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                    Chevythunder-2010 Project  Iron Horse LS6

This page is only as an guide and not a specific means of fabrication and installation, use the information at your own risk, as the author is not responsible for any damages from use of such information or lack of information  here within.


Why I am doing this?

I started pursuing the LSx project as early as the spring of 2005, when I ordered the Tuner Cat OBD II tuner kit to be able to work on and make changes on my wife's 2001 Buick Century pcm and also spent the next year learning on how to use this powerful tool. I was only going to use this basically to retune the V6 and V8 computers. Building my own Gen III engine for my Camaro was not even on the horizon. By early 2006, I was starting to investigate the possibility of building Gen III harnesses and programming the pcm acquired through various outlets as kits. I was building TPI harness-ecm kits but, GM had raised the prices on the programmable proms by over 300% and the handwriting was on the wall that they would be eventually made obsolete.

Finding the harnesses was the easy part, but getting the "seed" pcm programs for the Gen III LS1 and LS6 to be able to do custom kits was roadblock. It was just a stroke of luck on a whim and doing an online search on the night of March 19, 2006 that I stumbled on a site that had not only stock but custom programs, complete with descriptions for the 1998-2002 LS1 and LS6 engines, I spent a better part of the night downloading every bin file which would be a tremendous leap forward. Without that one part in the puzzle, the next step would be impossible. Still it would be nearly a year before I would pursue my own Gen III project.

In February of 2007, I purchased a used 1999 5.3L Vortec engine, complete with harness and computer. With this set up I was able to study and learn the engine, its history and start on the project I would dub "Project 2010". 

As good as the Gen I small block has been to me, once I got hooked on the power made by my 2006 Silverado with it's 5.3L V8, I was mesmerized by the power and torque made by its displacement, in spite of the 5000 lb. curb weight. I was immediately impressed with the instantaneous start up, smooth idle and the quick engine  warm up, which even on the coldest winter days, I was getting heat in the cabin only about two miles down the road!  The GM engineers did their homework on this one, and it shows. While the so-called experts scoff at the fact that this is a ancient cam-in-block, push rod, overhead valve design,  the big picture that it is hard to argue with its power output relative to weight, excellent fuel mileage, reduced NVH  (noise, vibration, harshness) industry standards, and below target emissions. It is almost hard to believe that this "ancient" engine can rival the OHC designs. 

The fact that I can build a  honest 400+ horsepower engine with excellent street manners and silky smooth operation without the annoyances of the older design is it itself a remarkable project. When I was back in high school and even shortly after, a 400 or even  300 horsepower (we're talking net power, not gross output) Gen I small block V8 was met with unstable idle, overheating in traffic and extremely high emissions. Even if you got a half way decent running ride, there were trade off's due to the inherit nature of carburetion. Fuel injection was still in its infancy, mostly imports, that used mechanical with analog systems, as digital fuel injection was still be engineered and tested. Over the last twenty-five  years as the systems go progressively better, the aftermarket and the enthusiast embraced digital fuel injection, such as I did. Once I was hooked on the fuel injection, I was not going to go back. 

My TPI equipped 383 Gen I small block is a great engine, which puts out a honest to goodness 300 rwhp. The large displacement allows the torque needed to move the almost 4000 lbs this vehicle carries. The idle is still relatively smooth due to its small cam, and the throttle response is a snap. This engine was a replacement for my first TPI in my Camaro, installed and fired off for the first time in August of 2000. It displaced 5.7L and put out 245 rwhp. The Gen I's that have been in my engine bay for over 32 years have proven themselves, and it is hard to argue with the low costs and dependability. 

The Gen III now occupies the engine bay, with power and torque coming on strong at low rpm's. Due to it's push rod design, the  throttle response will leave the OHC equipped vehicles napping at the stop light-without  winding up the rpm's into the stratosphere.  Fuel mileage will also increase and this is based  the engine design, but mostly due to the technological advances in the computer speed and the refined programming and the advancement of the engine's sensors to the pcm. The 200-R4 transmission combined with the 3.42 gear, will make this Camaro a hoot to drive, and still be able to cruise 70 mph without beating you to death in the process. 

