Читать книгу Ford Mustang 1964 1/2 - 1973 - Frank Bohanan - Страница 8
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INTAKE, EXHAUST AND FUEL SYSTEMS
Properly matched camshafts, valvetrains, and cylinder heads with great flow characteristics don’t perform at their maximum potential unless you’re able to efficiently get sufficient air and the fuel to them in the correct amounts. Not coincidentally, the air intake and fuel systems are responsible for these duties.
In this chapter, I discuss the path of the incoming air from where it enters the vehicle, through the throttle(s), and then into the cylinder heads and out the exhaust while also providing guidelines for each vehicle type. I address the fuel system in a similar manner; from the fuel tank to where the fuel enters the intake air. I concentrate mostly on carburetion because that’s what all of these cars originally came equipped with.
I also discuss some cost-effective options for electronic fuel injection (EFI) retrofits. (Completely custom EFI systems are not within the scope of this book and only provide a meaningful incremental benefit in competition/racing use.) The EFI systems I discuss are focused on providing better driveability, starting, and efficiency relative to carburetors while also having similar, if not better, performance for a reasonable cost, and with fairly easy installation.
The stock air intake systems of early Mustangs were, for the most part, not much to write home about. They were made for the masses with little attention to performance potential, except for the relatively rare performance engines not covered here. Most were a closed-element design with heated inlet air to help the engine run better when it was warming up in colder conditions. In warmer climates a common trick was to flip the lid upside down to improve airflow.
An open-element air cleaner was available in some cases, which allowed the engine to breathe better than the closed-element design. It was, however, still forced to ingest underhood air, which is hotter and less dense, therefore offsetting some of the benefit. The noise level also increased but that was usually considered a good thing.
Cold-Air Intakes
One option in terms of stock setups was a cold-air/ram-air type such as those with dual snorkels, which were routed to the fenders to get colder outside air. Another option was the well-known shaker-style hood scoops, which pulled cold air into an enclosure around the carb(s) and sealed to the bottom of the hood. Retrofitting one of these to a car that didn’t have them, even a mildly modified daily driver, should improve performance noticeably, particularly under certain weather conditions.
A cold-air intake helps produce maximum performance and it’s better if there is some degree of ram effect. This setup used on the Agent 47 Harbinger 1969 retro racer is a perfect example. The duct is located in a very high-pressure area on the front of the car for ram effect. A filter with large surface area and low restriction is used to keep dirt and debris out of the intake air.
Duplicating the OEM setup exactly can be costly but it ensures you’re a lot less likely to have issues with water ingestion, dirt, or other debris getting into the engine. There are many aftermarket variations of these options.
For a high-performance street car or a streetable track-day car, some form of intake upgrade is required to eliminate the restriction of the stock system and to have the higher flow you need for the higher power level. A minimally restrictive cold-air intake system that benefits from at least some ram effect/pressurization as vehicle speed increases allows all the other flow enhancements to realize their greatest potential.
When a MAFS-based EFI system is used, all the intake air must go through the sensor so only a single duct can be used. The duct size can be fairly large as long as the sensor is matched to it. This is a ram air setup on a 1965 fastback 347 stroker equipped with an EEC-IV. Placing the filter inside a box behind the grille ensures a good supply of cool, pressurized outside air. The larger (97 mm) Abaco/DBX digitally programmable sensor sits right behind the filter on the other side of the box. The sensor has a very large and smooth bell-shaped opening to aid flow into it, plus the straight ducting behind helps ensure accuracy.
The dual large-diameter ducts of the Agent 47 system allow a lot of cool pressurized air to reach the engine. The rubber material of the ducts also helps to slightly insulate this air from the underhood heat so less makes its way to the engine.
This EEC-IV installation system in a 1965 draws cool outside air into the filter box behind the grille (under the ZEX decal), passes it through the Abaco/DBX MAFS, and then straightens it out by a length of large-diameter ducting before it reaches the throttle body. There’s also a nitrous nozzle along the way. The thick rubber and plastic ducting (filled and smoothed inside) provides some insulation from heat to help keep the air cooler and denser for better performance.
Always use a less-restrictive but still effective permanent air filter (dry or oiled gauze, metal mesh, foam, or some combination of these) to avoid the performance loss that occurs as paper elements become dirty. Be sure to clean the filter when needed and carefully re-oil it if applicable. But remember that too much can cause issues with a mass airflow sensor (MAFS).
It’s generally not very beneficial to insulate the ducting from the cold-air inlet(s) to the engine but an open-mesh screen should always be used to keep any larger debris out of the engine. Make sure all of the joints are sealed but still leave a means for rain/water to escape.
Holley and other carburetors delivered fuel to many Ford small- and big-block engines. These ranged from a simple 1-barrel carb on 6-cylinders to dual 4-barrels as a dealer-installed option on some high-performance models. In most cases, a well-chosen single 4-barrel delivers just as much performance, or more, and it is a lot easier to tune and maintain while also being more driveable.
There are far too many carburetor options to provide a specific recommendation but there are some general things you can look for to help you make a better choice. Of these, the CFM rating (essentially the maximum amount of air it’s capable of flowing) of the carb is the first thing to nail down. Many people tend to think more is better; that putting a big carb on an engine always makes it perform better. Not true. Quite the contrary, actually. An oversized carb doesn’t improve performance but it significantly degrades driveability and fuel mileage while also making the engine harder to start and more prone to fouling.
