Who is running a Power Commander V on their bike?

The bike, as it comes from the factory, comes tuned for maximum mpg. One would think that with 1450cc's (88ci), you'd have a lot more than 59hp, but my stock Heritage was a dog and barely got up to 100mph. It lacked power at both the high and low end. So I opened up my intake with a Kuryakyn Hyper Charger Pro, and simply replaced my stock exhausts with Screaming Eagle slip on exhausts. Didn't do any engine work, but just the introduction of those two items helped a little bit, but it also made my bike run lean and that necessitated a fuel controller to add more fuel to the cylinders. After I added the Power Commander, it has a lot more get up and go; it purrs going down the highway and can hit 100+ with no problem. You don't get something for nothing though. When you take away the restrictions and add more fuel that extra power doesn't come free. My mpg went from 42 to 36. But when you consider how much more responsive the engine is, it's definitely worth it.

Here's a little more on the why... Think of your intake and exhaust like 3/4" garden hose pipes. If you want more out of the hose you can change the intake end to 1" and leave your exhaust end at 3/4" and you're still going to get about the same amount of flow through because of the restriction at the end. Similarly, you can change the exhaust end to 1" and leave the input end at 3/4" and you're still going to get about the same amount through the hose. In both scenarios you're going to get a little more through because you've removed some of the restriction but it's almost negligible. BUT let's say you change both ends to 1" hose. Now your throughput through that hose is going to increase dramatically. It works similarly with your bike. To get the most hp you want to remove any restrictions going into AND out of your engine.

If you open up your intake and leave the exhaust the same, the restriction on the exhaust will cause some backpressure which prevents all the air from being scavenged from the cylinder on the exhaust stroke and thus the incoming air is running into a cylinder that has not been fully scavenged and less can go in. So even though you've opened up the intake, you really aren't going to see too much difference in performance. You will get more air in than with the stock air cleaner, but it's not going to be enough to mandate the addition of a fuel controller.

Likewise, if you keep the intake stock and just open up the exhaust, you'll scavenge more of the air from your cylinder on the exhaust stroke, but with the restrictive stock intake, you're not going to be able to fill the cylinder to its maximum on the intake stroke because it will be like sucking through a straw. And so your fuel air mixture isn't going to change significantly. And just like when you just opened up your exhaust, you're not going to see a lot of difference in your performance. There will be some, but not enough to mandate the use of a fuel controller.

When you open up BOTH your intake and your exhaust, you reduce the backpressure on the exhaust which allows more air to be scavenged on the exhaust stroke, and with the restriction on your intake gone, you're going to bring a lot more air into the cylinder on the intake stroke. With these two things bringing more air into the cylinder, you have to introduce more fuel to maintain the proper ratio or you will run lean. Running lean will also make you run hot since the fuel also helps cool the cylinder. How? You're injecting cold fuel into a hot cylinder and it draws heat from the cylinder as it atomizes just prior to ignition. Since the V-twin is an air-cooled engine, you don't want to run hot. Running hot makes your oil run thinner, which increases the wear on the moving parts, and shortens the life of your engine... If you've even been stuck in stop and go traffic on a hot day, you may have noticed your engine rpm change. If the engine starts to overheat, it will actually dump more fuel into the cylinder to help cool the engine. You can hear when that's happening because it will begin to run a little uneven and that's normal.

[As an aside: I mentioned that the V-twin is an air cooled engine, but it really is an air/oil cooled engine. The oil absorbs heat from the engine and circulates the heat around to areas that the air flows over more (like the cylinders) and the heat is radiated through the metal back to the air. I've heard arguments for and against the addition of an oil cooler. Some will argue that if you have no air running past the cylinders to cool them, you aren't going to have a lot of air running past your oil cooler either to cool your oil. In part that is true, but you're still going to have a little more oil in your system AND you have more surface area exposed to the air so there will still be some benefit. I went ahead and added an oil cooler to my bike. If nothing else, it adds to your coolness factor LOL.]

So the introduction of a fuel controller (such as the Power Commander) IS NEEDED to override the bike's computer and introduce more fuel into the engine when you modify the intake and exhaust. The Power Commander plugs in under your seat but it isn't plug and play. [My mistake. I was thinking from a mechanical standpoint, not a software standpoint.] It needs to be programmed with parameters and you hook a laptop up to it through a USB connection as SFC (Join to see) correctly pointed out. You'll need to put the settings on that match your bike's configuration. In the instructions, they do give you some help as far as what to initially put on it (based on similar configurations) and that will get you very close.

You can take and have your bike dyno'd and they will dial it in perfect at the shop. But understand that in order to do that they will red line your engine and some people may not like that. I had mine dyno'd and I didn't see a whole lot of difference between the recommended settings that I had put on and what they did. It had a lot more torque on the low end and was smooth across the rpm range. Was curious to see what the difference in hp was and on my 2005 Heritage, I went from 59 hp (stock) to 70 hp -- just with the Kuryakyn Hyper Charger Pro and Screaming Eagle slip on exhausts. Again, the engine is still stock and nothing has been done inside the engine.

[As another aside: The best exhausts for adding hp are the "Two into One" exhausts. (The exhaust from the one cylinder feeds back and improves the scavenging of the other cylinder and provides the right amount of backpressure to keep the intake air from flowing out the exhaust during that brief time when both sets of valves are partially open.) Another thing you can do to add hp is tape your headers. The tape is like insulation on your headers and helps keep your exhaust from cooling as it flows out. The hotter you can keep your exhaust, the more rarified the air and thinner it is, and thus it flows more freely out the exhaust. It might give you .5% difference but every little thing adds up.]

So bottom line: The Power Commander is needed if you want to override the bike's computer and increase the amount of fuel introduced into the cylinder to restore proper balance to your fuel air mixture. The introduction of the extra fuel is going to up your hp and it will also help your engine run cooler. It is not plug and play; it has to be set up for your bike. You can find settings for a comparable setup and run with them OR you can take it to a bike shop and have it dyno'd. If you dyno your bike, they will redline it, but you will also find out how much hp you added and they can adjust settings to give you more torque at the bottom end. I would recommend adding a Power Commander if you change ANYTHING from stock but am told you can get away without it IF you ONLY change intake OR exhaust.

PCV is not plug n play. You'll need a laptop compatible with the software Dynatek provides in order to upload maps, change air fuel ratio, turn on rev extend etc. additionally if you want to run the AutoTune feature that is an additional purchase that needs installed.

Nope, still have the PC III for my Ultra. I had to step up to the SERT Pro for my Softail. Just not enough adjustment. I hear the V is good though.