Classic Cubes From An LS1 Part 1

The boring head is attached and the boring process begins on fourcylinders. A total of 10 passes per bore is required to open thecylinders from 3.900 inches to the required 4.283 inches on the lowerportion of the bore. Once one bank of cylinders is complete, the blockis rotated and the other cylinders are bored.

Once complete, all eight cylinders have to be opened up to 5.139 inches at the top of the bore to support the enlarged flange area of the Darton sleeve.

Here is a completed cylinder that has been bored to accept the Dartonliners.

The block is thoroughly cleaned and then heated in an oven at 220degrees in preparation for installation of the liners. After beingbolted down on a special fixture, MTI gets out the liners and preparesfor the installation. Shown are the fixture and a single liner.

Darton's sleeves are centrifugally cast nodular iron, as the benefits ofcast iron for ring sealing are long established. Darton manufacturessleeves for the Gen-III engine in various sizes, including the picturedbore size of 4.110 inches. Stock sleeves are easily identified by theirribbed construction and cast-iron grey color (right). The Darton sleeveshave cylindrical grooves on the upper half and coolant passages, whichreplace the factory passages that were eliminated during the boringprocess. In addition, Darton states the liners have additional coolantpassages, which provide more even cooling of the upper portion of thesleeves.

While the block is heating, three O-rings are lubricated and attached toeach liner. As soon as Betty Crocker finishes, McCleskey liberally coatsthe flange area groove with Loctite 518 and uses a rubber mallet to tapeach liner into its respective location. A minimum of four hours isrequired for the Loctite to cure. Shown are a liner, O-rings, 0-ringlubricant and Loctite to facilitate the process.

After a single liner is installed, you can see how it fits into theblock. Note that one side of the liner is squared off and designed sothat the corresponding cylinder press fits against it.

After the liners are properly cured, the main caps are torqued back tospecification and the block is put back into the Rottler F-65A,three-axis CNC machine. Since the liners protrude above the head decksby 0.005 inch, surfacing is required to level the liners and block. Anominal piston-to-deck height of zero is the target, with a totalnominal deck height of 9.235 inches.

After surfacing is complete, the next step is to prepare the liners forthe proper piston size. Since we started with a 4.110 inch bore, ourfirst step is to increase the bore to 4.15250 on the Rottler F-65A,three-axis CNC machine. Once complete, the block is transferred to aSunnen CK-10, where the cylinders are honed to the final dimensions of4.160. This is accomplished using a BHJ aluminum torque plate and honingstones that range in grit from 70 to 280. The Sunnen machine continuallypumps oil during the honing process to achieve consistent honingresults.

The bore size is set up to be measured with a dial bore gauge to verifyeach cylinder's size through the process until the final specificationsare achieved.

Here is a side-by-side comparison of the stock 3.622-inch LS1 crank(left) and the 4.185-inch Lunati unit (right). The factory crank is madeof nodular iron and is externally balanced to within 9 grams. It canreportedly handle close to 650 flywheel horsepower or 525 rear-wheelhorsepower during continuous use before failure. The custom Lunati crankis made of billet steel and is balanced down to a scant 2 grams throughthe use of Mallory metal. MTI has seen the crank withstand 1080 rearwheel horsepower in a twin-turbo application.