LS1 vs. LS2: Which engine should I choose?

Many people are torn between either swapping their engine block with an LS1 or LS2. While some might argue that old is gold or new is best, the outcomes might not always be as you predicted.

LS1 and LS2 engine blocks have several architectural design feature differences that dictate their different attributes. Their design distinctions result in critical fuel economy, power, torque, and rpm variations.

This post highlights the variations between these two engines. Hopefully, towards the post’s end, you will make an informed decision to either choose an LS1 or an LS2. So, let’s dive into it!

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Overview

GM released the LS series in 1995 with the GEN III LS1 engines. Its rise was due to the pressure to produce a lighter engine that was more powerful and had improved fuel efficiency.

The LS1 and LS2 are small-block pushrod 90° V-8 engines. These engine blocks are primarily cast in aluminum, making them lighter and more robust than their cast-iron predecessors. They have a Y-block design which increases their rigidity at the main cap area.

Y-block design uses a snap-fit cross-bolting, implying that four vertical facing bolts and two horizontal ones clamp the engine block to the main cap area. Therefore, a superior crankshaft and engine block rigidity is realized.

Over the years, the LS1 and LS2 engines have become significantly cheaper. This is because they have been put in several vehicles, making it easier to locate a second-hand engine block. The rise in popularity of engine swaps has also undoubtedly lowered the cost of purchasing LS1 and LS2 engine parts as there are more in the market due to popular demand.

Moreover, there is a variety from which motorists can choose from. They can choose parts to maintain or enhance the performance of their engines.

GM produced LS1 and LS2 engines in several displacements between 4.8L and 8L. Furthermore, they were more compact and lighter. This improved their popularity among vehicle manufacturers who fit the LS engines within their vehicles.

Let’s have a closer look at why the LS1 and LS2 engines are so famous!

LS1 vs. LS2

Specs

The LS2 engines have a larger cylindrical bore length than the LS1s. Moreover, the LS2s have a smaller combustion chamber compared to the LS1s. A higher compression ratio is achieved through these modifications. Therefore, the LS2s can realize a higher torque, greater power, and improved rpm than the LS1s.

Both the LS1 and the LS2 have the same deck height, indicating an equal amount of piston compression height. This contributes to the interchangeability between the two piston rods of the LS1 and the LS2.

Like all other modern V-8 engines, the firing order of the LS1 and LS2 is 1–8–7–2–6–5–4–3. This is the most efficient way of firing the cylinder piston to ensure the smooth rotation of the crankshaft and reduce the secondary imbalance experienced in the vehicle.

The compactness between the two engines can be attributed to OHV 2 valves per cylinder valve train configuration, as it utilizes the valuable space that is wasted in OHC engines.

ls1 vs ls2
The LS1 and LS2 mostly have close but different specifications. For example, the LS1 has smaller specs due to it’s smaller size.

Read more: What is LS firing order? Should I swap to an LS firing order?

Differences in parts

Position of the valves and combustion chamber

LS2 features hidden valves with raised combustion chambers and intake ports, which, when combined with the pistons’ flat-tops, yields an enhanced air/fuel mixture. This authentic flat-top design with an improved tension ring frees up more horsepower in an LS2 than an LS1. Moreover, levitating wrist pins in LS2 eliminates the “piston slap” sound experienced in Gen III engines.

Exhaust manifold

The LS2 exhaust manifold is lighter than the LS1 by a third of the weight. The reduced wall thickness improves by an overall 4% flow efficiency. 4% may sound small, but in design, it is of great significance.

Oil Pan

The LS2 has an amended oil pan with an enhanced baffle design that ensures sufficient oil supply during strenuous activities. Contrarily, the LS1 suffers from oil starvations under these conditions.

Throttle body

The LS2 has a large throttle body controlled electronically, ETC. GM exchanged the cable throttle body in the LS1 with this modern computer-controlled fly-by-wire. Moreover, the LS2 throttle body is secured on a slightly upward angle, thus decreasing the water puddling effect towards the throttle body’s bottom.

