The LS1 vs LS2 debate has long raged amongst Corvette and GTO fans since the LS2 succeeded the LS1 in 2005. Some claim the newer LS2 is a more capable motor, while others prefer the older but still powerful LS1. Previously, we’ve looked at the LS1 vs LS3 and LS2 vs LS3, but today we’re going to tackle the LS1 vs LS2 debate.
There really is no right answer, but we’re going to compare everything between the LS1 vs LS2 to see what the differences and similarities are. First we’ll look at the LS engine history, technical specs, and car applications, before moving onto the differences in engine design, reliability, performance, and top mods. Let’s get started.
Gen III/Gen IV LS Series Engine History
In 1997, GM/Chevy introduced their Gen III V8 small blocks, now colloquially known as the LS series. The name is derived from the first engine in the engine series, the LS1. The LS1 was a 5.7 L V8 engine that was a successor in the Corvette, Camaro, and Firebird to the Gen II 5.7 L LT1 engine. GM subsidiary Holden also used a version of the LS1. The LS1 made between 305-350 horsepower and 335-365 lb-ft of torque, depending on which car it was in.
When GM/Chevy first released the LS1 it was considered a pretty big deal in the car world. The LS1 was the first GM V8 to be made with an aluminum block, which shed 50-80 lbs of weight from the iron block LT1. It used lots of new tech from a new ECU, while still retaining the old school pushrod OHV valve train.
The LS1 lasted in the US from 1997–2004, when it was succeeded by the larger Gen IV 6.0 L LS2. The LS2 had a lot in common with the LS1, but also mixed various parts from the LS6 engine, which was a high performance version of the LS1. The LS2 produced 400 horsepower and 400 lb-ft of torque, massive improvements over the LS1.
GM/Chevy produced the LS2 from 2005-2009, after which it was succeeded by the LS3 and LS7 engines. There are tons of LS1 and LS2 powered Corvettes, Camaros, Firebirds, and GTOs still on the roads today, and many LS1 and LS2 engines have been used for various “LS swaps.”
While stock, the LS1 and LS2 make between 300-400 horsepower and torque, and modified versions have gone clear past 1,000 horsepower. The LS1 vs LS2 debate will forever rage, as they are both more than capable engines.
Gen III/Gen IV LS Technical Engine Specifications
|Family||GM Gen III Small Block||GM Gen IV Small Block|
|Model Years||1997-2004 (domestic)||2005-2009|
|Displacement||5.7 L (346 cid)||6.0 L (364 cid)|
|Aspiration||Natural Aspiration||Natural Aspiration|
|Compression Ratio||10.2:1 (10.1:1 advertised)||10.9:1|
|Bore and Stroke||3.898 in x 3.622 in||4.000 in x 3.622 in|
|Valve Train||OHV (16 valve)||OHV (16 valve)|
|Fueling System||Fuel Injection||Fuel Injection|
|Horsepower Output||305-350 horsepower||300-400 Horsepower|
|Torque Output||335-365 lb-ft of torque||360-400 lb-ft of Torque|
LS1 and LS2 Car Applications
LS1 Car Applications (Domestic):
- 1997–2004 Chevrolet Corvette
- 1998–2002 Chevrolet Camaro SS & Z28
- 1998–2002 Pontiac Firebird Formula & Trans Am
- 2004 Pontiac GTO
LS2 Car Applications (Domestic):
- 2005–2007 Chevrolet Corvette
- 2005–2006 Chevrolet SSR
- 2005–2006 Pontiac GTO
- 2006–2007 Cadillac CTS-V
- 2006–2009 Chevrolet TrailBlazer SS
- 2008–2009 Saab 9-7X Aero
LS1 vs LS2 Engine Design Basics
The LS1 is a 5.7 L V8 engine with an aluminum block and heads. The bore and stroke are 3.898 in x 3.622 in, and it is an OHV, 2 valve/cylinder, 16 valve, pushrod-actuated engine. The LS2 uses the same OHV design and also has an aluminum block and heads like the LS1, but is bored out to 4.000 in x 3.622 in, for a total displacement of 6.0 L.
