I recently purchased a 08 v-rod and I'm starting to make performance upgrades. So far I only installed a factory replacement K&N air filter. I plan on installing some type of exhaust (which I placed another thread about) and the power commander soon. I've heard you can go "topless" with the factory airbox. What exactly does that mean? I'm guess removing the plactic cover held on by 1 plastic wing nut just above the air filter? Will this make any difference if I remove this now or should I wait until I make the other 2 upgrades that I mentioned?

 

The "topless" mod consists of removing the top (lid) of the inner air box. To see if your bike has already been made topless remove the outer (steel) air box cover. If you see a sort of dome shaped plastic cover with a small snorkel coming off of it that is held to the lower air box tray by several silver clips then you are not topless. To go topless just remove those silver clips and take the dome shaped top cover off. Once it's off just replace your outer air box cover and you are officially topless. Don't take the plastic air filter cover off (the one that's held in place by the wing nut). That will allow debris to be sucked into your throttle bodies. If you pull of your outer air box cover and you see your air filter, you're already topless. You can go topless before you do the exhaust and tuner, but my recommendation is unless it's already done, don't worry about it until you add the exhaust and the tuner.

 

I completely understand what your talking about since I took that airbox apart the other week to install the K&N. Will that make a difference to do that to the bike now, before exhaust and the power commander?? I know it takes 5 min and costs something so if it does anything positive, I don't mind doing it??

 

About the only thing it will do is lean out your fuel mixture. I would just say to go ahead and wait to do it until you do the exhaust and tuner, that way you can dial everything in at once instead of having to change your maps several times, or create a problem with running too lean.

 

Here is why "going topless" is a very bad idea:

Millions of dollars went into the computer optimized design of this motorcycle which included a collaborative effort on the part of Porche which designed the tuned intake tract for the VRod building from their unique knowledge and design skills (accumalated from years of racing). So... if you think you can just remove the airbox cover and call it a "performance improvement" to make the engine breathe better you have made a base assumption that those designers didn't know what they were doing... so you think maybe they are frauds? LOL Or let me ask you a better quesion... what engineering pricipals or at least dynometer performance metrics are you basing this mod on? None... cause you would see at least a 5 HP decrease in output.

The tuned intake tract on the Vrod helps the engine to develop about 5-6 HP at cruising speeds. How is this done? By timing the intake pulses caused by the engine so that these pulses ampliy each other in such a way that some "greather than ambient" air pressure pulses are created. In short folks... don't let the "restrictive sucking" sound fool you into thinking that is "breathing resistance" -- this passive system does generate some air pressure... it is a free mini-supercharger so to speak. Porche and only a few other automotive manufacturers have an understanding ot how to apply this technology.

To ensure it works make sure there are no wires or other obstructions leaning against the front trumpet and make sure all the gaskets are in place and the box is well-sealed. If you have located an air compressor or something else to this "empty space" you have reduced the volume of the air plenum and may be impacting the tune of the tract. Better to re-locate that. The velocity stacks are also an important part of this system... they need to be unchanged -- correct height.

Also, one last thing... even in the HD exploded views they show the rubber ring at the base of the velocity stacks but I do believe these are vibration dampners designed to be rolled up to the top of the velocity stack to keep the inlet from vibrating and reducign the effecitve apeature of the stack (reducing air-flow). Someone tell me if I am off on this one but I think the design called for these rubber rings to be rolled to just under the top lip fo each velocity stack.

 

This is a complicated issue... but I can tell you that the stock Vrod ECM fuel maps are designed for economy and complete burn of the fuel. Some folks think that means and Air Fuel Ratio of 14.7 air to 1 of fuel (lean) for gasoline. That is the perfect burn ratio for Gasoline but we don't use gasoline anymore. Generally at least 10% of our Gasoline is now Ethanol (a radio of ~19:1). Also best performance is not "lean" but depending on many other factors somewhat rich.

That is why the ECM fuel map is based on RPM in many RPM range bands. Best to use an ECM mapper that allows you to address the fuel map at all RPM ranges and doesn't "saddle" onto your existing elecronics but rather lets you make configuration table changes and then take the device off if you wish (and he ECM retains the new programming). Companies that do that test various performance combinations and develop full maps that you can download to your system and re-use. These maps are based on true Dynometer results (true performance metrics).

 

You forgot to attach your dynometer performance metrics you're basing this 5HP decrease claim on.

 

The O ring is to keep allen bolt in place should be placed at the bottom of the stacks 1) if one allen bolt should vibrate loose, it wont be flopping around and possibly end up in the intake 2) when servicing the intake ie Valve adjust or spark plug change the O rings keep the bolts with the velocity stack and lessens the chance of dropping 1 in the engine.

 

I find it interesting that instructions for the SE Stage2 air cleaner kit, say remove top of plastic air cleaner and discard. It then goes on to describe new placement for air pressure sensor, and provides a template for drilling holes in the bottom section of air box that remains. Jus' sayin'

 

I was tryint to do you a favor -- to point out that Porche is one of the few manufactures that know the trick to creating a tuned intake tract. The "fer sure" indicator that this is a tuned intake tract on the VRod is the long trumpet inlet, the air-tight sealed air box (rubber gasket and clamps all the way around), and the variable height velocity stacks that aren't interchangable (you can't change their positions front to back -- they are keyed uniquely).

The principle which make it work are the same principles used by header- exhaust manufactures to use an exhaust pulse in a lenght-tuned system to "pull on" the following exhaust pulse -- to scavange the exaust out of the cylinder as soon as the exahaust valve begins to open. The tuned intake track works the same way except in reverse.

In a tuned air intake tract the intake pulse that feeds a cylinder is timed so the pulse pulls on the next "gulp of air". As the pulse travels torwards the intake port that is open the lenght of travel is tuned to time the pulse to reach the cylinder at the right time (for a specific optimal rpm). That is why one of the velocity stacks is taller than the other -- to lengthen that path to correct the timing of the pulse.

Tuned exhaust and intake tracts have a specific rpm range that they operate opimumly.

Dynometers are over-blown as far as value. They may allow you to get an initial tune but only real-world on-the-road trials will allow you to develop a tune that is optimal.

Another reason you don't show an increase of HP/torque with the airbox installed is because the entended end of the trumpet gets air from a high-pressure zone that forms when the motocycle is moving through the air-stream. You can't duplicate that with a dynometer.

I don't need to argue about it or convience anyone. I would much prefer a performance monitor like Veypor. It measures real-world conditions and takes everything into consideration including air drag, tires, etc. www.veypor.com (I am not affiliated with them). You can make all the power you want on a dyno but if you can't transfer that power to the road where does that get ya? [Retorical question -- no answer needed]