Air Duct Mod and/or K&N Filter?

[NJRTrider]

I changed my air filter in my 08 RT and just as an experiment ran it without the air duct attached. I didn't ride it like this since the filter was not captured by anything without the duct there but just cracking the throttle a few times and it seemed way more responsive.

 

The plastic air duct necks down to a pretty narrow opening at the front and I was wondering if anyone has cut the air duct back where the cross section of the duct is much larger and therefore would allow more air in.

 

On a similar note, anyone using the K&N filter on their R1200 and was there a performance gain?

 

Thanks

 

Wil

 

 

 

[Tony_K]

Until you have put your bike on a dyno for before/ and after mods... and have quantifiable results... this thread is just fluff.

 

 

[NJRTrider]

Until you have put your bike on a dyno for before/ and after mods... and have quantifiable results... this thread is just fluff.

 

 

That's why I asked "was there a performance gain?"

[Tony_K]

Let the dyno tell you. It costs a few bucks if you don't know someone but you will have a answer first hand on YOUR bike.

 

 

[Firefight911]

Until you have put your bike on a dyno for before/ and after mods... and have quantifiable results... this thread is just fluff.

 

 

That's why I asked "was there a performance gain?"

 

Search is your friend. To help out, and to give the Reader's Digest, version of this topic allow me to summarize -

 

There are no quantifiable gains by using any aftermarket air filter over the stock. There ARE verifiable issues subsequent to a K&N air filter use in your vehicle. These include increased wear and contamination of sensors and the air/throttle body throat due to oil coating.

 

The air box is not your limiter on the bike. The parts downstream of the filter and box are much more restrictive than the box itself due to size/design. You can only get it in if you can get it out. This is to say that any change upstream will require a downstream change as well. This is not as easy as a simple bolt on aftermarket noise maker either.

 

The vehicle you have will not show any appreciable gains in performance/response/etc. by the addition/replacement of parts. It will require engine management computer changes, valve train re-engineering, and other $$$$$$$$$ intensive parts.

 

Keep it tuned properly and ride it.

 

This subject tends to go the way of asking what oil is the best threads and gets beat to death equally well so understand that the responses you get are not personal but more of a been there done that tone. Marketers of the world have done a good job and getting the consumer public to believe that the widget they have will transform their vehicle into an F1 rocket ship with the best gas mileage known to man for mere pennies a day. It ain't so! If it were, the OEM would already have incorporated a good portion of them into the original design of the vehicles in question.

 

Ride it, service it, fuel it, repeat!

[2bigalow]

Interesting thread.

Keep in mind cold air provides more HP than warm air, and since the base intake (without the manifold) is behind / on top of the engine, warm air is being sucked in and not cool air from the front.

But, more air volume can increase horsepower too (if it is usable).

Some air boxes work on positve pressure at high speed. IE "ram air" so taking off the manifold could decrease HP too.

Threads like this are abundant on racing sites.

I really think in depends on the bike.

Without two identical bikes running side by side down a front straight we'll really never know. Unless someone has a dyno in a wind tunnel.

Would be a cool project.

 

ADD-The crispness in the throttle could be from more "immediate" air volume available to the engine when you crack on the gas.

 

 

[ShovelStrokeEd]

The removal of the restriction in the snorkel has proven to give a substantial (2-3%) gain in top end power on the R1100S bikes with no loss of torque or holes in the curve subsequent to the modification.

 

It would probably help on a hexhead as well.

 

To be fair though, each and every time it was done, the bike(s) in question had also gone through other modifications, cams, less restrictive exhaust, cylinder head porting, etc.. Doubtful the single modification would have much effect.

 

BTW, universally, the best "bang for the buck" is cylinder head porting, provided you have someone who really understands the BMW combustion chamber and port shapes. San Jose BMW has probably done more work on this stuff than anyone else and their stuff just flat works.

[Firefight911]

The removal of the restriction in the snorkel has proven to give a substantial (2-3%) gain in top end power on the R1100S bikes with no loss of torque or holes in the curve subsequent to the modification.

 

It would probably help on a hexhead as well.

 

To be fair though, each and every time it was done, the bike(s) in question had also gone through other modifications, cams, less restrictive exhaust, cylinder head porting, etc.. Doubtful the single modification would have much effect.

 

BTW, universally, the best "bang for the buck" is cylinder head porting, provided you have someone who really understands the BMW combustion chamber and port shapes. San Jose BMW has probably done more work on this stuff than anyone else and their stuff just flat works.

 

As I stated

The vehicle you have will not show any appreciable gains in performance/response/etc. by the addition/replacement of parts. It will require engine management computer changes, valve train re-engineering, and other $$$$$$$$$ intensive parts.

 

And it brings to the forefront the inevitable question asked by engine builders/tuners/riders/racers throughout -

 

Mechanic #1 to rider/racer - "So, How fast do you want to go?"

