Chevrolet Gemini small-block engine#LT6

{{Infobox automobile engine

| name = Gemini small-block engine

| image = 2023 Chevrolet LT6 engine, NYIAS 2022.jpg

| caption =

| manufacturer = General Motors (Chevrolet)

| aka =

| production = 2022–present

| predecessor =

| successor =

| configuration = 90° V8

| compression = {{ubl

|12.5:1 (LT6)

|9.8:1 (LT7)

}}

| displacement = {{convert|5463|cc|cuin|abbr=on}}

| bore = {{convert|104.25|mm|in|abbr=on}}

| stroke = {{convert|80|mm|in|abbr=on}}

| block = Sand-cast A319 Aluminum

| head = Aluminum

| valvetrain = DOHC 4 valves

| turbocharger = Twin-turbo (LT7)

| fuelsystem = {{ubl

| Direct fuel injection (LT6)

| Direct and port injection (LT7)

}}

| management = GM E68 (32-bit)

| fueltype = Gasoline

| oilsystem = Dry sump

| coolingsystem = Water-cooled

| redline = 8,600 RPM (soft), 9,000 RPM (hard)

| power =

| specpower =

| torque =

| length =

| width =

| height =

| weight =

}}

The Chevrolet Gemini small-block engine is a dual-overhead cam (DOHC) V8 engine designed by General Motors. While technically a small-block engine because of its bore spacing of 4.4 inches,{{cite web|author=Steven Rupp|date=October 26, 2021|title=Flat-Plane Crank DOHC LT6 to Power the 2023 Corvette Z06! Details and Specs|url=https://www.motortrend.com/how-to/lt6-engine-2023-corvette-z06-details/|access-date=October 27, 2021|website=motortrend.com}}{{cite web|date=October 26, 2021|title=2023 CHEVROLET CORVETTE Z06 ELEVATES THE AMERICAN SUPERCAR|url=https://media.chevrolet.com/media/us/en/chevrolet/home.detail.html/content/Pages/news/us/en/2021/oct/1026-corvette-z06.html|access-date=October 28, 2021|website=media.chevrolet.com}} General Motors engineers do not consider it to be a part of the traditional Chevrolet small block lineage because of the substantial reworking, specialized development, and unique technical features distinguishing its design.{{cite web|author=Joe Kucinski|date=February 18, 2022|title=LT6 Engine Deep Dive: Everything You Need to Know about the Corvette Z06 Flat-Plane-Crank V8 |url=https://www.corvetteforum.com/articles/lt6-engine-deep-dive/|access-date=March 5, 2022|website=corvetteforum.com}}{{cite news |author=Wren, Wesley|title=5 Fast Facts About Chevrolet's LT6: The Corvette Z06's Heart |url=https://www.autoweek.com/news/sports-cars/g39138002/5-facts-about-chevrolets-lt6-corvette-z06/ |work=AutoWeek |date=February 18, 2022}}{{cite news |last1=Kelly |first1=Iain |title=The LT6 V8: Inside GM's most powerful small-block |url=https://www.whichcar.com.au/news/gm-most-powerful-small-block-lt6 |work=Street Machine |publisher=WhichCar |date=28 October 2021}}

The Gemini is a clean-sheet design, mechanically unrelated to both the LS-based engines and the Cadillac Blackwing V8. Its most notable traits include a flat-plane crankshaft and dual-overhead camshafts, which represents a departure from the traditional pushrod valves and crossplane crankshafts found in all previous generations of Chevrolet small-block engines. As of July 2024, the Gemini engine has two variants, dubbed LT6 and LT7.{{Cite web |last=Tingwall |first=Eric |date=July 25, 2024 |title=Monster! The Story of the Corvette ZR1’s LT7 V-8 Engine and How It Makes 1,000+HP |url=https://www.motortrend.com/news/2025-chevrolet-corvette-zr1-lt7-v8-engine-deep-dive/ |website=MotorTrend}}

LT6

The LT6 is a 5.5-liter, naturally-aspirated V8 engine. It debuted in the eighth-generation Corvette Z06, and was unveiled on October 26, 2021.