It’s usually better to err on the side of caution and go with a slightly smaller carb rather than one that may be too big. Power may suffer very slightly but throttle response, driveability, and so forth is markedly better.
Selecting a Carburetor
Some very general guidelines for the CFM rating for a given small-block situation are that less than 600 cfm is almost always more than enough for a mildly modified daily driver. For a street-performance car with mild to moderate mods a 600-cfm carb works in some cases but a 680-to 700-cfm carb is probably called for when there are a few more modifications. By the time you get into upgrading the cylinder heads, cam, and so forth you’re probably ready for a 750-cfm carb. This is also good for most streetable track-day cars of about 600 hp or so. If you have a highly modified street-performance car with larger displacement or a streetable track-day car with more than 600 hp you may want to look at going to a carb with more than 800 cfm.
Other things you must consider are engine size, maximum RPM, level of modification, fuel, power adder usage, vehicle weight, transmission type, and gear ratios. Considering at least these main factors help ensure a wiser choice.
The brand of carburetor is less important than its features. Some are generally only needed for street use (such as a choke) while others are meant solely for the track (extra tunability provisions such as screw-in air bleeds, plus easy assembly and disassembly features, etc.).
A daily-driver carb needs to have all of the provisions in terms of vacuum and PCV connections, a choke, a simple idle circuit, and vacuum secondaries. The choke can be electric (for simplicity) or manual (for greater control). There’s no reason to try to reuse the OEM choke setup because the electric choke works much better and is far easier to adjust.
Quick Fuel Technology (QFT) offers several different series of carbs. The HR (hot rod) series is available in CFM ratings ranging from 580 to 780 for models with vacuum secondaries and 600 to 850 for those with mechanical secondaries. These carbs are aluminum and use separate float bowls and metering blocks. They use four-corner idle, screw-in idle feed restrictors, and air bleeds. They also have glass fuel-level windows and adjustable center-hung floats. The vacuum secondary models allow for adjustment using only hand tools with no need for an assortment of springs or the risk of torn diaphragms. (Photo Courtesy Quick Fuel Technology)
Edelbrock’s Thunder AVS carbs provide simplicity with excellent streetability. They don’t provide as many tuning options as some other brands but they build on the features of Edelbrock’s Performer series carbs by adding a Qwik-Tune Secondary Air Valve to the virtually identical features shared with the Performer carbs. This tunable air valve allows you to adjust the secondary opening rate with simple hand tools. Metering changes are made by simply swapping in new metering rods. (Photo Courtesy Edelbrock)
Stock throttle linkages can stick/bind and not operate smoothly. Replacing the stock throttle linkage with one of Lokar’s throttle cable kits ensures smooth, reliable throttle actuation. These cable kits provide extra flexibility in the way they’re routed and more precise adjustment. (Photo Courtesy Lokar Performance)
A high-performance street car likely has an electric choke and adjustable vacuum secondaries at the lower end of the power range and probably migrates to mechanical secondaries and a manual choke at the higher end. In most cases, a more sophisticated “four-corner” idle setup probably provides the extra adjustability needed for a stable idle with the more aggressive camshaft likely being used. The materials used are also better (billet aluminum and higher-quality gaskets, floats, and so forth), as is the design of other components such as the metering blocks, power valves, and boosters.
A streetable track-day car is usually just a larger evolution of what is used for a high-end street performance carb. It has a higher CFM rating, a manual choke (if any) plus all of the adjustability, tuning, and design features needed for optimum performance and durability during track use. It also very likely uses mechanical (instead of vacuum) secondaries and special bowl and float designs.
Some of these features may also be common to some high-performance carbs.
After the air and fuel have been introduced to each other in the carburetor the mixture passes into the intake manifold and makes its way to each cylinder. Although this sounds relatively simple, it is not. First and foremost, you ideally want each cylinder to receive the same amount of air/fuel mixture for each combustion event. This is impossible for a number of reasons so you just try to come as close as you can.
On a relatively well-designed, single, 4-barrel manifold you can get down to about a .5 air/fuel ratio spread across all eight cylinders under peak power conditions. This varies greatly with engine speed and load for no other reason than the differing positions of the throttle plates in the carb(s) affects the path of the mixture. The end result is that you have to tune (jet) for the leanest (weakest) cylinder to prevent detonation, which makes the other cylinders richer than you want. That lowers peak performance and wastes fuel (lower MPG).
Aftermarket manufacturers do their best to design intake manifolds with even flow distribution but they are limited by the location of the carb(s) versus the intake ports on the head as well as the size and shape of the intake runners of the heads. A single-plane manifold may have a straighter shot at each port but that doesn’t always ensure more even distribution. When a dual-plane manifold is used to improve low-end performance the increased complexity inherent in the design can also make balanced distribution more difficult to achieve. The higher-flow velocity of the dual-plane manifold (due to normally lower volume runners, among other things) can help atomization in general but not necessarily distribution.
