The LS1 has certainly come of age. Now in its sixth year of production, the aluminum V-8 is making quite a reputation for itself. It was big news in 1998 when reports started to surface of brand new, bone-stock F-Bodies running 12s right off the showroom floor. Three years later, there are an ever-growing number of F-cars squeaking into the 11s with just bolt-ons. It goes without saying that the LS1 aftermarket is booming.
At the forefront of the LS1 modification game is Agostino Racing Engines (ARE). It is no secret that proprietor Nick Agostino is very fond of the LS1. In fact, a stroll through his Toronto, Ontario, shop reveals a dozen or more LS1-powered F-Bodies and C5s waiting their turn at transformation. Agostino's specialty is tailoring each package to the client's specific needs. There are no cookie-cutter cars being pumped out at ARE.
Why the big demand for the Agostino touch, you wonder? After all, there are plenty of companies modifying the LS1 these days. It's a one-word answer: innovation. Agostino and his staff have one of the most exhaustive Gen-III R&D programs going. The result is a slew of custom parts, ranging from head bolts and main-stud kits to big-bore head gaskets and custom valvetrains. No stone has been left unturned in the quest for LS1 superiority.
Perhaps the most important development has been the advent of the big-bore LS1. Yes, you read that correctly. The technology is now in place for reliable re-sleeving of the LS1 block. What was once thought improbable has now become a viable performance alternative. Though the big-bore engine won't make the torque of a big stroker, it will crank out some very impressive numbers.
Agostino recently invited us to take a look at the build-up of a particularly stout big-bore/short-stroke engine. It's a 393ci, solid roller animal that should thrash out more than 450 hp, without a blower or nitrous, and put a full-weight F-Body solidly in the 10s. Will it? Follow along and find out!
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 The first step in building...  The first step in building a big-bore LS1 is to rid the block of the original liners. This is done on a standard boring machine and is usually accomplished in three or four consecutively deeper cuts of about .030 inch each. |
 This shot gives a good look...  This shot gives a good look at the outside of the sleeve's outer wall. Note the ridges that serve to lock the liner in place once the aluminum block is cast around it. The non-concentricity of the bore is attributable to core shift during the casting process. |
 ARE preferred that we did...  ARE preferred that we did not show their proprietary methods for installing and sealing the new cylinder sleeves. After all, it's this step that has kept everyone from doing it. Once installed, they can be bored like a standard engine block. Consider this, friends: If you don't have the dough for a complete ARE engine or think you can tackle it in-house, consider paying these guys for this service alone! Final honing is performed with a torque plate. While the bore could be as large as 4.125, ARE machined the bores to 4.1 inches, as Agostino elected to leave some material for future clean-up. After line honing, the block was ready for assembly. |
 Ross Racing Pistons supplied...  Ross Racing Pistons supplied these top-quality forged aluminum slugs with valve reliefs that provide much needed piston-to-valve clearance. This becomes a necessity when running aggressive cam profiles. The pistons have a compression height of 1.260 inches and a diameter of 4.095, which give a clearance of .005 with the 4.1-inch cylinder bore. The final compression ratio, when combined with the 54cc chamber cylinder heads, works out to a healthy 12:1 ratio. ARE selected Total Seal rings for this application. |
 The connecting rods are from...  The connecting rods are from Lunati. These forged 4340 Pro-Mod pieces are 6.125 inches in length and feature ARP bolts. They are designed to accept Ross' .927-inch tool steel wrist pin. ARE machined them to provide .0007 inch of clearance. Rod bearings from King were set up with .0027 inch of clearance with the bolts torqued to 70 ft-lb. |
 The stock LS1 crankshaft is...  The stock LS1 crankshaft is a remarkably stout piece. We have seen some seriously abused nitrous engines with all manners of broken components, but have yet to see or hear of crank failure. Knowing this, and that this engine was destined to remain naturally aspirated, ARE offset-ground the stock GM crank for a little added displacement. This upped the stroke to 3.7-inches and the final displacement to 393 cubes. Agostino Racing balances every reciprocating unit before final assembly. This was especially important for this engine, which will regularly see 7,000 rpm. Federal-Mogul main bearings were installed with .0026 inch of clearance. |
 In this shot, you can see...  In this shot, you can see the No. 1 piston and rod assembly already installed. Notice the new cylinder sleeves are siamesed. This is necessary to achieve the large 4.1-inch bore and retain proper liner thickness. It also contributes significantly to block rigidity. |
 A solid roller camshaft was...  A solid roller camshaft was chosen for this engine, as it was built with one goal in mind: all-out performance, a quarter-mile at a time. The Crane stick sports 252/260 degrees of duration at .050 with a 110-degree lobe separation angle and .680/.707 inches of valve lift. No doubt about it, this cam was chosen for top-end power, not a silky smooth idle. |
 Crane Cams recently released...  Crane Cams recently released this CNC-machined solid roller lifter designed specifically for the LS1. The cool thing about these Crane lifters is that they allow the continued use of the OEM lifter retainers. With the pushrods removed, these retainers will literally "grip" the lifters thereby allowing a camshaft change without removal of the cylinder heads. |
