The primary difference between the production Gen III block and this C5R race block is siamesed cylinders that allow a maximum safe bore of 4.160 inches. The liners were final honed with 600-grit stones.		Four main bolts and a pair of cross-bolts secure the billet steel bearing caps. Studs replace ordinary bolts. Note the bearing cap alignment dowel in the block between the studs.		HTC's Scott Bechtloff and Marty Cimaglia are responsible for this jewel-like stroker arm lathed from a solid bar of E4340 steel. The large 0.125-inch fillet radius on the main journals and 0.140-inch on rods was employed because of the smaller 2.00-inch pins.
Mallory metal is a tungsten alloy with an 18.5 density. In English this means it weighs more than double that of equivalent size material. For example, a 1.200-inch length of steel stock weighs 120g. The same size length of heavy metal is about 280g. Mallory in the second counterweight moves weight closer to the center of the crankshaft to minimize flexing. Hank sez: "This is NASCAR tech in a street application."		The Carrillo rods are 6.125-inch H-beam forgings fitted with SPS 3/8-inch Carr bolts (285,000-psi tensile strength) and Clevite bearing shells. These rods are on-center, possessing the same offset on both sides.		To accommodate the longer stroke and the compression height, the custom CP pistons are much shorter than stock, and the piston pins intrude into the oil rings.

Benchmark Carrillo connecting rods are the critical link between crankpin and piston pin. They are H-beam style forged from E4340 steel, measure 6.125 inches center-to-center (stock Gen III is 6.098 inches), and are fitted with 3/8-inch SPS fasteners (material is AMS 5842 MP 159). The SPS cap screws employ an asymmetrical thread that is 50 percent cold worked. Clevite (CL77 CB745H) rod bearing halves run interference with the crankshaft.

CP Pistons 2618 alloy forgings (420 grams apiece) dance on the wee end of the Carrillos. To clear the longer-stroke crankshaft journals, material must be removed from the pin bosses. Though the pistons are dished 18.2cc, the compression ratio is still a hefty 10.5:1 (with 65.8cc combustion chambers and Fel-Pro 0.038-inch composite head gaskets). The 9310 steel piston pins have a diameter of 0.927 inch, are 2.50 inches in length, and have a wall thickness of 0.150 inch. The Speed-Pro ring pack (R-20109+35) features 0.043 plasma-moly tops, 0.043 ductile iron seconds, and 3mm (SS50U) oil scrapers.

 

A Gen III Hot Cam roller hydraulic camshaft (PN 12480110) and LS6 valvesprings (PN 12565117) bump the valves. Lift is 0.525 inch, duration is 226/236 at 0.050, and the lobe separation is 110 degrees. In perspective, values for this stick are approximately those of the LT4 small-block cam, so there are much bigger things to come from the Department of Camshaft Events.

Sealing the package are CNC-ported '03 Gen III cylinder heads (PN 88958622). Intake runner volume is increased 250 cc's and the exhaust runner volume to 85cc. Both sets of hollow-stem valves are installed with a three-angle valve job. The intakes measure 2.05 inches (PN 12565311); the 1.55-inch exhausts (PN 12565312) are sodium-filled as well.

The top of the pads on either side of the number eight piston-pin boss were relieved to give the almighty reluctor wheel a hairbreadth clearance.		Just prior to the main cap torque sequence, Steve Moore applies washers and liberal doses of CMD #3 (Chicago Manufacturing and Distributing, Gagetown, Illinois) to the studs. The journals are already salved with Torco MPZ engine assembly lube.		Here's Moore ready to insert CP/Carrillo assembly. The small-end rod clearance is 0.0008-0.0010-inch. The pin bushings are bronze.
A paragon of bulletproof, the lower end is all buttoned up and ready to crank. Note how cozy the (notched) reluctor wheel is to the number 5 main-bearing cap. The rod side clearance is 0.019 inch.		The lower portion of the cylinder sleeves and adjacent block were relieved for counterweight clearance. A slot in each bulkhead facilitates oil flow.		Moore used a handmade tool to facilitate the bumpstick installation along with a good swabbing of Torco on every journal, then locked it in place with Z06 cam retainer.

ZO6 NO Screen Air Meter EngSpd STPTrq STPPwr F-Flow BSFC RPM Clb-ft CHp lb/hr lb/hph 1,225 424 99 45 0.477 1,570 428 128 58 0.476 1,984 469 177 78 0.464 2,400 480 219 97 0.471 2,792 512 272 119 0.466 3,208 544 332 140 0.447 3,611 552 379 164 0.461 3,985 555 421 181 0.459 4,410 574 482 208 0.461 4,825 562 517 213 0.441 5,215 539 535 228 0.456 5,614 503 537 222 0.444 6,029 458 526 223 0.457

85mm BBK Throttle-Body EngSpd STPrq STPPwr F-Flow BSFC RPM Clb-ft CHp lb/hr lb/hph 1,225 424 99 47 0.497 1,218 424 98 46 0.490 1,605 422 129 58 0.475 2,004 467 178 78 0.462 2,415 478 220 97 0.471 2,795 512 273 120 0.467 3,208 542 331 136 0.437 3,605 548 376 157 0.444 3,991 554 421 178 0.450 4,403 571 479 201 0.449 4,810 559 512 217 0.452 5,216 533 530 227 0.458 5,615 496 530 229 0.462 6,020 455 521 224 0.462

Katech's Steve Moore did the measuring, fitting, wrenching, and dynamometer work. We'd also like to recognize a couple of people on the Gen III program instrumental to this experiment: Bill Compton, the engine release guy and "Spark Plug Pat" Williams. The dyno exam was a series of quizzes that included a baseline and then the addition of a Donaldson air filter, a ZO6 air meter (without mesh), SLP 1.85:1 rockers, and a larger BBK throttle-body. Maximum production was 554 hp at 5,617 rpm and 577 lb-ft of torque at 4,399 rpm. The engine never made less than 420 lb-ft from 1,600 rpm up.