This Edelbrock RPM Air Gap dual-plane manifold is optimized for an RPM range of 1,500 to 6,500. The runners have been raised above the floor of the manifold (the “air gap”) to remain cooler and transfer less heat to the mixture. The exhaust passage for the choke has been eliminated so a manual or electric choke must be used. The intake runner cross-sectional area and the height of the carb-mounting flange have been increased to produce more top-end power with minimal loss at lower RPM. This type of manifold is exceptionally good for a moderately to heavily modified street-driven high-performance car. (Photo Courtesy Edelbrock)
A single-plane manifold is often preferred for 600 hp or more. This Summit Racing Street and Strip Stage 4 manifold provides gains in the 3,500- to 7,500-rpm range. This is more of a strip/track-oriented manifold in that it has four ports for coolant temperature sensors (two in front, two on the rear coolant crossover), cast-in bosses for nitrous nozzles or fuel injectors, and a larger, more-open plenum. The runners are separated from the manifold floor to keep the intake mix cooler. (Photo Courtesy Summit Racing)
Daily drivers and mildly to moderately modified high-performance street cars normally use a dual-plane manifold because this design is best for the 1,500- to 6,500-rpm range in which they are mostly operated. A more heavily modified high-performance street car and a streetable track-day car usually benefits from a single-plane design to get the more even distribution and better performance in a range of about 3,000 to 7,500 rpm.
Pure race manifolds, which may be hard to tolerate in street use, can go beyond this RPM level but are only appropriate for the highest power levels when there is little concern about significant street use.
The conversion from carburetion to fuel injection offers many potential benefits. Among them are better mixture distribution, idle, throttle response, driveability, and gas mileage, plus lower pollution. The knock on fuel injection has been that it was complicated, costly, and didn’t make as much power as carbs. It’s safe to say these concerns have been almost completely eliminated with modern aftermarket EFI systems. (I don’t discuss mechanical fuel injection because there’s little, if any, benefit for street use and the cost is usually high.) EFI systems are now very simple to install and can even be “self learning” to a large degree so the task of tuning is greatly simplified.
Many systems just involve the removal of the carburetor and fuel pump so they can be replaced with a higher-pressure electric pump, a different fuel-pressure regulator, and components such as a throttle body (or multiples) and sensors. The simplest systems look very similar to a regular 4-barrel carb and even use a similar-style air cleaner. Most of the electronics are tucked out of sight so the original underhood appearance changes very little in many cases. At least one oxygen sensor needs to be installed in the exhaust and the fuel line usually needs to be upgraded with a higher pressure rating.
With many systems a laptop or other computer isn’t needed because the systems are self-learning. If you like to tune, the possibility of using a laptop is still generally available. These throttle-body systems have an air/fuel mixture flowing through the intake manifold so they are still subject to less-than-perfect balance between them.
However, the fuel is better atomized by the fuel injectors integrated into the throttle body and the fuel metering is much more precise and adaptive to temperature, barometric pressure, and numerous other parameters that are ignored by a carburetor. This allows the EFI system to continually re-optimize the mixture to compensate for changes in these factors while also continually monitoring the effects of the changes made through the oxygen sensor.
The Powerjection III kit from Professional Products provides throttle-body fuel injection. You have to install an electric fuel pump in the tank, install sensors, use high-pressure fuel lines, and adapt the system to your wiring harness. You hook up all the wiring and check everything for leaks and other problems before you turn the key to start it. You can use it in a “blow-through” configuration with a supercharger or turbocharger because it has a built-in 2.5-bar MAP sensor that can read up to 25 psi of boost. The Powerjection III is good for up to about 550 hp with the standard parts. A larger throttle body (1,200 versus 750 cfm), larger fuel injectors, and a more-powerful fuel pump can raise the power capability to about 700 hp. (Photo Courtesy Professional Products)
Fuel Injector
To get the full benefit of EFI requires that you no longer inject fuel into the manifold like a carburetor. Instead, you point a fuel injector at each intake valve and spray the fuel directly into the intake port. This does several good things. First, by only flowing air through the intake manifold the distribution is instantly better because air, being a gas, is naturally inclined to distribute itself more equally. In addition, spraying the fuel right at the valve means there’s no chance of the fuel puddling on the floor of the intake manifold or wetting the walls of the runners to any significant degree. This also helps distribution as well as overall metering. Finally, if you fire the injectors individually (sequentially, as opposed to groups) you can also realize better throttle response and further improvements in overall fuel control.
Modern fuel injectors running at higher pressures do an excellent job of atomizing the fuel into a fog that’s more easily burned. Individual injectors at each port are better than fewer larger ones farther upstream because each one has to deliver less fuel and can thus be more precise and responsive. As the oxygen sensors read the composition of the exhaust gases they can make the necessary corrections to the fuel flow more quickly and more accurately by doing so one cylinder at a time. Combined with the same ability to compensate for other factors such as temperature and pressure, a sequential EFI system provides the potential for extremely accurate, precise, and adaptive fuel control with built-in learning capability and diagnostics for a very reasonable cost.
Engine Control Unit
The amount of fuel to be injected into the engine depends on the amount of air it ingests, just as with a carburetor. With EFI, however, the amount of air is just input data to the engine control unit (ECU), which is used to determine how long each injector stays open when it fires, thus determining how much fuel is injected.
There are two main ways to provide this data to the ECU: Measure it directly or calculate it based on other information. The first approach requires the use of a MAFS, which uses a very ingenious method of measuring air mass directly, based on how much electricity it takes to maintain a constant temperature on a wire that’s been placed in the airflow path. This has the advantage of being a direct measurement instead of a calculation. It also is able to compensate for modifications that improve airflow as you make them.
If you put in that new cam or exhaust system and the engine flows more air as a result the MAFS sees it and the ECU can act accordingly. Similarly, if the engine wears a bit and flows less air it can take care of that too. This ability to continually measure and correct the airflow is one of the main reasons Ford, for one, uses a sequential MAFS-based control system in virtually all of its new US production vehicles (at the time of publication).
