[EPS]

I would like to get more torque from my 03 EFI RK. If I install a Stage I air filter and have the ECM remapped can the Technican tune the fuel injection system for more torque from 2nd gear to high. The dealer says he makes test runs of the bikes performace on a Dyno.
What do I lose by optimizing the torque?

[aaron]

Good questions.

Torque is a product of rotating mass more than anything. Velosity of intake air charge and the "tune" of the exhaust for scavanging plays a large role in torque production. Generally if you gain torque in the low end you will loose some top end horsepower unless displacement modifications are made. Camshafts can play a part in the way an engine breathes but once a Harley reaches about 85%- 90% volumetric efficiency some internal modifications must be made. By internal I mean, bore, stroke, or head design/flow ect. Horsepower is nothing more than torque with a time factor figured into the equasion. The time factor in the engine being RPM. With that said HP peak is generaly in the upper RPM range and us Harley riders do not mind giving up some HP for Torque.

On to your question. Yes improving the airflow into the engine and remaping the fuel curve will yeild both more torwque and horsepower. I run carb Harley setups mostly but, I am not sure that the Delphi system used by HD is intelegent enough to tell what gear you are in and thus modify the tune for that gear. I am always open to corrections on this though.

I have a strong backround on engine management systems on race cars and base most of my nformation on this.

[aaron]

Oh yah, changing where in the RPM band the torque or HP comes in chan be changed by the jength and size of the header pipe or intake runner. The peak number cannot be changed by the lenght just where in the band it comes in.

Remember one good rule of thumb. Velosity in the intake and exhaust produces torque, Volume produces horsepower.

With large diameter pipes such as drag pipes you have alot of volume and the only way to get them in tune is to prodce velosity with piston speed or RPM. Same holds true with the intake.

[EPS]

Thanks aaron.
Since that Delphi system is not intellegent would a Power Commander or Vance & Hines Fuelpak provide better performance over the Delphi system?

I currently have V&H pipes on my bike.

[aaron]

All of these systems are a feedback engine management system but I do not believe you can get them to recognize what gear your in and change the map accordingly. Some chan tell what gear your in by comparing engine speed and vehicle speed but I dont believe any of the Harley systems can do this.
I have herd that the Power Commander system works well. I do not have any expierence to base this off of.
Hopefully somebody with M/C engine management expierence will chime in.

Most of my expierence is automotive using SCT or AEM engine management systems.

I would suggest having your ECU flashed with a stage 2 program and see how you like it. Remember, your style of exhaust is going to have the greatest effect of performance in your siituation. Long small diameter tubes with a baffle to provide backpressure and thus torque will probably work the best in this case.

[Harleyhog]

I recently had a HD Fuel Tuner put on my 02 Softail Heritage, due to the fact it was running too lean after getting Vance & Hines Longshots put on it. I gained just over 10HP and about 7-8 lbs of torque.

[hotroadking]

The first and easiest way to increase power is to do a complete stage 1 upgrade to the bike. That means new slip on mufflers, high flow air box kit and either stage 1 flash, powercommander or Race Tuner.

All this will remove the restrictions on the motor imposed by the EPA noise and emissions regulations on HD. BTW I would keep all the stock parts so if you have inspections in your state you can bolt the stock stuff back on if needed.

The stage 1 flash will raise the rev limiter on the HD ECM and it will add fuel, you'll pick up the 7 to 10 HP and TQ that you would like simply because the motor can breath.

The Powercommander with the stock ECM flash will do the similar but it helps to have it dyno tuned,

The HD Race Tuner ($500) is expensive but is the most flexible as you increase or change down the road, cams, heads, big bore etc.

Once you're used to the stage 1 power and you are ready for more a cam change will help move the tq band more than anything else. Big bore will increase the volume of the motor and raise the overall powerband as well.

Usually cams and big bore (95) are done together as these changes work better together. However a properly selected cam like ANdrews tw26 will work well with a stage 1 88, but you'll want a powercommander or Racetuner and a good dyno operator to make it all work together.