I will document the things you will need to be aware of when doing this swap. As good as the books are that  I have suggested for you to purchase if you desire to pursue your project, there are some details I will point out that will save you time and frustration. In other words, I am going through the pains to help you avoid some of the pitfalls you are sure to face.  I am surly enjoying this project, as I am sure you will find pleasure in your own project as well. 

Good luck and happy wrenching!


My Camaro Project

The harness has already been fabricated by yours truly and the pcm will be mounted on the firewall inside the  left side fender well, with the major bulk of the harness  in the engine compartment. The only wiring that will penetrate the firewall will be for the DLC trunk and cruise control. Even though I have the drive by wire (DBW) module, pedal and throttle body, I realize that for the majority of people who are wanting the do the same project, you  will be using a cable throttle set up, for the sake of simplicity, I too, will use a cable throttle in the beginning and eventually swap to DBW.

I had contemplated  using a 4L60E, and I have one in my storage shed that came out of a 1996 9C1 police cruiser that needs to be gone through. I have decided to stay with the 200R4 transmission and beef it up using a Transco shift re-programming kit. I have already installed a Sonax Servo which has helped somewhat with the soft shifting, as well as a B&M "shift kit". However, this shift kit does not address the issues that the Transco kit will, and you can search them online for information and specifics, which is too much for me to cover here. Since the older lock up transmissions are not compatible with the the LSx based PCM, for controlling the lock up, it will be necessary to add an aftermarket lock up kit, and the simplest ones use a fourth gear sensor, which grounds the lock up solenoid only when the transmission is in fourth gear, I will include the diagram to do this and it will still be in series with the lock up control on the brake switch, so full control can still be maintained if you are cruising in high gear and have to use your brakes, you still want the torque converter to disengage. 

Another thing you need to consider when using a 200/7004R, is that you will need a special TV (throttle valve) cable and bracket for the LS1 drive by cable, which can be purchase through Bowtie Overdrives, or use a full pressure valve body made by TCI

If you plan on doing this project yourself and are installing this in any vehicle but a truck, you will need to get the alternator bracket from the Corvette, as well as the power steering pump and alternator. These are not interchangeable with the Vortec truck set up.  If there is any questions on what will and will not work, I suggest looking at the May 2009 Craft Craft magazine, or you can access the article at

Another good source of information for the LS1 GEN III engine can be found here at:

I have included some part numbers and pictures on some of the things for my swap. This list is not complete and will be updated as research continues.

It would be nearly impossible to include every aspect of fabrication and modification to retrofit the Gen III into your vehicle and there is many good books on the subject. 


Cylinder head: "243" casting, "D" shape ports, SPM casting. These were brand new take off from a LS2. Be prepared to pay a princely sum. But sometimes bargains can be had if you find a desperate seller.  If you buy a set of used heads, consider what it would take to rebuild them back to "like new" condition. These will be mildly ported to give it some extra "edge". 

The SPM (Semi-Permanent Molding) 243 heads have a smoother runner and combustion chamber  finish than its regular cast counterparts and can be identified by the "triangle" cast lines under the spark plug holes. Some say the difference can be 7-10 hp. 

The stock LS1 heads are great for making power as well, so don't overlook them as well. 

GM MLS head gasket for 5.7L  part number 12589226  It is recommended to use the MLS ( Multi Layer Steel) over conventional compression gaskets on both iron or aluminum block /aluminum head engines. 

Camshaft: Z06 GM part number 12565308. 

This camshaft was used on the 2002-2004 LS6 producing 405 hp/400 ft/lbs of torque when all other LS6 spec. components are used. 

Pistons: LS1/LS6  with coated piston skirts. I picked up a complete of these on Ebay for less than $150, two years ago. A pretty rare find, so expect to pay much more or get lucky. Fortunately, these showed very little wear and full skirt oil retention ribs with no scarring.

          Scat floating pin rod with ARP bolts

This is the most common set up using the flat top piston with .945" press fit pin, moly coated skirts. Pistons are made by Mahle. Rod length is 6.098". 