The knock against this approach is you must have a MAFS and place it somewhere close to the engine. It also needs to have a certain length of straight ducting immediately after it to ensure an accurate measurement. This need to have/position a MAFS and use a single inlet duct for the intake air can sometimes be problematic. Still, for the majority of high-performance street cars a sequential MAFS-type system provides the best overall performance and driveability for a reasonable cost. Fortunately, the EEC-IV system used by Ford on production V-8 Mustangs from 1989 to 1995 lends itself very well to retrofitting older carbureted Mustangs with EFI.
This assortment of aftermarket upgrades can replace their respective standard 5.0L components. The Trick Flow Specialties (TFS) Track Heat intake manifold is similar to the OEM manifold but has been revised to flow much better in the 1,500- to 6,500-rpm range while providing even more balanced distribution to each port. The higher-flow (36 lbs/hr) TFS TFX injectors provide significantly better response and atomization compared to stock injectors. Using the basic EEC-IV control system with various component upgrades gives the benefit of a proven OEM system with more and better features, which is also scalable for higher power and is ultimately very cost-effective because you change the system very little as you make more modifications.
These systems can very easily be adapted to older vehicles. When supplemented with aftermarket performance parts they produce very high power levels with better performance than most aftermarket systems. Better still, as modifications continue to be made and/or other changes occur the system can readily be retuned as needed by simply swapping in higher flowing fuel injectors and then recalibrating the ECU. Products such as the TwEECer make the latter process much simpler by either interfacing directly with the EEC-IV ECU to selectively modify its input and output signals or by using a special/digital MAFS made by Abaco Performance.
You can upgrade a MAFS to make an EEC-IV perform better. The stock Hitachi sensor is relatively restrictive because of its basic design and small bore. It’s also not the best in terms of accuracy under some conditions, particularly if the intake ducting isn’t done right. The first aftermarket MAFSs from companies such as Pro-M solved these problems by redesigning the sensor body, so it was much less restrictive and had a larger bore. These parts still used the OEM sensor’s electronics though they were modified and tested to yield much better accuracy and precision.
When different fuel injectors are installed, however, the electronics must again be modified (usually by sending it back to the manufacturer) to match the new injectors. Abaco’s DBX line of digital MAFSs eliminates this limitation while also making comprehensive tuning and recalibration much simpler. Using an even larger and less-restrictive bore Abaco installs four sensors inside the housing so the product is virtually unaffected by the configuration of the ducting or other things such as reversion, which can throw regular sensors off. (Photo Courtesy Abaco Performance)
The Abaco MAFS has the ability to be programmed as needed to revise its internal “transfer function,” which is used to provide air mass data to the ECU. This is a better approach than having to get a new MAFS or having the one you have recalibrated by the manufacturer. The Abaco MAFS can be reprogrammed as often as you need for best performance, whereas regular analog MAFSs must have a specific combination.
Here is a 75-mm Professional Products throttle body and EGR spacer installed on a TFS intake manifold in the same manner as OEM components. Provisions exist for all related OEM components, such as the EGR valve, idle air control (IAC), and throttle position sensor (TPS). This combination is completely compatible with the other OEM (or aftermarket replacement) parts yet it provides much better performance and efficiency.
If you extrude hone the intake manifold, this process removes the rough casting from the interior surfaces and balance flow for the best possible cylinder-to-cylinder air/fuel distribution. It removes and/or smoothes any surface imperfections leaving a very smooth and uniform surface finish. This greatly enhances flow, and each runner can then be treated individually to achieve virtually identical flow through all runners.
The Professional Products high-flow fuel rails and adjustable regulator have been installed on this Windsor. TFX injectors were mounted on the TFS lower intake. These components are an improvement over stock parts. Note how the fuel injectors are precisely aimed in line with the ports to ensure minimal wall wetting or potential for fuel to migrate back up the runners. The fuel rails can accept the stock-type fuel couplings or the fittings can be replaced with those that accept AN hoses. Fuel pressure adjustment is by turning the center screw and then tightening the lock nut.
TFS TFX fuel injectors are a far-superior design compared to OEM EEC-IV 5.0L injectors. The most obvious difference is three exit holes instead of a single pintle type of exit. The revised nozzle design improves atomization and reduces the potential for deposit buildup. TFX injectors use disc-type control valves and improved windings for better response with less noise. Stainless steel bodies with Viton O-rings ensure superior durability and sealing while internal 1/2-micron-thick filter screens protect the injectors from dirt and debris. Each TFX injector is fully tested for quality and comes with an OEM-compatible EV-1 type of connector.
EFI systems can also use individual runner-type intake manifolds and can do so very effectively. Because only air is being throttled, there are fewer potential variables compared to multiple carbs so the effect on balance is less. There is still the need to ensure each cylinder receives the same amount of air but this is easier. The short runner lengths are less restrictive than those of a conventional manifold and can thus improve responsiveness and maximum power. The downside of many such installations is they usually end up ingesting hot underhood air.
A design that allows the stacks to protrude through the hood or to be enclosed in a “box” (which seals to the underside of the hood and allows only cooler outside air to be taken in) is better for performance. The use of a hood scoop to create a ram effect is a further improvement if the flow is evenly distributed to each inlet.
Racers prefer the second approach because they don’t usually want the restriction of a single-duct MAFS system, however slight it might be. Many aftermarket manufacturers, and even some OEMs, prefer to calculate the air mass using the “speed density” method. You calculate air mass based on measurements of engine RPM and manifold pressure along with a volumetric efficiency correction factor determined during the calibration process. This gets you pretty close (at least during steady running); then you still use the oxygen sensor data to refine your calculation.
