This may fall under the heading of "too much information", but I'll give it a stab anyway. /w3tcompact/icons/smile.gif
I took the previous side-by-side chart comparing all of the B-series, plus the
BX2200, added a couple bits that weren't available in the previous version, and added my own interpreted information from the charts available at
Kubota Engines.
What I did was expand the information on horsepower and torque to include the following four bits of detailed information.
1. SAE Net Intermittent HP
2. SAE Net Continuous HP
3. SAE Net Intermittent Torque
4. SAE Net Continuous Torque
The expanded information comes from interpolating the graphical information for each engine every 200 RPM between 1800 RPM and 3600 RPM. Some of the information is incomplete because the graphs listed do not include information above 3000 RPM for the D1105-E-D16 (
B2410) or the V1505-E-D16 (
B2910) engines. It should be noted that the RPM ranges below 1800 are not listed, so are somewhat missleading in those lower operating ranges for the larger engines.
Before anyone nit-picks me to death /w3tcompact/icons/smile.gif, I would also like to point out that I had to examine these graphs rather closely,
but the graphs lack enough detail, that some of the information could be off by at least a tenth (or two) in several areas. For that reason, I chose to give Kubota "the benefit of the doubt" in showing the "sweet spot" for each engine.
The new information is shaded (compared to black on white for the all the previous information, which is still there). Follow this key to understand:
Pale Yellow = Data points that are below Kubota's stated "rating" for that engine.
Blue = Data points that are at or above the rating for that engine. (sweet spot)
Bold Box = PTO speed range.
To help you go through the data, look the D1005-E-D16 engine for the
B7500. The yellow range (below advertised rating) goes from 1800 RPM through 2200 RPM. The blue range (AKA sweet spot) runs from 2400 RPM through 3600 RPM. The PTO speed is 2600 RPM, at which point the engine capable of 22.6HP
intermittently or 18.6HP
continuously. Likewise, this engine also produces the advertised horsepower when de-rated for continuous use, but only if operated at 3000+ RPM (22-24 HP).
I went through this exercise simply because I wanted to know what the real penalties were for going with the smaller BX engine, even though it is
rated as having 1 more horsepower than the larger engine in the
B7500.
Others might notice some interesting facts as they go over this data when presented this way. Here's a couple of observations that I have made:
1. All of the engines execpting the D905 have the what I've been calling the
"sweet spot" for both horsepower and torque at or around the PTO speed. The D905 has its HP sweet spot at PTO speed, but its torque sweet spot is in the 2200-2600 RPM range. What does this mean? My interpretation is that the BX will do better doing "torquey" operations at the lower speed rather than PTO speed. So things like FEL work or pulling a plow or box blade would probably work better when operating slower.
2. This was a real surprise. The
B7500 engine actually produces more horsepower than the
B2410 in several parts of its operating range. In fact, the
B7500 engine can actually produce rated power continuously at 3000 RPM. It's possible (probable) that the
B2410 engine produces rated power continuously at 3000 or so RPM, but the graph did not provide the data.
3. I think, after looking at the data that torque is much more important for a tractor engine than horsepower. Sure, I HP is what is on the brochures, but it's clear that the larger engines are optimized to produce more torque at the typeically expected operating speeds.
4. All these engines produce relatively flat torque curves. If you expand the "sweet spot" to be 95% of rated power, they all produce rated torque all the way through the operating range. Nice.
The GlueGuy
