Gen III (3) LS 1200 Horsepower, 387-Cubic-Inch C5R Power Guide

In case you should ever feel the need to slide behind the wheel of a car powered by a 1,200 hp, centrifugally supercharged Gen III V-8, you’re about to learn what it would take. The only detail you’ll need to figure out for yourself after reading this chapter is how to pony up a fair amount of resources (we mean money!) to make it a reality.

The component list for this engine is race-inspired, expensive, and requires considerable knowledge to maximize the power production — but this engine can make sick power all day long when it’s done. Just to give you an idea of the type of components shown here, the C5R Corvette racing engine block lists for $6,500 from your local GM Performance Parts dealer — and then you need to do a bunch of machine work to make things fit! The heads here look like regular Gen III aluminum heads, but they’re the special 12-degree (instead of 15-degree) valve angle C5R cylinder heads, also available from GMPP, which require a fabricated intake manifold and other one-off pieces. The Mallory distributor and MSD 7AL ignition system are completely custom, as is the oiling system.

1. Even though the C5Rs are meticulously machined, W2W recommends always measuring the bore size, deck height, main bearing diameters, and other critical dimensions of any block instead of assuming the tolerances are okay. Writing these dimensions down in an engine log keeps all the critical info in one place and minimizes tolerance problems as the build progresses.

2. With the ProCharger F1R centrifugalsupercharger whistling a 21-psi wind into the intake, even the mighty C5R Gen III V-8 engine block is stressed to its limit to hold the cylinder heads down tight. Because of this, W2W prefers to convert the block from the original 11- mm head studs to 1/2-inch head studs. (Note: the top 5 head-bolt holes on the C5R are 5/16-18 thread, so you don’t need to change these threads when going to 1/2-inch head studs.) The 1/2- inch studs are a custom design that W2W has ARP create for them to install in the C5R block. W2W positions the C5R engine block on a Bridgeport mill so the deck surface is perpendicular to the drill. Then, they drill the holes out and thread them with a 1/2-13 tap. The threads are drilled out about 1 inch down to mimic the factory setup. The mill guides the tap into the drilled-out holes on the block to maximize the chances of the studs being perpendicular to the deck face.

3. Here are the original 11-mm C5R studs (left) and the W2W 1/2-inch (right) to show the difference in size. Remember, the holes in the heads will need to be drilled out to accept these bigger studs. W2W says this work is required if you want to keep the head from lifting off the block while making more than 800 hp – and it works on either the stock short block or the C5R block.

4. This engine will use a Gen III V-8- specific Jesel belt drive to spin the camshaft. While the Jesel drive is designed for the C5R, there’s still a considerable amount of machining required to install it. Jesel provides a paper template to determine what areas require machining. Since W2W does this work often, they created a 1/4-inch aluminum plate template to use as a guide for the machining. To get the Jesel base plate to bolt to the block, you need to machine-off the stock oil pump mounting bosses (see shaded area on block) and make a few other modifications.

5. When you use the Jesel base plate, it exposes the pressurized main oil galley opening on the driver-side of the engine block, so you’ll have to plug it. This opening in the main galley would normally be covered by the stock front cover, which isn’t being used on this engine, so plugging it won’t affect the oil flow. Oil will instead come from an external multistage dry-sump oil pump.

6. Prepping the cylinder bores is a major step in building this engine. To do this, W2W has created a torque plate to work with 1/2-inch studs and a 4.155-inch bore, which you’ll need for honing the bores. Every engine builder has their own combination of grinding stones and speeds to get the surface prepped properly for each specific piston and ring combination, so find a reputable shop and let them do their thing.

7. Since this block has had a lot of machining done to it and hasn’t been run, now is a good time to inspect it for metal burrs on the edges of any machined surfaces. A good example is where the cylinder liners were trimmed. The sharp edge left over was removed with an edge-cutting stone or file. This is a good idea as these sharp lips have a tendency to fall off once the engine gets going and could get lodged in a bearing surface or gear, causing a failure.