Speed density systems don’t have the requirement of using a MAFS or needing straight ducting, etc. This makes them better suited to crowded underhood areas and the use of more complicated intake manifolds (such as multiple carbs) and/or a power adder with positive manifold pressures. A speed density system can make virtually any amount of power, whereas a MAFS system eventually becomes impractical beyond a certain (though still very high) level.
Sequential MAFS-Based System
Avery easy way to retrofit a sequential MAFS-based system to your older Mustang (or other vehicles) is to purchase a complete kit such as this one from Pro-M Racing. This system uses mostly 2005–2010 OEM Ford components and a few special items to make it work on older, previously carbureted cars. Some improvements over the older EEC-IV system include the ability to use wideband oxygen sensors as well as the original narrow-band type, full OBD II diagnostic capabilities, customizable datalogging, and the ability to easily reflash/recalibrate the ECU via a simple USB connection.
When you get the system it has been calibrated based on the information you provided about your engine. When combined with the inherent capabilities of a sequential mass-air system to adapt as needed you should have an optimized calibration soon after the start. If you change things later, you can just enter the changes (such as new injector size) via the proprietary software provided for installation on your laptop. If you want to do a full-blown calibration/mapping program, you can, but it’s usually not necessary.
The Pro-M Racing system truly is “plug-and-play” from the start. The single-plane manifold has been modified to accept the fuel injectors and rails while maintaining a low underhood profile. Both the manifold and the 1,000-cfm throttle body can support very high-power outputs. The throttle body retains an IAC motor for idle control. A compatible distributor, coil, and full, high-quality wiring harness are also provided with all necessary sensors.
Perhaps the most ingenious aspect of this kit is the use of a modified GM MAFS, which mounts directly above the throttle body. This allows it to sense the mass of the incoming air without the usual limitation of the ducting having to conform to certain requirements. Other MAFS options are also available for different applications (such as a blow-through system with a power adder) but this standard sensor (shown here below the fuel injectors) allows a more classic underhood look without sacrificing performance or driveability. A signal conditioning box is included to convert the digital GM signal to be compatible with the Ford electronics. Because the kit takes care of fuel and spark, you just need to get enough fuel to the rails at the right pressure.
Pro-M also sells pre-bundled packages, which have everything you need: an OEM-level sequential, multiport, MAFS system, which provides dramatic improvements in starting, driveability, fuel economy, and more. It can automatically adapt to changing conditions and modifications plus it can be easily upgraded with new fuel injectors, etc., as needed. You can easily recalibrate at any time via laptop, if necessary, to optimize for any new modifications you make.
All components of the Pro-M Racing MAFS-based system are shown here. The wiring harness, distributor, intake, throttle body, ignition box, and all the necessary parts to complete the installation are included in this kit.
A new high-quality EEC-IV wiring harness from companies, such as Ron Francis Wiring or Painless Performance is necessary. They use superior more-modern materials, which provide better durability and connectivity. These aftermarket harnesses can often be bought in special configurations made for use in older vehicles. In this photo you can clearly see the labels/tags used to identify individual circuits. The color coding and looming of the wiring is also more simplified. (Photo Courtesy Painless Performance)
At the highest levels, say 800 hp or more, the speed density system may make a bit more power. This can matter to a racer, but it’s usually not worth the tradeoff in terms of driveability and long-term adaptability, if the car is still driven on the street. Racers are constantly tuning their cars anyway so they are recalibrated on a frequent basis to compensate for changes. For a high-performance street car or a streetable track-day car this level of interaction may not be desirable or practical.
Whether you use a carbureted or fuel-injected approach you still need to pay attention to the details to get maximum performance, especially with a lot of modifications. An incorrect manifold gasket or cheap fasteners, for example, can negate all of the improvements you’re attempting to make, or even result in expensive damage to your newly improved engine. One precaution that can be taken (especially if there are no special features such as sealing beads, etc., on the gasket) is to apply a thin film of RTV or another suitable sealant around the ports and water passages. Be careful not to apply too much; you don’t want any of the excess getting into the wrong places. This better holds the gasket in place during assembly and further reduces the chance for leaks with negligible risk of other problems.
Stainless steel ARP fasteners for the intake manifold and other external engine components can be part of a complete engine kit or can be purchased separately. In addition to not corroding they are stronger, have a more compact head design for easier access, and were manufactured to tighter tolerances than cheaper bolts.
Reliably getting the fuel to the carb or EFI system in sufficient quantity under all conditions is also necessary for maximum performance. As power levels increase so does the amount of fuel that must be transferred. Likewise, higher acceleration and cornering forces cause more movement of the fuel within the tank, thus potentially moving the fuel away from the pickup. Under some conditions it can suck vapor instead of liquid, with the expected negative results.
Although you always want to be able to use all of the fuel in your tank, with EFI it’s also critical to preventing damage to the fuel pump and other components. That’s why virtually all modern production vehicles equipped with EFI have fuel tanks with internal sumps and/or baffling to keep fuel around the pickup as much as possible. In a high-performance street car or streetable track-day car it will inevitably be necessary to upgrade the fuel supply system to better cope with the need for higher fuel flow under more-extreme dynamic conditions.
Always use a premium gasket, such as this Edelbrock intake example. It isn’t the least-expensive option, but it’s made from high-quality materials and has desirable features such as the imprinted bead around the port opening. You need to make sure they don’t block the ports. Sometimes it’s just a matter of repositioning them. Sometimes you may have to trim them to match the ports.
