Читать книгу EFI Conversions - Tony Candela - Страница 9
ОглавлениеNow that you’re convinced that converting to EFI is right for you, the legwork begins.
Converting to EFI isn’t quite as simple as purchasing a system, unpacking it, and bolting it on. Furthermore, no system that I’m aware of is designed to work in all applications. Fortunately, the process of narrowing the field of available products to determine which system or systems are best suited to your needs is a pretty easy one. This chapter provides all the information you need to easily choose a system for your vehicle as well as any additional parts to ensure your installation goes smoothly and gives you years of reliable service.
I’m one of those guys who prefers to do a job once and then enjoy the fruits of my labor. And that means I install it right the first time so I can drive and enjoy my vehicles versus spending a bunch of time troubleshooting an installation that wasn’t done correctly on the front end.
Before you can choose which system is right for your application, it’s vital to consider the following: parts combination compatibility, fuel system requirements, ignition system requirements, and electrical system requirements.
Parts Combination Compatibility
Most aftermarket EFI kits are designed for naturally aspirated engines making less than 650 hp. The size of the injectors included in the kit (typically four), the airflow capability of the throttle body itself, the fuel pressure, fuel pump, etc. determine how much horsepower the engine can produce. These kits represent 90 percent of the market. That being said, some products are compatible with much-higher horsepower, naturally aspirated combinations as well as those kits that are fully compatible with power adders.
Fig. 2.1. The FAST EZ-EFI 2.0 system is the company’s latest offering at the time of this writing. The 4150 throttle body has eight injectors and supports up to 1,200 hp. The base system includes all of the components shown here, including the color touch screen handheld/dash-mount controller. This system performs fuel metering and offers electronic timing control when you add the company’s EFI-style distributor and crank trigger. (Photo Courtesy FAST)
650+ HP Applications
If your naturally aspirated combination makes in excess of 650 flywheel horsepower, you should be looking at an MPFI system, a TBI system that allows you to run dual throttle bodies, or a stack system. At the time of this writing, both FAST and Holley offer TBI systems that allow you to run a slave throttle body.
Fig. 2.2. This .030-over 327-ci small-block Chevy sports a pair of FAST EZ EFI throttle bodies on an Offenhauser Cross Ram manifold. A setup like this provides that classic look with the performance of modern fuel injection! (Photo Courtesy Ed Taylor)
In addition, FAST offers a TBI system that uses a single throttle body with eight injectors that is capable of 1,200 hp.
Fig. 2.3. Holley HP and Dominator EFI systems are fully compatible with nitrous and water/methanol systems. If you’re a hard-core nitrous user, the software allows you to configure the ECU for up to four stages of nitrous, each of which can be wet or dry and even progressively controlled if you desire.
Power Adders
If you’re using or intend to use a power adder (nitrous oxide, superchargers, or turbochargers), you should shop for an EFI system that was designed from the ground up to be compatible with your power adder of choice. For example, the Holley HP-EFI and Dominator EFI systems are designed to work with all power adders and have lots of features that are readily accessible in the tuning software. Either platform is ideal for nitrous or water/methanol users, and both have four stages of progressive control available.
I’ve used a Holley HP-EFI system with my 6-71 blown big-block Chevy for three years now and I couldn’t be happier (see Chapter 4 for more details).
Camshaft Compatibility
One of the limitations of speed-density EFI systems is that they typically require a good vacuum signal at idle, such as 10 inches of manifold volume or more. Some manufacturers specify camshaft profile limitations (e.g., duration at .050 inch must be less than 250 degrees). If your camshaft profile falls outside of their recommendations, you should pick up the phone and contact their tech support department for recommendations before proceeding. Don’t be shocked if they recommend a different camshaft profile.
Fig. 2.4. This Phantom 340 Stealth Fuel System from Aeromotive allows you to add an EFI-specific fuel pump inside your factory tank. The kit includes the 340 Stealth fuel pump, baffle, pre-filter, and all parts required to install it. The kit supports naturally aspirated EFI engine combinations making up to 850 hp or forced-induction EFI combinations up to 700 hp. (Photo Courtesy Aeromotive)
Each of the following should be considered in an effort to ensure your fuel system works efficiently and reliably.
