The biggest differences between the 5.3 and 6.2 GM engines – Jalopnik

What’s the biggest difference between General Motors’ 5.3-liter and 6.2-liter V8 engines? 0.9 litres. Good night!

Okay, 5.3s and 6.2s contrast more than that, and quite a bit. There’s plenty to talk about even if you leave out the 4.8-liter V8 or the 4.3-liter V6 based on the same architecture, which is a completely different engine than the 4.3-liter V6 from before the 2000s. GM likes to reuse engine codes, brand names and displacements.

The company’s truck engines were formerly called “Vortec”, not to be confused with supercharger manufacturer Vortech. (And yes, people have put Vortechs on Vortecs.) The name Vortec is a portmanteau of “vortex” and “technology.” It was first used to describe the efficient ‘vortex swirl’ that takes place in the combustion chambers of the GM/Chevrolet 4.3-liter V6 (from the ’80s), which was not actually part of the Vortec range. Then in 2014, GM changed the Vortec series to “EcoTec3”. These engines have nothing to do with GM’s Ecotec four-cylinder engines – without the capital T. And now the new 4.3-liter V6 is actually part of the EcoTec3 series that replaced the Vortec series.

This brings us to the Gen-III, Gen-IV and Gen-V “small-block” 5.3 and 6.2 V8 engines. Colloquially, people often refer to these engines as “LS” and “LT”, but technically “Vortec” and “EcoTec3” would be more accurate, as the truck engines have different tunings and parts here and there.

As far as truck engines go, the LM7 5.3 debuted in 1999 as the Vortec 5300. GM’s 6.2 Vortec 6200 didn’t hit the market until 2007, when it became the engine of choice in the Cadillac Escalade, replacing the old 6-liter Vortec 6000 V8. Both the Gen-III 5300 and 6200 were available as flex-fuel engines, as were the later EcoTec3 branded versions, meaning they could also run on E85 (a mixture of 85% ethanol and 15% gas).

It would be helpful to say that since these are all truck engines, they all have iron blocks. But only five 5.3s have iron blocks, namely the LM7, L59, LY5, LMG and LMF engines, while the rest are aluminum. Meanwhile, all 6.2s have aluminum blocks, with the exception of the aftermarket LSX376, which is iron (and not an EcoTec3 engine).

Motor trend I bought an LM7 5.3 especially for this purpose. Dyno testing showed up to 384 pound-feet of torque at 4,300 rpm with stock cam lift of 0.466/0.457 and duration of 190/191. Switching to an LS1 cam (like those found in C5 Corvettes) with its 0.496/0.496 lift and 202/210 duration increased peak torque to 389, but was 22 pound-feet less than stock at 2,500 rpm. Meanwhile, in an EcoTec3 6.2 you will find a cam with a lift of 0.551/0.524 and a duration of 200/207. That engine manages to hit 460 pound-feet at 4,100 rpm.

Compression-wise, the 5.3s range from 9.5:1 for Vortec-era versions to 11:1 for current EcoTec3 engines. 6.2 seconds were 10.4:1 or 10.5:1 in the Vortec times, and they now run at 11.5:1 – Mariana Trench compression levels. Check the owner’s manual for a 2024 Chevrolet Silverado and you’ll find two different octane recommendations. 5.3 seconds can be crazy all day long with a regular 87 octane rating. At 6.2 seconds, a 91 octane rating is recommended, but you can also use 87 if you don’t mind the engine making less power and possibly knocking.

So what about room volume? In general, the smaller the chamber, the higher the compression. With the L86/L87 EcoTec3 heads, the chamber volume is only 59.02 cc, almost 10 cc less than the LS3. And golly, the LS3’s compression is 10.7:1, and the EcoTec3 6.2’s is 11.5:1.

And no, you can’t swap 6.2 heads for a 5.3 – at least according to all the engine forums. Apparently the problem is that the bore of the 5.3 is not big enough for the valves. But if you’re a 5.3 owner and want more power, you can use the 64cc chambered LS6 heads, as seen on the (now quite cheap) C5 Corvette Z06 and the first generation Cadillac CTS-V. They are also called ‘243 heads’, the number stamped near the outside corner above the exhaust flange. You may get reduced compression compared to the stock 706 heads and their 61cc chambers, but you can always get new pistons to bring it back up.

With the 6.2, all Gen-IV Vortec versions have the same materials for the spinny bits. But once you enter the modern EcoTec3 era with the L86 and L87, you will discover that the crankshaft has absorbed its vitamins. Gone is the cast iron crank of yesteryear, and in its place is a stronger forged steel crank. We’ll ignore for now that L87s often have improperly finished, incorrectly sized cranks, which can completely destroy the entire engine as the connecting rod bearings build up sediment. This is purely a discussion about materials. No need to mention the 28,000 L87 failures and GM’s recall of 600,000 trucks with the L87 6.2. No, not necessary at all. Put it out of your mind.

EcoTec3 5.3s include the L82, L83, L8B and L84. Like the LT engines, these all have direct injection. Flexfuel L83s can make 380 horsepower and 416 pound-feet of torque on E85, although L82s and L84s only make 355 horsepower and 383 pound-feet. The L8B is essentially a mild-hybrid version of the L83, and the current 2019 L82s are largely L84s with AFM. Yes, the L84 went to the possibly even more hated dynamic fuel management (DFM).

Vortec 6200 series RPO codes are L92, L9H, and L94. They all have VVT ​​and 10.5:1 compression (well, L94s have 10.4:1), and they each make 403 horsepower and 417 pound-feet of torque. 2009 L9H engines gave a flex fuel rating of 6.2 seconds, and AFM appeared in the 2010 L94. EcoTec3 6.2s increased to 11.5:1 compression for 420 horsepower and 460 pound-feet of torque. The current L87 of 2019 ditched the AFM from the L86 in favor of DFM.

Oh, and the L92 6.2 in ’07-’08 Yukon Denalis only made 380 hp, and in ’08-’09 Hummer H2s it made 393 hp. The only explanation we can find for this comes from the implication that this was done to protect the 403-horsepower Cadillac Escalade as GM’s most powerful SUV. Place the eye roll here.