writer: Randall D. Allen
photographer: Randall D. Allen
Whether it's reworking the ignition curve on a 400ci Ram Air III or cutting down the EGR tube on an LS1 displacing 346 ci, Pontiac owners love to tweak their machines to extract additional power. In Part I of our LS1 bolt-on bonanza, a group of engine and induction modifications for the '98-'02 LS1-equipped Firebirds were introduced.
For the LS1 faithful, the "free mods" were created when innovative owners started pulling parts and experimenting to see if the changes would net power gains. Since the LS1 responded so well to minor bolt-ons, the quest for additional power was on, and in no time a set of "cost effective mods" were developed that are widely embraced by the community for their bang for the buck. For the '98-'00 LS1, the swap to an LS6 intake manifold is very popular and typically nets the owner around 10 rwhp on a stock vehicle. The remainder of the free and cost-effective mods can be applied in an afternoon and provide significant power increases for the money and time spent. If you have a free-flowing exhaust, a hotter cam, and/or port work done to the heads, even more power can be produced.
Kadin Betts of Carrollton, Texas, owns and drives daily the 57,000-mile '99 T/A that was upgraded for this story. Real Perform-ance Motorsports (RPM) in Lewisville, Texas, performed the installation and testing of the modifications.
In the first installment, the stock LS1 intake manifold was removed, and the SLP Performance-sourced LS6 intake manifold was prepared for installation by transferring-among other items-the MAP sensor, fuel rails, EVAP canister, lines, and PCV valve. Since the owner wanted to retain full EGR functionality, he purchased a used SLP manifold and placed a call to SLP for a set of new EGR O-ring gaskets. To purchase a new SLP manifold with EGR function-ality, ask for PN 30041 that retails for $499.95. The manifold includes a predrilled hole and EGR tube. Alternately, the manifold can be purchased from SLP without the EGR provisions for $399.95 under PN 30039. Both manifolds come complete with the required pipe assembly, covers, and seals.
Completion of the LS6 intake manifold installation on a '99 Trans Am follows, as does an aftermarket lid and ported throttle body install. And, of course, most of the free and cost-effective modifications will be performed. The airbox mod, however, will not since this Bird is subjected to the ele-ments each day. Subsequent dyno testing will verify the results of our efforts by comparing baseline pulls with those done after the mods. We're shooting for 20 rwhp. Will we make it?
Recommended Parts and Supplies
- SLP LS6 manifold (with EGR provisions), PN 30041, $499.95
- SLP LS6 manifold (without EGR provisions), PN 30039, $399.95
- GM manifold gaskets, PN 12533587, $76.30
- GM LS6 intake manifold, PN 12561269, $851.46
- GM front pipe assembly, PN 12581213, $39.00
- GM throttle-body gasket, PN 12552542, $12.06
- GM covers - Qty 4, PN 12570678, $5 each
- GM seals, PN 12551933, $6.28 each
- Shaner S2 throttle-body, exchange, $119.95 satin finish, $139.95 polished
- Motorsports Technology Inc, carbon-fiber-look airlid, $129, K&N filter $49
Cost-Effective Mods
- Aftermarket Air Filter - Factory-style paper air filter replaced with a drop-in filter utilizing a cotton gauze or foam element to increase airflow, $25-$50
- Aftermarket Airbox Lid - Lid replaces factory upper airbox assembly to increase airflow, $75-$150
- LS6 intake manifold (with or without EGR provisions) - LS6 intake manifold to increase airflow, used or new parts, $300-$500