Fuel Pressure
If you didn’t already know, EFI systems operate at a much higher fuel pressure than do carburetors. A typical carbureted system requires between 5 and 7 psi of fuel pressure. EFI systems require a higher operating fuel pressure (typically from 20 to 80 psi). This necessitates the installation of an EFI-style electric fuel pump, which can be installed in the tank or externally. If your vehicle is still equipped with the stock fuel line, it may also be necessary to upgrade it to meet the fuel demands of the system. Keep in mind, some systems are not compatible with hard lines.
Fuel Filters
Equally important are filters for the fuel system: one before the pump itself (pre-filter) and a much finer one before the injectors (post-filter). Some systems include one or both filters; others rely on you to supply them.
Return Line
Many aftermarket EFI systems also require a return line to the tank, which requires that the tank also have a vent. Don’t let the installation of a return line discourage you from considering a particular system. Most factory tanks have a vent, but its size may be a limiting factor. Some EFI systems, such as the MSD Atomic system, can be installed with or without a return line. However, MSD encourages the use of a return line (see page 76 for installation details). It is imperative with a returnless-style system that the fuel pump be located in the tank to keep it from overheating.
In addition, you really shouldn’t expect to supply fuel to your brand-new EFI system from a 40-year-old tank that is full of sediment and rust. Also, realize that such a tank was designed for a low-pressure carbureted fuel system, not a high-pressure fuel injected system. If you elect to use the stock fuel tank, you’re going to have to remove it to add the provisions for the return line so this is the perfect time to flush it out. If you are running a stock-style tank, you have a few options. You can flush it and add provisions for a vent and return line, or you can install one of the readily available in-tank fuel pump kits.
Additionally, a return-style system requires the use of a return-style regulator. Many companies offer them. The main difference between a return-style and a traditional regulator is that a return-style regulator is designed to install at the end of the fuel system and is the point of origin for the return line.
Fuel Tank
Another option is to replace the tank altogether with one that has been specifically designed for an EFI system. If you elect to go that route, several companies offer fuel tank kits that have a fuel pump, filter, and sending unit located within the tank and all the provisions to easily install it.
Removing the stock fuel tank and replacing it with an EFI-specific tank is really not as expensive as you may think, and it offers several benefits:
• You start with an absolutely fresh tank with zero rust or sediment
• The internal fuel pump is cooled by the fuel it is submerged in
• The pickup has been located in such a way that it won’t be uncovered during hard acceleration or cornering, as is possible with a stock pickup
Keep in mind that fuel injection systems don’t have a fuel reservoir, such as the bowls of a carburetor, in which fuel is stored. Aside from the relatively small amount of fuel in the fuel lines and the fuel rails, no fuel is stored other than in the fuel tank. If you spend time autocrossing, road racing, or in high-g cornering situations, you absolutely should consider a fuel tank specifically designed for EFI as fuel slosh can uncover the pickup in a stock tank.
Fig. 2.5. This Holley EFI regulator is designed for return-style EFI fuel systems, on which the regulator is located after the throttle body/fuel rails and before the return line (see Figure 2.6 for clarification). (Photo Courtesy Holley Performance Products)
Fig. 2.6. Plumbing a return-style EFI fuel system differs from a return-style system for a carburetor, specifically in the location of the regulator. Thus, EFI systems utilize return-style regulators. (Illustration Courtesy MSD Performance)
Fig. 2.7. This Stealth Fuel Tank for 1964–1968 Ford Mustangs from Aeromotive allows you to remove the factory tank and install one that is completely EFI specific. The kit includes a 340 Stealth fuel pump, pre-filter, internal baffling, sending unit, flanged filler-neck adapter, universal rubber-filler neck, and three ports for the outlet, return, and vent. (Photo Courtesy Aeromotive)
If you elect to use the stock tank, you should consider keeping it more than half full at all times to prevent fuel starvation from the pickup being uncovered. Edelbrock has an ingenious solution that allows you to retain the stock fuel tank. Their Universal EFI Sump Fuel Kit is designed to work in conjunction with your stock tank to provide predictable performance with an EFI system of up to 60 psi in fuel pressure.