8. An engine block casting that has never been used should be thoroughly inspected for remaining sand or rough metal areas. This is especially important for the crankcase, where oil will be whipped around at high forces. W2W does this inspection, then removes the sand and smoothes the rough areas with a metal bit first, then with an 80- grit sandpaper “tootsie roll” on a die grinder. Once this is done, the engine block needs to be thoroughly cleaned, which includes removing the factory installed cam bearings.

9. With the block machined and cleaned, W2W sets the ring gaps on the top and second rings (see page 105 for details). The rings being used on this engine are Speed Pro’s heattreated, ductile-iron Hell Fire rings. These rings are designed for pressurized applications. W2W likes to set ring gaps using the following equation: 0.004 to 0.006-inch per inch of bore diameter. With that in mind, the gaps were set at 0.024 inch, which is on the high side, to account for the abuse encountered in a supercharged engine. As an aside, if this was a nitrous engine, the ring gaps would have been set at 0.028 inch to take into account the severe thermal and pressure shock that occurs when the nitrous hits. The block is cleaned again after all ring gaps are set to remove any metal shavings.

10. The dimensions for the main and rod bearings are then rechecked. To do this, install the main bearings in the main caps and bolt them into the block with the torque/torque-angle process. The main, rod, and head fasteners are all initially torqued, then turned a pre-determined angle to provide a torque-angle clamping load. These values are different from the stock Gen III V-8 figures, as the block, mains, rods, heads, and fasteners are all different from the stock Gen III V-8.

11. The C5R block torque/torque-toyield scheme is different from the factory engines. In fact, based on their experience, W2W has developed their own scheme to perform the torqueangle process. First, all the fasteners are lightly covered with #3 lube on the threads and washer heads (this lube comes in the C5R block packaging). Then, the crank main studs are torqued to 100 in-lbs. The inner and outer fasteners are then torqued to 20 ft-lbs. With the torque-angle socket, the inners are then turned 80 degrees, and the outers 60 degrees. The side bolts are then torqued to 20 ft-lbs.

12. The crank journals need to have 0.0025 inch of clearance. This tolerance is measured with the bore gauge feelers in the twelve-to-six and threeto- nine o’clock positions on the inside crank journal bearing of the torqueddown caps. Sometimes the inside diameter (ID) is measured in the 10:30 to 4:30 and the 2:30 to 8:30 positions as a check to the initial measurements. The 0.0025-inch tolerance is attained by putting together combinations of bearing shells. As a note, W2W usually builds their engines with a main bearing clearance of 0.002 inch in aluminum blocks, but since this is a big-power engine with a dry-sump oiling system, they are opening the tolerance up a little. To give you an idea of how sensitive this area is, W2W says they would not build anything with 0.003-inch clearance, as it would have an oil pressure of 80 psi at startup, but once the oil got up to 180 degrees and higher, the pressure would drop to 20 psi.

13. The Lunati forged crank was washed before beginning the assembly process (to remove the shipping Cosmoline), then wiped with engine oil before being installed.

14. The amount of heavy mallory added to the counterweights in this Lunati crank is substantial, to balance the heavy-duty rotating/reciprocating components used to handle the 1,400+ hp crank power — the blower eats about 200 hp and the dyno showed 1,200 hp — that’s 1400 hp at the crank!

15. Here is a great comparison shot of a stock Gen III V-8 connecting rod on the right of the Oliver billet steel rod. With the difference in size, it’s easy to see why there is so much mallory in the crank.

16. The covers that bolt on the front and rear of the Gen III V-8 block have a dual lip seal to prevent oil leaks. For boosted Gen III V-8s, this factory seal needs to be replaced with a TKO high-performance seal. W2W built this special tool to remove and replace this seal. Installing these covers also requires a lip-setting tool to get the seal seated properly on the crank surface.

17. The rod bearing clearances are attained by measuring each crank rod journal and the ID of the appropriate connecting rod in the multiple positions as on the crank main bearing setup (twelve-to-six and three-to-nine o’clock). For more on this, see page 106. Again, using various bearing shell combos helps to get the proper clearance. Once these numbers have been determined, the engine is tightly “bagged” with a plastic bag, to prevent dust and dirt from adhering to the inside of the engine.

