Dyno comparison Alta Vs two stroke and four stroke

Edabdo

Well-known member
Likes
67
Location
Western New York
#1
Here are a few images of an 2018 Alta MXR versus a 2000 Honda CR250R and a 2015 KTM SX250F.
I have separated the HP and Torque runs to get a better look and prevent any confusion
Also ran the Alta in mode 3 and 4

CR250R HP comparison in mode 3
altaand 2000cr250 HP mode 3.png


CR250R HP Comparison in mode 4
altaand cr250R HP mode 4.png

CR250R Comparison Torque Mode 3
altaand cr250rtorque mode 3.png

CR250R Comparison Torque Mode 4
altaand cr250rtorque mode 4.png

KTM 250SXF Comparison HP Mode 3
altaand ktm hp mode3.png


KTM 250SXF Comparison Torque Mode 3
altaand ktm torque mode3.png



KTM 250SXF Comparison HP Mode 4
altaandktm hp mode 4.png



KTM 250SXF Comparison Torque Mode 4
altaandktm torque mode 4.png

Working on getting some 350 and 450 runs in soon.
Yeah, it's kinda like cheating...
 

Philip

Administrator
Staff member
Likes
2,989
Location
Ann Arbor, MI
#4
So, according to these charts, the 250's do not stand a chance.

I have some 450's charts in my dyno thread. They too need to be revved and shifted at high RPM to keep up with the MXR.

One question remains: Does Alta reduce the power after the throttle is held at WOT for X number of seconds? I am asking because many EV manufacturers state a high HP number, but then they say that the "continuous" power number is like 20% lower. Does Alta do that? These dyno runs were acquired on an inertial dyno in like 5-8 seconds each run, right? To acquire a continuous power one needs to use an electric or hydraulic brake, the type than can hold a constant resistance for extended periods of time. Without it, it would be hard to figure out what the bike does on a long straightaway.

Sometimes I get passed by other bikes on straightaways, but then I notice that my throttle is not fully pinned. It is really hard to keep the throttle pinned in Map 4!
 

Edabdo

Well-known member
Likes
67
Location
Western New York
#5
So, according to these charts, the 250's do not stand a chance.

I have some 450's charts in my dyno thread. They too need to be revved and shifted at high RPM to keep up with the MXR.

One question remains: Does Alta reduce the power after the throttle is held at WOT for X number of seconds? I am asking because many EV manufacturers state a high HP number, but then they say that the "continuous" power number is like 20% lower. Does Alta do that? These dyno runs were acquired on an inertial dyno in like 5-8 seconds each run, right? To acquire a continuous power one needs to use an electric or hydraulic brake, the type than can hold a constant resistance for extended periods of time. Without it, it would be hard to figure out what the bike does on a long straightaway.

Sometimes I get passed by other bikes on straightaways, but then I notice that my throttle is not fully pinned. It is really hard to keep the throttle pinned in Map 4!
Yes power is reduced through the firmware. You can visually see this while doing a full throttle run! The bike is trying to rip through the hold down straps and then literally backs down on power! It's pretty awesome to see!
 

Edabdo

Well-known member
Likes
67
Location
Western New York
#6
So, according to these charts, the 250's do not stand a chance.

I have some 450's charts in my dyno thread. They too need to be revved and shifted at high RPM to keep up with the MXR.

One question remains: Does Alta reduce the power after the throttle is held at WOT for X number of seconds? I am asking because many EV manufacturers state a high HP number, but then they say that the "continuous" power number is like 20% lower. Does Alta do that? These dyno runs were acquired on an inertial dyno in like 5-8 seconds each run, right? To acquire a continuous power one needs to use an electric or hydraulic brake, the type than can hold a constant resistance for extended periods of time. Without it, it would be hard to figure out what the bike does on a long straightaway.

Sometimes I get passed by other bikes on straightaways, but then I notice that my throttle is not fully pinned. It is really hard to keep the throttle pinned in Map 4!
They key is to understand how to use the power of the Alta. If you twist the throttle as you do on a combustion bike the ice bike will likely beat you. But understanding how and when power is being made can better educate the rider.
 

Edabdo

Well-known member
Likes
67
Location
Western New York
#7
So, according to these charts, the 250's do not stand a chance.

I have some 450's charts in my dyno thread. They too need to be revved and shifted at high RPM to keep up with the MXR.

One question remains: Does Alta reduce the power after the throttle is held at WOT for X number of seconds? I am asking because many EV manufacturers state a high HP number, but then they say that the "continuous" power number is like 20% lower. Does Alta do that? These dyno runs were acquired on an inertial dyno in like 5-8 seconds each run, right? To acquire a continuous power one needs to use an electric or hydraulic brake, the type than can hold a constant resistance for extended periods of time. Without it, it would be hard to figure out what the bike does on a long straightaway.

Sometimes I get passed by other bikes on straightaways, but then I notice that my throttle is not fully pinned. It is really hard to keep the throttle pinned in Map 4!
I also have full load control and imitate virtually and condition. All of my runs were from dead stops. Something you can't do on a ice bike!
 

