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LT1's Fuel System Modification - Project Snowball, Part III
Modifying the LT1's fuel system for third gen use
From the July, 2009 issue of GM High-Tech Performance
By John Ulaszek
|  Starting at the driver-side...  Starting at the driver-side frame rail is the easiest route to fueling your LT1. TPI and TBI small blocks will have a 14 and a 16mm metric fitting on the end of the steel lines. |  Pure Choice Motorsports offers...  Pure Choice Motorsports offers the quickest way to connect the factory steel lines to your LT1 with a complete kit including everything you will need from the adapter fittings on the frame rail to push/connect fittings on the fuel rail. The kit includes 14 and 16mm metric O-ring-to -6 AN adapters (part No. 5090), fully assembled Teflon lined braided -6 line, and lastly a pair of Push-Connect-to -6 AN adapters. All of the parts appeared well engineered with obvious attention to detail. Both Pure Choice and Aeromotive stressed changes in fuel additives in 2002. If you don't use the appropriate fuel system components, the new fuels will eat right through the lines. Pure Choice addresses these issues with its Teflon braided line. |
For many of us, our first engine upgrades involved saving up for a Holley carb and intake--we sure didn't have money left over for fancy braided steel lines and aluminum fittings, nor did we need them. A couple of hose clamps and some rubber fuel line was all it took to feed that Holley. With the advent of fuel injection, fuel lines and fittings are no longer an afterthought. High pressure AN or O-ring fittings and plastic or Teflon lines have replaced hose clamps and rubber lines that fall apart from high pressure and modern fuel additives. While the LT1's push-connect fuel line fittings may simplify the assembly process for GM, they can easily confuse the rest of us. For Project Snowball, I chose to cut the fittings off the ends of the fuel rails and weld on AN fittings. Converting directly to AN allows me to use an external adjustable regulator from Aeromotive, which just looks cool. I realize not everyone would want or need to take such drastic measures, so I will also cover a much simpler and quicker approach using adapter fittings from Pure Choice Motorsports. While I had a basic idea of what I needed to set up my fuel lines and fuel system, a call to Pure Choice made routing the fuel system a pleasure. Before I started this project I spent a good deal of time talking to Brett Clow over at Aeromotive about possible fuel system upgrades. According to Brett, the LT1 has excellent fuel rails, but fuel pressure and flow consistency starts to suffer above 350 horsepower as Chevrolet plumbed the rails in series. While Brett admitted there are cars making more than 350 horsepower in stock configuration, those same engines could make even more power if they were converted to a parallel system such that each rail is supplied with fuel independently. Because I may add more power later, I chose to run my fuel rails in series, but upgrade to AN fittings and an external regulator so I would be ready to run a parallel system later. While bumping up fuel pressure will only give temporary horsepower gains on an LT1, an Aeromotive regulator will allow you to run the optimum pressure for a given injector, connect an Auto Meter fuel pressure gauge, provide consistent pressure and look good doing it. In addition to setting up an external regulator, I'm going to cover Aeromotive's on-rail regulator (part No. 13107). As my car was originally a TPI car I am going to use the factory fuel pump. In order to supply the LT1 with its required fuel pressure, you TBI and carburetor types will have to upgrade your pumps. To round out this round of upgrades, a BBK 58mm throttle body came from the Summit Racing catalog and a fuel injection pressure gauge came from Auto Meter. In part III of Project Snowball I will show you how to integrate an LT1's fuel injection into a third-gen's fuel system.  On the driver-side fraim rail,...  On the driver-side fraim rail, remove the two short flexible lines connected to the hard lines. Before you thread on the appropriate Pure Choice adapter (blue fittings), I would recommend replacing the O-ring at each fitting as the newest cars already have twelve-year-old O-rings on them. Lightly lube the O-ring with clean engine oil before assembling the adapter. The Pure Choice braided -6 Teflon line threads onto the adapter. |  Save yourself some time and...  Save yourself some time and order up any O-rings you might need before you get started. Neither your LT1 or third gen is likely to have O-rings in good condition. |  If your plans don't call...  If your plans don't call for any fuel system upgrades, you can go ahead and connect the Pure Choice fittings to the LT1's fuel rails. If your plans are a little more ambitious, then follow along as I cut up a set of fuel rails. |  Based on input from Aeromotive...  Based on input from Aeromotive I chose its part No. 13101 regulator. This is a very versatile regulator with large -10 ports. As I am using -6 line I used Aeromotive's -10 to -6 adapter fittings (part No. 15609). I removed the brass pipe plug to install an Auto Meter fuel pressure sender. The -6 port on the bottom is the return line port, the stainless steel nipple on the top right is for vacuum, and adjustments are made up top with an Allen wrench. Since I am running my rails in series, I capped off the fitting on the left. |  While this picture shows...  While this picture shows an external regulator, the flow of fuel in series is just as you would find in a stock LT1. Because I have added an external regulator and -6 AN fittings to the ends of the rails, upgrading to a parallel system is going to be easier later. |  The arrows show how the fuel...  The arrows show how the fuel rails would be plumbed in parallel. The crossover tube is removed from this configuration and its holes welded shut. Holes for AN fittings are drilled into the end of each rail so that an AN fitting can be TIG welded. A Y-block is required on the pressure side supplying each rail independently. Although packaging this setup is a bit more complicated, if you're making big power with your LT1, it is worth the trouble. |  I have always liked having...  