18. W2W has JE Pistons machine valve reliefs in the pistons based on their experience building these engines. Once the piston-to-valve clearances were checked, W2W deburred all the edges on the piston using a 180-grit tootsie roll sandpaper attachment on a die grinder. As a final touch, DART coated the top of the pistons with heat-reflecting material and the sides with moly-based material to minimize wear.

1. Cleaning all the parts is critical to building an engine that will last. W2W has a solvent tank that is only used to clean parts for the engine assembly area. To start the cleaning process, W2W uses wire brushes of every diameter and length you can imagine to clear out the passages.

2. W2W uses Scotchbrite to lightly scrub all the piston thrust faces and brushes to clean out the ring lands and holes. The gloves are for anyone who has a brain and wants to keep it— especially if you’re washing parts in a tank all day.

3. The piston dish faces also get the Scotchbrite treatment, especially in the valve relief area.

4. After being thoroughly soaked, brushed, and scrubbed, each component should be blown off with pressurized air that has a water separator and filter in the system — this avoids spraying the part with water vapor that will invariably have micro-sized rust particles in it.

1. After cleaning the parts, place them in a clean area in preparation for assembly. It’s important for the assembly area to be surgically clean — notice the unsoiled white butcher paper on the countertops. Here, the rods and pistons are assembled together. The first step is to install the double spiral locks in one side of the piston. Then, the piston pin bores, rod bore, and pin are lightly coated with engine oil or assembly lube before being slid together. Most pistons need to be clocked on the rod, as they are built to handle forces in a certain orientation, and the valve reliefs need to mate with the valves they are meant to clear. If you are unclear on this, check it with the piston manufacturer.

2. The last step to assembling the rod/piston combo is to install the final two spiral locks in the piston. For more details on the piston/rod assembly process, see the buildup in Chapter 7 (see page 108).

3. It’s important that after you assemble the rods and pistons, the rings are installed on the pistons and the entire combo is immediately installed in the engine. Why? Because these components have lube on them and this oil attracts dirt and crud and you don’t want any of this in the engine — especially not in the piston/bore/crank/ oiling-system areas.

4. Before installing the pistons, W2W wipes the face of the top and second rings with a light coat of 30-weight oil dripped on the fingers. They then wipe the rings with a non-linting towel before installation. Using a light brush, the oil ring lands are lightly covered with 30-weight oil, and then wiped with a non-linting towel to remove any excess oil. You need to remove the excess oil to prevent it from “cooking” into the ring lands upon startup, which could prevent the rings from sealing properly.

5. W2W uses ring spreaders to install the top and second rings. Many believe winding rings onto the piston ring land introduces a twist on the ring, which negatively impacts the ring’s ability to seal the combustion pressure. The rings will be stressed to hold the supercharger’s boost, so they’re installed with the spreader, just to be sure.

6. W2W believes the way you set up the oil rings is critical to achieving good oil control. They don’t use the small red spacer on the spreader portion of the oil ring for fear of it ending up somewhere else in the engine. Instead, they carefully position the spreader so it isn’t overlapping, and install the piston.

7. The rings are clocked on the pistons for startup using the GM Power Book recommendations. This puts the rings in the best location during startup to insure proper ring seating in the ring lands and on the bore surface.

8.Wipe a light coat of 30-weight oil on the thrust faces of the pistons just before they’re installed.

9. Don’t forget to apply two drops of engine oil to each bore and wipe it evenly across the entire bore before you install the rods and pistons. Give the rod bearings a thick coat of Pro Blend assembly lube before you carefully lower them down into the bore.

