The short coolant line (PN...
The short coolant line (PN 30041K) and rear block-off blocks (not seen, bolted to the rear side of the heads) will be installed just as the factory did to fit the LS6 intake to the LS engine. Even without the line flowing coolant to the rear of the heads, GM engineers didn't see any adverse effects in keeping the hot LS6 cool.
On The Dyno
With the T/A safely strapped to the SuperFlow dyno, SLP's director of engineering, Hank Daniecki, put the hammer down. Peak power was now up to 349 rwhp and peak torque was 352 lb-ft. The headers dramatically broaden the power curve. Now there's over 300 rwhp from 4,500 to 6,500 rpm. Before the headers, 300-plus rwhp was only between 4,800 to 6,000 rpm. Peak at the flywheel was up to 418 hp. This had us surpassing the 400HP Pacs' rating, which was our goal.
Ironically, without the LS6-intake swap, we would have just made it to the 400hp mark. Now the T/A can proudly wear its 400HP PerformancePac badges!
Strip-Test Prep
When the Poncho was on the lift receiving its headers, we decided it would be wise to install SLP's bolt-in subframe connectors. With the added power and sticky tires, we wanted to stiffen the chassis to prevent possible creases in the quarter-panels. On the 30-minute ride home, the Bird felt much more solid (like a full-frame car), without any T-top or dash rattles.
Next, the Nitto Extreme Drag Radials were mounted (Shore Wheels, Tuckerton, New Jersey) on the stock 16-inch wheels. Afterwards, tire spin was virtually nonexistent on the streets. Pre-Nittos, out of the hole, and on a WOT one-two up-shift, the car wanted to go sideways and off the road. Now prepared with the SLP frame connectors and new Nittos, it felt safer and more surefooted for our return to Raceway Park.
It was a hot and humid, early-October, Indian Summer-type day upon arrival at E-town, New Jersey. The temperature rose to 82 degrees, which is not conducive to low e.t.'s as compared to cool 50-degree air. We popped the hood and flipped the fan switch to let the LS1 engine cool down from the 90-minute ride. Tire pressure was adjusted to 40 psi for the fronts and 22 psi for the rears. In past testing, we have found drag radials work best with anywhere from 18-24 psi, depending on vehicle weight.
Due to the added weight of the frame connectors (30 pounds), we were surprised when the scales showed us a test weight of 3,690 pounds (test weight for the 350 and 375 Pacs was 3,680 pounds). At a test weight of only 10 extra pounds, we figured the weight savings must have been from the lighter headers versus the heavier cast-iron manifolds because even the fuel level was the same.
We swapped all the parts (injectors,...
We swapped all the parts (injectors, fuel rails, brackets, hoses, and throttle body) from the LS1 manifold to the LS6 without any modifications. (It's important to attach the power-brake hose, shown connected to the vacuum port, at the back of the manifold.) The back of the manifold also has a connection for manifold vacuum and the MAP sensor. We will connect them before the intake is bolted in place, because once its bolted on, we can't get our hands back there.
After a one-hour cool-down, we went to the line with the needle just coming off the 160-degree mark. This was after a 6-second burnout to heat up the new Nitto drag radials. Off the line, I looked at the board and noticed a decent 1.96 60-foot without any hint of tire spin. The T/A boogied down the track. On the return road, I looked up and saw the score, a 12.83 at 107.77 mph. We pulled right back up to the line for our usual minute-later hotlap and slowed to a 12.95 at 106.83 mph.
Though we were expecting mid-12s, we shouldn't with the lousy air (for the time of year). The weather conditions were possibly costing us a few tenths and mph. We made two more pairs of passes with cool-downs and couldn't manage to go quicker. We'll just have to persuade the T/A's owner to get to the track when the air is cool and crisp (35-55 degrees).
Conclusion
Installing and testing each stage of SLP's PerformancePacs proved to be well worth the effort. With better, cooler air, mid-12s may have been possible, as stated in SLP's catalog for its 400HP Pac. The LS6 intake and SLP headers proved themselves as very effective power producers. Now with over 400 flywheel horsepower, the owner can remain fearless if a new GTO pulls up alongside her SLP-equipped T/A.
Once the intake was installed,...
Once the intake was installed, we covered the motor and cut the EGR tube with a handy hacksaw right below the hat-mount ridge. Then we deburred the shortened tube before installing it into the brass fitting. (This photo is a mockup. Always cut away from your fingers and use protective gloves, or hold the item with a clamp instead of your hands if a vice can't be used.)
The LS6 intake looks virtually...
The LS6 intake looks virtually stock on the LS1 engine except for the brass fitting and nut that enables the use of the EGR system. We also bypassed the throttle-body coolant line to keep the hot coolant from flowing through it. The 5/16-inch rubber hose that goes from the radiator can be extended and connected to the coolant line we installed earlier.
Now that our LS1 is blessed...
Now that our LS1 is blessed with the stellar LS6 manifold, it's good to see the obstructive EGR tube out of the picture. With the EGR tube removed and the LS6 intake installed, airflow volume will increase and be smoother.
Another spin on SLP's dyno...
Another spin on SLP's dyno showed us a whopping 17-rwhp increase (310 to 327) from the LS6 intake. This brought us from a 372 at the flywheel to 392. Now we were beyond the 375HP Pac's rating. The additional lift and duration from the '98-'00 LS1 cam is claimed to add 5-10 hp.
SLP's 400HP Pac includes everything...
SLP's 400HP Pac includes everything we previously installed and tested (350 and 375HP Pacs) plus the company's tuned-length, long-tube, stainless steel headers and cool 400HP PerformancePac fender badges. The headers are ceramic-coated inside and out for extra-long life and will look good for years. Included is a power-matched, 3-inch Y-pipe. Also shown and required to connect the headers to the Y-pipe are the high-flow catalytic converters.
The header-install kit is...
The header-install kit is also required to hang the headers. Multi-layered steel header gaskets, EGR gaskets, 3-inch Torca exhaust clamps, 02-sensor extension harnesses, and heat-shield tubing for the passenger-side wiring harness.