Screamin' Eagle Race Tuner - Induction System Basics

Harley-Davidson's Screamin' Eagle Race Tuner is a software map-based reprogrammer that requires no add-on module because it has the ability to reprogram the stock ECM. The Race Tuner software allows connecting a PC to the stock ECM. Once the Race Tuner uploads a new map into the stock ECM, the PC and required hardware key are removed and no additional parts remain on the bike. ECM fuel, ignition, start-up, warm-up, and rev limit values can be modified. The Race Tuner also includes a function for setting injector size for greater tuning flexibility. Several operating modes are available, from basic to advanced and data monitoring. The Race Tuner and Power Commander are similar in that fuel map cells represent the percentage of change, either plus or minus.

Aftermarket EFI Systems
Several aftermarket companies offer complete replacement EFI systems for the stock fuel injection system. These systems include their own ECM and software for controlling the ECM. Additionally, aftermarket EFI systems offer carbureted bike owners the ability to upgrade to fuel injection while offering owners of early stock Magneti- Marelli EFI systems an upgrade path that may better accommodate major engine performance modifications.

Final Thoughts
Regardless of whether you are modifying a carbureted or electronic fuel injected engine, the induction principles remain the same, only the way you go about making modifications changes. Remember that the objectives are to increase airflow while adding fuel through either jetting or fuel mapping changes to maintain an optimum fuel ratio for maximum power. For '06 Dynas and all '07 bikes, the Delphi EFI system operates in a closed-loop mode, requiring O2 sensors in the exhaust. Be sure any new exhaust system includes bungs for the sensors. Some '06 and up Twin Cam EFI models run very hot. The problem is related to the EFI closed-loop operation. Re-calibrating the ECM and installing an engine oil cooler are temporary measures that can help minimize the problem, but first check with your dealer for any warranty implications.

If you have a carbureted engine, you still have the simplicity of tuning the induction manually by changing jets, needles and orifices. As for EFI owners, despite the complexity of fuel injection, you'll find yourself much more comfortable working with them once you learn the basics. But in spite of the type of nduction system you have, carburetedor EFI, remember to upgrade and tune it as a complete system of interdependent parts and always identify the true performance bottleneck before making haphazard modifications.

10. Dynojet's Power Commander is a map-based reprogrammer that connects in series between the ECM and fuel injectors. The Power Commander can be reprogrammed using a PC. Fuel, ignition and rpm values can be changed for both cylinders.
10. Dynojet's Power Commander is a map-based reprogrammer that connects in series between
11. S&S' new EZFI is an add-on tuner for tweaking the fuel curve on engines using a high-flow air cleaner and free-flowing slip-on mufflers. The EZFI fits Delphi equipped Big Twins, including '01 Softail, all '02-07 Big Twins, all V-Rod, and '07 Sportster models.
11. S&S' new EZFI is an add-on tuner for tweaking the fuel curve on engines using a high-f
12. Harley-Davidson's Screamin' Eagle Race Tuner is a comprehensive software map-based reprogrammer that requires no add-on module because it can reprogram the stock ECM. Using a PC, the Race Tuner can reprogram the ECM's fuel, ignition, start-up, warm-up, and rev limit maps for virtually an unlimited range of engine combinations.
12. Harley-Davidson's Screamin' Eagle Race Tuner is a comprehensive software map-based rep

13. Aftermarket companies offer complete electronic fuel injection systems for upgrading carbureted engines, scratch-built engines and as a replacement for early stock EFI systems that may have performance limitations. Shown is the S&S Variable Fuel Injection (VFI) system featuring dual independent tuned intake tracts.
13. Aftermarket companies offer complete electronic fuel injection systems for upgrading c
14. BC Gerolamy offers a complete EFI system and a choice of either a twin 50mm or 54mm TB. The system uses a Daytona Twin Tech ECM and O2 oxygen sensor, which results in a variable closed-loop system. Dual runners can provide increased torque and tunability.
14. BC Gerolamy offers a complete EFI system and a choice of either a twin 50mm or 54mm TB
15. Highly modified engines or engines with aftermarket EFI require map-based reprogrammers because map-based systems offer virtually unlimited fuel map changes to the ECM. Map-based systems, like S&S's ProTune II shown here, allow the tuner to load, modify and save fuel maps using a PC to maximize power on modified engines.
15. Highly modified engines or engines with aftermarket EFI require map-based reprogrammer

16. Most modified EFI engines require dyno tuning to eliminate pinging, stumbling, surging and overheating, and for optimized power. One factor for successful dyno tuning is to find an experienced tuner who thoroughly understands your EFI system. Dan Klann of Chester's Harley-Davidson in Mesa, Arizona is doing some baseline ower tests on this newly builtbig-inch Twin Cam using Screamin' Eagle's Pro EFI Race Tuner.
16. Most modified EFI engines require dyno tuning to eliminate pinging, stumbling, surging
17. Zipper's Performance offers their ThunderMax with AutoTune system, which provides tuning as you ride through wide band oxygen sensors. The system includes an extensive library of dyno-tuned maps for the most popular applications/setup. Once installed the system will adjust the base map accordingly to accommodate for riding habits, altitude, or ambient temperatures.
17. Zipper's Performance offers their ThunderMax with AutoTune system, which provides tuni