More power and torque from a B11?

[GrahamNZ]

What are the most effective ploys to extract more power and torque from a B11? Not just noise, but real performance gains.

There's been talk here of airbox opening, dispensing with the exhaust collector and fitting a crossover and different muffler, all of which may be moves in the right direction, but has anyone actually proven that any perceived improvement is real?

 

[Spaceclam]

THe breva makes a few hp less than the griso, dispite being the same engine.

If you have looked at a stock airbox, it wouldn't suprise you. IT has to make a tight 120 degree bend, past foam, through a smallish hole and into the filter. Compared with the GT model which is just a straight intake through a much larger hole into the filter.

Opening the griso airbox seems to be good for an HP or two. Compared to the griso, the breva's airbox lid is INCREDIBLY restrictive. I would imagine, though i do not have the dyno to prove it, but based upon opinions i have heard as well as logic, that the GT lid would bring the airbox side of things, about equal to the open griso. Thus, about 4hp. The most noticeable difference on the griso, however, is where the "power kick" begins, and it's willingness to rev freely.

The muffler on the griso made a HUGE difference. Some mufflers are different than others, and the dyno graphs are easy enough to find, but the BIGGEST gain replacing the muffler happens below 4k rpm. It's like a whole different bike. With no fueling correction, the griso experienced an additional 5 ft/lbs of torque in that area.

They are the same engine, so i'd expect the results to be similar on the breva.

Here are two torque graphs compared. One supplied to me, by Todd, showing stock vs pipe ONLY. The other, the result of a dyno run in january (including fuel corrections, ECU reflash, squish and compression mods, as well as open airbox and pipe)

 

[GrahamNZ]

Thanks Spaceclam.

Pretty impressive results, but I should have added the question, "What can be achieved in NZ without having the ECU altered by Todd?"

 

[Spaceclam]

The mufflers are good for some extra power but the weak link is the fueling. opening the airbox/doing any of the stuff I did would be counter productive without fueling correction.

 

[GrahamNZ]

Thanks again, Spaceclam.

I feared as much, which is why my Breva has been left stock until now.

 

[john zibell]

Graham,

I got a bit more performance (only seat of the pants judgment) just by putting a K&N air filter and using the Guzzitech crossover. I left the stock muffler and air box lid. These two mods don't seem to need re-fueling as the bike runs great with them.

 

[GrahamNZ]

Thanks, John

That sounds more like something I can embrace.

 

[Spaceclam]

As long as it doesnt ping, you will be alright.

 

[nel]

I did the same as John Z. and put a xover on. The bike revs more freely which is imediately noticable. There are a lot of breva race only reduced Mistal cans on ebay and I was tempted but given Peter R. comments on tuning Grisos and the detremental effect of no exhaust restrictions in the muffler I stuck with the stock can. Plus I spent to much at dealers on oil leaks and think a race can might be to loud.

 

[Skeeve]

This same question was hashed out repeatedly over @ v11LM.com years ago. Of course, the new CARC (double spine) bikes use an entirely different airbox than the old spine frames, but one telling comment in that thread from Phil A. [dry lakes racer in OZ] who "showed us the way" was to the effect that "two 45mm throttle bodies can't be fed by a pair of 25mm snorkels."

The later 2v CARC bikes only have 40mm throttle bodies, iirc, but the idea is the same: the throttle bodies should be the narrowest constriction point from the point of air entering the airbox to where the intake runner bolts up to the head, so look for ways to "make it so, #1."

Big, 2v agricultural ditch pumps like our Moto Guzzis tend to have all sorts of muffling installed at the factory by govt. edict: its up to you to remove the stuff that no longer applies in your local jurisdiction [ie: Germany, you're hosed. Here in CA, once it's sold it never gets smogged, but you can get a fixit ticket for aftermarket pipes. Mexico - pretty much anything goes, if you've got the "mordida"... ]

That said, since modern bikes are all delivered w/ fairly lean fueling down in the bottom of the powerband where the off-idle smog measurements are taken, any changes to the intake or exhaust are likely to require recalibration ["rejetting" only we don't use carbs any more, so we've got to use the new "Web2.0"catchphrases... ]

Minor changes to the intake so that the bike can still breathe @ WFO are less likely to require such adjustments to fueling, since as Pete Roper & others have repeatedly noted, modern bikes are typically jetted over-rich on top to make up for the part-throttle stumbles & keep the motor from seizing up as soon as you wring it out a bit once outside city limits...

One last thing: any small increase to intake noise on the Norge will be magnified by the full fairing; this isn't unique to the Norge, but common to all full-fairing touring machines: leads to all kinds of "my motor sounds funny" complaints from new owners transitioning from unfaired bikes, as any dealer will tell you. Probably why "they all do that" is such a common litany heard by anyone making a complaint about their new bike to the dealer... :roll:

 

[3ackok]

I bought my bike with crossover and Mistral silencer. I removed the crossover and install the stock catalytic to reduce noise. Didn't notice any change in power delivery, although my butt is not calibrated.

 

[nel]

Sorry to disagree but put the cat back on surely was a bad choice. You must have noticed it doesn't rev as freely. On a hot day the extra heat from the cat cooks the engine. Was your mistral end can without baffles or a race can? That got to be a misnomer a b11 with a race can. I guess mistral produces race cans for the b11 because the bike can get away with it with the cat on ie not to loud but with the cat off you need baffles.