I have always liked having a fuel pressure gauge inside the car, but I have never liked the hassle of running an isolator, and running a pressurized fuel line to the gauge is just asking for trouble. Auto Meter's new full-sweep electric gauges solve all the problems elegantly. They are extremely light, insanely simple to hook up with Weatherpack connectors and deadly accurate with precision stepper motors. While paying for a full suite of the full-sweep electric gauges is a stretch for most of us, it's worth picking up the ones that solve difficult packaging or routing issues. I would like to run a complete set, but I will probably mix and match with its other mechanical and electric Ultra-Lites. |  Now that all the players have...  Now that all the players have been introduced, its time to start cutting up my fuel rails. This view shows how the rails look with the stock regulator removed. The supply line is not going to be so easy to remove. Pull on it all you want, it's not coming out. |  A Dremel tool with a cutoff...  A Dremel tool with a cutoff wheel makes short work of the hard line. Try to cut the line as flush as possible to the rail, this will make the next step a little easier. |  I chose to weld two Aeromotive...  I chose to weld two Aeromotive -10 AN to -6 reducer fittings (part No. 15609) to my fuel rails. Unfortunately the beautiful black anodizing had to come off as it is not compatible with TIG welding. Easy Off oven cleaner removes anodizing without harming any of the aluminum. Use gloves and do this in a ventilated area. Make sure you get the Easy-Off in the yellow can as the other versions won't cut through the anodizing. I scrubbed the fittings with a green scotch-brite pad to remove any stubborn anodizing. |  Once I had the fuel line cut...  Once I had the fuel line cut off, I squared the fuel rail up against the disc on my belt/disc sander and sanded on it until I had removed about .125 inches. Only remove as much material required to remove the rest of the steel line and get a flush surface for welding. Once you get the line out you can sand down the threads on the large diameter of the reducer fitting until it fits inside the fuel rail. While a lathe and a mill would have been nice for these operations, a belt sander will get the job done. |  John Parsons took time to...  John Parsons took time to help me out with the TIG welding again. Make sure you remove any O-rings and the rails are absolutely clean and free of any fuel residue. If you can't find someone to trade favors to weld your rails, it should not be terribly expensive if you do the prep work I have shown. |  Since the factory rails are...  Since the factory rails are such nice extrusions, I could not resist the urge to polish them after they were welded. Not only will a little work and polishing compound yield a good looking part, it will help you see any cracks or imperfections in your welds. |  If you're looking for a quicker...  If you're looking for a quicker and easier approach, Aeromotive has you covered with its on-rail regulator. While the stock regulator works fine for mild applications, it looks rather humble compared to the adjustable unit from Aeromotive (top). Aeromotive recently changed the design of the LT1 regulator due to the corrosive nature of fuel additive changes in 2002. This change resulted in a more robust but larger regulator which requires some minor fabrication in its installation. In response to customer feedback, Aeromotive is now shipping the new regulator with an installation kit and updated instructions. |  The regulator installation...  The regulator installation kit has all the components you will need to install your new regulator without any extra trips to the hardware store. |  Because of varying tolerances...  Because of varying tolerances in the LT1's regulator bracket, you may need to use the included shims to make sure the regulator is mounted squarely into the end of the fuel rail. |  You will need to drill a hole...  You will need to drill a hole in the end of the regulator bracket to install the new clamp. Be sure to start your hole with a center punch before you drill. |  I recruited Glenn Estelle...  I recruited Glenn Estelle to install the on-rail regulator (part No. 13107) in his LT1-powered '92 Camaro. I figured I would let Glenn do all the work while I snapped pictures, he seems happy enough as he is not doing this install on a fourth gen F-body where the back of the LT1 is buried under the windshield. |  The installed regulator looks...  The installed regulator looks and works great. While the installation was fairly straightforward for a third-gen LT1 car, it will require a little more patience and time on a fourth-gen LT1 car. |  As part of my fuel system...  As part of my fuel system upgrade I went with a 58mm BBK throttle body. While a 58mm holds the promises of more horsepower over a 48 or 52mm model, it is not without some difficulty. In my case I didn't do my research like I should have, so I will have to pull the intake off to open up the throttle bores in front of the intake. It's not a major problem, but it is something to be aware of if you decide to upgrade your throttle body. If you look inside the bores it's clear where the bore creates a step in the airflow. | |
| Parts list | P/N | Price | | Pure Choice LT1 Fuel Line Kit | N/A | 99.95 | | Pure Choice Push Connect Adapters | 5800 | 39.95 | | Aeromotive Regulator External | 13101 | 135.95 | | Aeromotive Regulator On Rail | 13107 | 154.95 | | Aeromotive -10 to -6 Reducer | 15609 | 15.99 | | Aeromotive O-rings -10, 10 Pack | 15623 | 9.99 | | Aeromotive O-rings -6, 10 Pack | 15621 | 9.99 | | Aeromotive -6 AN Flare Union | 15602 | 8.39 | | AC Delco Fuel Rail O-rings | 17113086 | 8.39 | | AC Delco Fuel Rail O-rings | 17113544 | 20.95 | | Auto Meter Full Sweep Fuel Pressure Gauge | 4363 | 191.95 | | BBK Throttle Body | 1544 | 309.88 |
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