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Motorcycle Consumer News report substantial difference in HP between Wet Head Models

dbrick said:
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
Click to expand...

Good question, I was referring to dyno measurements used to calculate actual horsepower.

If the inertial dyno operator is very careful to add an eddy current load so that there is a cruising load (meaning a load before the throttle is cranked open), confirms that the bike is cruising in Closed Loop as shown by an AFR reading, measures AFR ahead of the catalytic converter, and has insured that all Long Term Trim values are stable (meaning that the bike has been ridden for several tanks of fuel without any modifications, then I would have comfort in the results as an indicator that could be used for tuning but still don't think it could be relied on as actual top HP.

Look at the AFR plots for many dyno runs. They start at AFRs of 18-22:1, how exactly is the engine running at those AFRs? The answer is that the dyno wheel forced the engine into overrun fuel cutoff after decelerating from the previous run and dried up the TB and intake of its usual wetted-wall fuel. This results in sluggish initial acceleration.

Because the nature of an inertial dyno test--no initial load usually, inertial resistance of the wheel about 50% of road resistance, and because of the limited duration of the test--I wouldn't use one as an indicator of engine horsepower which is measured on a different type of dyno.

Interestingly, a GS-911 set in high speed logging mode can be used to measure acceleration, from that you can calculate torque and horsepower if you've previously measured the bike's Cd and frontal area. Then several runs can be made on a level road and averaged. And on-road acceleration and top speed is what we're after.
 
strataj said:
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
Click to expand...

Me too

That is why I was so surprised they left this big 10HP discrepancy between wet heads with essentially no answer.

When I wrote them their reply was indifferent. I hope they take put their journalist hats back on and check things our with there Dyno and ask BMW what is going on. I hope to read the answers some day.
 
BMW Magazine, Winter 2015

tlcoulter said:
Look at the Winter 2015 issue of BMW Motorcycle Magazine. Maybe the oil level of the three bikes differed!
Click to expand...

Right~pp.74-75 the magazine reports a drop of 6hp due to having the sight-glass filled all the way to the top. Proper level should be the half-way mark, dead center in the glass. There was also a complaint of hard shifting in the lower three gears with the engine overfilled. Four Quarts (3.8 liters) is the proper refill volume to bring the level to the center of the glass.

All this with reference to the R1200RS

On draining and refilling the bike to the proper level, the used oil was poured out into a vessel to measure the overfill amount. Turns out the crankcase had been filled with 4¾ quarts.

After setting the proper oil level horsepower was re-measured. Three of the six lost horsepower were regained.

Cheers!

~Radix
 
Mcn

Late in 80's MCN wrote an article not favorable or accurate for my 1988 K100RT. I attended the International MC show at Long Beach shortly after and asked the man in MCN booth about it. He said with a twinkle in his eye that they sell more mags with discontent with readers about articles, but he liked BMWs. His name was Fred Rau. And I no longer subscribed to MCN. It seems they haven't changed their business plan. Newspapers work the same. Believe 40% what you read still holds true.
 
I finally received my December MCN last week.
I've always enjoyed the magazine but of course they don't have all the answers for everyone, and so does nobody else (as a co-worker used to say).

I read the comparrison of the 3 bikes, the RS, Caponard and FJR.

The writer did express surprise at the HP difference between the various LC BMW that they have tested.
So, they did notice the discrepancy.
They mentioned that perhaps the quieter, more restrictive exhaust on the RS as opposed to the RT and the GS that they had tested was at least in part accountable.

Also in the article, I was very surprised to read that the RS has the lighter crankshaft engine of the 2013 GSs.
I just assumed that this early version had been replaced by the heavier crank version and was never to be used again.
Is that right, is the lighter crankshaft engine being utilized again?

d'milan
 
dmilan said:
I finally received my December MCN last week.


The writer did express surprise at the HP difference between the various LC BMW that they have tested.
So, they did notice the discrepancy.
They mentioned that perhaps the quieter, more restrictive exhaust on the RS as opposed to the RT and the GS that they had tested was at least in part accountable.

Also in the article, I was very surprised to read that the RS has the lighter crankshaft engine of the 2013 GSs.
I just assumed that this early version had been replaced by the heavier crank version and was never to be used again.
Is that right, is the lighter crankshaft engine being utilized again?

d'milan
Click to expand...

What puzzles me not that they noted the discrepancy but they accepted it with out serious question. Yes they said the exhausts was "quieter" but by my equally valid subjective "ear", my RS barks more that my friend GS WC. When the exhaust valve opens.
All this while BMW claims the same out put of all WC R engines. 10% difference is a lot!
Not sure about the lighter crank....MCN has several other errors, this may or may not be one too.
 
No measurement without error

Maybe it's time to remember that it is not a measurement unless it has an error/uncertainty associated with it. Meaning, if you think you measured something, you should also have an idea of the precision you achieved. And state it.
Measuring the same thing three times and have all values land within 10% of each other is not so bad. Doing it to 1% is a lot harder.
 
Gruesome said:
Maybe it's time to remember that it is not a measurement unless it has an error/uncertainty associated with it. Meaning, if you think you measured something, you should also have an idea of the precision you achieved. And state it.
Measuring the same thing three times and have all values land within 10% of each other is not so bad. Doing it to 1% is a lot harder.
Click to expand...

+1, 10% spread, which would be +/-5% spread would be quite good. You've said it more simply and better than I did earlier in the thread.