 It is always advisable to...  It is always advisable to degree the camshaft to ensure accurate cam timing. The camshaft is spun by a Cloyes Hex-A-Just timing chain. This timing set allows the cam to be advanced or retarded without the need for offset bushings or keys. ARE elected to install the cam at 109 degrees straight up. |
 Crane Cams also supplied these...  Crane Cams also supplied these 1.550-inch diameter Pacalloy springs. Normally utilized in big-block applications, these springs provide 230 pounds of seat pressure and 600 pounds of open pressure. Spring pressures of this magnitude would collapse a hydraulic lifter. Solid roller cams require increased valvespring pressures to keep the lifter in contact with the camshaft lobes at all times, thereby preventing valve float. It's important to note that these springs are not a drop-in replacement for the small diameter stockers. ARE milled the spring seats on the heads to accept the big Cranes. |
 Agostino elected to use LS6...  Agostino elected to use LS6 castings (from the new Corvette Z-06) on this engine for their incredible efficiency and superior flow characteristics. Looking at the combustion chamber, notice there has been extensive porting in the bowl areas, but only minor clean up done in the chamber. Once the heads were decked, chamber volume wound up at 54 cc. Notice, too, that larger seats have been installed to accept the substantial 2.1-inch intake and 1.6-inch exhaust valves. |
 The intake ports on the LS6...  The intake ports on the LS6 heads have been opened up substantially. At .650 inch of valve lift, the ports flow 330 cfm at 28 inches of water while volume is 235 cc. This won't do low-end torque production any favors, but a big-bore, (relatively) short-stroke engine like this is all about top-end power--it'll still build enough torque to blow off the tires. |
 The distinctive D-shaped exhaust...  The distinctive D-shaped exhaust port is indicative of an LS6 cylinder head. As with the intake ports, the exhaust was opened substantially. These flow approximately 230 cfm, again at the .650 inches of lift. Contrary to some rumors out there, standard LS1 headers bolt right up to these heads. |
 Checking piston-to-valve clearance...  Checking piston-to-valve clearance is a crucial step. Aggressive camshafts open the valves a greater distance and for a longer time. As such, there is a greater risk of experiencing piston-to-valve interference. The clearance in this engine was well over .100 inch thanks to the valve reliefs in the Ross pistons. Piston-to-valve interference is obviously a very serious problem that will result in bent pushrods, bent valves, broken rockers and even broken pistons. |
 Jesel's J2K Millennium Series...  Jesel's J2K Millennium Series shaft rocker arms systems feature tool steel lash adjusters in an ultra-light .750-inch aluminum body. The rocker body is shot-peened, equipped with a .250-inch needle nose roller and available in a variety of ratios. The innovative .375-inch shaft eliminates the need for spacers or snap rings. Jesel includes a full complement of ARP fasteners with their J2K systems. ARE specified a 1.7:1 rocker ratio for this engine. This rocker system makes for a rock-solid valvetrain. The only real disadvantage to running a solid roller cam is that they require periodic valve adjustments. Many assume that lashing the valves is a difficult and time-consuming proposition, but it is really quite an easy task. With the engine at operating temperature, a feeler gauge is inserted between the valve tip and the roller on the rocker arm. ARE recommended the lash for these valves be set at .024 inch. |
 With the car strapped down...  With the car strapped down on the dyno, the ARE staff found that the serpentine belt would tend to walk off the front of the tensioner pulley at very high rpm. It seemed the OEM tensioner just didn't have the necessary spring pressure to keep the belt taut. Already familiar with this problem, Katech whipped up this billet aluminum manually adjustable belt tensioner. This component was developed for the C5-R Le Mans race program when those guys began having the exact same problem. |
 Katech also modified this...  Katech also modified this pair of C5-R valve covers. The C5-R covers are ideal because of the extra rocker arm clearance they provide. Katech milled the C5-R logo away before CNC-machining both the Agostino Racing Engines' and Katech logos. Rather than use a messy conventional valve cover breather, ARE used this AN- fitting and braided hose that lead to an oil evacuation can situated in the battery's former location. Because ARE's valve covers of choice have no gasket provisions, other arrangements were necessary. Katech Engine Development machined an O-ring groove for valve cover sealing. Though it looks downright fragile, it seals perfectly. The C5-R valve covers do not duplicate the factory coil pack mounting design. With the coils relocated to where the A/C accumulator would normally live, valve cover access is greatly improved for hassle-free valve adjustments. The LS1's appearance is certainly cleaner once the cluttered coil pack wiring is moved, and the engine looks pretty darned good in its racy form. |
 A very common modification...  A very common modification in the LS1 world is porting of the stock mass airflow sensor. Jim Pace Performance Parts has one-upped this practice with their line of Velocity Volume recalibrated 85mm MAFs. These MAFs can be ordered pre-calibrated for several different injector sizes. This allows you to upgrade injectors without a costly PCM re-flash. This one is calibrated for the 30-lb/hr SVO injectors in use on the engine. |
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