One of the most popular USDM swapped engine is the Corvette's LS1. Even though it's not from overseas, the LS1 has been swapped into most of the cars we deal with, and rightfully so. The LS1 deserves an analysis and a comparison to our recent victor; the 2JZ. Now we've brought it to you.
Chevrolet/GM LS1 Engine
First used in the C5 Corvette in 1997, the LS1 all-aluminum engine represented a radical departure from previous small-block designs, but the design found instant favour with street racers, hot-rodders, and power junkies because of the almost unlimited tuning and conversion options available for this engine.
However, because the LS1 has a relatively small-bore diameter for a V-8 engine at 3.89 inches, the possible modification options are limited to cylinder heads from the closely related LS6 and LS2 variants, to prevent interference between valves and the block. Nonetheless, LS1 engines are capable of more than 900 HP in factory trim, but relatively minor modifications will allow 1400 HP and more with no trouble at all, which is mainly due to the “interference fit” design principles incorporated into the block casting.
For instance, the main bearing caps are designed to wedge into machined-out shoulders in the casting, a feature that imparts great strength to the block, yet obviates the need for dowels to locate, and hold the bearing caps in place. Another feature is the use of extra long cylinder bolts; by screwing deeper into the block, deformation caused by bolt torque is eliminated, and by using four bolts per cylinder in conjunction with multi-layered steel head gaskets, the LS1 engine is leak proof, even with dramatically raised compression ratios and boost pressures.
Nevertheless, the LS series of engines offer arguably the greatest possibilities for mixing and matching parts from across the range than any other series from any other manufacturer, even though there are several devils in the detail: some cylinder heads do not work with some blocks, and some cylinder head/block combinations do not work with all crankshafts, which makes it a good idea to obtain an authoritative guide on building/converting the LS1 engine before starting out, such as "How to Build High-Performance Chevy LS1/LS6 V-8s"- P/N 88958786, by Will Handzel.
Known Reliability Issues.
Apart from some piston slap problems on very early LS1 engines, which has since been eliminated, and some cylinder heads that were prone to cracking (casting #706), because of excessive porosity around the oil drainage channels, the good news is that there are no known reliability issues with the LS1 engine in standard form; however, unless the provenance of a rebuilt, or heavily modified engine is unknown, it would be wise to have it assessed by an authority on these engines. The possibilities for tuning and modding are almost endless, which means that unreliable or unsuitable double valve springs, insufficient lubrication, or even an incorrect flywheel/flex plate could conceivably cause expensive failures.
Nonetheless, in standard, or near standard form, the LS1 engine is near indestructible, and mileages of more the 200 000 are common with no discernible smoking, or other issues such as noises on start-up, or sustained high engine speeds. Extreme modifications have a direct bearing on reliability, and due to the vast number of possible modifications, it is impossible to give estimates on expected longevity, except to say that the more extreme the modification, the higher the chances that the engine will not survive past a few thousand miles if the aluminum block is retained; it cannot supply the structural rigidity of the cast-iron Vortec engine block, and should not be used for extreme power development.
LS1 versus 2JZ
From an engine developer’s point of view, there exists no logical reason why anybody would want to swap either of these engines, unless the swop is for the sake of change and nothing else. Both engines have seen extensive application in all motorsport disciplines, and it does not make sense to want to swop one for the other, since they are equally reliable in both standard and near standard form. However, while the 3000cc 2JZ-GTE 24V belt-driven DOHC, intercooled twin-turbo, inline 6-cylinder engine is available only with a cast-iron block, the all-aluminum construction of the LS1 engine represents a significant weight advantage.
Nevertheless, the inherent high power capabilities of the 2JZ engine (up to 2000 HP) could force adherents of the LS1 engine to resort to the high strength cast-iron variant to match, which is heavy enough to negate much the advantage of having the low torque characteristics of a V8.