Simulated FJR vs C14 race

[cruppelt]

I would need a torque chart from such a bike to answer that question. Conventional wisdom on this forum seems to indicate that a PCIII alone does not significantly improve full-throttle torque on the FJR, but instead smooths out the partial throttle areas. I have not seen a before/after dyno chart for a stock bike adding a PCIII, so I don't know how true that is.

Wow, that is kind of weird. I though there were tons of before and after comparisons out there, but you are right, it's pretty much always only after modification charts that are out there.

Marks Johnson's website at Mark's Dyno page is the only one I could find that has some comparison at all, based on new mapping.

 

[UselessPickles]

The FJR is going to be very competitive until it has to shift into second gear and then the party will be over...and that is exactly what happens in real life when doing first gear roll-ons at 20 mph (which takes the rider's ability to launch from a dead stop out of the equation).

I simulated a 1/4 mile race with a 20mph rolling start, and the simulation's results are just as you have observed: the C14 passes the FJR soon after the FJR shifts into 2nd gear. Like I said, a rolling start is quite different from a launch from 0mph.

Also, here's the results of FJR vs FJR with lighter rider (or less fuel, less luggage, etc). A quick Google search finds that the average American male weighs ~190 lbs. My full riding gear weighs 14 lbs. The "average rider" in my calculations is therefore a total of 204 lbs. Up against Mr. Average are two other riders on exactly the same FJR, bu they weigh 20 lbs less (184 lbs) and 40 lbs. less (164 lbs). you could also view it as Mr. Average compared to himself with a full tank, half tank, and empty tank of gas. Just like before, it's a 1/4 mile drag race, launching at 6800 RPMs.

Results are...

Avg: 10.99s @ 124.88mph

-20: 10.91s @ 125.61mph

-40: 10.82s @ 126.35mph

Doesn't look much different?

Now look at the lead the 2 lighter riders have over the average weight rider:

 

[HYCLE]

Have you compared a Gen 1 to a Gen 2, would the rear axle ratio make much difference?

 

[lnewlf]

Back when I used to run cars in the 1/4 mile I soon learned that the biggest gain for the dollar was to drop in a 4/11 or lower ring and pinion in the pumpkin. The '06 and newer FJR has a tall rear end..I've heard that a VMax pumpkin is lower and will bolt on..?? Any ratio that would let the engine red line in fifth at the traps would be perfect.

 

[UselessPickles]

Adjusting the final gearing has effects that surprised me a bit, but make sense now that I've seen it. Conventional wisdom is simply that lower gearing means more acceleration, but lower top speed (if you reduce the gearing enough such that top speed is now limited by redline rather than drag).

That's true to a certain point. In any given gear at any given RPM, you will always accelerate faster if you have lower final gearing. However, it does not have much of an affect on maximum possible acceleration beyond peak HP in 1st gear. The biggest change with lower final gearing is 1st gear acceleration. Hard to explain; maybe I can make a graph to illustrate later.

On many sport bikes, 1st gear already has the ability to lift the front end at peak torque. It already requires careful control (purposely using less throttle or maybe even non-peak torque RPMs while launching) to keep the front down. On a bike like this, lower final gearing will not really help you in the 1/4 mile, because you won't be able to make use of the extra acceleration in 1st gear (unless you stretch the swing arm, strap the front suspension, etc.). Keeping 1st gear as-is and packing the rest of the gears tighter so that you can stay near peak torque for more of your run probably would help a lot more, but there would be a fine balance between that and spending too much time shifting gears (~0.25s is spent decelerating every time you shift).

Depending on the weight of the rider, the FJR is not wheelie-happy. A lighter rider on an FJR would actually be able to make use of more acceleration in 1st gear. I'll make some comparisons between Gen I and Gen II sometime. There's also a weight different that will come into play, so maybe I'll also do a hypothetical Gen II with the gear ratios of a Gen I.

 

[wheatonFJR]

Now look at the lead the 2 lighter riders have over the average weight rider:

I see that I am a much faster rider now that I am 40 pounds lighter! :lol:

...Man, I am smokin' now! :clapping:

 

[Bounce]

My shift points are determined by finding the speed at which the next higher gear begins to produce more acceleration than the current gear

excellent choice. people shifting at red line and behind the power curve on the FJR because output starts to dip before that.

the point of all of this is not whether or not such a comparison of raw acceleration is meaningful for these particular bikes

it's to point at the Street Glide's results and laugh?

 

[UselessPickles]

My shift points are determined by finding the speed at which the next higher gear begins to produce more acceleration than the current gear

excellent choice. people shifting at red line and behind the power curve on the FJR because output starts to dip before that.

