Is Katech’s 525-hp CTS-V the g-Machine of performance luxury sedans? We wouldn’t want to be the AMG in the other lane to find out…

The face of Cadillac has changed. For those of you sleeping under a rock for the last two years, that means performance is back in a big way. The go-fast gurus within GM’s Performance Division have turned the new Cadillac CTS—itself a vast improvement over previous Cadillacs—into the velvet hammer otherwise known as the CTS-V. Hot rodders will appreciate the specs: a 400-hp LS6 (just 5 hp shy of the Z06 Corvette version) is stuffed into a substantially beefed up chassis packing stronger subframes, axles with six-lug hubs, a 3.73 rearend, 14.4-inch brakes with Brembo calipers and 245/45R18 tires. The list of hardware, however, doesn’t adequately convey the excellent dynamics of the CTS-V and its refined balance between performance and luxury. All the limp-wristed wine and cheese magazines are falling over themselves with praise for the CTS-V, and rightfully so—it really hauls ass without spilling the Grey Poupon.

The CTS-V goes toe-to-toe performance-wise with cars like the AMG55 and BMW M5, but at $50K, the V’s competitors are about 50 to 100 percent more expensive. Big deal, you say, for $50K give me a ’69 Camaro with a big-block crate motor and I’ll be on my way! That’s one way to look at it, but the folks at Katech, one of the world’s most respected names in LS1/LS6 performance, see it differently: stuff one of their world-famous race-winning big-inch LS6s into the CTS-V and watch the competition shrink in the rearview mirror. Katech calls their new creation based on the CTS-V the K-Series. “The real key is driveability,” says Warren Frieze—Katech’s vice president and general manager. “A guy with a K-Series can literally drive his family to the church on Sunday then get on the highway and humiliate anything on the road. That blend of quality and luxury along with performance is the key.”

For about $35K to $40K over the price of a new CTS-V (exact pricing hasn’t been set), Katech will do one of its K-Series conversion on your CTS-V at its Clinton Township, Michigan engineering facility, or for $85K to $90K they can buy the car for you and do the complete turnkey deal. At the heart of the K-Series is a 6.5-liter (396 cubic inches for us knuckle draggers) LS6 making 525 flywheel horsepower at 6,200 rpm and an extra-fat 510 ft.-lbs. of torque at 4,800 rpm. The 6.5L Katech mill relies on many theories developed from its winning C5-R GTS-class Le Mans effort. Caleb Newman, Katech’s director of engineering and program manager for Cadillac’s World Challenge race engines says, “There are some valvetrain dynamics that we borrowed from the racecar and a little bit of the cylinder head flow work. They’re different heads from the C5-R, but some of the improvements we found transfer over to the port so that we’re able to develop a 335-cfm LS6 port with real good mid-lift flow too.” In a car like this, getting a lot of air through a small hole is important in maintaining driveability, emissions and a broad power band. Incredibly, that’s accomplished with a modest hollow-stem 2.10-inch intake valve and a stock-sized 1.55-inch exhaust valve, both with a 30-degree back-cut and a competition valve job.

The cam in the Katech mill is a mild single-pattern street grind from Comp Cams which specs out to 226 degrees duration (at .050-inch lift) and .570 inches of lift using SLP 1.85:1 rocker arms. That’s tame by the measure of most builders of race-oriented LS6 engines, but it’s important to remember that the idea is to retain as much poise on the street as possible and maintain long-term durability. “Once you cross that line on high horsepower you get into the lopey idle, the jerky clutch and the wheelhop. This is at the edge of that but it doesn’t go over the line,” says Warren Frieze. Newman agrees and adds: “We really want to integrate the race stuff with the street stuff to make a good daily driver, especially one that will tolerate stop-and-go traffic and idle at the stoplight. Yet the torque curve will still pull real well down the straight. This is our first real attempt to integrate a street vehicle—typically we’re engine oriented, but we wanted to create a refined total vehicle package.”

The Katech stroker motor utilizes a production LS6 block which has been sleeved and bored out to 4.060 inches. Forged Carillo rods ride on a Callies 3.819-inch stroke forged crank and are topped with Katech 10.5:1 forged pistons. The CNC-ported LS6 heads mentioned above are fed by a FAST intake manifold with a ported LS6 throttle body. A set of Katech valve covers with a coil relocation kit makes things tidy while allowing easy valve cover removal for maintenance. A Katech belt tensioner, blueprinted oil pump, ATI damper, 1.75-inch stainless steel headers and a pair of electronically-activated exhaust cut-outs finishes the engine compartment. The ECM is then recalibrated on one of Katech’s engine test cells.

