Saturn 5 Engine

[Odon Irving]

Thepowerplant used in Saturn S-Series automobiles was a straight-4 aluminum piston engine produced by Saturn, a subsidiary of General Motors. The engine was only used in the Saturn S-series line of vehicles (SL, SC, SW) from 1991 through 2002. It was available in chain-driven SOHC or DOHC variants.

This was an innovative engine for the time using the lost foam casting process for the engine block and cylinder head. Saturn was one of the first to use this casting process in a full-scale high-production environment. Both engine types used the same engine block.

The engine utilized a water-cooled aluminum block. The main bearing caps were made of ductile iron and held in place with two bolts each. The cylinder block bores had interference fit cast iron liners for the piston rings to sit against. The engine block was made from 319.1 aluminum alloy and the liners were made from grey iron.

The crankshaft was supported by five main bearings with thrust taken at the middle bearing. 1991 and 1992 engines had a different crankshaft from 1993 and later engines, whose crankshafts had reluctor ring slots advanced ten degrees for easier starting. 1991 to 1998 crankshafts incorporated four counterweights, while those from 1999 to 2002 incorporated eight.

From 1991 to 1998 the connecting rods were forged steel with standard type crank pin bearings. SOHC engines during that period used a dished piston design whereas the twin cam engines used a flat top piston with 2 recesses for the intake valves. Twin cam pistons received several re-designs throughout the production run aimed at reducing oil consumption issues. These included reducing the clearance between the top of the piston and the first compression ring, redesigning the skirts on the pistons and the oiling ports on the bottom of the pistons. For the 1999 model year all pistons were totally redesigned. Both engines used the flat top pistons with 2 valve recesses and featured a new hypereutectic design with coated skirts. Also for 1999 all connecting rods switched to a slightly longer powder forged design and cracked bearing caps. The piston pins floated in the connecting rod bushings. The pistons were cast aluminum alloy with the piston pins being retained with snap rings.

The timing chain was hydraulic tensioned and had a ratchet mechanism to keep the chain tight. The timing chain rode on one pivoting chain guide resting on the ratchet tensioner and one fixed guide attached to the engine block and cylinder head. The 1991 to 1998 DOHC engine had an upper timing chain guide in between the camshaft sprockets. The timing chain was lubricated via cast-off from the top of the cylinder head and one 'squirter' on the oil pump housing. The SOHC, 1991-1998 DOHC, and 1999-2002 DOHC engines all used different timing chain sets.

The SOHC (LK0/L24) cylinder head had 8 valves and was made of lost foam cast aluminum. The camshaft was located in the center of the cylinder head and driven by a chain off the front crankshaft sprocket. Motion from the camshaft was transmitted to the eight valves by the hydraulic lifters and rocker arms.

Some 1992 through 1998 L24 cylinder heads developed cracks in the fifth camshaft journal, located closest to #4 cylinder. The hairline crack would form between the oil feed port of that journal and the coolant passages in the cylinder head. Symptoms would range from overheating to low coolant, however, most cars affected by this issue exhibited oil migration into the cooling system. The resulting mixture of the two fluids would result in a thick brown "milkshake"-like mixture, visible in the coolant overflow tank.

Saturn released unadvertised policy which would cover this issue, extending the warranty on the cylinder head to 6 years or 100,000 miles (160,000 km). Repair required the replacement of the cylinder head. and flushing of the coolant system. Badly affected cars would see coolant in the oil, as well as oil in the coolant, and would require the replacement of the complete engine assembly. Until the cylinder head casting was redesigned some time in 1998, some vehicles would require this repair more than once, and replacement cylinder heads could develop the same crack.

The 1991-1998 DOHC cylinder head had 16 valves and was made of lost foam cast aluminium. The camshafts were held in the cylinder head with bearing caps and driven by a chain off the front crankshaft sprocket. Motion from the camshafts was transmitted to the 16 valves by direct-acting hydraulic lifters.

LL0 cylinder heads were changed slightly in 1995, when Saturn adopted electronic, linear EGR mechanisms, over the previous vacuum actuated design. The head casting was changed to accommodate different mounting surface of the new valve. (1994 CA emissions engines used an adapter to mount the LEGR valve.)