If you are going to use a floating pin piston, you will need to obtain the floating pin rods that match your piston pins. Most floating pin pistons will come with the wire locks that are installed at both ends of the piston pin bores, but the more secure and recommended way to do this is to use a Spirolox wire retainers. Follow the manufactures instructions on the number needed for each piston and the installation procedures. 



Mahle floating pin piston shown above.           Visual differences between floating (left) and pressed fit pin (right).

Spirolox piston pin retainer                      "C" ring piston pin retainer

The Spirolox retainer is much more secure way of retaining the piston pin and is a much better choice than the "C" clip


Alternator/Power Steering Bracket  GM part # 12578068  The power steering pump retainer bracket GM part # 12555693. 

Corvette power steering pump. GM # 88985228. A cheaper alternative is to pull one from a FWD mid 1990's Cadillac 4.5L, the only difference is that you don't have a supply tube on the top (with red plug). You will have to have this tapped for a 1/2" NPT tap and install a 1/2 NPT to a 5/8" barbed outlet. This will mean you will have to do it is such a  fashion (such as upside down) to keep metal shavings from entering the chamber or have this professionally done( recommended). 

Power steering pump pulley I used (since I am using the Corvette set up). This is made specifically for the Corvette accessory brackets. Do not substitute any other pulley as the belt alignment will be off. GM part number 12559890.




Corvette Alternator: Will only fit the Corvette bracket. The F-body and truck alternator are interchangeable and can be used on the F-body bracket set up, if you have clearance on the frame to install the alternator in the F-body position ( low on the driver side). 

Water pump differences:

The differences in the water pump is evident in the pictures. The top pump is used on the trucks and the outlet will not clear the LS1 style intake and throttle body.  The pump on the bottom can be use on either manifold design.  One major thing that will have to be done, since the provision is not provided on the retro swaps most people do, and that a fitting will need to be drilled and tapped on the water pump near the outlet as a provision for the throttle body cooling line on the passenger side, see picture below for the outlet fitting installed on the water pump. The fitting I used is a 3/8"-18 NPT to 5/16"  barb fitting. The proper drill size for the pipe tap is 7/16"


. The left side cooling line that fits under the manifold will have a flexible hose to go to the left side of the throttle body. the cooling line that feeds the cylinder heads is shown below. The fitting on the water pump can be mounted straight up for the F-y body pumps, a 90 degree fitting will have to be used on the truck water pump. 

This cooling bypass lines will only fit under the LS1 or Vortec truck manifold, if you are using a LS6 manifold, you will need to  modify this piece or order the kit #12602544 (front line) and 2 each of # 12602540 (rear block offs). Or you can modify your existing ones shown here.

Melling high volume oil pump should be part of your high performance rebuild.



Sensors (partial list)


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Setting up for the engine build process: 

Fuel Pump and related parts

There are two different ways to supply the fuel to your project and will involve some detailed planning. Since you are dealing with a flammable liquid and consequences can be fatal if you fail to take the safety precautions seriously. I recommend that a professional do the lay out and installation of your fuel system. 

The first system was used on the 1997-98 LS1 engines, and the fuel rails are equipped as a return (dual line system). The fuel pressure regulator is built into the fuel rail and is vacuumed controlled. thus under high load, low manifold vacuum (near atmosphere), the pressure regulator would raise the fuel pressure slightly for the higher fuel demand. If you desire a dual line set up, you can have your single line fuel rail modified by Street and Performance of Mena, Arkansas. Their website is: The costs is roughly $175.00. This is found on page 95 of their online catalogue. 


 The only other thing besides the fuel lines is to replace the fuel pump with a higher pressure pump required by the LSx system which is around 58 PSI nominal.  The Walbro 255 will be the perfect companion. Their website is

Most everyone that has the single line fuel rail found on the majority of the LSx set ups, and this is what I will use on my Camaro.


