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Motorcycle Consumer News report substantial difference in HP between Wet Head Models
- Thread starter vtbob
- Start date
jimvonbaden
Kool Aid Dispenser!
Absolutely correct, I was just saying they will "feel" different because of the other factors.
Jim
The RS uses a lighter flywheel, this was in the article.
lee
Debbie's Servant
Does the watercooled boxer have a flywheel?
marcopolo
Active member
Must have, because BMW's press materials for the introduction of the new GS Adventure for MY 2014 touted the 2.1 lb heavier flywheel. See paragraph extracted from press materials below:
"The new R 1200 GS Adventure is powered by the same spirited air/liquid-cooled boxer engine featured on the R 1200 GS, with a displacement of 1,170 cc and an output of 92 kW (125 hp) at 7,750 rpm. The stand-out feature of the power unit – introduced last year after being newly developed for the R 1200 GS – is the new precision cooling system which uses water instead of oil as a cooling agent. Also new is the engine’s through-flow (intake/exhaust), which is now vertical for even more efficient power output, as well as the six-speed gearbox that is integrated into the engine housing along with the wet clutch. For the first time on a BMW production motorcycle, the maintenance-free cardan-shaft drive is now positioned on the left-hand side. To enhance rideability, especially on off-road terrain, the drive’s flywheel mass has been increased by 2.1 lbs. and an extra vibration damper has been incorporated into the powertrain."
lee
Debbie's Servant
That's interesting, I thought it was the crank that had the added weight.
I looked at the parts fiche and could not spot a flywheel.
lee
Debbie's Servant
Thanks. I was looking for a flywheel like the R90 and older bikes had.
lee
Debbie's Servant
The four Wethead models have the same part number.
I would actually like to hear more about those u-joints. I just did 7 on my Jeep......Would have bought some of those- if I thought they existed
OM
deilenberger
A bozo on the bus
I'd say based on the above - the content of the press release is very questionable. Guess whoever wrote it never saw a 2013 K bike?
lee
Debbie's Servant
jimvonbaden
Kool Aid Dispenser!
Is that another way of saying they Googled the information
No.
The two articles by Tony Foale addressed extrapolating from known data to determine a bike's acceleration curve and top speed. The question to be answered was: how accurate were the extrapolated figures?
The impetus for the examination (and the two articles) was explained a few months ago: MCN was busted out at its secret desert high speed test site (read: some public road that's barely used), and won't in the future be able to measure actual top speed there as it has before. The editor wrote that MCN hoped that they'd be able to present top speed information that was reasonably accurate in spite of not being able to actually run test machines to their top speed.
The articles' conclusion was: pretty darn accurate. The editor writes a monthly column, and I'll bet he'll write again about their change in procedure.
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BMW Motorcycle Magazine is very closely tied to BMW, their spokes man if you will, and probably can not be considered truly independent.
it is interesting that they show over filling the Wetheads with 700ml of oil( almost 1 qt) shifting is more difficult and HP suffer up to about 3hp.
Also in the details they show that the GS and RS dyno curves which shows the GS put out about 2or 3 HP more at low RPMs, the same in mid range and again 2-3 more at the top of the RPM range. Seems the GS has superior in take and exhaust design.
This with the published data that the Rain mode does not cut HP, leaves the MCN report and the 10% difference in HP between wet heads they tested MUCH larger and un explained . MCN dyno test error....or BMW has more compromises in the RS design then they are willing to share.
roger 04 rt
New member
An inertial dyno measurement, like that used by MCN for this "data", produces HP information of limited accuracy. I went into detail on this problem here: http://advrider.com/index.php?threa...-af-xied-for-bmw.749080/page-33#post-23436774.
Looking at the big picture, the inertial dyno produces a load that's only about 50% of an actual "road" load. Also, unlike riding, where the load on the engine increases as the speed of the bike increases (due to aerodynamic drag), the dyno load is constant. Some other problems are that when the bike is on the dyno, cruising usually produces no load at all, and often results in engine braking just before the throttle is opened. The effect of engine braking almost always shows up in very high AFRs at the start of the dyno "pull", which the tuners like to show you because it's so lean.
However, that high starting AFR means there was engine braking before the pull, pretty much negating every thing that follows. A typical pull is 5-6 seconds long so every 500 RPM is about a half second or less. The highest horsepower is always in the 6500 so the peak horsepower measured on an inertial dyno is over a duration of about a quarter or an eighth of a second--not long enough for a precise measurement.
So my 2 cents is that I wouldn't put any stock in the MCN measurements.
Looking at the big picture, the inertial dyno produces a load that's only about 50% of an actual "road" load. Also, unlike riding, where the load on the engine increases as the speed of the bike increases (due to aerodynamic drag), the dyno load is constant. Some other problems are that when the bike is on the dyno, cruising usually produces no load at all, and often results in engine braking just before the throttle is opened. The effect of engine braking almost always shows up in very high AFRs at the start of the dyno "pull", which the tuners like to show you because it's so lean.
However, that high starting AFR means there was engine braking before the pull, pretty much negating every thing that follows. A typical pull is 5-6 seconds long so every 500 RPM is about a half second or less. The highest horsepower is always in the 6500 so the peak horsepower measured on an inertial dyno is over a duration of about a quarter or an eighth of a second--not long enough for a precise measurement.
So my 2 cents is that I wouldn't put any stock in the MCN measurements.
Roger,
No stock in MCN's measurements, or no stock in anyone's dyno results? Is MCN doing something different with the dyno compared to other reviewers?
-D
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I haven't received my December issue, a week ago seems earlier for it's release unless you are able to see an advance copy.
I may have my head in the ground but I enjoy MCN and look forward to every issue. I have used their recommendations and have been happy with the outcome. I don't remember when I started my subscription but its close to 2000.
Jay
I may have my head in the ground but I enjoy MCN and look forward to every issue. I have used their recommendations and have been happy with the outcome. I don't remember when I started my subscription but its close to 2000.
Jay