The engine, as installed in the Australian Holden passenger car range (Commodore sedan, wagon and ute, Statesman/Caprice limos and Monaro), is somewhat down on power compared to the engine in C5 Corvette and F-body cars, with a rated output of 220/225kW.
This is generally regarded as being for marketing reasons - the previous Australian-made Holden 5.0-litre cast-iron V8s (similar to the 305TPI Chev V8) had outputs of 179, 195 and 220kW (5.7-litre version) and to go too far, too fast with power outputs may have been seen as a politically bad thing...
This quoted output climbs to 250/255kW for the higher-performance HSV versions (Maloo ute, ClubSport and Senator sedans, Grange limo) with intake, exhaust and minor factory management changes to fuel and ignition parameters. The Australian market requirement of being able to tow caravans, boats and horse floats close to two tonnes using low-octane 91RON fuel also has bearing on Holden's conservative state of tune compared to its ultimate factory output in the US market C5 Corvette.
Apart from some significant reliability issues (the related problems of piston slap and oil consumption in some engines being the biggest cause for concern, as far as we can ascertain) the engine has been the starting gun for a new race of performance development. Straight out of the blocks came the simple 'bolt-ons' of exhausts and cold air inductions, freeing up a few horses. Soon after, ported/modified MAFs began to proliferate, tricking the factory management into spinning the dyno rollers a bit harder, but without packing out the low-end torque to any significant degree.
With its mild cam timing, the LS1 relies as much on capacity for its power output as it does on breathing. In short, it's a large, low-stress engine with plenty more performance potential from its standard head and intake hardware and without having to spin the engine any faster.
Australian cam manufacturer Crow Cams has undertaken a development program over the last year or so to develop a cam that considerably increases the bottom-end pull and throttle response of the LS1 as well as packing out its top-end power without the need for cylinder head modifications or stressing the components beyond the factory rev limit. The result is a stunning increase in 'real-world' driveability and performance.
The Upgrade
Sam at Hornsby Prestige and Performance in the northern suburbs of Sydney was commissioned by Crow's development doctor to install the final prototype cam into an HSV Clubsport R8. The higher-performance HSV's mechanical specs differ from the standard issue Holden product by having lower 3.73 diff gears behind its six-speed gearbox, in place of the base model's 3.45s. (Due to the large increase this seemingly modest ratio change has on performance - for the weight of the car, the Holden's T56 six-speed and diff ratio combination is too tall for both acceleration and fuss-free top-gear cruising - and the fact the management system changes are calibrated to this diff ratio, it is recommends these diff gears be fitted before the conversion.)
The cam installation begins with the PCM being removed from the car so that it may be posted away (an air express bag is provided!) for its new program to be loaded. Then comes removal of all engine 'dress' such as engine covers, air cleaner, MAF pipe, radiator and coolant hoses. Coil packs, rocker covers and water pump must be removed next. The LS1 uses current-generation silicon beaded gaskets for all mating surfaces that make disassembly an easier task than with older engines with conventional gaskets. Chev designed the engine this way to cut down on assembly time when the engine is manufactured, but for us in the aftermarket, it means quicker and cleaner modification - gaskets come apart without sticking and often don't require replacement. Despite what you see here, and unlike most other V8s, it is not necessary to remove the LS1's intake manifold and associated hardware for the installation of the cam (other than removing the throttle body for a bit more room around the front of the engine). We'll explain why later.
The real work began with the removal of the front pulley on the engine. It's a press-fit (ie interference) onto the crank snout without a key way. So rather than simply sliding off with a minimum of fuss, the pulley must be tugged with a large puller - larger than the one you see here. After struggling with this one for most of an afternoon, Sam spent the money on a bigger puller more suited for the job. Once again, Chev's choice of this production technology is a decision based on reduced manufacturing cost (no keyway to be machined in the crank or pulley, lower-spec tolerance for the interference fit of the pulley on the crank) but this time, there's no benefit for the aftermarket like there is with silicon gaskets. Getting it off was a tough job.
With water pump and pulley gone, the timing cover can be removed to expose the cam gears and timing chain. Also behind the timing cover is the oil pump that swings off the front of the crank. Its removal is not as simple as it seems. The oil pickup pipe must be disconnected from the oil pump and that was devil of a job on this car, requiring the sump to be unbolted from the bottom of the crankcase and its front edge lowered to give access to the two tiny bolts that hold the pickup into place on the pump. What at first looked like an easy job - like getting the pulley off - once again tested the mettle and patience of all who were present. With the pickup disconnected, the pump slid off the crank.
Then it was the timing chain and gears' turn. The timing gear is held to the cam by three bolts. Once out of the way, the gear drops off (no tight interference fit). The LS1's timing chain is a single-row item that had, for us, a surprising amount of slack in it for an engine that had turned just on 10,000km. It may have been within factory tolerance - we didn't check - but compared to other V8s we've pulled the chains from it seemed a little loose.
That left the crank timing gear. Unlike the crank pulley, the timing gear is a transition fit (not too loose, not too tight) on the crank nose and is positively keyed to the crank. A light tweak with a puller and it was off. The whole set was to be replaced with a Crow double-row timing chain package, so it was into the bin with him!