Fuel Type
The type of fuel you intend to run influences the type of fuel lines, pump, and regulator you should run. For example, if you’re presently running E85 in your carbureted setup, you know that this fuel is caustic and corrosive to traditional fuel system components. I recommend that you determine this early in the process so you can narrow down your choices.
If your E85 combination produces in excess of 450 hp, some kits may not be compatible simply because of the additional fuel volume requirements of E85 as compared to traditional gasoline. In some cases, the fuel requirements are beyond the capability of the included fuel injectors. In other cases, the components themselves may not be designed to work reliably with E85 (see Chapter 6 for more details).
All components of a fuel delivery system should be chosen to complement one another: feed line, delivery line, return line, regulator, filters, etc. Some kits include some of these components; others include none. Because fuel system components can be one of the biggest expenses in an EFI conversion, it’s best to understand the exact requirements of a particular system before selecting it for your application.
Fig. 2.8. This clever EFI Sump Kit from Edelbrock allows you to retain the stock fuel tank and mechanical fuel pump. The kit installs under the hood and the fuel pump and regulator are mounted within the sump assembly. The kit includes pre- and post-filters, fuel line, fittings, and all of the hardware required to install it. Edelbrock offers kits designed to deliver a constant 49 or 60 psi. (Photo Courtesy Edelbrock)
Fortunately, I’ve got some fuel system gurus at my fingertips and they’ve proven to be an incredibly valuable resource. The more time I spend designing and building fuel systems the more I find hints and tricks for getting the job done correctly (and avoiding problems). When designing a fuel system for your vehicle, your goals should be performance, reliability, and safety.
Fuel Lines
The fuel system should be designed so that it is capable of supplying all the fuel your engine requires. Choosing the correct fuel pump is the easy part, as most companies provide compatible maximum horsepower levels. Once you choose the pump, it’s also easy to select the pre-filter, post-filter, and regulator to go with the pump because most manufacturers recommend components that are compatible with a particular pump.
The difficult part is deciding what size and type of fuel lines to use with all the new parts. If you’re installing a throttle-body-style EFI system, the system’s manufacturer typically specifies a given diameter of fuel line to supply the throttle body, but not much more. And, depending on who you ask, you may get varying answers. In my experience, I have found the following to be true:
Fuel Line Size to Throttle Body: Use what the manufacturer of the throttle body specifies. This should be in agreement with the manufacturer of the fuel pump. (Keep in mind that the post-filter is in-line here.)
Fuel Line Size from Throttle Body to Regulator: Use what the throttle body manufacturer specifies. This should be in agreement with the manufacturer of the regulator. Use a minimum of -6 line for returns.
Fuel Line Size from Regulator to Tank: Use what the manufacturer of the throttle body specifies. This should be the same size as the size of the fuel line from the throttle body to the regulator. Use a minimum of -6 line for returns.
Size of Line from Tank to Pump: Use one size up from the size of the fuel line to throttle body. Keep in mind that the pre-filter is in-line here.
Size of Line for Vent: Use the same size as that of the return line. For example, if you install a throttle-body EFI system that calls for -6 feed line to the throttle body, the line specifications are as follows:
The type of line you use is a function of the fuel you run as well as personal preference. Push-lock line is probably the most common choice for fuel systems because it’s inexpensive and easy to install. That being said, if you choose a push-lock line that does not have a non-collapsible design with a tough core, it absolutely cannot be used for the inlet of a high-volume pump. High-volume fuel pumps are in many cases capable of creating a high vacuum on the inlet. This can collapse any line that does not have a non-collapsible design, creating a restriction and possible pump failure.
Pump Location
Mount the fuel pump in a location where it can run cool. Heat is a fuel pump’s worst enemy and you want your electric fuel pump to live a long and healthy life. If you choose to locate the pump externally, choose a location that has good airflow and is preferably not within close proximity to the exhaust.
Or, you can do what the OEMs do, which is to locate the pump in the tank. The obvious advantage to this is submerging the pump in the fuel keeps it cooler than locating it externally. If you elect to locate the pump in the tank, it (and the wiring to it) should be designed specifically for an in-tank application. As with any vehicle with an in-tank electric fuel pump, you should avoid running the gas below 1/4 tank so that the pump is always submerged in the fuel, especially in the summer.