There are many sources of error and non-repeatability when making this type of measurement. Here are some of them:

--Air Temperature
--Barometric Pressure
--Engine Temperature
--Fuel Manufacturer, Octane, Summer/Winter Blend, Ethanol Content
--State of Engine ECU Adaptation (Are all long term trims, final and stable for the conditions?)
--Pre-Conditions: Has the engine been statically loaded so the ECU is in Closed Loop at the start?, How long since the prior deceleration (has the intake tract been restored to stable fuel conditions)?
--Repeatability of Dyno Equipment being used
--Location of AFR probe (should be ahead of catalytic converter)
 
HP is great for bragging rights, but means little in the real world. Torque, Gear ratios, driveability etc are far more important.

On top of that on the street anymore than about 90 HP is generally just a waste, unless you are always 2 up, hauling the kitchen sink with fido in a trailer behind. 0-60 speeds from the 650 twins to the 1200LC's, with the exception of the RR's , are all within a second of each other, Roll on 40-60 is very similar, if in the correct gear. Yes HP/Torque can make you lazy, if you gon't like to shift, but personally I find shifting part of the fun, that is why I have sticks in my cars.
 
Gear ratios do NOT effect Dyno readings ( beyond the difference in drag between gearsets, but that is another story ).

If ALL bikes were not tested on the SAME Dyno at the same time the readings are not good to compare. I have personally seen readings vary by 40+ hp on a 450 hp engine under same conditions. Difference was brand and settings of Dyno. Quite common for some Dyno operators/owners to "tune" the Dyno to show on the high side. Especially if they are the ones doing the "tuning" on the engine. Makes them look better than the other guy you just paid money to for the same thing.

I would much rather see the charts of hp and torque than peak numbers of each.
 
All the recent comments here regarding dyno hp ratings make sense to me.

As far as the HP output on the RS, again, to their credit, it's good that they noticed a difference from the prior BMW bikes tat they tested.
They're not going to start a federal investigation about it. I doubt that too many folks were very concerned when they read it. I'm not tryin' to disrespect you O P, it's just that they just gotta move on. New month, new issue, new items to review, new deadlines.
Maybe they'll follow up on the topic in a future edition .

One last thought on the subject. OP mentioned that his RS seems to be louder than a friends GS.
When I read the MCN comment about the exhaust being more subdued on the RS it struck me as odd. The RT is generally designed more for the more mature (older) crowd, and the long distance crowd, yes?
The RS is generally more for a younger, more sport riding, day touring crowd right?
Doesn't make sense that the RS would be the more quiet of the 2.
 
This has been a good discussion. I have no personal experience with dynos.

It seems I should be taking the dyno reading from MCN or any other source with a grain of sand. A large error, 10% is to be expected. Any inference of a more accurate measurement should be looked at with a substantial amount of skepticism.

MCN stating previous dyno HP readings for the LC BMW is really of no value (why did they post it?) and it is all with the likely error of the dyno measurement process.

A learning experience for me
 
I know this thread is sort of Muerto, but I just stumbled upon a bit of info today while waiting at hospital.

I brought along a copy of Rider Magazine to pass the time, January 2016 issue..
There is an article within titled Build my Bike.
The author, Mark Tuttle, tries to respond to a gent that is looking for a machine to fit his needs and desires.
One of the bikes that author Tutle offers up as a possible candidate is the 2015 R1200 R.

Here's the important part

He wrote that the bike made 106.7 HP on Jet Tuning's dyno.
That's nearly as low as the 104.55 listed in the MCN article that is the focus of this thread.

fwiw
 
Some facts would be nice

Yep I saw that too. How can different dynos be so similar....there are so many variables??!!

Now we have two independent "Dyno tests" that show about 10 hp less than than Dyno's LC RTs and LC GSs from other magazines

You know, I think BMW, at best, is not being straight with us. The new R and RS seem to be detuned by approx 10 HP. BMW's advertising should not be listing them as the same.

Some nice repeatable facts would be nice.
 
dmilan said:
He wrote that the bike made 106.7 HP on Jet Tuning's dyno.
Click to expand...

Dyno measurement at the rear wheel. BMW's claim is the engine by itself, no losses from drivetrain.

Anyone seriously saying there is a lack of power in any wethead boxer engine? Come on...

Harry
 
strataj said:
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
Click to expand...

There is a back story here... Back in 2004 they didn't get to test the new 1200 GS along with the other mags and got a hair up their butt.. They proceeded to pan the new GS while every other Mag in the world raved about it and made it their bike of the year... So much for non prejudicial honest reports... Never looked at another issue after that.. I think they still try to stick it to BMWW when they can... They are identical engines...
 
dmilan said:
All the recent comments here regarding dyno hp ratings make sense to me.

As far as the HP output on the RS, again, to their credit, it's good that they noticed a difference from the prior BMW bikes tat they tested.
They're not going to start a federal investigation about it. I doubt that too many folks were very concerned when they read it. I'm not tryin' to disrespect you O P, it's just that they just gotta move on. New month, new issue, new items to review, new deadlines.
Maybe they'll follow up on the topic in a future edition .

One last thought on the subject. OP mentioned that his RS seems to be louder than a friends GS.
When I read the MCN comment about the exhaust being more subdued on the RS it struck me as odd. The RT is generally designed more for the more mature (older) crowd, and the long distance crowd, yes?
The RS is generally more for a younger, more sport riding, day touring crowd right?
Doesn't make sense that the RS would be the more quiet of the 2.
Click to expand...

The R1200RS is much louder than the GS or the RT. I own an RS and have ridden the others. MCN got this one wrong.
 
Regardless of the numbers, I've always liked BMW's blend of horsepower and torque in its boxers, which delivers good performance for touring.
 
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