Electronic Fuel Injection Installation - Thinking of Injection
Late Model Muscle
So far, we have focused more on retrofitting an earlier conventionally equipped engine to a programmable EFI system, but what about modern iron? Factory LS-series Chevys, Mopar Hemis, and Ford Mods are all very good engines, and fully computer-controlled in OEM application. Scalping one of these mills and installing it in your project can offer exceptional power and efficiency, but what about the controls? Trying to adapt an OEM engine management system is very complex, and these engines have no provisions for distributors, carbs, or any of the old familiar components. FAST has solved the problem with its E-DIST II setup, which, as the name implies, is an electronic "distributor." The E-DIST II makes the XFI brain compatible with these high tech engines. The unit takes signals from the factory sensors, and will run the factory ignition systems and coil packs. A fast harness plugs right into the OEM components, and it is tuning as usual with the XFI. Better still, as technology changes in the OEM world with things like sensor readings, different trigger wheels, and other updates, the E-DIST can be upgraded to make it compatible, simply by downloading a data file.
EFI has come a long way in terms of becoming a viable alternative to conventional carbs and ignition in high performance street or even many forms of race applications. For late model engine types, up-to-date and compatible electronic control systems are a must-have, especially in retrofit applications. However, don't contemplate the swap to EFI looking for big power and torque gains, because the reality is that a comparable, well-tuned carb system will make essentially the same power, if the same basic induction and engine configuration is used. EFI came into its own with the unrivaled tunability to optimize the system for any running situation, and its ability to compensate on its own. The drivability of a well-tuned injection system is demonstrated every time you drive a modern vehicle. That, and controlled efficiency, are reason enough to consider EFI. However, EFI can offer a tremendous advantage in engines boosted with turbos or centrifugal superchargers, where the control of an EFI system can't be matched. EFI systems also allow for advanced "dry" manifold designs, where taking advantage of ram tuning can add tremendous torque gains. It's becoming a digital world, and in the world of engine performance, EFI is leading the way.
A valuable feature for any...
A valuable feature for any aftermarket EFI system is the ability to run in closed loop, which means the mixture (air/fuel ratio) is monitored continuously, and the processor makes continuous minor adjustments to the injectors to keep the ratio in the targeted zone. A wide-band Lambda sensor creates a signal that corresponds to the air/fuel ratio at any instant. EFI can also be run in Alpha-Numeric mode, which means closed-loop, where the fuel delivery at the injector is strictly controlled by pre-programmed fuel maps. Street or street/strip performance cars really benefit from closed loop capabilities.
One of the inputs the XFI...
One of the inputs the XFI processor needs is a throttle position sensor (TPS). A TPS tells the control unit how far the throttle is open by an electronic signal that varies with throttle position.
EFI is readily adaptable to...
EFI is readily adaptable to a coil/distributor ignition. With the XFI, the control box electronically handles the timing functions, so the distributor's advance mechanism must be locked out. MSD distributors come with instructions and the required pieces to lock out the advance mechanism, and this is a modification accomplished relatively easily on most distributors. The FAST XFI is compatible with OEM electronic ignition distributors from most manufacturers. A conventional distributor will allow batch-fire of the injectors. A sequential system follows the firing order with the injector pulse on a cylinderby-cylinder basis. To time a sequential system, a cam-position signal is required so that that the control unit has a reference of which cylinder is firing. A dual-sync distributor is needed for this cam reference signal. MSD and Mallory among others manufacture distributors with this feature, while FAST is tooling up for a full line of dual-sync distributors.
We ran a simple batch-fired...
We ran a simple batch-fired system on this 454 Chevy, using a locked-out conventional distributor combined with a MSD ignition system. Batch fire works very well, and testing shows very little appreciable advantage to sequential, though with the dual-sync distributor, a sequential system can be easily accommodated if desired. The MSD "points" signal is wired to the XFI controller to provide the rpm signal.
Engine and sensor functions...
Engine and sensor functions are all monitored and can be recorded with key information available on the tuning screen via the dashboard functions. The FAST system also has useful data-logging capabilities. Base maps are provided, which should get you going, once the menu-driven engine setup settings are completed. Fine-tuning dials it in, as Westech's Tom Habryzk is doing with the fuel table for our 454 here. Various tables control all the required fuel and timing functions, with a variety of options on how to change the settings and by how much.
That pretty much covers the...
That pretty much covers the hook-ups and equipment in a basic EFI conversion. From here, all that is left is fine-tuning the system. The FAST XFI comes with a well thought out software package and is connected to a computer for tuning with a communication cable. The system can be tuned on the dyno or in the car.
There are numerous 2D graphs...
There are numerous 2D graphs that super-tune the system, like the "fuel pulse-width vs. MAP rate of change" table being adjusted by Tom here--basically this is the equivalent of tuning the accelerator pump circuit on a carb. Tuning help is available on the XFI program menu, from FAST's tech line, or by watching FAST's feature-length tutorial DVD about the system. There is even the ability to link to a technician via modem, which is like having a technician sitting in front of the computer hooked to your engine.
Some of the most modern engines,...
Some of the most modern engines, like the LS2 we were running here, are designed for very advanced engine management systems from the factory. FAST has systems available that mate these late-model wonders, including the new Mopar Hemi, or Ford's Mod motors with the XFI, allow them to be plugged in and run using all the factory sensors.
The LS2, like many modern...
The LS2, like many modern engines, uses a coil-on-plug ignition and no distributor. FAST's new E-DIST II has the logic to run these advanced engine systems. The end-user is only required to plug in the harness.
We had one of the first prototype...
We had one of the first prototype units of the E-DIST II, allowing us to run the most current engine systems with the readily tunable FAST system. Our prototype came in a gray box, though by the time you read this the attractive red-anodized production units will be readily available.
Jay Rohrbach and the rest...
Jay Rohrbach and the rest of the team at FAST worked hard to design the harnesses and connections so that they are simple for the end-user to install. The terminal ends match the factory sensors and are all clearly labeled to make hooking up the harness a breeze.
The factory GM LS2 crank sensor...
The factory GM LS2 crank sensor lives down low, behind the starter. The crank sensor is one of the two additional hook-ups you'll find on these distributorless modern engines. FAST's XFI and E-DIST are built to interpret the signal from the factory sensor, just like the OEM management system.
Likewise, distributorless engines rely on a signal from a cam-position sensor, mainly to tell which cylinder is ready to be fired. Again, the XFI with E-DIST works with the stock sensor, while the harness end marked "cam sensor" plugs right in.
Fuel Air Spark Technology/FAST
1490 Henry Brennan Dr.
Westech Performance Group
11098 Venture Dr., Unit C