The entire package benefits from lessons learned by Team Cadillac’s Speed World Challenge team, which won the first race of the season at Sebring by a wide margin. Ironically, the margin of victory for driver Max Angelelli and Team Cadillac was so great that SCCA levied hefty weight and induction penalties on the CTS-V. Clearly, Team Cadillac, of which Katech is a pivotal part, has its work cut out for it during the remainder of the season, and that work on the race car should benefit the K-Series in the suspension department as well.

To that end, Katech has enlisted the help of some top drivers including Boris Said and Team Cadillac driver Andy Pilgrim. “Instantly, the thing that hits you is the power,” says Pilgrim. “Tremendous power. The K-Series has great torque out of the turns in third gear. I did a little of the development work with the CTS-V, and when I compare the two this car has a quicker feel to the steering. It’s more sportscar-like than sport sedan-like. When you turn the steering, you want to feel connected. The heavier the vehicle or the more utilitarian it is, the more you have to wait to feel the vehicle start to turn. This is more instantaneous. Going along with that—it’s no good having a car with good turn-in but without good suspension and good balance. Katech made some subtle changes to the shocks, the springs and swaybars. In order to put that power down, you’ve got to deal with the suspension to make the car go around corners quicker. Suspension is where you have to go to make those changes to use that horsepower.”

At the moment, the K-Series’ designers have deemed the stock LS6 clutch, T56 six-speed trans and the remainder of the CTS-V driveline adequate for 525hp. Likewise, the CTS-V’s 14.4-inch Brembo brakes are some of the largest ever seen in a large-scale mass-produced car—bigger in fact than the Z06’s.

With driver, the CTS-V tops out over 4,000 lbs., so there was reluctance on the part of Katech to stay with the stock 245/45R18 tires, especially with an additional 125hp on tap. As a result, the K-Series now rides on larger 255/35R19 tires (on 8.5-inch rims) in front and 275/35R19 (on 9.5-inch rims) in the rear. According to Fritz Kayl, president and technical director of Katech, even larger tires would be preferable given the power level and mass of the car, but that isn’t practical. “With the stock CTS-V, you hit the apex and nail the throttle and it would track out right. With this thing, you have to modulate the throttle or you will spin the car. The 275 tires are as large as we can go without extensive modifications.”

PHR recently had the opportunity to sample Katech’s K-Series at GingerMan Raceway near South Haven, Michigan. This technically challenging 11-turn 1.88-mile road course generally yields lap times which are slower than tracks of similar or slightly larger size. In short, it’s a slow, cut-and-thrust track which emulates the street very well.

Prior to being modified, our test car was brought out to GingerMan for some baseline evaluation. Most of the test driving was performed by Katech’s senior development engineer, Stephen Chue. The quickest laps were in the 1.47 range using the stock tires, suspension and engine tune. This figure improved in a subsequent test session in which the stock CTS-V suspension, tires, springs, and swaybars were evaluated with the new 6.5L engine. This configuration (with Chue driving) yielded lap times in the 1.43 range. At that same session, veteran race driver Boris Said also drove the car and turned laps in the 1.39 range.

Finally, our test day rolled around and the Caddy had upgraded Penske single-adjustable shocks, Hypercoil springs and Eibach swaybars. Tire size was increased to 255/35R19 all around. (The larger 275/35R19s were left off the rear due to unresolved clearance issues but put back on for our photo shoot.) In this trim, Chue turned laps in the 1.40 range—a three-second improvement from the stock suspension/tire combo and a full seven seconds faster than the stock CTS-V. Folks, that’s a monumental improvement on a track like GingerMan. To help with the tuning and evaluation, Team Cadillac driver Andy Pilgrim was on hand and stopped the clock at 1.37. Pilgrim’s consultation on the project resulted in a slight increase in the rear spring rate and some minor adjustments to the shock valving for this early production car.