The LS1 was rated for 305-350 horsepower and 335-365 lb-ft of torque. Comparatively, the LS2 was rated higher for 395-400 horsepower and 390-400 lb-ft of torque.
GM/Chevy advertised compression on the LS1 as 10.1:1, but in reality it was 10.25:1. Compared with the LS1, the LS2 engine has a higher compression ratio at 10.9:1, higher lift cam, 15% better intake flow, and 20% better exhaust flow.
The LS2 retains the six-bolt main caps, 4.40 in center bore, and deep-skirt case from the LS1. Both had steel crankshafts and sequential multi-port fuel injection, with the LS2 having 34 lb/hr flowing injectors vs the LS1 30 lb/hr injectors. As you would expect, the LS1 is going to make better fuel economy than the LS2 due to its smaller displacement.
In the Corvettes, the LS2’s aluminum block weighs 15 lbs less than the LS1 Corvette block. This weight reduction is courtesy of a thinner-walled exhaust manifold, smaller water pump, and a smaller oil pan. The pan has completely redesigned baffles to keep oil flowing through the pickup and is wingless instead of “gull-wing” design. Again, this revised oil pan was just for the Corvette version of the LS2.
Gen III/Gen IV LS Cylinder Heads and Other Differences
Both the LS1 and LS2 have the LS-cathedral port cylinder heads. The LS2 cylinder heads outflow the LS1 heads by a decent margin, and is often used as an LS1 mod. GM/Chevy made the LS2 heads very similar to the LS6 heads which as we mentioned was a high performance version of the LS1. Starting in 2001, GM/Chevy gave the LS1 the LS6 heads. The LS2 is the only Gen IV motor to use the cathedral heads, as all other ones use the superior flowing rectangular-port heads.
LS2 exhaust manifold walls are 1mm (30%) thinner than the LS1, but weigh less and flow 4% better. The LS1 uses two different methods for throttle control, drive-by-wire in the Corvette and drive-by-cable in all other applications. All LS2 powered cars use the drive-by-wire throttle system. The LS2 also has a 500 RPM higher redline than the LS1, at 6,500 RPM.
The LS2 knock sensors are outside of the cylinder banks to allow for more precise readings, which was an improvement over the in-bank LS1 sensors. GM also moved the cam sensors to the front timing cover on the LS2 from behind the intake on the LS1. Both the LS1 and LS2 pistons are hypereutectic aluminum, and the LS2 pistons have full-floating wrist pins to reduce pistons slap – which was a common issue on the LS1.
LS1 vs LS2 Engine Reliability
We’ve said it before and we’ll say it again, If there is one thing you can describe the Chevy LS engine series as it’s reliable. The entire LS-series is pretty much bulletproof in any respect, and there are really no significant widespread problems with them. A stock LS1 and LS2 will easily go past 200,000 miles if taken care of and with proper maintenance.
However, with that being said, neither the LS1 or LS2 is completely free from minor problems, including when modified. For the LS1, the main issues are Piston Ring Seals, Water Pump Failure, Bent Pushrods, Piston Slap (Oil Consumption), and Oil Pump Failure.
While this might sound like a lot of issues for a “reliable” engine, these are not very widespread and do not affect a huge amount of LS1 cars. Still, they’re important to mention. Check out our LS1 5 Most Common Problems Guide for an in-depth breakdown on each of these issues.
The main issues with the LS2 are oil starvation, rocker arm bearing failure, and harmonic balancer failure. The oil starvation issue was more related to early LS2 builds from 2005-2006 and was fixed for later years. The rocker arms on the LS2 are prone to premature wear and failure after 100,000 miles. The LS2 harmonic balancers have attracted several complaints for premature failure, too. Check out the Common Problems and Reliability section of our LS2 engine guide for a more in-depth breakdown.
Overall, both the LS1 vs LS2 have pretty much the same reliability, though the LS2 did fix the piston issues from the LS1. Both of them are excellent power plants for starting any build, and can definitely be counted on for reliability. They are both widely used in “LS swaps” into various vehicles and for big power builds.
