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
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.
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.
1 With only 20psi of oil...
1 With only 20psi of oil pressure at speed and even less than that at idle, it was time for a tax refund rebuild. After towing the Camaro to Tune Time Performance, Matt Hauffe and the crew had the engine out of the car in a day. The entire engine and trans assembly stayed mated to the K-member, and came out from under the car.
2 Tune Time drained the fluids...
2 Tune Time drained the fluids and stripped the engine down to a long-block in order to be dropped off at MCP Competition Engines. Once there, we would be able to crack it open and find out just what was going south internally.
3 Once the engine got to...
3 Once the engine got to MCP, Mike Tiedemann got to work tearing the LS1 apart. We would be saving the crank, rods, pistons and such, as well as looking for the cause of the lost oil pressure.
4 Here you can see a slight...
4 Here you can see a slight bit of scarring on the Number 6 rod bearing. It wasn’t enough to cause any significant damage, but according to Mike, it was probably a reason why the oil pressure was starting to dip.
5 Thankfully there was nothing...
5 Thankfully there was nothing wrong with the crank journals, so we didn’t have to cut the crank down. Mike just cleaned it up and got it ready to be put back in. The factory nodular iron crank is quite beefy, and more than capable for our stock block, naturally aspirated needs.
6 With this being a budget...
6 With this being a budget build, aftermarket cylinder heads and even LS6 heads were out of the question. Besides the initial cost of the heads themselves, we’d also need new valve covers, coil brackets and other accessories to convert. Not to worry though, as Mike stated that doing some port work on the stock “806” heads would do wonders. Here you can see how Mike opened up both ports, especially the top port, that being the exhaust. Mike stated that these heads should be around 290-295cfm (a 25-30cfm improvement) on the intake, and about 240cfm on the exhaust.
7 Mike cleaned up the rotating...
7 Mike cleaned up the rotating assembly, and laid everything out for assembly including Clevite rod bearings (PN CB663P) and GM piston rings (PN 88984247). The fresh piston rings were installed with the top ring gap set at .018, .026 for the second, and .022 on the oil ring.
8 The block was hot tanked...
8 The block was hot tanked (to clean it) and then inspected before Mike put a quick “puff hone” on the cylinders with a 501-grit stone to true up the bore. The ’97-98 block has thin cylinder liners, but since we were reusing the stock pistons that wouldn’t be an issue. Final bore size was 3.898-inches, meanwhile the main caps (.0018-.0020) and lifter bores were all within factory spec and did not require machining.
9 Before Mike assembled the...
9 Before Mike assembled the heads, he cut (30-deg.) and back-cut (45-deg.) the stock valves, and performed a quality four-angle valve job on the seats. Intake: 38, 45, 60 and 70-degrees. Exhaust: 36, 45, 60, and 70-degrees. The 36-degree opening angle on the exhaust improves low-lift numbers.
10 There was no way we were...
10 There was no way we were putting this engine back together with the stock 202/210-duration cam, so Mike spec’d a custom grind from Comp Cams to work with the ported heads. Like the stocker, the cam is ground on a 116 center, but it is a single-pattern cam showcasing 228 degrees duration on both sides and .570-inch lift. According to Mike, this cam is a great performance grind, will get good mileage, have great drivability, and will make great power. Of course the increased lift meant we’d need a quality set of springs, so we ordered these dual valve springs from Manley as well as locks, retainers, seats, and seals.
11 Before Mike got to putting...
11 Before Mike got to putting the short-block together, he assembled each cylinder head one at a time, one valve at a time. The springs, which are rated to .650-inch lift, were installed at a 1.750-inch height.
12 Mike started reassembling...
12 Mike started reassembling the short-block by lubing up the cam and slipping it into the block. After that, he dropped in the crank and main caps sandwiching Clevite bearings (PN MS2199P).