The internal fuel pump is recommended, as it will be much less prone to cavitation problem, especially when the fuel gets warm. The pumps are generally the same, the single line fuel assemblies have the regulator built into the fuel assembly itself.  The last picture shows a typical F-body fuel pump assembly. 

Click here  for the aftermarket fuel pump assembly made by tanks inc. , set up  that was originally used with my TPI setup, the only thing I had to change was the fuel pump to a Walbro GSS340 pump for the higher pressure and flow capability. 

If you are going to use a single line fuel rail, I suspect this will be the most common way to go for most folks, you will need a way to have a pressure regulator/filter for your set up. Although S&P sells such an item, it is very pricey $170.00. I found a less expensive alternative, that was only around $40 or so. 

The common part number is Hastings GF336, which has been superceded by part number 33737. It has a fuel inlet line as well as a return to the tank and the output to your injector fuel rail. 

Other part numbers for the same item that is more expensive is: Wix 33737, GM 10299146, Purolator F55493, GF1822,  PGF336.


You will need to obtain the correct fittings and parts to connect to the fuel filter/regulator assembly.

NOTICE!  Always practice safe fuel handling and installation techniques. If there is any doubt about this, seek professional automotive technicians advise. Don't take chances or shortcuts!


Engine mounting

Most everyone that is installing a LS1 in place of the early small block V8 will need to obtain the adapter plates to make this happen. Fortunately, the engineers designed the block to mounted in different configurations, so adding a set of adapter plates is a snap. Most performance specialty shops will see these. An example is shown below, sold as a pair with mounting bolts. 

If you are installing a LSx in a "F" body or similar vehicle, be aware that you may need to purchase the LS1 mounting plates that set the engine back to attached to the transmission bell housing. . Always research your fitment to your transmission in its original mounted position. Be aware that some engine mount kits may raise or lower the height of the engine to respect to the transmission and may affect the drive line angle. If there is any questions about this, consult an expert to assist you. 

To be able to keep my transmission in the stock location and not modify my driveshaft length, I used the 1" set back motor mounts. But be aware that your situation may be different.

Oil Pans

Two of the most common oil pans to use will be either the truck pan  or the F-body pan which is shallower and may aid in clearance in tight mounting situations. The most common pan to use will be the F-body due to the clearance needed on the front tie rod ends on the "F" body cars. The truck pan front sump hangs down around 2 1/2"  while the "F" body pan is only 1 1/4" deep and this will clear the steering components. 

Above the oil filter is a adapter fitting that can be tapped and drilled for your mechanical or electric oil pressure gauge. 



The most common transmission configurations will involve using the THM350, 400, THM200R4, THM700R4 (non computer controlled  4L60E-square electrical plug for TCC lock up), and the 4L60E (early style with transmission cover) and later 4L60e with the 360 degree (full) bell housing, and the large array of manual transmissions including the T56. 

The Flexplate difference are the result of the design difference on the engine bell housing, resulting a "dished" flexplate being used on the LSx engines. These are a 14" diameter wheel, 300mm bolt circle,  the GM part number is 12563136. The flex plate bolts are part number 12553332. This is for the 4L60E (full bell housing).

If you are using a older automatic, the GM number 12551367 flex plate must be used. It is a flat design that requires the use of a special spacer (GM # 12563532) and bolts (GM# 12563533- six are required). The flexplate has a 6 lug designed used on the THM400 and 4L80E. The mounting holes must be modified to be used with the Gen I and II with the 298 mm bolt pattern. 

A GM number for the whole kit which includes the flexplate, spacer and bolts can be  found under part # 12621399


For manual transmissions, the LS1 crankshaft is approximately .400" shorter than the earlier small blocks and a special pilot bearing (GM #125575830 and this compensates for the difference and allow the user to use standard input shaft length  If you are using a early 4 speed transmission you will need flywheel part (GM # 12561680). The 6 speed will require GM part number 12562765.

Recommended Reading: 


Consider these two books a recommended reading. These can be purchased through much cheaper than other sources. 

More information will follow in regards of exhaust and cooling hose fabrication and modification. 

 Need a custom Gen III  harness, Click here

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