Yet the optimal shift point for 1st -> 2nd is just after redline (basically as close as you can get to the rev limiter without hitting it), and 2nd -> 3rd is only 100 RPM below redline

Where the power curve starts to to dip isn't really a factor:

More details in this thread: https://www.fjrforum.com/forum//index.php?showtopic=142341

the point of all of this is not whether or not such a comparison of raw acceleration is meaningful for these particular bikes

it's to point at the Street Glide's results and laugh?

Yes! I should show the race results of a Street Glide vs FJR!

 

[FJR Bill]

Fascinating info and I appreciate your efforts. I also understand what you are trying to do...Not to recommend one bike over another but give reasonable comparisons of what is predicted when all variables are equal. Love it. I can almost guarantee you that in the near future, motorcycle magazines will be posting similar presentations...The Pickle man was there first. Congratulations.

Bill

 

[wheatonFJR]

Fascinating info and I appreciate your efforts. I also understand what you are trying to do...Not to recommend one bike over another but give reasonable comparisons of what is predicted when all variables are equal. Love it. I can almost guarantee you that in the near future, motorcycle magazines will be posting similar presentations...The Pickle man was there first. Congratulations.

Bill

+1, great job pickles! :clapping:

I'm lovin' the graphs....

 

[UselessPickles]

I've made a few enhancements to my code to generate more plausible results...

First, I put a limit on the jerk (change in acceleration) during the launch. It's impossible for something to go from 0g to 1.1g acceleration instantly. Based on a data log from the drag strip, it looks like I hit 1g within 0.12 seconds, so that's what I'll go with.

Next, I found from my data logs that my clutchless shifts actually take about 0.32s, rather than the 0.25s I was using. That's been updated.

Finally, and probably most importantly for 1/4 mile times, I implemented allowing a roll-out distance before the timer and distance counting starts. When you stage up at the starting line at the drag strip, you move forward until the staging light turns on (your tire breaks a beam that is about 1-2 inches off the ground. The timer doesn't start until your tire moves out of the beam. About 11 inches of roll-out seems reasonable based on measuring the length of my front tire about 2 inches off the ground.

Using my new tweaks, here's the FJR vs Harley Street Glide results. Both riders are average weight (190lbs + 14lbs of gear), and both riders launch at peak torque RPMs.

08 FJR: 10.84s @ 123.94mph

Street Glide: 13.68s @ 95.8mph

Now for some Gen I vs Gen II action!

08 FJR: 10.84s @ 123.94mph

05 FJR: 10.72s @ 125.23mph

And finally, a Gen II FJR vs a hypothetical hybrid with the weight of a Gen II, but the gearing of a Gen I.

08 FJR: 10.84s @ 123.94mph

05 Gearing: 10.81s @ 124.38mph

As you can see, the gearing difference alone doesn't have a huge impact. The lower gearing alone only yielded a 5 foot lead at the end, while the lower gearing AND lower weight yielded a 22 foot lead.

All these numbers are still coming up quite optimistic, but that's probably partly due to me simulating an absolutely perfect launch. It makes me wonder if the magazine testers launch the bikes at the peak torque RPM, or if they launch at a more "gentle" RPM. I also wonder when they shift. It's possible that they might subscribe the the "shift just after peak HP" theory, and they end up short-shifting a bit. With my recent changes for more "realistic" results, I decided to try out an 08 FJR launching at 4000 RPM and shifting at 8400 RPMs. The result was 11.12s @ 123.8mph. MCN's reported time on a Gen II FJR is 11.12s @ 119.60mph.

I'm finding that there's so many variables (weight of rider, launch RPM, shift points, shift quickness, how deep into the starting beam did the rider stage) that can dramatically affect the results. None of this is standardized (or even disclosed) in tests of different bikes by the magazines, so is there really even any point to comparing performance numbers from different similarly-performing bikes in the magazines? This just seems to make what I'm working on even more meaningful. If I could get dyno data for multiple bikes from the same dyno, with SAE correction applied, then I could provide standardized simulated comparisons that take all those unknowns away. The results themselves might nit be accurate representations of real life, but at least the differences in results between any 2 bikes would be representative of real life differences in potential performance.

 

[mcatrophy]

I've made a few enhancements to my code to generate more plausible results...

...

Great job, eminently plausible.

Just out of curiosity, are you doing it all in Excel? (The graphs obviously are.)

 

[dbvolfan]

That is some interesting stuff there and good reading! Thanks! This reminds me of an episode of Deadliest Warrior

Having an '05 FJR and an '08 C14 I'd have to say it really comes down to the rider.

My .02 on twisties involving 100% stock bikes?

