Third-Gen LS1 Swap Guide
#1
12-17-2015, 02:51 PM
Join Date: Mar 2009
Location: Tokeland, Washington
Posts: 21,637
Third-Gen LS1 Swap Guide
LS1 Engine Swap - GM High-Tech Performance Magazine
here is the article just so it does not get lost if page is taken down.
First thing's first, if you plan on tackling this install you will obviously need to acquire an LSx engine and transmission, complete with the front accessories. Depending on your budget, you can purchase any LS engine, including one from a truck (4.8, 5.3, 6.0 iron block), F-body (5.7, aluminum block), GTO (5.7, aluminum block), or Corvette (5.7, aluminum block). While all of these "Gen III" blocks share the same architecture and will all bolt in the same location, the fourth-generation F-body ('98-02) can't be beat, as its oil pan and front accessory drive will drop right into your engine bay without any troubles. If you do choose to go with a truck, GTO, or Corvette engine, it is still useable but you will find yourself swapping the pan, water pump, balancer, and accessory pullies, which can complicate the install. Once you have decided on an engine, you will also need to pick a transmission, opting for either the 4L60E four-speed automatic or the T56 six-speed manual transmission, found in the fourth-gen F-body. Both units will bolt into the third-gen chassis with minimal fuss and both have provisions for the torque arm found in both the third- and fourth-gen cars.
With your engine and transmission on hand, the next decision you have to make concerns the engine and transmission crossmembers. Up front, you have two choices; modify the stock K-member or install an aftermarket tubular unit, which has been built specifically for this conversion. Concerning the stock K-member, you will need to make one or two modifications, the first in the rear to allow the main support bar to clear the stock F-body LS1 oil pan. While this doesn't require any cutting or welding, it does require a firm hand with a large hammer and some serious persuading to make enough room; you don't want the aluminum oil pan to touch the K-member under any circumstances. The second modification, a much more serious one, involves notching the front of the K-member to allow room for a stock fourth-gen low-mount A/C compressor. If you aren't comfortable chopping and welding on your K-member, any good fabrication shop should be able to help you out or you can order one already modified from Hawks Third Generation in Easley, South Carolina. If you do stick with the stock unit, you will need a pair of custom motor mounts for the K-member, which can also be found at Hawks. The other option here is to purchase a new tubular K-member from a company like BMR Fabrication, which would save you the trouble of modifying your stock unit, while also offering a significant savings in both weight and room in the engine bay.
Once you have the engine in place, you will then have to secure the transmission, using either a custom-built crossmember or a bolt-in unit, like the one from Hawks Third Generation. Using the Hawks unit, we were able to gain significant ground clearance by being able to tuck a 2.5-inch Y-pipe right up in the tunnel, which is very important on stock or lowered vehicles. Depending on your transmission choice (automatic or manual), there are two different crossmember part numbers, just give Hawks a call and tell them what you need.
Exhaust
If you are looking to swap a stock-power LS engine into your third-gen, you have the option of using the stock exhaust manifolds that come on a stock fourth-gen F-body. These manifolds flow enough for stock to slightly modified power, although there are some big gains to be had from swapping to a set of long-tube headers. Unfortunately, if you do want to run a set of long-tubes, you can't just run any fourth-gen set, none of them will fit without some serious modification. Luckily, Hawks teamed up with Stainless Works to build a really nice set of 1.625-, 1.750-, and 2.00-inch long-tubes, with either 2.5- or 3-inch collectors. For most builds the 2.5-inch collector will flow more than enough and easily bolts to the provided 2.5-inch Y-pipe that comes in the Hawks kit. Once you get past the Y-pipe almost any cat-back exhaust could easily be adapted to work, although you may find that a trip to the exhaust shop is needed to get everything perfect.
Fuel
The Gen III engine family requires much more fuel pressure (58 psi minimum compared to the L98's 42 psi) than a typical third-gen car can deliver and as such, almost the entire fuel system must be converted. Starting at the back, it is highly recommended to upgrade to a high-pressure fuel pump, one capable of feeding the LS1. For this, Racetronix offers a really stout plug-and-play system, which comes with a drop-in wiring harness and a Walbro GSS340 fuel pump. You will also need an upgraded fuel pressure regulator and lines, which you can either fabricate yourself or purchase from Hawks as a full kit. The regulator, in our case an Aeromotive unit, will need to be able to return fuel to the tank, hooking back to the stock return line found in the engine bay.
Electronics
Ah yes, the bane of every common hot rodders existence: electronics. This is easily the trickiest area of the LS swap and unfortunately, almost every car has different needs. At the bare minimum, you will need an engine wiring harness and a PCM from a fourth-gen F-body, along with several extra sensors and converter boxes. We recommend sticking with a '99 and up PCM ('99-02), as they have the largest aftermarket support and offer much more tuneability. Regardless of your harness choice, you will need to make several modifications to power up all of your accessories and engine sensors. To do this, you will need to find a wiring diagram for both your stock car and the engine harness from your donor. Alternatively, you could have someone like Hawks build you a harness for your application, which would only need to have power and ground hooked to it in order to get you up and running. Whichever way you choose to go, you will need to find a competent PCM tuner in your area, one that is capable of spending time with you to dial everything in on your new LS engine and transmission combination.
For more information on the swap, follow along with us as we go over all of the required bits and pieces in more detail on the following pages and remember, the fun is in the entire build, not just the end results!
