Engines that were once just tuner folklore are now quietly dragging entire model lines up the price charts. As collectors chase originality and period-correct performance, a handful of underappreciated powerplants are turning formerly attainable cars into serious investments. I look at five engines whose reputations are now directly inflating the values of the cars wrapped around them.

Toyota 2JZ-GTE

The Toyota 2JZ-GTE in the 1993-1998 Toyota Supra MKIV has shifted from cult favorite to blue-chip asset. According to Hagerty Valuation Tool data, average Supra MKIV values have risen 25 percent year-over-year to 120,000 dollars as of 2023, a surge explicitly tied to this engine. The 2JZ-GTE is a tunable 2.0L twin-turbo inline-six design that enthusiasts routinely push to more than 1,000 horsepower without catastrophic failure, a durability record that few modern powertrains can match.

That combination of reliability and headroom means buyers now pay a premium for unmodified, low-mileage cars, expecting both long-term usability and future appreciation. For tuners, the 2JZ-GTE remains a blank canvas that can support huge turbo upgrades and track abuse. For investors, the same overbuilt architecture signals scarcity and staying power, which is why even automatic and higher-mileage Supra MKIVs are being pulled upward by the engine’s reputation.

Nissan RB26DETT

The Nissan RB26DETT in the 1999-2002 Nissan Skyline GT-R R34 has become a cornerstone of rising JDM values. Since 2020, R34 GT-R prices have appreciated 40 percent, with clean examples now fetching 150,000 to 200,000 dollars at auctions like Mecum in 2023. That climb is anchored in the 2.6L twin-turbo inline-six, whose durability in Japanese imports helped cement its status as one of the most celebrated Japanese performance engines.

Because the RB26DETT tolerates significant boost increases and track use, collectors view stock, well-maintained cars as increasingly rare. The engine’s racing pedigree and tuning potential mean that even lightly modified R34s are being reevaluated upward. As import rules open more markets to these cars, the RB26DETT’s legend is translating directly into higher hammer prices and stronger private-sale demand, pulling the entire Skyline GT-R family along with it.

BMW S54 Inline-Six

The BMW S54 inline-six in the 2001-2006 BMW E46 M3 is now a key driver of that model’s value surge. ClassicCars.com reports that E46 M3 prices have increased 30 percent to an average of 35,000 dollars by 2024, a move closely linked to the S54’s character. This naturally aspirated 3.2L high-revving engine produces 333 horsepower, delivering a sharp throttle response and a linear powerband that many enthusiasts feel modern turbocharged cars lack.

As resto-mod builders and track-day drivers seek analog performance, the S54 has become a centerpiece for high-end builds, further validating original cars. That demand is lifting coupes and convertibles alike, with manual examples commanding the strongest premiums. The more the S54 is celebrated in swaps and custom projects, the more collectors are willing to pay for intact, numbers-matching E46 M3s that showcase the engine in its original chassis.

Honda B18C

The Honda B18C in the 1996-2001 Acura Integra Type R is transforming a once-accessible front-drive coupe into a serious collector car. Hagerty notes that prices for low-mileage Integra Type Rs have climbed 50 percent to between 40,000 and 60,000 dollars in 2023. At the heart of that rise is the 1.8L DOHC VTEC inline-four, rated at 195 horsepower, which delivers a screaming top end and razor-sharp throttle response that defined late-1990s tuner culture.

Because the B18C rewards high revs and precise driving, many cars were heavily modified or tracked, making original examples scarce. That scarcity, combined with the Integra Type R’s legendary handling balance, has pushed collectors to lock in clean cars before values climb further. The engine’s influence on later VTEC performance models also means younger enthusiasts see the B18C as a foundational piece of Honda history, reinforcing its pull on the market.

Porsche M96 Flat-Six

The Porsche M96 flat-six in the 1997-2004 Porsche Boxster 986 is a rare case of a once-maligned engine now lifting values. MotorTrend’s 2024 analysis reports that Boxster 986 prices have doubled since 2021, with averages now in the 15,000 to 25,000 dollar range. The 2.5L to 3.2L water-cooled engine was initially overshadowed by early IMS bearing issues, but extensive aftermarket support has provided reliable fixes and upgrades.

As those solutions gained traction, buyers began to focus on the M96’s accessible performance and classic flat-six sound rather than its early reputation. The result is renewed interest in first-generation Boxsters as affordable entry points into Porsche ownership, with documented IMS repairs now a selling point. That shift shows how a once-underappreciated powerplant, supported by a strong parts ecosystem, can reverse market sentiment and pull an entire model upward in value.