Water pump

The LS2 water pump has an amended design with enhanced sealing to eliminate chances of leakage. Additionally, they are more powerful than LS1, and therefore deliver more GPM while running the engine.

Coil pack system

Contrasting the LS1s’ coil pack system, the LS2s’ are more reliable. They generate better spark while using less voltage. This impacts the higher amount of torque, rpm, and the improved fuel efficiency in the LS2.

Intake manifold

An LS2 has a better intake manifold with larger opening and intake runners. When dyno testing, the LS2 will make 10hp more than the LS1, which makes about 15hp.

Cylinder bore

Unlike the 3.9in LS1 bore, the 4in bore makes it easier to swap the LS2 head with the better flowing rectangular port LS3 head.

Smog gears

Running engines with no smog gear such as the EGR and AIR might subject you to heavy fines in areas with strict smog regulations. However, you don’t have to face such trouble with an LS2 engine as it has neither of the two smog gears. Nevertheless, the early F-body LS1 had both. A swap from an LS1 to an LS2 might save you the hustle and maintain a cleaner engine bay.

LS1 vs LS2
Compared with the LS1, the LS2 has some differences in parts, which makes it more powerful than the LS1.

Fuel economy

On average, the LS1 engines consume about 15/21MPG on the city roads while they consume about 21/34MPG on the highways. Conversely, the LS2 engines will consume about 14/19MPG on the city roads and about 20/30MPG on the highways. This difference arises as an LS2 runs more efficiently than an LS1.

Adaptability

LS engines are pretty compact and fit in most average-sized engine compartments. LS1 and LS2 are nearly identical. They share almost exact dimensions, and each weighs about 460lbs. All these factors contribute to the ease with which these two engines fit in the base of most vehicles and still leave room for tuning the engine.

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Performance

Perhaps the 350hp output of the LS1 engine with its 350lb-ft torque may not be very impressive to most of you, but back in the nineties, it was. The LS1 has so much more capability if they are correctly tuned. Vehicles running on an LS1 engine can reach speeds of over 150MPH while harnessing a considerable amount of their power.

Cars running in LS1 have a decent amount of acceleration. However, improvements are viable. For example, the Chevrolet Corvette C5 Coupe running in a 5.7L V-8 LS1 engine could accelerate from 0-100MPH in just 15.7S.

Although the LS2 runs on a 400hp motor revs at 6,000rpm, they can achieve higher performance. They generate an equivalent of 400lb-ft torque at 4,400rpm. Depending on the transmission, LS2 can sustain between 320-340rwhp. However, tuning experts can raise this number to jaw-dropping figures.

The LS2 engines can reach a top speed of over 180MPH. Modern LS2 engines have incredible acceleration. For example, the C6 Z06 Corvette can achieve a quarter-mile in 10.98seconds. Moreover, it tops at 198MPH.

Cost

As the LS2 engines outperform the LS1s, it is without a doubt that they are more costly. Restored LS2 engines may sell for around $4,500, nearly the price of new LS1 engines, which cost about $4,900. However, getting a cheaper rebuilt LS1 engine with all the stock components is possible, selling at about $2,500.

LS2 engines are also sold at a higher price as they are produced in lower numbers than LS1. This increases their demand to supply ratio. Moreover, the LS1s showed up in the production line first and are found in more vehicles.

Taking into account the features described above, here are the ratings we calculated comparing the two engines.

FeaturesLS1LS2
Engine Block Components8.5/109/10
Fuel Economy8/109/10
Adaptability10/1010/10
Performance7.5/109/10
Cost7.5/105.5/10

Conclusion

The LS2 wins in terms of fuel efficiency, torque, and power. They possess more aggressive camshafts and better flowing heads.

However, is that enough to justify the $3,000+ difference in cost between the two stock engine blocks?

If you have the budget for it, choosing an LS2 will save you a ton of trouble. However, if you’re running on a tight budget but still crave that thrilling performance, you can upgrade your LS1 and perhaps outperform an LS2 while still spending less.

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