USA without people caring and just kept at it.

Part of it really is the Kool-Aid mentality in the USA - smarter consumers elsewhere don't put up with this BS. Case in point - check out the resale value of the first-generation BMW M6. BMW didn't change anything on the car for YEARS and these can be had for almost a quarter of the sticker price now (seriously... ~$40k used, 10-15k mile cars) with next to no mileage.

Quote:
Originally Posted by 12wrx1 View Post
It is possible that Subaru added something to the casting process to make this "new" piston stronger. If you know about how they make cast pistons then you probably know that you can add elements in the casting process that can make a cast piston significantly stronger while keeping the same characteristics of a cast piston vs forged. You would not be able to see this as it is the material itself that is stronger.
Keep trying to justify that $50k price tag

Last edited by mrsaturn7085; 06-20-2018 at 02:53 PM.
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Old 06-20-2018, 03:32 PM   #18
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only company ive noticed getting some nice reliable gains from 4 cylinders is Volvo.
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Old 06-20-2018, 05:58 PM   #19
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Thanks for doing this.

I suppose we'll just have to wait and see how many RAs blow ring lands to find out if the pistons are any better.
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Old 06-20-2018, 07:05 PM   #20
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Default RA short block

Would you say that the bearings are the same too?

I assume older ej257 head will mate with RA short block no issues, right?

Last edited by redrexmeister; 06-21-2018 at 10:36 PM.
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Old 07-06-2018, 07:11 PM   #21
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Really cool investigation. Keep us posted with more findings.
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Old 07-06-2018, 07:50 PM   #22
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mrSaturn makes some good points above although I don't fully understand the M6 comparison (perhaps you can elaborate)

A couple points- one Subaru only claimed that the pistons were stronger, nothing else. They do appear to be stronger. Wouldn't it have been nice if they used forged pistons though?

Subaru needs to price to be able to cover a given model's potential warranty claims. That said, the "track inspired" car will likely see more claims than the standard Impreza, thus the higher price.

Second, there is something to be said for a limited run. Porsche is the worst with these. They create these low production runs knowing fully that dealers will be able to charge a premium on top of stickers, and that the collector set will go mad (see 996 GT3 prices) I spent some time earlier this month trying to buy a 22b, a car with less performance than a current STI that can be beaten by an Evo of it's own generation yet is 5x the cost of either. When you enter the collector zone sanity and reason go out the window.
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Old 07-06-2018, 08:25 PM   #23
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Quote:
Originally Posted by Bimmubishi View Post
mrSaturn makes some good points above although I don't fully understand the M6 comparison (perhaps you can elaborate)
The BMW M6 went relatively unchanged year-by-year and this has a tendency to cause a sharp drop in sales as interest drops off. Resale on used M6 cars, in turn, plummeted.

The powertrain (as well as drivetrain) of the STI has also gone unchanged for years and years, and generally when something has changed, it has been a downgrade. The chassis has gotten more rigid, but at the expense of weight (granted, not a ton - some 200 lbs).

So aside from the cosmetic face-lifts, the only thing keeping people interested in the STI is the BS that Subaru of America spews as 'upgrades'.

Quote:
Originally Posted by Bimmubishi View Post
A couple points- one Subaru only claimed that the pistons were stronger, nothing else. They do appear to be stronger. Wouldn't it have been nice if they used forged pistons though?
They did in 2000-2001. It's a shame they decided to charge the same price for the new RA pistons as spare parts as the markup on the forged EJ207 pistons. You can still order these pistons all day long outside the USA.

Quote:
Originally Posted by Bimmubishi View Post
Subaru needs to price to be able to cover a given model's potential warranty claims. That said, the "track inspired" car will likely see more claims than the standard Impreza, thus the higher price.
2004 STI MSRP = $32,000-$32,500
2018 STI MSRP = $36,000

This is still pretty well in-line, here.

2018 STI RA MSRP = $48,995

This isn't.

I'm not talking about the price of an STI vs. the price of an Impreza. I'm talking about the morons that pay a $12k+ premium for the RA thinking it's something special. It's a limited-run, yes... but I'd give 10:1 odds that less than 100 will remain unmodified. Start buying crappy parts and suddenly you've got an STI with a carbon roof that likely under-performs the actual stock STI. In Japan, where you actually get a totally different car with the Spec C (or even more limited R- and S- series cars), there is a reason behind the price difference!

Quote:
Originally Posted by Bimmubishi View Post
Second, there is something to be said for a limited run. Porsche is the worst with these. They create these low production runs knowing fully that dealers will be able to charge a premium on top of stickers, and that the collector set will go mad (see 996 GT3 prices) I spent some time earlier this month trying to buy a 22b, a car with less performance than a current STI that can be beaten by an Evo of it's own generation yet is 5x the cost of either. When you enter the collector zone sanity and reason go out the window.
First off, I'm talking pre-dealer mark-up. The MSRP of the RA is $12k over the base STI. $12,000. That's a down payment on a good house in literally all but the highest priced areas of the USA.

The 22B had the tech. to back up the MSRP over base models.

Porsche GT3, GT2 RS, etc. has the tech. to back up the price tag over base models. Hell even the 'S' models in the the 997 range (which weren't even that limited) had active suspensions added as standard. Active suspension is no small change!

Aside from sheer greed, I don't quite understand the drive for this with SoA and the USDM RA... it's not like the bubble burst and we're not going to see performance stuff for a decade out of Japan at the moment (though the tariff stuff isn't looking good). Subaru *could* make a better performance car (look at the missed potential with the BRZ after all these years... seriously). They *could* give us the good parts they're still stuffing into the JDM models (though we'll never see the EJ207)... but they're not.

They've taken the 'RA' name that actually meant something on older models and just made it next to worthless. It used to be - 'we're gonna celebrate our success by offering a kick-ass car with a limited run to our most loyal consumers; make it fast, cost is no object'. Now - 'we're gonna celebrate our success by offering an assembly-line car with a limited run badge to our most gullible consumers; here's $2000 bucks to add some parts, make sure you bring me back the change'. It's not like the RA shares anything in common with the GT car they ran on Nurburgring anyhow. That car shares more in common with Super GT and WRC cars than anything else.
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Old 07-07-2018, 07:27 AM   #24
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I agree with a lot of what you're saying but not that there was tech in earlier premium models like the 22b which still had a 5 speed yet commanded 40+k new in 1998.

The M6 is still a weird example. BMW only produced 4000 cars and the engines were essentially group-A hardware which wasn't cheap to begin with. The E24 chassis had a long run though so I get you there but the tech carried over to later models to some degree and the price was likely justified given that the car was an M1 derivative and VIP car.

Subaru also had forged pistons in the 1993/4 Sti Version. I know which have them and which don't, my point was only that for 50k this car should have them too. (and I think you agree!)

I agree with you that the RA isn't worth an extra 12k just for the record. I think an argument can be made that the car will be worth something as a collector's item down the road but it's unlikely. The carbon roof is such childish costume jewelry. The spoiler too.
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Old 07-07-2018, 09:10 AM   #25
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Default 2018 STI RA Engine Block Teardown

muricains will pay a premium for exclusivity. SoA could have done literally nothing except add an RA badge, jack the price $12k, and they still would have sold all 500 units.

they need to show their neighbours that the are doing better than them... objectively
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