Sources
Hawks Third Generation
here is the article just so it does not get lost if page is taken down.
First thing's first, if you plan on tackling this install you will obviously need to acquire an LSx engine and transmission, complete with the front accessories. Depending on your budget, you can purchase any LS engine, including one from a truck (4.8, 5.3, 6.0 iron block), F-body (5.7, aluminum block), GTO (5.7, aluminum block), or Corvette (5.7, aluminum block). While all of these "Gen III" blocks share the same architecture and will all bolt in the same location, the fourth-generation F-body ('98-02) can't be beat, as its oil pan and front accessory drive will drop right into your engine bay without any troubles. If you do choose to go with a truck, GTO, or Corvette engine, it is still useable but you will find yourself swapping the pan, water pump, balancer, and accessory pullies, which can complicate the install. Once you have decided on an engine, you will also need to pick a transmission, opting for either the 4L60E four-speed automatic or the T56 six-speed manual transmission, found in the fourth-gen F-body. Both units will bolt into the third-gen chassis with minimal fuss and both have provisions for the torque arm found in both the third- and fourth-gen cars.
With your engine and transmission on hand, the next decision you have to make concerns the engine and transmission crossmembers. Up front, you have two choices; modify the stock K-member or install an aftermarket tubular unit, which has been built specifically for this conversion. Concerning the stock K-member, you will need to make one or two modifications, the first in the rear to allow the main support bar to clear the stock F-body LS1 oil pan. While this doesn't require any cutting or welding, it does require a firm hand with a large hammer and some serious persuading to make enough room; you don't want the aluminum oil pan to touch the K-member under any circumstances. The second modification, a much more serious one, involves notching the front of the K-member to allow room for a stock fourth-gen low-mount A/C compressor. If you aren't comfortable chopping and welding on your K-member, any good fabrication shop should be able to help you out or you can order one already modified from Hawks Third Generation in Easley, South Carolina. If you do stick with the stock unit, you will need a pair of custom motor mounts for the K-member, which can also be found at Hawks. The other option here is to purchase a new tubular K-member from a company like BMR Fabrication, which would save you the trouble of modifying your stock unit, while also offering a significant savings in both weight and room in the engine bay.
Once you have the engine in place, you will then have to secure the transmission, using either a custom-built crossmember or a bolt-in unit, like the one from Hawks Third Generation. Using the Hawks unit, we were able to gain significant ground clearance by being able to tuck a 2.5-inch Y-pipe right up in the tunnel, which is very important on stock or lowered vehicles. Depending on your transmission choice (automatic or manual), there are two different crossmember part numbers, just give Hawks a call and tell them what you need.
Exhaust
If you are looking to swap a stock-power LS engine into your third-gen, you have the option of using the stock exhaust manifolds that come on a stock fourth-gen F-body. These manifolds flow enough for stock to slightly modified power, although there are some big gains to be had from swapping to a set of long-tube headers. Unfortunately, if you do want to run a set of long-tubes, you can't just run any fourth-gen set, none of them will fit without some serious modification. Luckily, Hawks teamed up with Stainless Works to build a really nice set of 1.625-, 1.750-, and 2.00-inch long-tubes, with either 2.5- or 3-inch collectors. For most builds the 2.5-inch collector will flow more than enough and easily bolts to the provided 2.5-inch Y-pipe that comes in the Hawks kit. Once you get past the Y-pipe almost any cat-back exhaust could easily be adapted to work, although you may find that a trip to the exhaust shop is needed to get everything perfect.
Fuel
The Gen III engine family requires much more fuel pressure (58 psi minimum compared to the L98's 42 psi) than a typical third-gen car can deliver and as such, almost the entire fuel system must be converted. Starting at the back, it is highly recommended to upgrade to a high-pressure fuel pump, one capable of feeding the LS1. For this, Racetronix offers a really stout plug-and-play system, which comes with a drop-in wiring harness and a Walbro GSS340 fuel pump. You will also need an upgraded fuel pressure regulator and lines, which you can either fabricate yourself or purchase from Hawks as a full kit. The regulator, in our case an Aeromotive unit, will need to be able to return fuel to the tank, hooking back to the stock return line found in the engine bay.
Electronics
Ah yes, the bane of every common hot rodders existence: electronics. This is easily the trickiest area of the LS swap and unfortunately, almost every car has different needs. At the bare minimum, you will need an engine wiring harness and a PCM from a fourth-gen F-body, along with several extra sensors and converter boxes. We recommend sticking with a '99 and up PCM ('99-02), as they have the largest aftermarket support and offer much more tuneability. Regardless of your harness choice, you will need to make several modifications to power up all of your accessories and engine sensors. To do this, you will need to find a wiring diagram for both your stock car and the engine harness from your donor. Alternatively, you could have someone like Hawks build you a harness for your application, which would only need to have power and ground hooked to it in order to get you up and running. Whichever way you choose to go, you will need to find a competent PCM tuner in your area, one that is capable of spending time with you to dial everything in on your new LS engine and transmission combination.
For more information on the swap, follow along with us as we go over all of the required bits and pieces in more detail on the following pages and remember, the fun is in the entire build, not just the end results!
Sources
Hawks Third Generation
Thread
Thread Starter
Forum
Replies
Last Post
libertyforall1776
LS Series Tech
0
04-29-2014 10:16 PM
[god]speed
Wheels, Tires and other Exterior
1
03-18-2009 07:09 PM