The stock fuel tank and lines are usually sufficient for a daily driver unless it’s been more extensively modified to produce significantly more engine power or generate much higher cornering forces. When an upgrade is required it normally involves installing a new tank with an internal sump and/or baffles such a those made by Tanks, Inc. When much-higher performance levels and/or event rules require, a fuel cell may be needed for safety and better fuel control. In any case, care must be taken to ensure the fuel pickup is also upgraded to reduce restriction to the fuel pump inlet. Not doing so can reduce the fuel flow rate significantly and also cause pump damage or failure.
A higher-output fuel pump (such as those produced in the United States from Aeromotive) is needed along with upgraded fuel lines, filters, and fittings, etc., to reliably provide the needed fuel. An in-tank pump is normally adequate for most street-driven vehicles while a larger-capacity external pump is needed at the higher power levels and/or when a power adder is used.
Aeromotive’s Phantom Fuel System effectively converts a stock fuel tank to EFI, or to a higher-volume in-tank pump (with better fuel pickup) for a carbureted engine. Cut a hole in the top of the tank with a 6- to 12-inch depth, trim a few pieces to fit, install the baffling/foam into the tank along with the lower retaining ring, and then install the pump and mounting bracket assembly into the tank and on top of the foam sealing ring. The result is a quiet, high-volume pump that runs cool, keeps the fuel cooler, and doesn’t run dry even in very extreme maneuvers. (Photo Courtesy Aeromotive)
If your Mustang is going to be used for competition, you need to install a fuel cell that has a safety bladder. Fuel Safe offers premium-quality fuel cells for first-generation Mustangs. The aluminum outer containers are TIG welded, and the fuel bladders are FIA FT3 approved. The bladders contain full safety foam baffling for excellent fuel pickup and inhibit the possibility of an explosion.
For a conversion to EFI, it’s best to get a fuel tank that’s been modified to accept the necessary hardware, such as this one from Tanks, Inc. This 16-gallon fuel tank is a direct bolt-in for 1964½–1968 Mustangs. It’s been designed with an internal 4.3L sump and baffling that keeps the fuel pump pickup fully immersed even under the most extreme dynamic conditions. The electric fuel pump module/bracket is installed through a hole in the top of the tank that’s been located over the sump. You can use one of the pump modules available from Tanks, Inc., or the pump of your choice so long as the mounting bracket is compatible. A standard five-hole aftermarket fuel sending unit can be installed in the top hole for a fuel gauge.
If an external pump(s) must be used, it is critical that the size of the outlets from the fuel tank/cell be large enough to not cause a restriction. The higher the engine output and fuel flow requirements, the bigger the outlets need to be. Any reasonably powerful street performance car should have at least one -8/.5-inch outlet. As fuel demand increases the outlet size (and fuel line diameter) should also increase to avoid restriction, which may reduce the amount of flow and may cause the pump(s) to overheat or fail.
Aeromotive’s Eliminator pump is their highest-flow pump meant for continuous/street duty. (Only their Pro Series pumps, which are meant for short-time use, flow more.) The Eliminator pump can support up to 2,300 hp carbureted and 1,900 hp with EFI. Those figures drop about 26 percent with boost. The pump has a dual-chamber pumping mechanism and, like its smaller in-tank brother, is especially good at having higher flow at higher pressures. (Photo Courtesy Aeromotive)
In some cases you have to use an electric pump because the timing covers on later engines (such as the 5.0L) have no means to drive a mechanical fuel pump. An excellent example of a mechanical fuel pump upgrade is this 110-gph Edelbrock Performer RPM Street. It’s good up to about 600 hp on a carbureted engine (EFI systems can’t use it). This pump greatly increases flow and also provides larger ports for larger fuel line fittings. This pump runs at 6 psi (no regulator needed) and also features a “clockable” lower housing, which allows you to rotate it as needed to get the best alignment for the inlet and outlet ports. Also shown is an Edelbrock high-flow fuel pump to carb hose kit.
Aeromotive Stealth 340 is a small, yet very powerful, in-tank fuel pump. It can be installed in virtually all fuel tanks/cells likely to be used in these engines. It flows enough fuel to make about 1,000 hp carbureted or 700 hp with EFI, even under boost. It’s a turbine-style pump so it’s very quiet and durable. It comes with a filter sock to pre-screen the fuel and prevent pump damage. It can be used with carbs or EFI. (Photo Courtesy Aeromotive)
Aeromotive’s Billet Fuel Pump Speed Controller (FPSC) is a good addition to any vehicle with an electric fuel pump but is especially beneficial with EFI. The FPSC monitors engine speed and modulates fuel pump speed to better match demand. Unlike other systems that do this by reducing the voltage to the pump (and can lead to damage and possible failure), the FPSC duty cycles the pump power circuit to harmlessly reduce output. (Photo Courtesy Aeromotive)
Nitrous Oxide Injection
Once you’ve upgraded the fuel supply system to get more fuel to the engine you may also want to consider adding a simple and relatively inexpensive way to allow the engine to use the extra fuel supply to provide even more power, at least for brief intervals. This can be done very effectively with the installation of a nitrous oxide injection system.
