Last month we looked at what it would take to convert your carbureted engine over to electronic fuel injection--in theory. This time we break out the wrenches. Remember we are performing two significant modifications: 1. We are eliminating a carburetor/intake/ignition and installing a new fuel delivery system; and, 2. We are now introducing a computer where none existed.
OK, you have had a month to think about it--are you ready to make the swap? Well, to take some of the fear out of the leap, follow along. Not being one to jump without a net myself, I have enlisted copious amounts of help from the pros. On my way home (that's 1,952 miles) from the Nats in Louisville, my roadster and I paid a visit to COMP Cams in Memphis, Tennessee, where we hooked up with the staff from FAST (Fuel, Air, Spark Technology). The old adage about, "If it works, leave it alone!" is true, but I couldn't resist. I was looking for something that would enhance the roadster's driving characteristics, improve cold and hot starting, and enhance performance. I wanted a roadster that didn't care if it were being driven along Pacific Coast Highway or making the climb over the Rockies, and most of all I didn't want any woes while dealing with the heat of the desert during the summer or getting caught up in the high temps and humidity of the South in August! Did I mention I am not opposed to better fuel economy and lower emissions?
The advantages of electronic fuel injection cannot be overstated. Yes, there was a time when automotive electronics and hot rodding were at odds, but no more. The little "black box" may still be a mystery to most, but the installation and programming should no longer be a cause of panic. It was back in 1957 that Chevrolet introduced the Rochester Ram Jet mechanical fuel injection and, while it appeared on several brands and models of cars over a short period, the most famous was the Corvette from '57 to '65. Today all three versions of the mechanical Rochester are highly desirable, especially to restorers, but the most popular from a performance standpoint was the '63-65 version commonly called the "big box" injector. The earliest fuel injection systems were mechanical and were more complex than carburetors. Consequently, they were expensive and their use was limited.
Ram Jet Fuel Injection Manifold Kit & FAST Electronics
In this particular application, a GM Performance Parts Ram Jet Fuel Injection Manifold Kit (less electronics) is a retro fit to engines (265-400) with iron Vortec (PN 12558060) or aluminum (PN 12464298) cylinder heads. This system requires an aftermarket ECU and wiring harness and that's where FAST comes into play. We started with a FAST XFI ECU (PN 30-1000)--wow, gymnastics for my fingers! The ECU comes with a wideband O2 sensor (all necessary software and instructions). From here we rounded up a FAST main wiring harness (PN 30-1101), an ignition adaptor (PN 30-1302), a fuel injector harness (PN 30-1200), and FAST fuel injectors (PN 30-2408), which are rated at 24 lb/hr.
The GMPP Ram Jet Manifold Kit (PN 12498032) comes with fuel injectors, fuel rails, throttle body, knock sensor, distributor assembly (PN 1104060), ignition coil, fuel pressure regulator, MAP sensor (PN 16194007), as well as an assortment of brackets, sensors, bolts, nuts, and gaskets. The GMPP cast-aluminum intake manifold (PN 12489371) is designed for port fuel injection and comes with two holes in the rear of the plenum that are tapered for a 3/8-inch NPT vacuum fittings. The hole in the rear of the plenum is intended for a brake booster while the hole in the right-hand side of the rear of the plenum is for a fuel pressure regulator (provided). To the system we added throttle cable hardware from Lokar Performance Products, a K&N air filter, Pure Choice braided fuel hose and hardware, and alternator and water inlet relocation hardware from Street & Performance. (When using braided hose be sure to flush all hoses and lines with fuel to keep any fine particles from plugging the injector screens.)
We are going to begin with an assumption, which can be a bad thing! However, if you cannot get the carburetor, intake manifold, mechanical fuel pump, and distributor off your engine, you really shouldn't attempt the following installation. So, let's all agree that we now have a long-block staring us in the eyes that needs a GMPP Ram Jet kit along with the accompanying FAST ECU system installed.
Last month we talked about the areas of concern and what you would address before tackling this project, remember? The gas tank and fuel pump are areas of major concern and should be attentively addressed. In this particular swap we planned ahead and ordered our Tanks Inc. 16-gallon tank with provisions for both an internal pump and a return line for the inevitable fuel injection. The internal pump was selected over an external system for several reasons. not the least of which are quietness and the elimination of heat as a potential cause of pump failure.