My own lap times, which are perhaps more representative of the novice track junkie, were in the 1.49 range. It was interesting to compare notes with Pilgrim, who besides coming in second at the Speed World Challenge opener in Sebring, also came in second place in last year’s 24 Hours of Le Mans in the GTS class with a Corvette C5-R. We’re talking about two people who are at opposite ends of the skill spectrum, which is probably a good thing since most potential K-Series customers are closer to this author’s skill level.

The Katech engine imbues the 4,000-lb. Caddy with an ocean of torque at virtually any rpm. It didn’t seem to matter if the shifter was in second, third or fourth gear on corner exit—lap times were always within a few seconds. Third gear seemed best, but the power curve was very forgiving. We also tried leaving the shifter in third for shorter stretches where it might’ve been better to upshift to fourth, but the engine seemed perfectly happy in either gear.

With this much power, so much weight and such a small tire, it’s really important to find yourself at the right apex when you pour on the power. Turn in too soon and the power will have you headed for the grass. I felt comfortable with Katech’s relatively soft suspension, as did Pilgrim. The transitional balance of the Caddy is far more forgiving with this sort of set-up and most drivers will find it easy to step back a notch or two from the edge if needed. A modest amount of body roll helps plant the loaded tires as opposed to a stiffer suspension which would put all four tires into a drift.

As for the brakes, I felt them to be significantly over-matched to the engine’s 525hp—especially in light of the vehicle mass. On several occasions I found the pedal soft and in danger or bottoming out from brake fade. As a side note, when this happens, it makes it virtually impossible to heel-and-toe downshift given the throttle’s elevated position in relation to the brake pedal. Pilgrim, however, was far more parsimonious with the brakes, carrying much more speed through the corners and setting the car up in a full power-on drift through the apex. We doubt most customers will have that kind of skill and by extension we think they’ll be putting in a call to their favorite brake vendor to beef things up a tad.

The same goes for the Michelin Pilot tires, which were perhaps unfairly pushed beyond their intended range. For on-track use, a 255 cross-section tire is entirely too narrow for a 4,000-lb. car, regardless of power level. Using a street compound and applying 510 ft.-lbs. of torque to it makes it that much more difficult. If this were our car, we’d pull off the Michelins for racing, change back to an 18-inch rim for some more sidewall compliance and throw on some R-compound tires by Nitto, Kumho or Hankook. The consummate pro Pilgrim, however, was nonplussed by the screaming quartet of tires and delighted in the prolific drifting capability of the Caddy.

In Katech’s defense, the tire size issue is for all intents a moot point. There simply is no more room for a bigger tire, so the alternative is to dial back the power (we vote a resounding “NO!”) or live with a lifetime of lurid tail-out drifts. Those customers who elect to track their K-Series should be advised to set up a wholesale account with their favorite race tire supplier. In as-tested form, we found the stock CTS-V seats barely adequate for the track work we were doing. On the highway, however, these provide a great balance between comfort and lateral support. For comparison, we had at our disposal a heavily tweaked BMW M3 with a sequential gearbox and racing seats, which turned out to be the ultimate in driver support. The Bimmer’s hard aftermarket suspension rode like a go-cart and inspired far greater confidence, but was practically unusable for every day driving.

Based on our seat of the pants, we’d guess the K-Series to be good for 12-flat ETs in the quarter mile. Forget about power shifting anything but fourth gear—you’ll find yourself headed for the guardrail in short order. A Nitto Drag Radial would help keep tirespin under control—just barely.

By the end of the day, all who drove the K-Series Stage 1 were irrevocably addicted to the sedan’s power. This is one intense g-Machine and this day will not be forgotten by us for many years. It should be noted that our foibles with the K-Series are traits that would only manifest themselves on the toughest of road courses—not on the street. For those who anticipate heavy track use or who decide later on to track their K-Series, there are more speed goodies coming down the pipe from Katech. Vice President Warren Frieze was optimistic about the possibilities: “Our next stage we’re looking at spoilers, carbon fiber pieces, different wheels, exhaust…there’s a lot of options that we haven’t taken that next stage on. We want to roll it out and get a feel for it from people. We’re already getting feedback from Andy Pilgrim and members of the press. At some point there is the issue of how much power can the car handle, but within that envelop you can explore the possibilities within that.” For those looking for the ultimate in a domestic luxury g-Machine, we think Katech’s K-Series is the hands-down leader. There just simply isn’t anything on the horizon like it for anything close to the price. Cue Robert Plant here…