10. W2W follows the Oliver-spec torquing procedure for the rods to torque/torque-to-yield them. The process is similar to that for the production rods. First, the rod bolts are torqued to a relatively low 30 ft-lbs. Then, a vertical line is drawn on the rod bolts with a Sharpie pen — do this so you don’t forget which ones you torqued already. Use the torque-angle socket to add 40 degrees of rotation to the rod bolts. Note the factory crank sensor wheel on the crank. This was removed after a few mock-up sessions revealed that it was in the way. The OE trigger wheel crashes when a a 6-1/8- inch rod and 4-inch stroke are used. On big-inch, big-hp engines, the trigger wheel also limits the amount of mallory that can be put in the crank to balance the rotating/reciprocating assembly.

1. Lube the cam up with engine oil and install it (for cam installation tips, see pages 93-94). The next step is to soak the Jesel solid roller lifters in engine oil before you install them. The tip here is to make sure the lifter is installed with the open oil feed hole exposed to the main oil galley. The Jesel lifters have two holes 180 degrees apart: one that is open and another that is blocked off. The way to make sure you are installing the lifter correctly is to plunge a small Allen wrench in there to make sure you have the open hole in the right spot.

2. The result of the offset of the Jesel lifters, which makes room for the C5R intake ports, can be seen here. The factory Gen III V-8 plastic lifter carriers are used, but the pushrod holes need to be ground on to open them up to an oblong shape so the Smith Brothers 3/8-inch pushrod can seat in the offset lifter bucket.

1. This photo shows the degree wheel zeroed to top dead center (TDC) on the number-1 piston, but you always want to check this before going on to the next step of checking the specs on the camshaft.

2. To check the degree wheel location to the piston location, rotate the crank 360 degrees to get the piston to 0.050 inch before TDC on the number-1 piston, as shown. Note that the degree wheel is showing 12 degrees approaching TDC. The 0.050-inch value is used to ensure the tolerances in the components don’t affect the readings.

3. Then, rotate the crank 360 degrees the other way to get the piston back to 0.050 inch BTDC on the other side. Note that the degree wheel reads 12 degrees on the other side of TDC. This is a good check to make sure you have the degree wheel zeroed to piston TDC.

4. With a solid roller lifter and pushrod in the block on the intake cam lobe, rotate the crank until the dial indicator reads full lift. Set the dial indicator to read zero.

5. Go to 0.050-inch lift on each side of the cam lobe, rotating up to the location by turning the crank in both directions. Record the numbers off the degree wheel. In this case, the degree wheel is reading 154 degrees. When the crank was rotated the other way, the degree wheel read 66 degrees. Add the two figures together, 154 to 66 degrees to get 220. Then, divide that figure by 2 to end up with 110 degrees.

6. While it doesn’t need to be done, the crank is rotated back to 110 degrees on the degree wheel to show the intake lobe center of 110 degrees. Now you can read the cam card to determine whether the cam is set properly in relation to the crank location. In our case, if the cam wasn’t located properly, we could use the Jesel belt drive for exacting adjustment.

1. Once the heads were checked to make sure they were within spec, the valves were installed. To do this, the valve stems were coated with Pro Blend assembly lube and then slid into the valve guides.

2. Next, the valvespring seats, valvestem seals, and Jesel rocker stands are installed. The seats are provided with the heads, but W2W had to purchase the TKO seals. The Jesel rocker mount required the cylinder head bosses be machined down about 0.130 inches so they’d end up at the proper geometry. Notice the O-ring in the groove in the head — this is only on the C5R head, as the stock head has the O-ring groove in its valve cover.

3. Since this engine is going to run above 20 psi of boost, we’re using a coated copper gasket with a steel oring in the deck surface. Copper gaskets are for full-out engine combinations because they don’t have as much give as composite gaskets, but the clear coating does improve their sealing capability over older uncoated copper gaskets.

4. The C5R cylinder heads have a valve angle of 12 degrees (vs. the factory 15 degrees) and offset intake ports. Because of this, the intake flange is different from the production Gen III V- 8 heads (so the stock intake won’t bolt up), and the rockers are different. You’ll also need some special pistons, but the exhaust flange is unchanged. The C5R head fasteners are torqued to 105 ft-lbs, which is much more than the factory head fasteners.