The Tanks Inc. internal fuel pump is based on a GM-style (capable of supplying 35 gph with an operating pressure of 43-55 psi) has an internal filter and reservoir tray (prevents fuel starvation when cornering or accelerating). To this an AC Delco GF-481 (or FRAM G-3727) fuel filter with a Street & Performance 16mm to AN-6 fittings and mounting bracket are used. (GMPP also recommends an AC Delco GF-626, 10-micron filter with 3/8-inch fittings.) In this application the bracket is bolted to the mechanical fuel pump block-off plate since this original fuel pump is no longer present. Pure Choice braided lines and fittings are used, and remember fuel lines for most applications should have a 3/8-inch for the supply side and 5/16-inch on the return side. The fuel hose and filter must be fuel-injection rated. (Keep this in mind: A Ron Francis fuel shutoff relay and switch that kills the power to your electric fuel pump serves as an effective theft deterrent system and as an aid in the event of a crash.)According to Mark Campbell of S&P, he receives calls every year in July and August from people experiencing vapor lock, so here are a few tips:
"Vapor lock is the heating of the fuel to a point where it turns to a vapor--logical enough! Internal pumps will help keep exhaust heat away from the pump, lines, and tank. Making a heat shield between these parts and exhaust will also help. High altitude can also be responsible for vapor lock. Another way to prevent vapor lock in the late afternoon is to top off your gas tank with cool fuel. You should keep fuel lines as far away from headers as possible, because with hot air coming off of the radiator and the headers and blowing over the fuel lines, it acts like a heat exchanger. Using an improper fuel filter, such as a billet style designed for carburetors, restricts fuel flow and places added backpressure on the pump. Fuel injection works better than a carburetor because it circulates cold fuel at the injector, a carburetor the fuel "dead heads" and is warmed by the engine heat which takes away horsepower."
INTAKE MANIFOLD INSTALLATION
Installing the Ram Jet intake manifold (PN 88959395) is accomplished in the same fashion as any small-block Chevy manifold--something many of us have done repeatedly during our formative mechanical years. But, let's go over some basics since we are dealing with the "new" Vortec manifold/head combo, which has several inherent changes.
The Ram Jet kit is comprised of new components so there shouldn't be a need to inspect the machined surfaces, but forearmed is forewarned. Make sure to check the manifold's machined surfaces for flatness using a straight edge. If the manifold is warped or the machined sealing surfaces are damaged, it may not seal properly, allowing water and other contaminants to enter the combustion chamber or lubricating system.
Clean the intake manifold thoroughly before placing it on any engine. You will need to clean your cylinder heads of any old gasket material and here are some recommendations from GMPP when prepping gasket surfaces, whether it be the manifold or head surfaces:
Do not use any form of blasting media and/or surface conditioning discs when cleaning the intake manifold.
When cleaning gasket sealing surfaces on new and remanufactured engines and/or cleaning parts, the use of surface conditioning discs that contain abrasives, such as aluminum oxide, may cause premature bearing failure. Now you should be ready to install the new Vortec gaskets (PN 88959395, two). Install the intake manifold side gaskets and the end seals on the block and cylinder heads, placing RTV sealant (3/16-inch bead) at the corners. Install the intake manifold, making sure to tighten the eight bolts (PN 12550027, they are different from other intake bolts) in the proper sequence. Tighten the bolts from the inside out, alternating sides and crisscrossing front to back. You will perform the torque sequence in two passes, with the first pass at 9 lb-ft, and the second pass at 11 lb-ft. Please take note it is 11 lb-ft and not a pound higher! These intake manifold gaskets are designed to seal at low clamp loads; excessive bolt torque may damage the gasket(s). If the intake manifold does not seal properly to the heads, water and other contaminants can enter the combustion chamber causing considerable damage.