Supercharging and turbocharging are other examples of “power adders” that provide extra air mass, thus allowing more fuel to be burned to create more power. These are not discussed here due to their high cost and frequent need for custom installation procedures. Besides, the injection of pressurized nitrous oxide along with additional fuel can provide tremendous increases in power for short periods of time. This is because nitrous contains much more oxygen per unit mass than does air so injecting it instantly adds additional oxygen into the combustion chamber, which in turn allows more fuel to be consumed. This creates higher cylinder pressures that translate to more power.
Nitrous can be injected into each intake runner or from a plate underneath the throttle body/carburetor. It can be introduced with the additional fuel (a “wet” system) or it can be injected alone with the additional fuel coming from elsewhere, such as the fuel injectors on an EFI engine (a “dry” system). It can also be injected in multiple locations and in multiple stages to achieve different performance levels and benefits based on intended use.
In drag racing, for example, a two-stage system may inject a smaller amount during the beginning of a run to help prevent excessive wheelspin and then add the remaining amount later in the run once more-stable traction has been achieved. The Nitrous Express Gemini Plate System uses a specially designed, billet Spraybarless plate mounted underneath the carb. It provides 50 to 500 additional horsepower for a limited time. This superior design provides exceptionally balanced distribution along with excellent atomization to deliver maximum performance and efficiency. The high-quality components provide the required flow and have exceptional durability.
Nitrous Express (NX) specializes in later-model EFI-equipped vehicles and have also applied their technology to products for older carbureted vehicles. Systems with power-boosting capabilities from as little as 50 to several thousand horsepower are available. The Gemini wet plate system (shown) is capable of adding up to 500 hp at the wheels. This “next-generation” system has some very unique features. NX claims this system and its advanced plate design are especially beneficial to carbureted Fords.
The Gen-X Accessory Pack offered by NX has everything you need to complete your nitrous installation, including an automatic bottle heater. The heater has a pressure transducer to provide feedback used to keep the bottle pressure in an optimal range, regardless of the ambient temperature. Also included are a liquid-filled pressure gauge for installation on the bottle valve, an NHRA-approved pressure-release fitting (with a replaceable pressure disc), blowdown tube (for venting nitrous to outside the car if the bottle pressure should exceed 3,000 psi), fuel pressure safety switch (stops nitrous flow if fuel pressure drops too low), and all the associated hardware and connectors. (Photo Courtesy Nitrous Express)
These NX Lightnings are advanced solenoids. NX redesigned the flow path inside the solenoids to eliminate unnecessary turns and changes in direction while maintaining a more-constant cross section for the still-liquid nitrous. By raising the inlet port and using a bottom exit, NX eliminated several 90-degree turns and one expansion area. These solenoids have a bypass port that allows you to hook up a purge valve directly to the nitrous solenoid for a neater appearance and more effective venting.
Plate-type systems provide enough nitrous for most high-performance street and street/strip applications plus they’re easier to install and tune. This Gemini Twin Plate uses a perimeter spray system, which acts like a direct-port system in the sense that it directs the plumes toward each runner (in a single-plane manifold) to get a superior mixture balance at each port/cylinder and between them. This approach combines the benefits of direct-port systems (mixture balance and response) with the benefit of injecting farther upstream (more mixing and cooling).
Regardless of the type of system chosen, the mounting position of the bottle is critical to getting all the nitrous out of it. The valve end must be raised and the bottle lined up along the centerline of the car so liquid nitrous covers the internal pickup tube (at the bottom of the bottle) even under hard acceleration. Never mount the bottle sideways (90 degrees to the centerline) or level.
Water/Methanol Injection
Water/methanol injection systems allow increased ignition timing and/or compression ratios, thus improving performance. In essence this can compensate to a degree for inadequate fuel quality and/or octane. This is particularly true in certain areas of the country, such as in California, because these systems can be used to compensate for the availability of only 91-octane premium pump gas. The injection of a water and methanol mixture (along with the potential addition of other additives such as nitromethane) primarily has the effect of cooling the intake charge through the process of converting the injected water into steam during combustion. This lowers the peak combustion temperature while also increasing the burn rate due to the increased surface area of the fuel droplets coating the water droplets.
Water/methanol injection systems have become much more sophisticated over the years. This Stage-3 Boost Cooler from Snow Performance is a perfect example. Snow uses a special, very high-pressure Ultra High Output (UHO) pump that provides greater flow potential and allows for better atomization with smaller droplet sizes. It receives the mixture from standard (shown) or optional, larger reservoirs, which have a bottom outlet for all the fluid.
When a combustible liquid such as methanol is included in the mix the additional energy from its combustion is added to that from the combustion of the primary fuel mixture. This results in a greater total release of energy over a longer period of time and the extra performance comes without the higher pressure spikes that lead to detonation.
One of the more sophisticated injection systems is manufactured in the United States by Snow Performance. This Stage-3 system uses true 2D mapping to ensure the precise delivery of the correct amount of liquid under very high pressure so it is more evenly distributed throughout the intake charge and is more quickly and completely ignited.
The LCD display mounts with Velcro strips, usually on top of the dash, in the driver’s line of sight. The display shows boost pressure, fuel injector pulse-width, and the percent of maximum flow at any given time. The parameters for the mapping are all quickly and easily programmed from the driver’s seat using two buttons (shown). A mixture flow gauge is also available for standard gauge pods.
A unique control unit allows for mapping based on manifold pressure and fuel injector pulse width (in the case of EFI) in any proportion desired by the user. The control unit can also be programmed to operate only under specific conditions and to also provide a warning should the included reservoir run out of liquid. These features allow for extremely accurate metering of the injected liquid, which can reduce the amount of liquid used and/or needed to achieve the desired result. This generally yields better performance in the low- and mid-range load points because they are not receiving more liquid than is really needed, as is common with less-capable systems.