Fig. 2.9. This Aeroquip push-lock hose has a tough core that is very resistant to collapsing. It is also compatible with E85 fuel.
Fig. 2.10. When converting to EFI, retaining the stock fuel tank and adding an external fuel pump is the least expensive way to upgrade your fuel system. The pump in this 1970 Olds (featured in Chapter 6) is located along the frame rail on the passenger’s side of the fuel tank as low as possible. The factory tank in this Olds has been upgraded with a sump.
Ask any engine builder where you should install an external electric fuel pump, and they will tell you the same thing: locate the pump rearward of the fuel tank and below the lowest point of the tank. This is because electric fuel pumps are better pushers than pullers. By locating the pump below the lowest point of the tank, gravity feeds fuel to the pump, no matter the level in the tank. Locating the pump rearward of the tank ensures that the pump is never starved of fuel during hard acceleration, which is also sound thinking. In many cases, however, this is simply undesirable as it places the pump well below the rear bumper of the vehicle and in plain sight.
Regardless of whether or not you locate an external pump rearward of the tank, it absolutely needs to be mounted as low as possible with respect to the fuel tank. It goes without saying that you can’t locate it in such a fashion that it or the fuel lines can be damaged from debris on the road. In some cases, you can find a place along (or even within) the frame rail to locate the pump that keeps it protected and places it below the lowest point of the fuel tank. If you are simply unable to locate the pump below the lowest point of the fuel tank, you need to keep the level of fuel in the tank above the inlet of the pump or you risk damaging the pump.
Fig. 2.11. The fuel pump and pre-filter are installed in this 1964 Chevelle (featured in Chapter 5). These components are located in front of the stock fuel tank and as low as possible. We used the stock pickup assembly in the tank in this installation. If this pickup has a sock, it should be removed as it can be a restriction and isn’t necessary with the pre-filter.
Pickup for External Pumps
Any competent engine builder will also tell you to use a sump to supply an external electric fuel pump. Again, this is not always possible and you may choose to rely on a pickup within the tank. This is fine, as the principle of a siphon allows fuel to remain in the fuel line all the way to the pump, once it has been filled by the pump during the initial power up of the pump, that is. If you elect to run a pickup, keeping the level of the fuel in the tank above the inlet of the pump is that much more critical.
Return Fuel
Placement of the return line within the tank is often overlooked. I’m talking about where the fuel is returned within the fuel tank and whether that’s above or below the level of the fuel within the tank. Any fuel system with a return line returns all unused fuel to the tank. It is preferable to return the fuel below the fuel level in the tank and not above it. If fuel is returned above the level of the fuel within the tank, this can cause aeration (the addition of air to the fuel) which can cause the pump to cavitate.
High-Horsepower Fuel Pumps
So, you’ve got a nasty combination that makes serious horsepower. This means that you’re also running a high-flow electric or mechanical fuel pump. As you convert to EFI, you may need to replace that fuel pump with a high-flow electric fuel pump capable of much higher operating pressure. Big electric fuel pumps require big current, so it’s critical to wire it per the manufacturer’s explicit instructions and even more important that your charging system can adequately power it. If you’re also converting to a return-style system at the same time, you’ve got a new concern: heating the fuel.
Most of the big high-volume electric fuel pumps on the market (including those for carbureted applications) are really more suited for short-term operation at the drag strip than they are for long-term operation on the street. When you use such a fuel pump in a return-style fuel system for a street application, you’re moving a great deal of fuel to the front of the vehicle and fuel that’s not burned is returned to the tank. As the fuel is circulated it is also heated. Operating a high-volume pump for long periods of time isn’t the best idea as it can result in pump failure. Managing the pump speed based on fuel demand is a far better idea, but how? Pulse width modulation (PWM). That’s how.
PWM allows the pump speed to vary based on the actual fuel demands of the engine. A PWM fuel pump controller manages the pump speed by varying the duty cycle in the same way that the ECU manages the output of a fuel injector. This is typically done by tracking engine RPM. A few companies offer PWM solutions for high-volume electric fuel pumps, including Fuelab, Weldon, and Aeromotive. (See Chapter 4 for details on installing an Aeromotive Fuel Pump Speed Controller, a PWM controller compatible with any electric fuel pump.)
