Subaru OEM 2.5L Shortblock Subaru STI Type RA 2018 / STI 2021 | 10103AD020

Rated 5.0 out of 5
Based on 9 reviews
SKU: sub10103AD020
Availability: 3 In Stock Learn more
Type: Short Blocks/Long Blocks/Heads
Regular price
$2,388.00
Regular price
$2,400.00
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$2,388.00
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Subaru OEM Parts
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Genuine OEM Parts Part #: 10103AD020

The block is the same casting as the latest engines, numbered "705." The crankshaft is the same nitrided, full-counterweight design found in previous EJ25s. Unfortunately, the crankshaft doesn't have the additional oiling ports found in other special edition EJs. The bearings and clearances thus far have been within typical late-model EJ257 specs as well.

Type RA Piston Differences

Type RA vs. STI Piston Crowns

Upon initial impression, the Type RA and STI piston are both machined cast pistons. The dish volume measured out very close to each other and the valve reliefs are the same depth. Unfortunately the Type RA does not have forged pistons as some had hoped for, although we haven't ruled out the possibility that the Type RA pistons are made from a different alloy that is less susceptible to fracturing (more ductile), as they are supplied by Hitachi rather than Aisin. The crown on the Type RA pistons appears to be 1 - 2mm thicker than the STI piston as well, which is hard to discern from the picture.

Type RA vs. STI Piston Side Profile

From the side profile you can see a few differences. First, the coating at the top ringland is extended to the crown on the earlier STI pistons. This is likely due to manufacturing differences (less tooling / different tooling) rather than any specific performance difference. Second, there is considerably more material supporting the wrist pin on the Type RA piston.

Compression height, ring position, and other dimensions appear to be the same. Meaning, there are no changes to the ringlands in position or thickness. Top ring gaps were 0.010", 0.010", 0.011", 0.011". and lower ring gaps were 0.014", 0.014", 0.014" 0.015".

Type RA vs. STI Piston Bottom

From the bottom you can see how much material was added to the wrist pin area (in red) as well as the reduction in the large center support (in green). The Type RA design is superior for piston rigidity since it reduces the amount of cantilever, as well as giving better support to the wrist pin itself.

Earlier STI pistons weigh in at 414 grams while the Type RA pistons weigh 424 grams. The extra 10 grams of weight is not a big deal when you consider the improvements made to the piston design. For comparison, forged pistons for the EJ257 typically weigh in the 370 - 400 gram range depending on bore size and design. The wrist pins weighed the same for both motors.

Type RA Con Rod Differences

Type RA vs. STI vs. JDM STI Rods

The Type RA rods are identical to the GR STI's rods as far as my eyes tell me. Not a big surprise considering the rods are definitely not the weak link in the motor. There are some differences in the late model rods compared to the earlier EJ257 rods and the EJ207 rods, notably the closed channel on the big end's internal bore and the lack of a perpendicular reinforcement rib .

Type RA vs. STI vs. JDM STI Rods - Side Profile

No visual differences between the GR STI rod, and in fact, the 2018 STI and Type RA rods share the same part number.

Type RA vs. STI vs. JDM STI Rod Caps

Part Numbers

Type RA Engine Assembly (Longblock)
10100CD390

Type RA Engine Assembly (Shortblock)
10103AD020

Type RA Piston
12006AE550

Warranty Disclaimer: Subaru of America will only warranty parts installed by a CERTIFIED Subaru Dealership. The part being installed must also match the vehicle VIN. IE If you install an STi block in a WRX at your friends shop, do not expect a warranty claim to come through if it explodes! Please use your best judgement.



average rating 5.0 out of 5
Based on 9 reviews
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Review posted
Reviewed by Tyrel W.
Verified Buyer
Rated 5 out of 5

exactly what it specifies

came the same week! definitely a very reputable company! will definitely be making more purchases in the future!

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Reviewed by Tyrel
Rated 5 out of 5

5 Stars

came faster than i had anticipated!

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Reviewed by TripleMag
Verified Buyer
Rated 5 out of 5

So far so good!

Block has been pretty solid so far, only pushing 320 WHP/350 TQ, and I've only had the setup going for about 1500 miles now, but no issues so far, no oil loss or anything has been great!

Got the block in two days from Import Image, very happy!

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Reviewed by Jared L.
Verified Buyer
Rated 5 out of 5

Great rebuild option

Great for stock rebuild

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Reviewed by Francisco R.
Verified Buyer
Rated 5 out of 5

Wow!

I cant thank the team enough, ordered on Wednesday and had it on Saturday. Steven made it easy and painless.

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Reviewed by John L.
Verified Buyer
Rated 5 out of 5

Made purchasing higher priced parts a little easier

Dane worked with me to get me the best prices on all my purchases. I Will recommend to everyone looking for new or upgraded parts.

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Reviewed by Victor M., from United States
Rated 5 out of 5

Vey Good OEM Block

Very good short block, can stand mild boost levels if you gap the compresion rings to acceptable levels, good customer service and fast shipping.

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Reviewed by Ryan, from United States
Rated 5 out of 5

Type ra

Shipping was fast and can't wait to finish assembling my engine and make a lil jam.

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Reviewed by Rocky R., from United States
Rated 5 out of 5

Type ra short block

Fast shipping l! Got it for my bugeye

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