LS1 Refurbish - Tax Refund Rebuild

We rebuild, refresh, and re-arm an LS1 on the cheap.

From the June, 2012 issue of GM High-Tech Performance

By Frank H. Cicerale

Photography by The Author

Ghtp 1207 Ls1 Refurbish Tax Refund Rebuild 002

With the economy being as it is, every dollar gets stretched to the limit and then some. In the case of the performance hobby, the more bang you get for your buck, the better. It costs money to go fast and make power, but what if good old Uncle Sam gave you enough to do it instead of trying to beg, borrow, steal, and suck up to your better half? Such is the case with our subject on the following pages. If this black '98 Z28 looks familiar, then you're not mistaken as this fourth-gen F-Body has graced the pages of GMHTP in the past. However, low oil pressure has forced the Camaro to not roam the streets as intended, but instead sit in the driveway waiting for some much-needed help. Enter our tax refund rebuild.

The 80,000-mile Z28 is no stranger to the chassis dyno, the famed Raceway Park quarter-mile, or anywhere in between. The last time the Z graced the pages of GMHTP we installed a set of Dynatech SuperMAXX long-tube headers and a Corsa 3-inch exhaust. Throw in the SLP 160-degree thermostat, an SLP air lid along with a K&N filter, and a custom tune from East Side Performance, and the Z28 laid down 328 horsepower at the rear tires while pumping out 339 lb-ft of torque as measured on the shop's Dynojet chassis dyno. Not too bad for a stock LS1.

After a while, though, high RPM gear changes took its tool on the all-aluminum bullet, and it was left stranded in the driveway. With low oil pressure (15-20 psi at idle and/or cruising speed), the time had come to do the girl justice and rebuild the aluminum lung. In this day and age, though, rebuilding a fuel-injected LS1 can be a hefty task with an even heftier price tag. While we would have loved to throw some aftermarket heads and an intake on this bad boy as well as upgraded some of the other stock parts still holding us back, we decided to go another route, and that would be rebuild, refresh, and reinstall the motor with a small upgrade or two for as cheap as possible.

We loaded the Camaro up in a race trailer and towed it down to Tune Time Performance in Toms River, New Jersey, where Matt Hauffe and crew were up to the task of refreshing our F-body. The plan was quite simple. Matt and the boys would be tasked with removing the LS1 and putting it in the capable hands of Mike Tiedemann at MCP Competition Engines, who had several tricks up his sleeve to make the most out of our '98 block and "806" heads. Once the motor was sealed up, it would be slung back into the Camaro where the engine would be broken in before being strapped to Tune Time's Mustang dyno for some tuning.

Wounded Bullet

The one nagging question we had was why the engine started to lose oil pressure, without the death toll of a rod knock or the evidence of a spun bearing on either the crank main journal or the rod journal. "There really isn't an explanation for the engine to lose oil pressure other than it was getting tired and the clearances were a bit wide," Mike replied. "There wasn't anything wrong at all with either the main or rod bearings when I pulled it apart. The crank journals weren't scarred, so it was just a matter of catching it in time before something really bad happened." It is worth noting that the early '97-98 blocks do lack the open oil passage at the back of the block, which very well could have exacerbated the issue.

We felt safe in Mike's capable hands knowing that we should make considerably more power without giving up any streetability or durability. Step one was spec'ing a custom cam, ground by Comp Cams. The new cam is a single-pattern piece showcasing 228 degrees duration and .570-inch lift on both the intake and exhaust sides on a 116 LSA. "While this is what I would call a baby cam for the LS1, this cam profile will work great with the ported ‘806' heads and the stock LS1 intake manifold," Mike stated. "This should put the engine somewhere between 350 to 375 rear wheel horsepower, yet it will have great drivability, a broad torque curve, and a great powerband upstairs."

Of course going with a lumpier cam meant upgrading the valvesprings as well, so we went just down the road to Manley to pick up a set of dual valve springs rated to .650-inch lift as well as locks, retainers, and seals. Manley also supplied a set of chromoly pushrods. "To be honest, we could have gotten away with single valve springs, as they wouldn't have run into any issues when it comes to coil bind, but I like the dual valve springs for two reasons," Mike explained. "First, having dual valve springs is an insurance policy in case one breaks as you don't hang a valve and create havoc. Second, when it comes to the LS motors, valvetrain stability is key, and for my liking, the dual valve springs add to the valvetrain stability."

Since there was little to no engine damage, most of the stock short-block was cleaned up and reused. "For the power level this engine will be at, the stock stuff will be sufficient," Mike says. "I just cleaned up the block, gave it a quick finish hone, and then cleaned up the pistons, rods, and crank. We are reusing the stock valves, so I cleaned them up as well." Meanwhile, new rings, bearings, lifters, and a timing set, as well as gaskets and bolts from Thunder Racing, were needed to complete the refresh. Wherever possible GM replacement parts were used, such as the oil pump. We had considered going with a high-volume unit, but Mike assured us that it was not necessary given our power level.