LS3 vs LS7

Updated September 29, 2026

The LS3 is a 6.2L aluminum V8 rated at 430 hp with a wet-sump oil pan. The LS7 is a 7.0L V8 rated at 505 hp, with titanium rods and dry-sump oiling. For most swaps the LS3 is the better pick: easier to fit and easier to buy new. The LS7 suits builders chasing displacement and power.

The sections below put numbers on that: the spec sheet, heads and valvetrain, the LS7 valve guide history, crate listing prices, and a pick by goal. The speed shop at Accelerate Auto Repair and Collision in Rowlett, Texas, does LS swaps and starts each one with a budget conversation before any parts are ordered.

What is the difference between the LS3 and the LS7?

The LS7 is larger, higher-revving and more expensive to build; the LS3 is the simpler, more common engine. Both are cast-aluminum, overhead-valve, two-valve-per-cylinder small-block V8s with hydraulic roller lifters, according to HotCars. The LS7 adds 0.8 liters, a longer stroke, titanium connecting rods and a dry-sump oil system.

Sources differ slightly on rounding (LS3 torque is listed from 420 to 428 lb-ft depending on the vehicle), and pages list the LS7’s peak-power rpm anywhere from 6,200 to 6,800, so the table gives its horsepower without an rpm. Wikipedia notes that powder-forged connecting rods "have been fitted to every LS and LT engine except for the LS7."

How do the LS3 and LS7 heads and valvetrain compare?

The LS7 has larger heads with titanium intake valves; the LS3 uses L92-style aluminum heads with 68cc chambers. A retailer listing of the GM LS3 crate engine describes aluminum L92-style port heads with 68cc chambers and 2.165-inch intake and 1.590-inch exhaust valves, paired with a hydraulic roller camshaft.

The LS7 uses CNC-ported aluminum heads with 70cc chambers, according to Vette Vues Magazine, with 56 mm titanium intake valves and 41 mm sodium-filled exhaust valves. Its hydraulic roller cam lifts 0.591 inch on both intake and exhaust. The LS7 block has pressed-in cylinder sleeves and six-bolt forged steel main caps; the LS3 block is cast aluminum with six-bolt, cross-bolted main caps.

What are the known weak points of the LS3 and LS7?

The LS7’s most discussed weak point is valve guide wear on C6 Corvette Z06 engines. GM Authority reported that plaintiffs in a Z06 class action alleged "improper clearance level in the valve guides" in the 7.0L LS7. GM Authority reported on January 14, 2022, that the Ninth Circuit Court of Appeals had dismissed the case, finding the plaintiffs "failed to produce admissible evidence" that their vehicles actually contained the alleged defect. GM Authority adds that, according to the lawsuit, GM had told the plaintiffs that excessive valvetrain noise in the LS7 is normal.

Vette Vues Magazine says some owners and engine builders raised concerns about valve guide wear on certain LS7 engines, particularly on the exhaust side. HotCars lists LS7-specific problems as cavitation in the oil system and exhaust valves sometimes separating from the stem. For a used LS7, that history is a reason for a valvetrain inspection before purchase.

HotCars lists the LS3’s most cited issue as faulty rings leading to higher oil consumption. It also lists oil pump failure and piston ring groove wear as problems shared by both engines. Treat all of these as things to check on any used engine, not as certainties.

How much does an LS3 or LS7 crate engine cost?

A new LS3 crate engine listed at $10,505 on September 29, 2026; the LS7 crate engine has been discontinued by GM. The $10,505 figure is a Pro Touring Store listing for GM part 19435098, marked backordered. HotCars cites a $10,550 MSRP, so expect prices near $10,500 for the engine alone. The listing notes the LS3 needs a separate controller kit (part 19354328) and ships with a wet-sump oil pan.

GM Authority reported in February 2022 that Chevrolet Performance discontinued the LS7 and the LS427/570, and pointed buyers to the LS3, LS9 and LT1 instead. HotCars cites a discounted LS7 crate price of $16,600. Motor Authority reported the wet-sump LS427/570 at $12,714.70 in a June 15, 2020, report, with a separate controller (part 19420000).

These are engine-only listings. Transmission, wiring, cooling, fuel system and labor are extra.

Which engine is easier to swap?

The LS3 is easier to swap because it uses a conventional wet-sump oil pan. A dry-sump engine like the LS7 uses an external oil tank and lines, which a wet-sump engine skips. Motor Authority says GM’s wet-sump LS427/570 removes the separate oil tank, oil lines and other parts the dry-sump engine requires.

GM’s own LS427/570, a 7.0L wet-sump crate engine, was built to make the installation easier and less costly than the dry-sump LS7, according to GM Authority. That confirms which of the two oiling systems is simpler to install.

Once the engine is chosen, the next questions are the transmission and the fuel system. See 4L60E vs 4L80E for transmission choice, LS vs LT engines if you are weighing GM’s newer V8 family, and carburetor vs fuel injection for the fuel-system side. The LS3 crate engine ships with injectors and a throttle body.

Which one should you pick?

Pick the LS3 if you want the simplest swap; pick the LS7 if displacement and top-end power matter most and you can handle dry-sump oiling.

1. Decide whether you want a new crate engine. GM Authority reported in 2022 that Chevrolet Performance discontinued the LS7 and kept the LS3 available; the LS7 means a used or leftover engine.
2. Decide how much oiling complexity you accept. Wet sump keeps the swap simple; dry sump adds a tank and lines.
3. Match power to the goal. The LS3 makes 430 hp from the crate. The LS7 makes 505 hp.
4. Budget for the whole swap, not the engine. Controller, transmission, cooling and fuel work come on top of the listing price.

Common questions

Is the LS7 a better engine than the LS3? It is bigger and more powerful, at 505 hp against 430 hp, but it costs more and needs dry-sump oiling by default. "Better" depends on the goal.

Is the LS7 still available new? GM Authority reported that Chevrolet Performance discontinued it in February 2022. Remaining stock and used engines are the options.

Does the LS3 use the same block as the LS7? No. The LS7 has a larger bore, a longer stroke and pressed-in cylinder sleeves.

Does the LS3 crate engine come ready to run? It includes the intake with injectors and throttle body, exhaust manifolds, water pump and balancer, but needs a separate controller kit.

Bottom line: For a swap, choose the LS3 unless you specifically want the LS7’s 7.0L displacement and are ready for dry-sump oiling.

Planning an LS swap in the Dallas area? The speed shop at Accelerate Auto Repair and Collision, 3002 Century Dr, Rowlett, TX 75088, handles LS swaps. Call (469) 501-5115 to talk through your budget and parts list first.