Edelbrock LT1 Performance Package - The Equalizer

Our test mule is a high-mileage '94 Z28 with an automatic transmission. With 125,000 miles of use, it's no spring chicken, but it is representative of what's out there in the $4,000 to $8,000 range. The stock LT1 long-block had no modifications prior to our Performer LT1 install and test, with the exception of Hooker 1 5/8-inch shorty headers, an aftermarket cat-back exhaust system, SLP cold air induction and a Holley throttle body airfoil. For a complete list of all mods done to our mule (including non-engine mods) check out the handy sidebar.

Other than development cars at Edelbrock, Popular Hot Rodding was the first to install the Performer LT1 for media evaluation. They didn't want to mess it up, so they turned to one of the top late-model GM tuners in Southern California--Harv's Auto & Dyno Tune in Whittier. Harv St. Mary and Sean Baisden are no strangers to fuel-injected GM machinery, and LT1s are an old favorite with them. After taking a tour of the shop and seeing the level of work performed there, we were suddenly in our comfort zone. Sean Baisden, who would be doing the work on our Camaro, is the owner of several awesome GM machines, including an 11-second road-raced LT1 Corvette, so they knew they were in good hands.

We should also note that they took the opportunity to change the oxygen sensors over to new Bosch units. Also, Edelbrock specifically specifies Champion RC-12YC plugs, which they complemented with a new set of Bosch spark plug wires. Since they didn't feel like chasing leaks later on, they used a complete gasket set from Mr. Gasket. As a precaution, they also replaced our worn timing set and pushrods with upgraded pieces from Comp Cams. The final piece of the puzzle was a throttle body swap. The factory 48mm air valve was replaced by a larger 52mm unit from Edelbrock. This swap meant eliminating the Holley airfoil because the Edelbrock unit has a cast-in airfoil.

After making a few baseline dyno tests with the stock motor, Baisden spent the next two days pulling down the engine dress, intake manifold, cylinder heads and cam, then installing the new pieces. This can be done over a weekend by the do-it-yourselfer with a well-stocked tool box, but if you don't have much experience with late-model fuel-injected cars, this might be better left to seasoned pros like those at Harv's. Fortunately, you won't have to get into computer reprogramming like most blower kits, turbos or stroker motors, so your angst will be limited to the knuckle-scraping variety.

As much as they wanted to dive into the cylinder heads, they resisted the urge to work them over. Under normal circumstances, it would be a good idea to do a simple bowl job and gasket match on these heads before bolting them on, but they really wanted to see how good they were right out of the box. Obviously, we were excited to fire it up for the first time, and the Performer LT1 heads and cam didn't disappoint.

Once he was finished checking for problems and leaks, Baisden gave the LT1 a good bill of health. A check of the idle vacuum showed 11 inches versus 18 inches for the stock long-block. A quick drive around the block showed that most of what they wanted to know--they had a radically sharp throttle response off idle and a noticeable amount of additional pull through the midrange and top end. Without the R-compound Nittos, there would've been serious rubber laid on Whittier Boulevard! It's a good thing the brakes still worked great with 11 inches of vacuum (a big plus given the plans to add some serious SSBC brakes down the line).

The only other thing needed was to know how much power? With the stock long-block, power peaked at 5,600 rpm and made 249hp at the rear wheels. If that sounds low, keep in mind that this is an automatic trans with a 2,800-rpm stall converter, so there is more than your average amount of driveline loss. Also, all runs were performed in second gear in order to keep the trans from downshifting mid-run. This typically holds power down because parasitic drag is greater in second gear. What's important is the relative increase, not the peak number. With the Performer LT1 heads, cam and throttle body, power peaked at 5,900 rpm and made 283 horsepower. That's a peak-to-peak gain of 34 rear-wheel horsepower.

Better yet is the fact that horsepower was up at all points in the power curve, except at 3,700 rpm where our runs began (it was down 1 hp at that point). Power was up 46hp over the stock heads and cam by 6,000 rpm, but they suspected a lot of that gain was because the old valve springs were worn out. Still, we're guessing there are a lot of high-mileage LT1s out there that could benefit from a better set of heads with fresh valve springs.

As you might expect on a motor with a hard-hitting torque converter (our Precision Industries Vigilante has to be one of the best out there) torque peaked down low at 3,700 rpm for both stock and Edelbrock combos. By 3,800 rpm, however, The Edelbrock Performer LT1 took the torque lead and by 6,000 rpm was up a whopping 40 lb.-ft. Clearly, the Performer LT1 intake port is not too small for a 350-inch LT1! They suspect there is even more power on the table with some rudimentary tuning via LT1 Edit, but we thought it better to let the out-of-the-box numbers do the talking. If some tuning is done later on, it will probably be to raise the idle speed and clean up the emissions for inspection time, but until then, they're just fine with the mule's street manners.We'd have to say the Edelbrock Performer LT1 combo is a homerun. It's relatively simple to install, the American-made parts fit well, the increase in power is in line with the cost of the parts, driveability on the street is excellent and reliability has proven to be good. For those stroker or blower customers wanting even more, keep your eye peeled for some bigger offerings down the road. If this is any indication, we can expect some more great news from Edelbrock.