OK, here's the bad news: The complete puppy is expensive, say over $25K, but the state-of-the-art aluminum construction throughout is significant, and we wanted to be the first to extol its virtues. Yes, the old-school Bill Mitchell 454 small-block crate tested this month makes more power and torque for less than half the cost of the C5R project, but it runs a single-plane intake, Dominator carb, a hairier camshaft, and larger valves. There's no doubt that it is the bargain, but this LS-based buildup is clearly the wave of the future. Remember that the original small-block was shunned by the hot rod community when it first appeared.

 

The timing gear and chain (PN 88958608) are installed with a nylon tension chain damper (PN 88958607). The camshaft can be advanced or retarded 5 degrees via the Cloyes Hex-Adjust cam button (between first and second cam bolt).		The abbreviated Camaro windage tray and companion oil pump pickup tube were trial fit to ascertain clearance between the bottom of it and the pickup face ... it was enough.		Moore measured deck height and degreed the camshaft. In this case, all pistons are 0.004-0.005-inch in the hole. HTC specified D-shaped recess to create an effective quench area between the pistons and combustion chambers.
Since the alignment of the mating surface between the front and rear covers is critical to maximum oil-pan seal, Moore used SPX Corp. (Owatunna, Minnesota) alignment plates at either end of the block and installed the timing gear and crankshaft covers.		The primary function of the cast pan is to quell elements of noise, vibration, and harshness. A custom sheetmetal pan is also viable.		The combustion chamber volume in the CNC-ported LS6 heads is 65.8cc. Valve head diameters are 2.05- and 1.55-inch. Static compression ratio is 10.5:1.

1.85 SLP Rocker Arms
EngSpd	STPTrq	STPPwr	F-Flow	BSFC
RPM	Clb-ft	CHp	lb/hr	lb/hph
2,020	467	179	79	0.466
2,410	476	218	96	0.471
2,812	511	274	122	0.474
3,193	544	331	138	0.446
3,607	551	379	162	0.458
4,005	554	422	179	0.452
4,399	577	484	209	0.463
4,808	571	522	214	0.438
5,203	551	546	228	0.447
5,617	518	554	230	0.447
6,020	475	545	230	0.455
6,401	435	530	229	0.468

 

On the Katech dyno, the 450 was dressed with 13/4x26-inch headers and 3-inch collectors, 60-inch tailpipes, and Flowmaster 3-inch mufflers. The oil was Mobil 1 5W-30, the plugs Denso 20s, and the injectors 36-lb/hr (P/N 24508208). While the camshaft (PN 12480110) and LS6 intake remained constant, upgrades that were tested included a Donaldson air filter, a ZO6 air meter (without mesh), SLP 1.85:1 rockers, and a larger BBK throttle-body, seen in turn here.

 

What if you could stretch the inside of a standard LS1 cylinder block to advantage? HTC has a deal for you: a prepped cylinder case that incorporates bore sleeves to expand the standard 3.980-inch dimension to 4.065-inch. HTC's ductile iron sleeves open the bore from 346 to 376 ci with a stock stroke crankshaft. Offset grinding the factory crank (3.700-inch stroke) and incorporating Carrillo connecting rods tip the total to 384 ci. Hank's Alternative is also fitted with steel rather than cast-iron main caps and ARP fasteners. Though cores are becoming more available, a new LS1 block costs about $1,500; the privilege of having Hank's Alternative will double that figure.

The intake (shown) and exhaust ports are smoothed and the intake and exhaust runners flow 235 cfm and 215 cfm at 0.525-inch lift, respectively. Note the tapered valvesprings. Moore secures the LS6 rocker stand and 1.7:1 ratio rocker arms. SLP 1.85:1 replacements later provided an A-to-B power comparison. The stock 6.0L MLS truck block cylinder head gasket is 0.038-inch thick and displaces 11 cc's. Gaskets are not available separately; order gasket kit PN 89017253. Before the lifters go in, Moore drops the oil pump sensor shaft into the block. Moore lubed up the lifters and installed them in four-packs with the stock LS6 retainers to keep the lifters from rotating in their bores. The stock LS6 intake manifold employs a 75mm throttle-body and 36-lb/hr injectors (PN 24508208) from a supercharged 3800 V-6. We also tried a 85mm BBK throttle-body (right).

The bores of Hank's altered LS1 cylinder case (left) with ductile iron sleeves (unfinished) are substantially larger than the stock block. Billet steel main caps and ARP studs replace the cast-iron ones on the LS1 block. Total outright cost is $3,000 (new block, steel main caps, sleeves).