Fig. 2.12. This fuel pump controller from Weldon offers PWM technology to manage the speed of electric fuel pumps. A controller such as this allows you to use even the biggest fuel pumps without fear of premature pump failure. In addition, such a controller minimizes fuel heating of any return-style fuel system, critical in street-driven applications.
Fig. 2.13. The Prodigy series of fuel pumps from Fuelab utilize built-in PWM technology. When used with the matching Fuelab PWM regulator, pump speed is managed based on actual fuel requirements of the engine. The two are interconnected by a single wire. Prodigy fuel pumps can also be interfaced to the PWM output of a compatible ECU to manage pump speed. (Photo Courtesy Fuelab)
Fuelab offers high-volume fuel pumps with built-in PWM control. In fact, these can be interfaced directly with their mating electronic regulator so that fuel pressure can be managed in real time based on actual fuel requirements.
One of the benefits of installing such a controller (or pump with a built-in controller) is that the pump noise is greatly reduced. Anyone who has ever used an electric fuel pump knows full well that they’re super noisy. I don’t know about you, but I’d rather listen to the blower whine and exhaust tone at the stoplight than the annoying buzz from the fuel pump.
Fig. 2.14. Interfacing the PWM signal to the Fuelab Prodigy fuel pump is simple. (Illustration Courtesy Fuelab)
In my time at cruises and car shows, I’ve heard plenty of stories about high-volume fuel pump failures. I’m convinced that 99 percent of these failures are a function of incorrect installation. If your installation requires a high-volume EFI pump, you’re well advised not to cut corners in its installation. Otherwise, when it fails, you know exactly who to blame.
Pump Safety
Consider that an electronic fuel pump can move a lot of fuel. What would happen if you were to become involved in an accident and the fuel system became compromised? Obviously, turning the ignition off would be your first move, which would instantly disable the fuel pump. But sometimes our brains don’t work like that in such a situation. Holley recommends the use of a simple pressure shutoff switch (PN 12-810) that can automatically disable the fuel pump if fuel pressure drops to below 5 psi. It can be wired to disconnect the trigger lead between the ECU and fuel pump relay or controller.
Fig. 2.15. The Holley 12-810 Fuel Pump Safety Pressure Switch can be used to shut off any electric fuel pump when oil pressure drops below 5 psi; never a bad idea. (Photo Courtesy Holley Performance Products)
OEMs often use an inertia switch that disconnects power to the fuel pump in the event of a sudden impact. They’re readily available and one could easily be wired to work with an aftermarket fuel system.
My dad taught me as a kid that any job worth doing is a job worth doing correctly. The fuel system is the heart of an EFI system so you mustn’t take any shortcuts. If you do, you will certainly have problems and you risk damaging the fuel pump and possibly your engine. Why take that chance?
As discussed in Chapter 1, some aftermarket EFI systems also offer the ability to manage the engine timing (engine management). In my opinion, this is absolutely the way to go. The MSD Atomic system and other more expensive systems offer this feature. Managing fuel delivery and engine timing separately is an antiquated idea, albeit a more affordable one. Managing fuel delivery and engine timing simultaneously and electronically provides so much more tuning potential, which allows you to more easily achieve better drivability and performance.
Fig. 2.16. This Ford inertia switch is designed to disconnect power to the electric fuel pump in the event of a collision, preventing the fuel pump from pumping fuel. If the fuel pump continues to operate, a bad situation can turn into a really bad situation. The red button allows it to be reset in the event it has been tripped. Ford used these for years and they can be found in your local salvage yard (located just in front of the driver-side taillight assembly of Fox-Body Mustangs) on the cheap and easily interface it with your aftermarket fuel system.
Regardless of which path you choose, it’s vital to understand the manufacturer’s recommendation for lighting the fire in the cylinders. Some kits allow you to utilize some or all of your existing ignition components. Other kits require that you upgrade some or all of them. Even others, such as the Edelbrock Pro-Flo EFI kits, include a distributor as part of the equation. However, most kits require that you supply these components separately.