TCMB371

The Silent Assassin
Forum's Sponsor
Likes
1,715
Location
Temecula, CA
#8
Yes power is reduced through the firmware. You can visually see this while doing a full throttle run! The bike is trying to rip through the hold down straps and then literally backs down on power! It's pretty awesome to see!
I would love to see the bike's log files for the dyno runs. That would be some good looking data to digest. Any chance you'd be willing to hook up MultiTool to the bike and download the log files of the dyno run(s)?
 

TCMB371

The Silent Assassin
Forum's Sponsor
Likes
1,715
Location
Temecula, CA
#9
Also, to get a better sense of how the MXR compares in raw accelaration, it would be cool to see dyno graphs with speed on the x axis and then run each bike up to something like 65mph, running the gas bikes through their gears in the process.
 

metallic88

Well-known member
Likes
168
Location
utah
#10
Yes power is reduced through the firmware. You can visually see this while doing a full throttle run! The bike is trying to rip through the hold down straps and then literally backs down on power! It's pretty awesome to see!
I figured they did cause on my mx i hated that I wanted power all the time like a Ice, but i couldnt get a good answer back then, but I thought the mxr did it also but since i regeared it its not as noticeable. thats my only complaint power wise over a Ice.
 

Philip

Administrator
Staff member
Likes
2,989
Location
Ann Arbor, MI
#11
I also have full load control and imitate virtually and condition. All of my runs were from dead stops. Something you can't do on a ice bike!
What kind of a dyno is this (type, brand)? If you can simulate any load, then you can record 1 run 0-60mph with the regular 400 lbs load (bike plus rider) and then another run with like 600 or 800 lbs load to simulate an uphill. The run with a heavier load will take much longer, so it would be interesting to see if the bike will produce a reduced power on a longer run.
 

bluefxstc

Well-known member
Likes
575
Location
Boise, ID, United States
#12
The torque reduction you are seeing is probably the result of Back EMF or Counter Electormotive Force and battery sag. As the motor speed increases, it also acts as a generator creating a Back EMF voltage proportional to the motor speed. The induced Back EMF opposes the battery voltage. When the Back EMF and the applied battery voltage are equal the motor can’t go any faster. Battery sag, while minimal in lithium batteries, is still present so the more current you draw, the lower the battery voltage. Here is a short article on Back EMF.
 

Mark911

Well-known member
Likes
669
Location
Corona Ca
#13
The Alta controller uses pretty sophisticated field weakening algorithms to reduce the negative affects of back EMF. That's the primary reason they're able to get the motor to spin as fast as it does. Otherwise, no way. Yes, voltage sag with the Alta is one of the biggest single limiting factors when it comes to producing power. The R packs are better than the A packs in this regard but they're both pretty poor (as all 18650s are) performers at high drain. However, these cells are worlds better in other respects (compared to other chemistries) and the right choice at this point in commercially available battery cell tech.

When looking at dyno sheets one should take in consideration the torque multiplication advantages of having gears. Possibly overlay the various curves for each gear to get a better perspective of what's really happening. Then somehow integrate the curves into a single one for direct comparison to the Alta curve.
 

C5tor

Chief Comedic Instigator
Likes
736
Location
San Ramon, CA
#14
When looking at dyno sheets one should take in consideration the torque multiplication advantages of having gears. Possibly overlay the various curves for each gear to get a better perspective of what's really happening. Then somehow integrate the curves into a single one for direct comparison to the Alta curve.
That's true. If you overlaid pulls in all 5 or 6 gears of the ICE bike over the graph, I bet it would look a little more interesting, and probably paint a bit different picture. This is just a snapshot in one gear.
 

Philip

Administrator
Staff member
Likes
2,989
Location
Ann Arbor, MI
#15
If you add other gears, then the HP chart will gain other blips of the same height but at different speeds, proportionate to the gear ratios. No surprises there, you can visualize it pretty closely without plotting.

On the Torque chart the blips will be higher at lower speeds and lower at higher speeds.
 

Mark911

Well-known member
Likes
669
Location
Corona Ca
#16
I agree. There’s some nonlinearities but it’d give a better picture. With the exception during gear changes I suspect the charts would be much more comparable.
 

Edabdo

Well-known member
Likes
67
Location
Western New York
#17
What kind of a dyno is this (type, brand)? If you can simulate any load, then you can record 1 run 0-60mph with the regular 400 lbs load (bike plus rider) and then another run with like 600 or 800 lbs load to simulate an uphill. The run with a heavier load will take much longer, so it would be interesting to see if the bike will produce a reduced power on a longer run.
Dynojet 250ix I don't ride any dirt bike at wot longer than a straight at a mx track. I suppose if you wanted to desert race it would make sense to run at long intervals. It indeed drops over time as I can read the voltage drop as I run it at full throttle using the multi tool software. But the power dies not reduce until the firmware tells it to.
 

Edabdo

Well-known member
Likes
67
Location
Western New York
#18
Also, to get a better sense of how the MXR compares in raw accelaration, it would be cool to see dyno graphs with speed on the x axis and then run each bike up to something like 65mph, running the gas bikes through their gears in the process.
Come on over and play if you want to. I'd be happy to run the dyno for any bike (s) you want to bring over! I'll see about the log files but they are such a pain to download!!
 

Similar threads