 

To which Mechanic #2 responds for the rider/racer - "How much money you got?"

 

Spend your money on riding courses and keeping good rubber on the bike. It's an investment that will pay dividends for a life time of riding.

[NJRTrider]

Thanks for all the input and comments guys.

 

I was just looking for people's experience with any intake mods for the RT. My RT just seemed to be more responsive without the air duct during a very informal, subjective experiment.

 

Since the RT has a closed loop system with the o2 and other sensors, it will adjust the FI pulse and compensate for greater air volume and keep the stoichiometric mixture at 14.7:1. Of course you would also need to add a less restrictive exhaust in order to move the higher volume of exhaust gas.

 

Most bikes and vehicles come from the factory pretty much choked up to minimize emissions and maximize fuel economy. Opening up the system on either the intake or exhaust end or preferably both will increase power and the closed loop system pretty much eliminates the need to re-jet a carb or re-map the FI. Then there're cams, higher compression pistons, head-porting, etc that basically allow better breathing and greater combustion charge. All good stuff!

 

Thanks again!

 

Later,

 

Wil

 

 

[jwt67]

I have an R1200ST which is basically the same bike. I installed this module:

 

http://www.powerfrkusa.net/.

 

One of these air filters:

 

http://www.pipercross.net/

 

And this slip on muffler:

 

http://www.bos-exhausts.com/bmw-eng-pond/index-bmw.html

 

And gained 4.9hp and 3.5lbs of torque.

 

Here is the dyno run showing before and after. The before was all stock. These runs were on the same dyno, same operator 3 days apart. The driveability has been improved immensely! Throttle response is much smoother! The way the bike should run from the factory. The engineers have several restrictions and compromises they need to make. The bike ran fine in stock form. It just runs that much better now.

 

Dyno Run

 

[Mister Tee]

I have an R1200ST which is basically the same bike. I installed this module:

 

http://www.powerfrkusa.net/.

 

One of these air filters:

 

http://www.pipercross.net/

 

And this slip on muffler:

 

http://www.bos-exhausts.com/bmw-eng-pond/index-bmw.html

 

And gained 4.9hp and 3.5lbs of torque.

 

Here is the dyno run showing before and after. The before was all stock. These runs were on the same dyno, same operator 3 days apart. The driveability has been improved immensely! Throttle response is much smoother! The way the bike should run from the factory. The engineers have several restrictions and compromises they need to make. The bike ran fine in stock form. It just runs that much better now.

 

Dyno Run

 

What about gas mileage? I see they (powerfrkusa) make one for an RT as well. Hmmm....

[Dick_at_Lake_Tahoe_NV]

Notice that all the gain is above 5,000 RPM and most of the gain above 6,000RPM--and with this kind of mod, that is almost always the case. Also, be careful about making these mods while you're still in Warantee--even using a K&N Air Filter can void your warantee--DAMHIK!

[jwt67]

Driven hard with lots of redline shifts and I am getting high 30's and when driven normal then low to mid 40's.

[jwt67]

What the dyno run does not show is part throttle response. Unless the dyno shop has the ability to tap into the tps then this cannot be displayed. But this is where this combination really shines! Part throttle response AND power are improved!

[DoctorC]

Anecdotal- A few months after I bought my ST, I replaced exhaust system and installed a K&N... before I read all the dread problems with latter.... engine response seemed much smoother than stock... as for HP or torque...??? I would have to have ESP to make any judgment. Could be less for all I know!

 

But by far the greatest improvement on the ST was replacing those stock shocks! If BMW had got it right, maybe they would have sold a few more STs.

 

[BanjoBoy]

I have an R1200ST which is basically the same bike. I installed this module:

 

http://www.powerfrkusa.net/.

 

One of these air filters:

 

http://www.pipercross.net/

 

And this slip on muffler:

 

http://www.bos-exhausts.com/bmw-eng-pond/index-bmw.html

 

And gained 4.9hp and 3.5lbs of torque.

 

Here is the dyno run showing before and after. The before was all stock. These runs were on the same dyno, same operator 3 days apart. The driveability has been improved immensely! Throttle response is much smoother! The way the bike should run from the factory. The engineers have several restrictions and compromises they need to make. The bike ran fine in stock form. It just runs that much better now.

 

Dyno Run

Fascinating...

I guess this is turning into an oil thread?

Some of you get good results and others say it's bunk.

Using the same dyno in a relatively short period sound like the way to go, but I know my bikes have always run better in the evenings as opposed to the middle of the day. Were your runs done at similar times of the day?

 

Thanks jwt67 for the report, I too have an ST. He, he, he.

 

[jwt67]

Yea I know what you mean, mine seems to run better after a few runs up to 100mph! Not so much the time of day though!

 

Seriously what a sleeper this model is! I bought it used with just 7k on it and got a great deal and love it! Pity BMW doesn't still build it.