Garrett G42 Turbine Housing Kit O/V V: Specs, Fitment, and Is It Worth It

The Garrett G42 Turbine Housing Kit O/V V-Band series provides three A/R ratio options for builders mounting a Garrett G42 Super Core on an exhaust manifold with a V-Band discharge outlet. The O/V designation indicates an open-scroll turbine housing inlet with a V-Band manifold connection -- the exhaust gas enters the turbine scroll from a single open passage rather than through divided twin-scroll channels, and the downpipe exits via a V-Band clamp connection on the turbine outlet. The G42 platform covers Super Core power ratings from 1200 to 1585 horsepower across the G Series lineup, with the turbine housing sold separately from the Super Core to allow the inlet type and A/R ratio to be selected independently for each application. The O/V V-Band series offers three A/R options: 1.01, 1.15, and 1.28. This guide covers the full G42 O/V V-Band catalog, how to select between the three A/R ratios based on engine displacement and power target, and when the O/V V-Band configuration is the appropriate housing choice for a Garrett Performance Upgrade build.

G42 O/V V-Band Turbine Housing Specifications

All three G42 O/V V-Band housings share a V-Band manifold inlet, open scroll design, and V-Band downpipe outlet in standard rotation. The three A/R options span the G42's full range from tighter spool-focused to wider flow-optimized turbine area:

• 1.01 A/R (757707-0011): The tightest turbine area in the G42 O/V V-Band catalog; maximizes drive pressure at low exhaust flow rates to push the turbine wheel at reduced engine RPM; generates the highest backpressure at peak exhaust flow of the three options; the appropriate choice when rapid boost onset is the primary performance objective and the power target and engine displacement fall within the comfortable operating range of the 1.01 housing on the G42 turbine wheel
• 1.15 A/R (757707-0012): The mid-range G42 O/V V-Band option and the broadly applicable starting point for new G42 installations on V-Band manifolds; balances turbine response with peak exhaust flow handling across the displacement ranges most commonly paired with the G42 Super Core; the correct first selection when no prior G42 data log exists for the specific application
• 1.28 A/R (757707-0013): The widest turbine area in the G42 O/V V-Band series; lowest backpressure at peak exhaust flow; for large-displacement engines, high-RPM power bands, and builds where data logging confirms the tighter housings are generating excess backpressure at the top of the RPM range under full load

The O/V designation in the Garrett G42 product naming identifies the housing as an open-scroll V-Band inlet unit. Open-scroll housings admit exhaust gas from all cylinders into the turbine scroll without separating cylinder bank groups, which simplifies exhaust manifold design and allows single-entry manifolds and collectors to feed the turbine housing directly. The companion Div T4 series (757707-0014 through -0016) uses a divided T4 flange inlet that maintains twin-scroll separation for pulse-energy spool benefits on engines with divided manifolds, but requires a four-bolt T4 manifold flange. A build using a fabricated V-Band collector manifold or a commercially available V-Band exit manifold uses the O/V V-Band housing; a build using a T4-flanged divided manifold uses the Div T4 housing. The A/R selection logic is identical between the two series.

Top Picks: Garrett G42 O/V V-Band Turbine Housings

For G42 builds on V-Band manifolds covering the widest range of power targets and engine displacements in the G42 Super Core range, the Garrett G42 Turbine Housing Kit O/V V-Band / V-Band 1.15 A/R (757707-0012) is the standard mid-range starting point. Builds prioritizing faster boost onset within the G42's power range use the Garrett G42 Turbine Housing Kit O/V V-Band / V-Band 1.01 A/R (757707-0011) for the tightest available turbine area. Large-displacement or high-RPM G42 builds where data logging shows excess backpressure with a tighter housing use the Garrett G42 Turbine Housing Kit O/V V-Band / V-Band 1.28 A/R (757707-0013). These housings pair with the Garrett G42-1200 Super Core Standard Rotation Super Core Assembly (860778-5004S) and the full G42 catalog available in the Garrett G Series turbocharger collection.