Failsafe Gauge
Even after you’ve made all the upgrades to the air intake and fuel systems you can never be totally safe from mishaps that are beyond your control and unexpected. Being able to watch what’s going on with your air/fuel ratio on the road while datalogging it with some other parameters (such as RPM, boost, etc.) for subsequent evaluation can help. The ability to immediately act on it to protect your engine is even better.
AEM Performance Electronics has developed just such a device for any vehicle: the universal Digital Wideband Failsafe Gauge. It provides a highly accurate Bosch wideband oxygen sensor (which never requires any open-air calibration to be performed) and an internal datalogger capable of storing up to three hours of data for subsequent playback using the included software.
A wideband oxygen sensor helps you tune your engine combination for the best performance. AEM’s Digital Wideband Failsafe (DWF) gauge displays air/fuel data and datalogs it along with other information. It provides a warning to protect the engine should the data fall outside the ranges you’ve set. The DWF uses a proven Bosch UEGO-type sensor for gathering the air/fuel data and an onboard vacuum/pressure sensor, which can read up to 29 psig. Both parameters can be simultaneously displayed on the gauge in real time by using the 24 tricolor LEDs around the edge and the full-color LED display screen in the center. A low-level signal output triggers a failsafe strategy through an external device (such as the ECU). An RPM signal input is used while tuning. (Photo Courtesy AEM Performance Electronics)
The gauge can simultaneously display boost pressure for pressurized cars. Best of all, the gauge can be programmed to provide a warning and an output signal that can be used to retard spark if the air/fuel ratio or manifold pressure/vacuum falls outside of the ranges that you’ve programmed into it. There’s also a trigger function to begin datalogging automatically.
After upgrading your engine to get more air and fuel into it you also need to upgrade your exhaust to get the extra spent gases out of it. For a daily driver this may just mean converting to dual exhausts and/or putting on a less-restrictive set of mufflers and at most, maybe a set of headers to go with them.
For high-performance street cars and streetable track-day cars, however, a complete makeover is needed. Functionality, performance, and durability under more extreme use are the main priorities. For most street cars a 2.5-inch exhaust should be used.
The streetable track car usually has larger (more than 3 inches) tubing and less concern over the noise level or appearance because the car also probably sits a bit lower and has a lot of undercar reinforcements such as subframe connectors. It may also be necessary to use oval instead of round tubing to maintain sufficient ground clearance. It’s also more likely that the exhaust terminates before the rear axle to not only reduce weight and restriction but also to avoid interference with the axle and suspension.
For example, Doug’s headers are manufactured with a machined sealing bead and a thick flange, and are stitch welded at the port. To minimize exhaust leaks the company includes a set of its own proprietary header flange gaskets so all of that good work doesn’t go to waste if inferior gaskets are used. Doug’s gaskets are super thick and made from a specially formulated material that can withstand temperatures up to 1,100 degrees F as well as up to 3,700 psig/255 bar of exhaust pressure. Each gasket is also precisely matched to the port shape of its respective header.
Whenever you use a wideband sensor to monitor the air/fuel ratio take care to be sure it is located where it can “see” the exhaust from all cylinders. On an X-pipe (shown) a good location is just before the merge. On an H-pipe the middle of the crossover is good. With open headers you should really use one per collector, but in any case, the sensor should be as close to the collector flange as possible. In addition, always tilt the sensor so water doesn’t ruin it.
Here is a “mid-length” header (top) and a “shorty” header (bottom). In general, the longer the header, the better it fits. For a mildly modified engine you don’t really see much of a difference, but as power levels rise it’s best to go longer if you can. Fortunately there are plenty of options for full-length headers for older Mustangs. In most cases a shorty header meant for a 5.0L also works in an older car. With small-blocks there’s a lot of crossover.
Installing an aftermarket exhaust system yields considerable performance. Even on a minimally modified car the reduced backpressure can provide more power and better throttle response along with a much better sound. In many cases fuel economy can even improve a bit. The key is to match the exhaust to the engine, particularly the cam and intake. A full package such as this one from JBA is easy to install because all the parts are compatible and complementary, rather than from different sources.
This 1965 fastback with a 347 stroker small-block and a T5 manual transmission has a typical high-performance street car exhaust. As you can see, the long-tube headers fit with no problem even though a hydraulic clutch is used and there are oxygen sensors in the collectors. This Magnaflow system uses 2.5-inch stainless steel tubing and an X-pipe design, which, thankfully, tucks up rather neatly under the driveshaft. One of the issues with X-pipes is they can sometimes hang down relatively low depending on where the “X” is. H-pipes are less prone to this problem but they generally don’t perform as well as X-pipes.
This small-block Windsor kit has multiple options for configuring the rear part of the system. The quickest option is to simply install turndowns on the muffler outlets (shown). This reduces restriction but causes a lot more noise inside the car. You also have to worry about the fumes getting into the car at low speeds or when sitting still. The main reason to use this type of setup is a lack of clearance around the axle due to intrusion by the suspension and/or other components such as a fuel cell. In that case you probably use a “turbo”-style muffler (shown) for clearance.
These small-block Ford Windsor headers from Doug’s are rare because they do double duty by being designed for a full race car and for the street with a much lower power level. A good compromise for such dual-use situations is to use a Tri-Y design instead of a race header with larger tubing.
