Improving exhaust note by opening up air box?

Hey all,

As I will be using the oem exhaust on the GRiSO for some time to come now that I have updated the map with one of Beetle's designed for that pipe, I am wondering if opening the airbox may add a slighhtly meatier grunt to it's note as shown in this video. If so, are there any drawbacks for the engine in doing this or should it be safe?

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Thanks,

1151

Beetle, if you read this, I will post again soon with my thoughts on the map you created and sent to me last year for the oem can / rollerized GRiSO.

For now let's just put it this way -

You won't change the exhaust note. What you will do is increase the intake roar. Thing is that buggering about with the intake is, basically, counter productive performance wise. Yes, if you are only interested in peak HP and couldn't give a shit about fuel economy or a decent torque curve you can open everything up to the max and turn it into an incredibly wasteful and inefficient pump rather than just a moderately wasteful and inefficient one. It will be loud as a very loud thing and have an awesome top speed but it will also be a complete pig to ride!

Mark's maps are all built for the stock airbox and filter and in the case of the GRiSO the snorkel on the airbox is removed. If you change things from those specs efficiency and performance will be sub-optimal.

From a personal point of view I find the intake *Honk*, (I can't hear my exhaust with ear plugs in.) quite satisfying and wouldn't want anything louder. Do bear in mind though that my dislike of almost anything noisy is well known and I have been labeled a 'Grumpy Old Man' by at least one panel of internationally renowned experts!

Pete

Thanks Pete, I appreciate your feedback. I didn't know the snorkel should not be in when using Mark's map. I'll pull it prior to my ride today or tomorrow.

At least you are not considered a Grumpy Old Sheila  

Tee, Hee. From memory, mine could be considered "too" loud, so I try and run at the back of the line of bikes - unless there is an awesome chance of overtaking someone and scaring the bejesus out of them. I can't catch Pete anyway because his bike has far more mid range than mine as well as double the valves.

Incidentally, removing the snorkel allows a slightly better midrange, with associated induction roar, and this applies to all the later 1100s, 1200s (2V) and the 1200s (8V) - probably there for EURO something initially...

Just got back in from an afternoon run. I removed the snorkel and immediately noticed the increase in the exhaust roar right off the bat in the midrange as mentioned thru the gears. Not quite a Termi or Zard etc. but it is louder than before and I think pretty well perfect at this point.

I also felt that the bike wanted to accelerate a little easier and or quicker? Not 100% sure on that but that was my initial impression as I set off and hit the hwy..

Damn happy with the way the bike is running and sounding now! Thank you both for the feedback and tips!

I like my snorkel...

I am running just a open BMC filter and no top on the airbox and the intake roar is great, I did have to adjust for the extra air.  I am very happy with the result and I didn't notice any loss in torque, but did notice a much faster revving to redline.   I wouldn't remove it unless you are going to adjust the fueling.

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Sigh.....

My old man once said to me with some gusto when I was a fiddling youngster,

Why fix it if ain't broke ??

Have a great day

Pete Roper wrote:

Sigh.....

Hey Pete .......... remember my nightmare with my Tenni.
After drinking massive amount of the bogus cool aid( read money ) I put it to the Dyno....... you were right. showed less horse power...more noise and a shit load of fuel burn.
Wont be repeating that to any of the herd any time soon that's for sure... Uhgg

Ciao

Oiled media filters?

Simple science says no bueno:

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I look at the title - Improving exhaust note by opening up air box? - and think, how is that even possible?

wardentm wrote:

My old man once said to me with some gusto when I was a fiddling youngster,

Why fix it if ain't broke ??

Have a great day

My ol' man used to berate me all the time coz I couldn't leave my bikes standard.
Then one day I was looking at his armoury and noticed something, not one rifle was standard.

He'd make his own stock and fore end with custom cheek piece, add a Leopold 3x9 variable scope blah blah blah.
So I asked him. "Hey Dad, you bed the action and float the barrel for accuracy, right"? "Yes"
"And you re-chamber for a bigger cartridge with a lighter projectile for greater muzzle velocity, right"? "Yes"
So how is that any different to my better suspension, brakes and big-bore kit"?
"Shut up smartarse"!
 I win.

I must have been in a coma when 1151 posted this.

Pulling the snorkel helps the mid range as VE on the 8V is less than stupendous between 3300 - 4800 RPM above ~15% throttle. Removing the air box lid and adding a rock strainer air filter requires adding beaucoup fuel to compensate. Of course this also does wonders for the inherent charge transition issue by not helping one bit. We really want to mostly slow down intake speed above and below the poor VE area for the aforementioned transition snafu. Adding an open exhaust just makes things worse.

Yep, push the (less) peak torque up the rev range and wallow in your intake roar. Meanwhile, the GRiSO's with a proper map and a stock snorkel-free air box are already in the next town before you shift down two gears to try and catch up.