INJECTOR SIZE
GMPP supplies injectors with their kit, however, we swapped these out for FAST injectors. Should you anticipate a higher horsepower application, here is something to keep in mind when determining injector size. Typically you would take into consideration the cubic inches of your engine and horsepower. For small cubic-inch motors like a 305, you would probably use 19.9-lb/hr injectors; the popular 350-inch small-block with horsepower somewhere between 225 to 275 would take 21.9-lb/hr injectors; and for the next jump to 300 to 375 hp (ZZ4, LT1, and LS1) you might use 24.9-lb/hr injectors and the new LS6s, which are 405hp, use 28 lbs/hr injectors.
INSTALLATION OF ECU
The FAST XFI Electronic Fuel Injection proved to be an easy installation. The ECU was mounted inside the passenger kick panel behind the upholstery and the wiring run forward to the engine compartment with an offshoot going to the fuse panel located behind the dash on the driver side. The fuel pump is grounded in the trunk area and the positive wire comes forward to the fuse panel. However, that's the really easy part. The segment that would normally "trip" a rodder would be the laptop tune-up. The FAST system comes with C-Com XFI-version software and communication table. Installed are parameters and a guide to get you going.
While the computer is connected and online, press the F9 key to display the main dashboard. You should be able to read the following dashboard parameters with the engine not running and the ignition on:
The TPS reading at an idle should be relatively low, and should increase as you open the throttle. If it doesn't go all the way from 0 to 100 yet, that's OK.
The MAP sensor should read approximately 20 kpa once the proper calibration has been entered. For now, a reading of 88 to 105 kpa or higher is OK. The air and coolant temperature sensors should read the approximate outside temperature, assuming the engine hasn't been run for some time. Battery voltage should be at least 12 volts. Check the LEDs on the face of your new FAST XFI ECU. The power should be lit as soon as you turn on the keyed power while crank and cam will flash once until you start turning over the engine. The cam will only flash if you're using a cam input of some type. NOTE: Keep the fuel injector harness unplugged at this time.
If all the above conditions have been met, then it's time to move on to the next step. If not, you'll need to go back and check connections in your wiring harness for things such as loose connections, improper grounds, or possible faulty sensors.
Engine Displacement (CID)
This parameter is apart of the ECU's calculation to determine the amount of fuel to inject when running in Speed Density mode. Enter the engine's displacement in cubic inches. This must be entered correctly or the engine will run richer or leaner than intended.
Map Sensor (1-5 Bar)
This parameter is used to scale the readings from the MAP sensor. MAP sensors are rated by their maximum sensing range. A 1 Bar sensor can read up to one Bar of pressure (atmospheric pressure), a 2 Bar sensor can read up to two Bar of pressure and so on. Enter a number between 1 and 5 that corresponds to your MAP sensor's rating.
Number of Cylinders (2,4,6,8)
This parameter is a part of the ECU's calculation to determine the amount of fuel to inject. Enter the number of cylinders the engine has. This must be entered correctly or the engine will not run correctly, if at all in some cases.
Injector Flow Rate (lb/hr)
This parameter is apart of the ECU's calculation to determine the amount of fuel to inject when running in Speed Density mode. It is also used for fuel flow and mileage calculations. Enter the flow rate of the injectors in lb/hr. This must be entered correctly or the engine will run richer or leaner than intended. Keep in mind that fuel pressure affects flow rate. When manufacturers rate injectors, it is at a certain fuel pressure. Injectors from FAST are rated at 45 psi. Firing Order
Enter the firing order of the engine. This information is used to correctly label the individual cylinder corrections setup screen. Changing this setting will NOT change the order in which the injectors actually fire. That is a function of the wiring from the ECU to the injectors. The injector wiring harness can be swapped out or modified if the system is installed on a different motor with a different firing order.
Sensor Calibration
This section will take you through "calibrating" your throttle position sensor and manifold absolute pressure sensor to give you full resolution for better engine control and optimum tuning results.
TPS Calibration
The throttle position sensor sends a varying 0-5-volt signal to the ECU as the throttle is moved. The TPS Calibration table tells the ECU how to relate the voltage level with throttle opening. A TPS calibration is typically linear.
MAP Calibration
The MAP sensor sends a varying 0-5-volt signal to the ECU based on the vacuum/pressure the sensor is exposed to. The MAP Calibration table tells the ECU how to relate the voltage level with vacuum/pressure. MAP sensors typically have linear calibrations. Information on MAP sensor calibration should be available from the sensor's manufacturer, which in this case is GMPP.