The LS1 uses roller hydraulic lifters than remain in place for the cam change. That's why the intake manifold may remain in place for the cam change. In fact, unlike a cast-iron oldie V8, it's impossible to access the lifters through the valley or remove them from the engine without removing the heads. They are buried in tunnel-like bores under the pushrod holes in the head. However, they must be raised in their bores to allow the cam to be removed and replaced. How the hell is this achieved? Either remove the heads with the engine in the car (as recommended by Chev/Holden); pull the engine and rotate it and let gravity do its job (well, it was one idea!) or do what Sam did: spend a few hundred bucks on some super-duper, super-small magnets and glue them to the ends of some metal rods so the lifters could be lifted clear of the cam.
The use of Sam's special magnet jobbies (part number LS1SAMBITS) made it relatively easy to raise the roller lifters clear of the lumps and bumps along the cam to allow it to be pulled from the engine. Roller followers (that operate the pushrods and valve train by rolling over the cam's profile) generally don't require replacing with new cams such as this, unlike old-tech flat-tappet lifters (that operate by sliding) that must be replaced with new or freshly-machined items so that they may 'bed-in' to the new cam's surface. It all adds up to make replacement of cams in a roller-lifter-equipped engine such as the LS1 (or EFI Ford Windsor) a cheaper and potentially more reliable proposition.
The Crow cam went in, the heavy-duty replacement Crow timing set went on and the engine was reassembled. Naturally, Sam double-checked the installed timing of the prototype cam.
Before the rocker covers and the ignition components went back on, attention turned to the replacement of the valve springs with Crow's upgraded units. This can be achieved relatively easily with the heads on the car by pressuring each cylinder with compressed air, to hold the valves closed during removal and replacement of its spring. The springs are an integral part of Crow's upgrade package. Like the original LS1 design, the heavier Crow springs are a 'beehive' design that are more resistant to valve train harmonics, and therefore valve float at high revs.
Previous to the cam installation, this car had been fitted with intake system modifications of K&N air cleaner element, aftermarket big-bore MAF-to-TB pipe and under-bumper cold air feed from ChipTorque. It is Crow's opinion that the MAF-to-TB pipe is of questionable worth, but the standard Holden airbox intake - with one small pipe drawing air from just below the bonnet line and another, larger, pipe drawing from behind the front bumper - is simply too small to let in enough air for 300kW. A Monaro unit, combined with a larger hole in the air box base, is a quick 'factory' fix. There has been plenty of discussion around the planet regarding the worth of mass airflow (using an air flow meter to measure air consumption of the engine) vs speed density (using manifold vacuum vs revs - no airflow meter) management of high-power LS1s: The Crow package retains the standard-screened, unported, absolutely stock unit to deliver its performance level and retain Australian emissions compliance.
The exhaust, too, was modified and, like the diff ratio change, is another must-have for this package to deliver its performance outcomes. The extractors are DeFillipo four-into-ones with a primary length of 36 inch and diameter of 1¾ -inch. It breathes into a pair of stock cat converters and a dual 2½ inch X-pipe system that uses two high-flow mufflers and a twin-in, twin-out rear muffler. SureFlow exhausts in Ingleburn, NSW was responsible. This system is drone-free inside the car but with the sharper cam, endows the Clubby with a harder-edged, jeez-that's-nice exhaust note.
The Results
I spent time driving this car during its couple of weeks of engine management calibration to provide some "outsider's" feedback for development and I can tell you that it's absolutely 'factory' - in fact better - in all aspects of idle control, tip-in throttle response and low-speed drivability. Huh?
Well, I reckon the ultimate test of a high-performance car is how well it drives in low-performance situations. It's easy to get the wide-open throttle stuff close enough to correct and spin the wheels to a big number but it takes a lot more effort and experience to tune a car to behave with docility. The Crow package offers a rock-steady idle and a lot less mush at low speeds than a standard LS1 around-town.
But, enough about idle - you don't do all this work for nothing! When the road ahead clears and the spirit beckons, this package is almost astonishing in its sweet power delivery and willingness to 'get on with it'. Independent testing with electronic equipment resulted in 13.7 seconds and 110.7mph for the 400m sprint. The owner reports that there was axle tramp (in standard trim, this particular car was prone to tramp compared to others, he reckons. Later inspection found a damaged diff mount) and wheelspin for approximately 50m and the 60-foot time was a very slow 3.4 seconds. His previous HSV was capable of a 1.8. That high terminal speed and the extra potential in the 60-foot time indicate a fuss-free 12-second supercar. And after driving it, I'll stretch my neck out and say the engine - internally standard except for the cam - is a better overall package than HSV's 300kW C4B unit. There's something about a well-designed upgrade package, such as this one, that the figures 13-something and 295hp just can't communicate.
And as you can see from the graph, the improvement in power is both even and strong - just what you'd expect with more torque right through the rev range.
After a couple of months on the road, the owner of this car, Jase, is rapt.
"It's better everywhere. It'll pull fourth gear from 50 kays with no worries. Even at 60 kays in sixth gear it's more driveable without rooting around, not that I do that much.
"Fuel consumption is better than standard. It does easy sub-10s on a trip and high 14s around town. Even flogging it, I honestly haven't cracked a 20 yet."
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