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2020 Subaru WRX STI, 2.4-liter turbo boxer engine, new Ascent engine
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By Denis Flierl Apr 29 2018 - 7:43am

Rumor Mill; Next-Gen Subaru WRX STI Might Get New 2.4-L Turbo

The next-generation 2020 Subaru WRX STI could get a new mill. See what rumors are swirling.
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The next-generation Subaru WRX STI could be coming with a new 2.4-liter engine if rumors are correct. According to a report from Road & Track, Subaru could use the new Ascent 2.4-liter turbo Boxer in the fourth-generation Subaru WRX STI replacing the aging EJ25 2.5-liter used in the current model when it arrives sometime in 2020. It’s reported the 2.4-liter turbo could make 330 plus horsepower in the new STI.

Subaru engineers developed the 2.4-liter powerplant for the Ascent 3-Row family hauler. The new FA24 Boxer engine comes with the latest direct injection and other internal upgrades for the best power and towing vs fuel efficiency. Could Subaru drop it in the fourth-generation WRX STI?

It features all-aluminum heads and block, to reduce weight and allows for more rapid warm-up. The internals include heads with dual overhead cams, driven by a timing chain rather than a belt, actuating 16 valves with variable timing.

It has a total engine displacement of 2,387cc with a 94-millimeter bore and an 86-millimeter stroke. The compression ratio is 10.6:1 which keeps cylinder pressures high for efficiency. It also features a twin-scroll turbocharger.

In the Ascent, the new FA24 engine develops 260-horsepower at 5,600 rpm and has a broad peak torque band of 277 lb-ft between 2,000 and 4,800 rpm. Subaru Technica International would rework the internals and bump up horsepower and torque considerably if they use it in the new WRX STI. Subaru could also use it mated with new hybrid technology being developed now.

Of course, this is all speculation and has not been confirmed by Subaru who declined to comment. Subaru needs to replace the aging 2.5-liter EJ25 Boxer in the fourth-generation 2020 Subaru WRX STI and the newest Subaru engine may get the nod. Stay tuned.

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Comments

Big Engines wrote on April 30, 2018 - 1:45am
Thanks Denis for this report I think maybe this engine only for WRX STI but WRX may have another engine maybe smaller than 2.4-liter, is that right? Do you think the next generation for Subaru Legacy 2020 will have the same engine from Ascent? cause they will drop 6 cylinder engine in 2020
A WRX guy wrote on April 30, 2018 - 2:06pm
Bad math is bad. The current WRX is the 4th gen. The expected 2020 model will be the 5th gen.
Dups wrote on May 1, 2018 - 3:26pm
What do you mean new? The 2.4 turbo engine first came out circa 2006. Get that right.
SubaStar wrote on May 2, 2018 - 9:53am
330 hp in 2020 when competitors offer 350 to 400 in 2018? Come on Subaru! Should I say: come back at the top of the niche you've created: a rally car barely legal on the road and make your loyal customers happy, the ones who forged your good, reliable and sporty image!
Drew wrote on May 22, 2018 - 6:57pm
Your knocking the company who just won the Nuremberg yet again with its 2.5. Also, competitors may be making 350-400 but they still barely run with a car that puts down 300hp because of awd and gearing. And weight... And a lot of variables other than just HP alone. 330 is still more hp than an STI at present, and not to mention with such a high compression ratio allowed with direct injection you'll get that 330hp SOONER and for a far longer period of time... and we all know time is money. No pun intended.
SubaStar wrote on May 23, 2018 - 5:02am
Hi Drew, Subaru and STI won their 5th SP3T-class tilte at the 2018 24H Race at Nürburgring with the EJ20 of 340 HP and not the EJ25 : it confirms Subaru is able to deliver a great output of its 2.0 mill with maximum reliability, we all know that. I know the power is not everything in a good sport car. I pretty share the Colin McRae's words: "Straight lines are for fast cars, corners are for fast pilots" and I really think that Subaru's philosophy has integrated that. But no matter which 2.0, 2.4 ou 2.5 power plant to come, 330 HP in such a famous sporty road car will remain too weak in 2020/2021, despite of Subaru expertise in AWD (less in gearboxes). In the 90's, the WRX and WRX STI were standing alone in their market segment. It's not the case anymore, and will be even less in the future : Subaru must react and I'm pretty nosy to discover how they'll manage the hybridation on their icon.
Paul wrote on June 3, 2018 - 1:13pm
+1 SubaStar. I love my 2015 WRX and want to upgrade to an STI once the new gen comes out in 2020, but if Subaru neuter it with under 350 HP, I will likely be giving my $$$ to another manufacturer. The next gen Golf R, also due 2020, should come with around 400 HP and may sport hybrid tech as well. Subaru has better AWD but in a sports car, power is important too. A next gen Civic Type R may also get a nice power bump. It's a shame Ford will not offer the next gen Focus RS in North America, that will likely sport 400 plus HP as well.
Brandon wrote on July 16, 2018 - 3:11pm
man I would love to see an inline 4-cylinder in a Subaru. they could squeeze it down a little by putting it into a w formation like Volkswagen. The boxer engine seems like they are a more complicated heavier design. it's hard to do a valve cover gasket on those and some you have to unbolt the engine mount and Jack the engine up just to get at them . And the exhaust is just a crying shame to look at from underneath. head gaskets I think have improved but are still a worrying issue to me to leak. There was a cam cover seal that was leaking on a 2011 and it dripped right onto the bank 1 O2 sensor and the engine had to be pulled to get that seal done which is ridiculous. I just think they need to go back to the drawing board on that engine. I love everything else about Subarus though.
Todd wrote on July 17, 2018 - 10:56am
I’ve been a loyal die-hard Subaru guy for 10+ years until recently. I sold my high mileage 2007 WRX reluctantly, and got into a BMW M235i only because there isn’t anything exciting about the WRX or STI at this time. I’m waiting to see what the next generation brings, but if styling isn’t more aggressive and performance numbers aren’t up there pushing the competitors I’m extremely disappointed in Subaru’s ability to keep up with incredible performance push from other manufacturers. COME ON SUBARU!!!
Ed B wrote on July 23, 2018 - 6:10pm
Too bad, it would have fit nicely in the Forester XT...