If you took the same average rider and put him/her on the two bikes and let them make multiple runs through the dragon, the FJR will win more than 60% of the time. I simply cannot get the same handling out of my C14 as I can the FJR. I know others will disagree but I am an average rider who doesn't drag the bag or pegs and having spent 5+ hrs at the Dragon early one morning with both bikes I made ~20 runs between the two that same morning. My times were consistently better on the FJR. One, because of handling. Two, it came out of the curves with incredible pull whereas the C14 felt like it had turbo lag for lack of a better phrase so I couldn't recover as fast on those shorter stretches. A far better rider would be able to keep it wound up better and likely minimize that issue but once again, I am an average Joe.

Straight line- Depends on how long the race lasts. These graphs point out what I discovered riding with my wife down the interstate one day. Rolling along (at well below legal speeds of course) the FJR would get an immediate jump on me but as soon as that 'lag' on the C14 went away I reeled her in rather quickly and would pull maybe a bike or two one her before reaching the ah, speed limit. I will say that I raced a Lambo Murcielago on my C14 from a certain hwy speed (I was in 3rd and I saw him entering the interstate on a ramp so I made sure we 'merged' at the same time..hehehe) all the way to a go to jail for life speed at which he let up and I had stayed side by side with him but was starting to fade a bit at that top end speed. I Know for a fact my FJR would not have been in that same position having run it against some highly modified cars in similar situations. The extra gear and red line at 10.5k give you some more room up top.

Like the OP, I am not saying one is better than the other. Heck, my FJR is ridden more than 50% of the time and I Love it. There pretty darn equal in the end IMHO.

 

[lnewlf]

An easy way to compare high and low gearing-You guys with 4 wheel drive pickups can put the truck in low range and floor it from a standing start-be ready to have you neck snapped. You will go thru 4 gears like mad and top out at @ 50 mph. My 6 liter Chevy will hurt the feelings of any tuner out there light to light [to bad there is no way to shift into high range for more gear]. My '89 FJ1200 ran average times of about 11 seconds with stock gearing-when I changed sprockets to a lower ratio I was able to turn low 10's.

 

[carlson_mn]

Well, somebody needs to find someone with a C14 and do a roll-race now, and compare the results. Oh, and get it on camera.

 

[MCRIDER007]

Well, somebody needs to find someone with a C14 and do a roll-race now, and compare the results. Oh, and get it on camera.

I have and the differences between the bikes are a lot greater than what is being shown in this thread...but in real world applications (between 4,000-7,0000) there isn't much difference. I also think handling is a push with OEM suspension, the C14 has more lean angle but the FJR carries its weight lower and is more nimble. If you want to mod the bike, the C14 has numerous options for dramatic HP gains, the FJR has better options for suspension upgrades (my personal preference to spend the $$$ on suspension upgrades, both bikes have more power than any sane person really needs).

 

[UselessPickles]

Well, somebody needs to find someone with a C14 and do a roll-race now, and compare the results. Oh, and get it on camera.

I have and the differences between the bikes are a lot greater than what is being shown in this thread

Have you seen my responses about this? Including this post where I show a simulation of your 20mph rolling start race that shows exactly what you described?

 

[MCRIDER007]

Have you seen my responses about this? Including this post where I show a simulation of your 20mph rolling start race that shows exactly what you described?

Yes, I saw your graphs but my experience is that the difference between the bikes after a 1/4 mile is going to be about a half second or 30 yards, not the 18 feet shown on your simulation.

The C14 also has the benefit of ram air which starts to kick in above 60 mph, did you factor that into your simulation?

 

[UselessPickles]

I wasn't aware of the RAM air, but I wouldn't expect that make a large difference in 1/4 mile times because it only is effective at higher speeds. It's what happens at the beginning of the race that has a large impact. Has anyone seen any info about how much extra HP is added by the RAM air at what speed? The best I can find with a quick search is some generalizations that RAM air can add about 10% HP at top speed on motorcycles. I'll try to work that into my simulation.

Also, when did you experience 30 yard and 0.5s leads on the C14? Was it with 1/4 mile runs from a stand-still? If so, what RPMs did you launch each bike at? What RPMs did you shift at in each gear on each bike? Did both riders shift equally quick? Is your C14 lead based on "who got to the finish first", or offset for reaction times? There's so many things that could be different between two riders and how they race their bike. Something as simple as a softer launch and being 0.1s slower at shifting could add up to several tenths by the end of the race.

 

[UselessPickles]

Did some more searching on the effects of RAM air and found this: https://www.sportrider.com/tech/146_9912_ram/index.html

Looks like the effects are not very predictable based on speed, but it also looks like the gains are only in the 6% range. I could work something into my simulation to at least attempt a vague guestimate of how the RAM air will help. I would have to make some assumption like 6% gain at 150mph to determine the gain at any speed. I'm not sure if it should be proportional to speed, or to the square of speed.