LT4 Encore

Since 1993, the Camaro has been the best bang-for-the-buck American-made performance car on the market. Even the base V-6 versions are decent performers in their own right. But the Z28 is the big favorite with most enthusiasts. Combined with the exceptional LT1 engine, it provides one of the best platforms going on which to build a killer modern-tech street machine.

As the fourth generation of the Camaro enters its fifth year, a strong historical perspective already exists that includes the 275hp LT1 getting a jump in its rating to 285 hp for 1996. Also new for 1996 was the SS package that included several tricks--most notable being a cold-air-induction system, 17-inch wheels and tires, a Hurst shifter, and an optional Torsen limited-slip differential.

While the 305hp Camaro SS built by Street Legal Performance (SLP) Engineering is likely the most potent Camaro ever built, there will now forever be a small asterisk to that statement in the form of the Camaro LT4.

After all the rumors and speculation about the LT4 finding its way into the Camaro, the fact is now a done deal, and the lucky souls who somehow got their mitts on one of these cars have themselves nothing less than the most awesome factory-built Camaro we've seen. The engineers at Chevrolet and SLP started with a 30th-anniversary Camaro Z28 SS, swapped out the LT1 for the 330hp LT4, and--presto!--the cat was out of the bag.

Although we extensively covered the LT4 engine in our Oct. '95 issue, a few basics on the engine easily explain its upgrades over the LT1. Much of the short-block remains similar to the LT1 except for the LT4 crank's undercut and rolled journal fillets. The crank is balanced for the LT4's slightly heavier pistons, which have reduced valve notches (3 cc's smaller) to bump the LT4's compression to 10.8:1 from the LT1's 10.5:1. The biggest changes were in the cylinder heads, where the LT4 has wider and shallower combustion chambers.

Lighter hollow-stemmed valves are bigger, too, with 2.00/1.55-inch sizes in the LT4 compared to the 1.94/1.50s in the LT1. Combine this with larger ports on the LT4 intake and a little bit more cam (LT4: 0.476/0.480-inch lift, 203/210-degree duration at 0.050-inch tappet lift, LT1: 0.447/0.449-inch lift), and the LT4's 330 hp comes up at 5,800 rpm--800 rpm higher than the LT1's 300 hp. Torque for both engines is 340 lb-ft, coming in at 4,500 rpm for the LT4 and 4,000 rpm for the LT1.

While the LT4 is a bit more high-strung, you can use every last bit of it, because the redline is now 6,300 rpm as compared to the LT1's 5,800 rpm. In fact, fuel cutoff doesn't occur until 6,400 rpm, which by then, you'd swear there was a DOHC LT5 underhood that was zinging to the moon. Combine all the attributes of the LT4 with the competent chassis of the current F-car body style, and the result is the best all-around performing factory supercar ever to come from the joint GM/SLP manufacturing program.

The car itself has all the standard updates of the SS package, and several options are standard with the LT4. These include a Torsen rearend, stainless exhaust manifolds, a Hurst shifter, and a Level II Bilstein suspension package that includes Bilstein shocks and progressive-rate springs. All LT4 SS cars have the 30th-anniversary package, which includes the orange stripes, white wheels, and 30th-anniversary interior appointments. The only SS LT4 options are a Level III Bilstein suspension package and BFG Comp T/A R1 tires, which are designed mainly for track use. Whether the standard Comp T/As or R1s are specified, they remain a P275/40ZR17 size all around.

Our time in the car was painfully brief as we wheeled around the area of SLP's Detroit offices. Putting the performance of the LT4 SS in terms we can all understand, SLP coins it "Viper territory for tens of thousands less." While track testing was definitely something we wanted to do, Detroit-area weather just wouldn't allow it. But the low-13-second numbers that SLP has generated are easily believable after having had a chance to feel the LT4's urgent power delivery on the street.

Unfortunately, there is a number that pertains to the LT4 SS that we are sad to report. It is, of course, 100--the scant number of cars that have been built and already sold. We have, however, settled on the fact that at least in today's times, we're all lucky enough to see this kind of outrageous factory performance being offered at all.