While the LT6 features a redline of 8,600 RPM, it generates a maximum of {{Convert|670|hp|kW PS|0|abbr=on}} at 8,400 RPM and {{Convert|460|lbft|Nm|0|abbr=on}} of torque at 6,300 RPM. These figures make it the most powerful naturally-aspirated production V8 engine of all time; the engine to previously hold this title, the Mercedes-Benz SLS AMG Black Series M159 6.2-liter V8, made {{Convert|622|hp|kW PS|0|abbr=on}} at 7,400 RPM. {{Cite web |last=Markus |first=Frank |date=October 26, 2021 |title=How the C8 Corvette Z06's LT6 Became the World's Most Powerful Naturally Aspirated Production V-8 |url=https://www.motortrend.com/news/2023-chevrolet-corvette-z06-lt6-v8-flat-plane-crankshaft-tech/ |url-status=live |archive-url=https://web.archive.org/web/20211026213025/https://www.motortrend.com/news/2023-chevrolet-corvette-z06-lt6-v8-flat-plane-crankshaft-tech/ |archive-date=October 26, 2021 |website=MotorTrend}}{{Cite web |last=Colwell |first=K.C. |date=October 26, 2021 |title=2023 Chevy Corvette Z06 Brings 670 HP of Naturally Aspirated Fury |url=https://www.caranddriver.com/news/a38044152/2023-chevrolet-corvette-z06-revealed/ |url-status=live |archive-url=https://web.archive.org/web/20211026175305/https://www.caranddriver.com/news/a38044152/2023-chevrolet-corvette-z06-revealed/ |archive-date=October 26, 2021 |website=Car and Driver}}

The LT6 is also the largest flat-plane V8 used in a production car by displacement, dethroning the Ford Voodoo. This is notable due to the additional vibrations inherent to this architecture compared to a crossplane V8, which tend to scale up with displacement.{{Cite web|last=Sommers|first=Alex|title=Chevy's eighth-gen Corvette Z06 is poised to topple these 3 production-car V-8 records|date=September 7, 2021|url = https://www.hagerty.com/media/lists/chevrolet-c8-corvette-z06-lt6-production-car-v-8-records/}}

A modified version of the LT6 has powered the Chevrolet Corvette C8.R since 2019, and many features in the racing engine carry over to the road engine. Other notable features include a cast aluminum block, dual coil valve springs supporting titanium intake & sodium filled exhaust valves, forged aluminum pistons, forged titanium connecting rods, active split intake manifold with twin 87mm throttle bodies, four-into-two-into-one stainless steel exhaust headers, and a factory six-stage 10-quart dry sump oiling system with individual crank bay scavenging.

Applications:

class="wikitable"

! scope="col" | Year(s)

! scope="col" | Model

! scope="col" | Power

! scope="col" | Torque

! scope="col" | Dyno Chart

2023–present

| Chevrolet Corvette Z06

| {{cvt|670|hp|kW|0}} @ 8400 rpm

| {{cvt|460|lbft|Nm|0}} @ 6300 rpm

| [https://www.motortrend.com/how-to/chevy-lt6-engine/?slide=4 link]

LT7

The LT7 is a twin-turbocharged variant of the LT6 which debuted in the eighth-generation Corvette ZR1 and was unveiled on July 25, 2024. The LT7 has a redline of 8,000 RPM, generating {{Convert|1064|hp|kW PS|0|abbr=on}} at 7,000 RPM and {{Convert|828|lbft|Nm|0|abbr=on}} of torque at 6,000 RPM.

Although it was released later, the LT7 was developed in tandem with its LT6 sibling. Compared to it, the LT7 has stronger pistons and connecting rods. Combined with the bigger combustion chamber in the heads, this lowers the compression ratio from 12.5:1 to 9.8:1. Unlike the LT6, the LT7 uses both direct fuel injection and port injection, with a total of 16 injectors. However, the block casting is identical, and the crankshaft is almost identical. The dry-sump oil system carries the same eight quarts as the LT6, although there is an additional seventh scavenge stage in the ZR1 to keep the turbos lubricated. The intake manifold has a much lower volume than the LT6’s and there’s no exchange between the two cylinder banks. The turbochargers produce up to {{convert|20|psi|bar|abbr=on}} in normal operating conditions and a maximum of {{convert|24|psi|bar|abbr=on}} under high temperatures. Other features specific to the LT7 include turbo-integrated exhaust manifolds, water-to-air intercoolers, and an electrically actuated wastegate.{{Cite web |last=Stafford |first=Eric |date=July 25, 2024 |title=2025 Chevy Corvette ZR1 Has 1064 HP and Is Poised to Slay Supercars |url=https://www.caranddriver.com/news/a61692733/2025-chevrolet-corvette-zr1-revealed/ |website=Car and Driver}}{{Cite web |date=December 4, 2024 |others=Narrated by Dustin Gardner |title=2025 Corvette ZR1 LT7 Engine Walk Around |url=https://www.youtube.com/watch?v=9E4gxsMZ5UU |publisher=savagegeese |type=Video |via=YouTube}}

Applications:

class="wikitable"

! scope="col" | Year(s)

! scope="col" | Model

! scope="col" | Power

! scope="col" | Torque

2025–present

| Chevrolet Corvette ZR1

| {{cvt|1064|hp|kW|0}} @ 7000 rpm

| {{cvt|828|lbft|Nm|0}} @ 6000 rpm