Match to the Build

• High-output diesel or gasoline single-turbo build on a V-Band collector manifold targeting 1000-1400 hp: The 1.15 A/R (757707-0012) covers this range for the most common G42 applications; V-Band collector manifolds are common on custom fabricated systems where the manifold runner merges to a single V-Band outlet before the turbine housing; the 1.15 mid-range A/R balances turbine response and peak flow for the displacement and RPM ranges typical of large-frame single-turbo diesel and gasoline builds in this power window
• Street-oriented large single-turbo build where boost onset matters alongside high peak power: The 1.01 A/R (757707-0011) delivers the fastest spool of the three G42 O/V options; on a street-driven vehicle where transient throttle response between gear changes is important, the tighter 1.01 housing builds boost pressure more quickly than the 1.15 or 1.28 at the cost of higher backpressure at peak RPM; appropriate when the engine's displacement and exhaust flow at the power target fall within the 1.01 housing's efficient operating range
• Competition diesel or gasoline build above 1400 hp on the G42 platform where turbine backpressure limits peak power: The 1.28 A/R (757707-0013) provides the lowest backpressure of the three G42 O/V V-Band options; on competition builds running the G42 at its maximum power ratings with large engines at high RPM, the 1.15 housing may generate sufficient backpressure to measurably reduce net power at the top of the RPM range; data logging the drive pressure-to-boost-pressure ratio during a full-load pull confirms whether a housing step to the 1.28 is justified
• Replacing a G42 turbine housing on an existing installation where the V-Band manifold is already in place: The O/V V-Band series is the correct replacement for any G42 installation using a V-Band inlet manifold; all three O/V V-Band A/R options share the same V-Band downpipe outlet, so a housing swap between A/R ratios requires no downpipe modification; a builder adjusting A/R after a power level change or based on data logging can step between the three options without changing the exhaust system beyond the housing itself

Signs the G42 Turbine Housing Needs Replacement

• Drive pressure exceeding boost pressure under data logging at peak RPM -- the turbine housing is restricting exhaust flow and building excessive backpressure at the engine's maximum output; when drive pressure climbs above the boost pressure at wide-open throttle, the net pressure ratio across the engine is reduced, costing power and increasing thermal load on the engine; stepping to a larger A/R or confirming the current housing is appropriately sized for the displacement is the diagnostic step before replacing
• Visible exhaust gas leakage at the V-Band clamp connection on the turbine inlet -- the V-Band joint between the manifold and the housing losing the seal from V-Band clamp loosening, manifold distortion, or housing flange face damage; an exhaust leak at the turbine inlet reduces boost pressure and can cause hot-spot damage on the housing and manifold; re-torquing the V-Band clamp and inspecting the sealing surfaces identifies whether a housing replacement is needed or a clamp retorque resolves the leak
• Turbine housing cracking at the scroll body or V-Band outlet groove on a high-cycle build -- thermal fatigue cracking from repeated heat cycles at competition duty; a cracked housing must be replaced before the crack propagates to an exhaust leak; any of the three O/V V-Band A/R options serves as the direct replacement for the cracked housing at the matching A/R specification
• Housing warping at the V-Band manifold inlet flange face causing persistent exhaust leaks after V-Band clamp service -- a distorted flange face from sustained high exhaust temperatures or mechanical stress that cannot be resolved by clamp retorque alone; a warped or damaged housing inlet face requires replacement to restore the sealing surface geometry needed for a consistent V-Band joint

Frequently Asked Questions

When should I choose the O/V V-Band G42 housing over the Div T4 G42 housing?

The choice is determined by the exhaust manifold, not by a performance preference. If the exhaust manifold or collector terminates in a V-Band outlet, the O/V V-Band housing (757707-0011 through -0013) is the required selection. If the manifold uses a four-bolt T4 flange in a divided twin-scroll configuration, the Div T4 housing (757707-0014 through -0016) is the required selection. The A/R selection logic, power range, and G42 Super Core pairing are identical between the two series. The divided T4 housing provides a pulse-separation spool advantage over the open-scroll O/V housing at equivalent A/R, but the manifold inlet type is a fixed constraint -- the Garrett Performance Upgrade housing selection follows the manifold, not the other way around.

Bottom Line

The Garrett G42 Turbine Housing Kit O/V V-Band series covers three A/R ratios -- 1.01, 1.15, and 1.28 -- for G42 Super Core builds using V-Band inlet exhaust manifolds in the 1200-1585 hp range. Start with the 1.15 A/R for the broadest range of G42 applications; step to the 1.01 for faster spool or the 1.28 for lower peak backpressure based on the build's power target, engine displacement, and data logging from the specific application.