5. The Jesel rocker system comes with a geometry-checking rocker, shown here, that measures the height required for the rocker stand. Often, the rocker stand will need to be shimmed up using the Jesel-supplied shims. One way to quickly determine the necessary shim pack is to stack up shims on the rocker until they match the distance that the valvestem protrudes past the rocker face.

6. This is what the valvestem should look like when the valvetrain geometry is correct. Many believe the best way to set the proper valvetrain geometry is to purchase valves that have the proper stem length.

7. To avoid valvespring coil bind, it’s a good idea to check the required valvespring height. You can do this with a valvespring height checker, shown, or a micrometer.

8. W2W used Smith Brothers’ 8.350- inch pushrods here. Notice how the pushrod has number-3 assembly lube on the tips (it comes with the GMPP C5R block). The camshaft comes from Cam Motion and features 257/270- degrees duration at 0.050 inches lift, and 0.726/0.713 inches of max lift on 114-degree lobe centers.

9. Another racing-type feature of the C5R heads is their ability to accept 1.650-inch-diameter valvesprings with only slight machining to open up the seat — even without changing the seat depth. To minimize valvetrain weight, this engine is getting Del West titanium locks and retainers.

1. This clean setup is the result of the early machining work. The Jesel belt drive is fully installed, the distributor drive pulley is on the camshaft, and a belt connects the Jesel/Mallory distributor on the offset mount (built by W2W). Since the intake inlet is at the front of the engine on this intake, W2W had to build a special offset plate to work with the special offset intake inlet that places the throttle body off to the passenger side of the engine.

2. The water pump on this engine is a high-flow Meziere electric unit. Notice the shallow cast-aluminum ARE oil pan with the three scavenge-stage pickups (lower left). The four-stage, dry-sump oiling system is used to keep oil off the crank (which would rob horsepower), but also to pull a vacuum in the crankcase to prevent a blowby explosion — which is not uncommon on high-boost engines.

3. This engine won’t be running the production engine controller, so the factory knock sensors aren’t required. Also, the knock sensors struggle to seal the crankcase on boosted engines, so W2W installed one of their billet valley covers. The bolts need to be torqued to 89 in-lbs at first, and then torqued to 18 ft-lbs in a radial pattern.

4. The W2W aluminum intake manifold was polished to a mirror finish by Gary Lentz and bolted to the cylinder heads. The intake is O-ringed, so no gasket or sealer is necessary.

5. There are two bolts in the intake manifold/head for each port. W2W has used all the intake bolts before, but found that they really aren’t needed. The bolt that’s under the short side of the port is very difficult to get in and out anyway — so it’s one bolt per port. Notice the injector seat placement and angle — injector placement is one of the reasons this engine makes the power it does. Next, the BBK 90-mm throttle valve was installed on the intake. There will not be a MAF installed, as this engine will run in speed-density mode on a F.A.S.T. aftermarket controller.

6. The deep C5R valve covers are different from the shallow factory valve covers in that they have these four unequal-length stands inside them and an O-ring on the valve cover. The production Gen III V-8 heads have the O-ring seat and O-ring in the head, not in the valve cover. The C5R covers have no provision for the factory coil mounts, but they aren’t needed anyway. The Jesel valvetrain is fully custom, with offset rockers to negotiate the pushrods around the oversize ports and large valvesprings.

7. The job of installing this engine under the hood of a Camaro/Firebird is always a challenge for W2W’s fabrication crew. There is little room for a 1,200-hp huffed C5R and its intercooler, so on this car the intercooler is in the back seat. The tubing runs through the firewall and into the interior. It looks impressive and took a long time to create, but even more important — it all works and makes tons of horsepower.

The engine was fired up with a W2W calibration and some soft pulls made without any boost to make sure that everything was working properly. The valve lash was set at a tight 0.025 inch. This is because W2W has seen the lash on an aluminum block/head engine grow as much as 0.015 inch from the cold lash settings. With 1.7:1 rockers like this engine has, that easily equals a total of 0.024 inch of hot lash. Once everything checked out, W2W hooked up the blower and made some power pulls, tuning on the cal and slowly inching up to the 1,200-hp range.