LS1 vs LS2 Performance and Mods
Now let’s get into the fun part, LS1 vs LS2 performance and mods. Stock, the LS2 makes a lot more horsepower and torque than the LS1, but both engines can easily be upgraded over factory power levels. The larger displacement of the LS2 will ultimately allow it to make more power, and the block is also known to be stronger.
If you plan on modding an LS1 or LS2 the upgrades are pretty similar. Actually, pretty much all LS engines can be built using a similar build plan, which we’ll outline below. With these mods, you can expect to put yourself in the 450-500 horsepower range, which is about as far as a naturally aspirated LS engine will go. If you really want to make above 500 horsepower, you’ll have to add a supercharger or turbocharger. Check out our LS2 Supercharger upgrade guide for more info on a forced induction LS build.
Top LS1 and LS2 Mods
Top LS1 and LS2 mods:
- Cold Air Intake
- Long-tube headers
- Larger throttle body
- Camshaft Upgrade
- Cylinder Heads Upgrade
- ECU Tuning
Gen III/IV LS Cold Air Intake, Long-tube Headers, Throttle Body
One of the most common mods for any LS build is a cold air intake. A quality cold air intake will add 5-15 horsepower and really helps the engine perform better when other mods are added. Long-tube headers are another good investment, as they really open up the airflow. Depending on if they are used with an upgraded cold air intake they can make 25-40 horsepower. Check out our LS2 header guide for the best Gen IV headers.
If you have an LS1, a very common upgrade is to put on the LS2 throttle body. The LS1 stock throttle body is 78mm, whereas the LS2 is much larger at 90mm. Upgrading the LS1 to an LS2 throttle body will add 5-10 horsepower and is great in conjunction with a larger LS2 style intake. Upgrading the LS2 throttle body is also done, and we have a LS2 throttle body guide that covers the best ones.
Gen III/Gen IV Camshaft and Cylinder Heads
For many people, after upgrading the bolt-ons listed above they start making the engine itself more efficient with an upgraded camshaft and upgraded cylinder heads. Cams are good upgrades for an improved horsepower on the top-end, and also sound great through the exhaust.
As we talked about before, both the LS1 and LS2 use the LS cathedral-port cylinder heads. The LS2 heads outflow the LS1 heads and is a direct bolt-on fit. The LS6 heads also fit the LS1 and outflows it as well, and GM/Chevy actually started using the LS6 heads on the LS1 starting in 2001. Upgrading to a better flowing and ported cathedral-port heads are an option for both the LS1 and LS2, but the better plan is to put on the rectangular style ports from the LS3 and LS7 series of motors. The rectangular ports outflow the cathedrals at higher RPM and are known to make better power.
If you do upgrade to the rectangular-port heads, you will also need a new intake manifold, making it a pretty pricey upgrade. If you do it, however, you will definitely see some solid gains with both a new heads and manifold, upwards of 20-35 horsepower.
LS1 and LS2 ECU Tuning
The last mod is also one of the best, LS1 and LS2 ECU tuning. In order to make sure that your mods are 1) running safely and 2) maximizing their performance, you definitely want to invest in tuning. Tuners are able to tweak the ECU to optimize things like fueling and ignition timing for the most horsepower and torque possible, while still staying reliable.
Most people will tell you, your build is only as good as your tune, and that’s certainly true. If you want your LS build to last you need to let a tuner take a look at it after you’ve added your mods.
LS1 vs LS2 Summary
Overall, both the LS1 and LS2 are two very capable motors that are capable of some gargantuan performance. The LS1 preceded the LS2 by nearly a decade, and both of them are considered some of the top engines in the entire LS series. The LS2 makes more horsepower due to its larger displacement, but the LS1 is more fuel efficient while still being very capable of making similar power.
GM/Chevy put the LS1 and LS2 into some of the most memorable Corvettes of the late-’90s and early-2000s, where they made some pretty good power numbers. The Gen III LS1 and Gen IV LS2 were also massive improvements over their Gen II predecessor in pretty every way possible.
Which LS series engine do you think is the best, the LS1 or LS2? Let us know in the comments below!