If you elect to go with a system that provides engine management, however, you need to eliminate all outside influences on timing, such as centrifugal advance, vacuum advance, boost retard, nitrous retard, dash-mounted timing controls, etc. The ECU electronically manages the timing automatically based on all of these variables. If your distributor has centrifugal or vacuum advance, it may be as simple as locking these out. Also, if you’re like most performance enthusiasts who use a stand-alone capacitive discharge (CD) ignition box for a hotter spark, you absolutely want to ensure that you select a kit that allows you to retain it.
Fig. 2.17. When converting to an EFI system that offers the ability to manage the timing, you need to choose ignition components that are compatible with the system to allow it to do so. I used these MSD components when converting the big-block Chevy in my Olds to EFI. An HEI-style distributor was required as I used the distributor to trigger the ECU as well (see Chapter 5 and Chapter 6 for more details).
Fig. 2.18. A crank trigger is an inexpensive way to get rock-solid timing. MSD offers kits for numerous applications. Shown here is their part (PN 8633) for small-block Chryslers (see Chapter 6 for more details). (Photo Courtesy MSD Performance)
In addition, this may be an excellent time to consider the triggering of the ignition system itself, either independently or via the ECU. Most common is the traditional method of allowing the distributor to manage this. However, it would be remiss of me not to mention that this is the time to consider a crank trigger. Several companies offer complete kits that are compatible with most EFI systems.
Running a crank trigger allows you to sidestep any slop in the timing chain and/or cam gear on the distributor. If you’ve fought a timing problem for whatever reason with your carbureted combination, you will fight it with the EFI system as well. Why not eliminate it altogether? The owner of the Olds Cutlass featured in Chapter 6 fought this problem for years. Converting to a crank trigger solved this problem once and for all.
Electrical System Requirements
If electrical isn’t your strength, consider picking up a copy of my other books, Automotive Wiring and Electrical Systems and Automotive Electrical Performance Projects to supplement this discussion. Look at it like this: The electrical system is the only system in the vehicle that can influence the performance of the others. If you have electrical problems that you’ve been “gonna get around to fixing,” get to them before undertaking an EFI upgrade. You will avoid all the heartache associated with choosing to address this “if it becomes an issue.” Trust me; it will.
I read many of the enthusiast automotive magazines, and all too often, readers have written to them when experiencing problems with their aftermarket EFI conversion. In many cases, the tech editor identified problems that were caused by electrical system inadequacies. It’s amazing to me how many perfectly good fuel pumps are burned up by inadequate wiring and excessive voltage drop especially when you consider how clear the included manuals are in regards to their electrical requirements.
If you take nothing else from this chapter, recognize that an EFI system is a major investment. If you starve its components of the current they require to operate optimally, you run the risk of damaging the components themselves or even damaging your engine. At a minimum, you have one heck of a time getting the system to operate properly, let alone getting it to work optimally.
Choosing the wrong alternator is the number-one mistake enthusiasts make again and again. If you’re making the conversion to EFI, you may also have to upgrade your alternator and possibly its wiring. You can easily (and definitely should) make this determination with your vehicle while it is in running state with the carburetor. I can’t stress enough how important this is.
Depending on the system you choose, the ECU can require between 10 and 40 amps of current to do its job. In addition, the electric fuel pump can require between 10 and 30 amps of current. On the low side, this is a 20-amp increase in current requirements over a carbureted application with a mechanical fuel pump. Now, let me quantify that further. On the low side, this is a 20-amp increase in the current required of your alternator at idle (800 engine rpm).
Establish Size of Alternator
Here’s the correct way to learn what size alternator you require after the upgrade:
1. Determine the maximum amount of current the system requires at 14.4 volts.
2. Determine the maximum amount of current the fuel pump requires at 14.4 volts.
3. Determine the maximum amount of current the ignition components require at 14.4 volts.
4. Determine how much current your existing vehicle accessories require at idle with the engine at operating temperature. (This process is outlined below.)
5. Add the above amounts together.
The ECU, fuel pump, and ignition components all require less current at idle than at 6,000 rpm, but that’s okay. By using these worst-case-scenario numbers, you have a bit of a buffer, which prevents your alternator from working at 100 percent of its capacity at idle. The net result is a reduction in heat created by the alternator at idle, so it has a nice long life.
Why Connect to the Battery?