Start Your Engine
The last step in this process is to plug in your fuel injector harness. Your engine is now ready to be started. If your vehicle is running and you would like to check your system, one of the best tools you could have is an infrared heat gun to check the exhaust temperature of each header tube. If all injectors are good, they should be within 35 degrees of each other at idle. They are normally between 225 and 300 degrees. For example, if you have one or more with a higher temp, you usually have a lean injector or one that is dripping. (Snap-On Infrared Temperature Measuring Instrument RTEMP6PB.)
Camshaft
Future plans call for one more modification and that is the changing out of the carbureted camshaft for a COMP Cams XFI 'shaft that should really bring the car to life, enhancing performance, economy, and driva-bility. A carbureted engine requires a strong signal or airflow at the carburetor booster to draw the correct fuel into the engine. Since that excess flow is not required in a fuel-injected engine, overlap and low lift flow requirements are not as critical. Therefore, COMP's engineers designed the new XFI series with wider lobe separations and higher lift.
In Conclusion
The data presented is an overview and is meant to get you going through the process but nothing--and that is to be repeated, nothing--is meant to replace reading the instructions from FAST and following along with their proven procedures.
It took 12 hours from start to finish converting the GMPP 383 crate motor from a carbureted engine to a Ram Jet 383. We spent about 40 miles driving time while Dave of FAST spent it observing the laptop computer and making final adjustments. Once this was done, we parked the roadster and the next morning made one last adjustment to the Cold Start (IAC) procedure and it was off on a 1,952-mile drive back to the West Coast from Memphis, Tennessee.
The car performed flawlessly and the high temps, humidity, and long days didn't affect the engines running (although I was a bit warn out) and it was noted that the car went from 14-15 mph to 16-17 mph. Well, there you have it. Going from carburetion to fuel injection.
(Editor's Note: To make sure I paid attention: A special "thank you" must be given to the following who made this project come together in the span of five days! A big "at-a-boy" goes to Bill Martens (special programs manager for GMPP) and Ken Casey Jr. (performance parts specialist for Burt Chevrolet) for helping us with the technical "wherefores" of the GMPP Ram Jet system. Additional accolades go to Dave Henninger and Tony Duncan (both project engineers for FAST), Mike Bond and David Page (both R&D for COMP Cams), and a special "at-a-girl" to Hailey Naylor (marketing coordinator for COMP Cams) for maintaining a steady stream of "answers," parts, donuts, and traffic coordination throughout the entire project! I would also be remiss if I didn't thank Mark Campbell of Street & Performance, Rick Craze of Lokar Performance Products, and Gary Clausen of Pure Choice for stopping during the midst of the NSRA Street Rod Nationals to make this story possible in the span of five days.)
10 Tips to Get Started
1.You will want to check for leaks; fuel pressure leaks or oil leaks from the installation of the intake manifold.
2.You will want to check all sensors for their response: throttle position sensor (TPS), idle air control (IAC), manifold atmospheric pressure (MAP), air temperature (AT), engine coolant temperature (ECT). This can be accomplished from your laptop through the software program.
3.You will want to check for engine spark with the fuel pump off, crank the motor.
4.You will want to check your operational parameters for the fuel pump prime, crank angle fan--on and off.
5.You will want to check the fuel calculation parameters to see if your injector constant and cubic inch and number of cylinders are correct. 1 Bar map for naturally aspirated and 2 or 3 Bar for boosted applications.
6.You will want to check the main spark table at 100 kpa and set your cranking timing to 10 to 20 degrees.
7.You will want to set your main fuel table to 45 percent at 30 to 55 kpa and 600 to 1,000 rpm. This is where the motor should idle when started.
8.You will want to crank the engine and look at the cranking fuel at this point. Hopefully it starts up; if not you may need to add or subtract 20-percent fuel while cranking with this table. If the motor needs throttle to start, remove fuel. If it does not, you may need more fuel.
9.You will want to check the engine vitals of the motor, such as oil pressure, engine temperature, and, again, leaks. Once the engine starts, don't worry about the idle quality--just get it running.
10.You will want to now begin the main tuning. You must have two people for this as it's the only safe way to do it. You will work on you base maps for fuel and spark until you achieve desired results.