A new LL0 cylinder head appeared in 1999 using a roller camshaft with hydraulic lifters and rocker arms, but power was unchanged. Also for 1999 provisions for a new air injection reaction system was introduced aimed at improving engine emissions.

Weird name for a game engine, huh? This game engine powered the Sega Saturn ports of Powerslave (Exhumed for those of you in Europe), Duke Nukem 3D and Quake. I personally think that these games have to be the best FPS for the Saturn. All and all, they provide pretty good console versions of Duke 3D and Quake, with the exception of a few quirks in level design. I feel like giving these games a mention, because nobody really seems to know about them, and they don't get the attention they deserve in my eye's. What did you think of these trio of games?

Powerslave was way better on the consoles than it was on PC, somehow - did the Playstation version use the same engine? Because that seemed to run a little smoother than the Saturn version, though it suffered from texture warping.

Powerslave on the PC was a completly different game (same assets) that used the build engine.

When the game was ported to the saturn and psx, it featured a totally different engine (Slavedriver) suited just for those consoles. It also had a different gameplay style and levels. That engine they used for the consoles served as a base for other FPS ports such as Duke Nukem (Saturn) and Quake (PSX/Saturn).

Thats only half right.

Despite popular misconception, the Slavedriver engine was designed specifically for the Saturn and was never used for any Playstation game. Power Slave on the Playstation is a port of the Build engine done by another team. Power Slave, Duke Nukem and Quake on the Saturn are the only released games to use Lobotomy's Slavedriver engine.

Like Tomb Raider (by Core) the renderer was designed specifically for the Saturn's quadrilateral-based hardware. This is particularly evident in Duke Nukem, where slopes intersect planes that would require triangles; Saturn can't "do" triangles the result being highly noticeable texture "pinching" because in addition to this, texture coordinates are tied to the vertex coordinates and could not be supplied independently (i.e., always [0, 0][1, 0][1, 1][0, 1]). Naturally, there are ways around this and apparently Lobotomy did plan to resolve the problem but as we know, that work was never completed. In fact, there are numerous instances where the original map geometry has been modified in an attempt to conceal some of the worst cases.

I played through the Saturn versions of Duke 3D and Quake first, and I was surprised at how different the levels were from the other versions. The engines restrictions were more notable in Duke 3D and Quake. Namely no vertical opening doors (funny in first Duke 3D level, as the stall doors are now gone), simplified levels to conceal the Saturn's limits (first level of Quake having a new wall in the second building to keep the framerate reasonable), and extremely butchered sound effects. It seems that every sound effect in the game has to be under a certain limit, as they all are very fast (really noticeable in Duke's phrases and most monster SFX in all of the games). Now while it sounds like I'm criticizing the games, I actually like some of these changes, as it makes seem like a new game in it's own right instead of a carbon copy console port. Powerslave really shines with the engine as it was designed for it though, like Use3D said.

I wouldn't trust wikipedia and certainly wouldn't trust whipassgaming considering in another article they contradict their earlier one and state that the Playstation version is not using the same engine.

I SERIOUSLY doubt the psx version is using the build engine, unless they did some really crazy modifications to get lightmaps to work on the psx version, there is no way that can be the build engine.

Ditto. If you look at how the renderer works, how the camera moves, the assets, and everything else, it doesn't seem like the Build engine.

I'm also looking at my copy of the PSX version right now. Can't find any specific strings in the files to say it's the Slavedriver engine, but I'm definitely not seeing any signs of it being Build.

Hmm, this is very strange. I was led to believe by the UK media, that the Playstation version didn't even have dynamic lights let alone lightmapping. Plus the screenshots shown during development which compared the two versions looked very much like the build engine was being used on Playstation. I must state that I've never even owned a Playstation nor have I seen Exhumed running on one.

I stand corrected.

From what I've seen and read about the PSX version, It seems that it is using a modified version of the SlaveDriver. Both versions share some of the same aspects, the always gibbing enemies, the same "head lag" camera movement when you move. The only difference I can see is different music in some levels, bigger screen display and modified levels. I haven't played the PSX version yet, but I'd be willing to bet it's using a modified version of the SlaveDriver engine.

In response to what DaniJ said, the dynamic lighting is for the Saturn only, as I've also seen it adding nice touches to weapon projectiles in all three of the Saturn SlaveDriver games.

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