I love the stock stelvio pipe growl up at 8K

I find the best way to improve the growl when the GRiSO is switched on is to say I am going for a ride when the misus has something 'better' for me to be doing. Works a treat every time, although sometimes it can turn into a banshee like wail if i do it two days in a row

You mean 'intake roar' unless you fart out of your mouth...............

1151 wrote:

Just got back in from an afternoon run. I removed the snorkel and immediately noticed the increase in the exhaust roar right off the bat in the midrange as mentioned thru the gears. Not quite a Termi or Zard etc. but it is louder than before and I think pretty well perfect at this point.

I also felt that the bike wanted to accelerate a little easier and or quicker? Not 100% sure on that but that was my initial impression as I set off and hit the hwy..

Damn happy with the way the bike is running and sounding now! Thank you both for the feedback and tips!

Me,. I just attach cards to the spokes.

Cred Papa +++

We did that as kids to give an "engine" to our pushies. I laughed.

Story time , an ex work mate ( read person who caused grief all around him ) rode to work on a push bike, not for fitness, but because he was too tight to buy a car or motorcycle.  The apprentices, 3 of the most obnoxious little turds you would ever find, attached a plastic card to his bike with rubber bands for a laugh. He did not see the funny side of this as he had absolutely zero sense of humour.  His reaction was more of a brain explosion than anything else I can think of. It was extremely funny to watch this unfold, but when it came time to Fess up, not an apprentice was to be found.  Not Me 

My GRiSO 1200SE (not rollerized) has been optimized by Roland Däs. It's now equipped with an BMC filter in an opened airbox, BOS double gun and an appropriate mapping. Dyno says 113 hp and 118 NM, fuel consumption is about 6l per 100km. I think Roland exactly knows what he's doing.

But now, how is this compatible to the statements mentioned before?

In my experience a lot of dynos have very small horses inside them. Also peak HP is a poor indicator of how an engine is running. How much time do you actually spend with the throttle pinned against the stop? Very little I'd guess.

Yes, everybody likes to see great peak HP figures but you will probably of noticed if you've read back through the posts on this board that if asked how many HP our bikes actually make both Mark and I are on record as saying "About a hundred at the rear wheel.". Unless he's been sneaking off to another dyno behind my back, (The harlot!) I'll stick with that. Our last runs. Which were a couple of years and many map itterations ago. Were conducted at 800 metres+ altitude with temperatures in the low thirties centigrade and humidity at >30%. Most of the 'Optimistic' runs are done at lower altitude, lower temperatur and higher humidity, (Shrug.) your bit of paper is better than ours, it may even be that someone else has managed to develop a management set up that delivers a motor that is more powerful, more flexible and offers better fuel economy than a virtually stock bike with a properly log developed map like Mark builds. I'll just say that I'll believe it when I ride it.

I love the BOS pipes. A few years ago I would of bought a set if I could! Unfortunately he runs a German only website which was virtually indecipherable to me and it never got done. I also believe that they could, with the dB killers installed be a great pipe. Open air filters though will shit all over that!

6 litres per 100km? As I said, beaucoup fuel. Also, his dyno horses have short legs.

118Nm of torque?  [You must be registered and logged in to see this image.]              
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.

What I liked from the Saints dyno chart, a dead straight torque curve flat from 3 to 8k.
Ok, it did have a slight curve, it went from 78 torques to 80 and back to 78t/lbs again over a 5,000 rpm range.

The number was not what impressed me, it was the horizontal line on the graph.
The horse power curve, like wise and for obvious reasons, was also a straight line, but at a reflex angle.

Oh Pete, this was one of those sea level dyno's, IMMIA, 115rwhp

And BOS in Ingrish. [You must be registered and logged in to see this link.]

Stumpy legged horses abound.

Hey Pete,

I love the BOS double guns, they are the only pipes I personally accept on my GRiSO because they point up my GRiSO`s roadster look and allow a free view to the wonderful spoke rear wheel.

I still own the original airbox with snorkel. As you pointed out it will be better for performance, I will the stock airbox give a try - but with pulled snorkel and lambda sensor ON, it`s currently switched OFF.

As mentioned, fuel consumption is about 6l and the same as before the modifications did by Roland - and not too much as I can see from other posts here. After all, not only for me Roland is something like a GRiSO guru and I therefore suppose he knows what he is doing, he enjoys my fully confidence.

I fully agree that only opening the airbox and plug in a BMC filter is completely useless and in contrary will lower the engine`s performance. It`s definitly not enough to fiddle around with only one parameter but rather the whole package of measures must be kept in view.

I will begin to experiment with the stock airbox and lambda ON in about 4 weeks, we still have a strong winter with - 15C here. My garage is heated, but for riding it`s a little bit - brrr - too cold and actually too much salt on the streets.

Besides this - sorry for my poor English guys, I hope everybody understands what I mean. As being new here, I don`t want to confront members of this awesome forum because of being misunderstood.