Kubota BX2200 or B7500

[TresCrows]

Displacement is a better means of increasing horsepower for tractors but RPM increase will also increase power. Not going into the fortmula for torque and horsepower but Kubotas claims for the BX engine are legit. The only reasons I would get a BX over the 7500 or 2410 is that it is in fact more stable on hills, it is much more manuverable, it is far--far--far better at mowing with it's 60 in MMM that the 2410 could ever hope to be and a 2910 is in MY opinion way to big to be used as a lawnmower esp with a MMM. Also, the frame on the BX is not lighter than that on the 7500, for it's size the BX is probably a stronger tractor than the 7500 or 2410. I can feel flex in the 2410 that simply is not there in the BX. The BX is a tight little bugger. The BX was intended for a different market from Kubotas larger more capable units like the 2910. If I had bought a deluxe riding mower--a ZTR or such--which are not cheap then I would have bought a 2910 instead of the 2410. Since I mow with my tractor it has to be a do everything unit and the 2410 in my opinion is max size for that purpose. It really is a pretty lousy mower. I did spread and smooth two huge loads of gravel with it around my new shop in about 4 hours. Still need some work but it is covered in snow. J

 

[buzst]

TresCrows,
I agree with all your points on the BX and that it truly can produce 22 HP. I have been hung up on these published HP ratings ever since I was shopping for my tractor. Kubota engineering designed a superb tractor and sized it for the D905 engine. Kubota marketing then selected a point along the power curve that fit its promotional requirements (how many competitors were selling 22HP machines at that price point?). However I really think that Kubota is doing its customers a disservice by promoting the D905-E as 17HP at 2600 rpm in the b1700 then calling it 22HP at 3200rpm in the BX2200. Even today they sell the D722-E engine as 18HP at 3200rpm in the BX1800 and 16HP at 2900rpm in the b7400. Are the numbers legit? Yes. Do they allow the customer the ability to make an accurate comparison? I don’t think so. Even worse, now you have to run the engine at over 3000 rpm just to hit PTO Speed for your mower, while the B1700 owner using the same engine achieves PTO speed at 2600 rpm. Most Kubota, Deere, New Holland, and Cub Cadet machines are rated at between 2500 and 2700 rpm, and reach PTO speed at that rpm. Anyway enough of my rant, I really wanted a BX but that was the primary reason I did not buy one.

 

[Anonymous Poster]

I found kyoders' info interesting, but a bit hard to read, so I formatted and PDFed it.

I also note with some interest that the minimum width on the B7500 is almost 3" narrower than the BX22. I wonder if some of the "pucker factor" comparisons people have done might be affected by this. For shipping, I assume the wheels are set to the minimum width and I don't see any reason for the dealer to change it. Widening the track would improve stability.

 

[Anonymous Poster]

Re-reading my own post I realize I left out a question or two- What is the maximum width of the B7500? Or the B2410 for that matter? Can you get anything approaching the same height/width ratio and the BX22?

 

[TresCrows]

The answer is mostly NO regarding wide wheels settings to equal the BX stability, even with the wheels spread my 2410 feels more tippy than the BX and you cannot have the wheels spread with the MMM installed! I am used to the 2410 now but I do not venture into some places I routinely went with the BX.
Yes and no again on the horsepower thing---if the 3200 RPM is what kept you from a BX you probably were concerned about nothing. The BX is quiter and smoother at that speed than my 2410 at it's 2600 or whatever exactly it is. I have no doubt that the BX with D905 engine will do just dandy for years and yes I knew that the B1700 (defunct) had the same engine rated at 17 at 2600 RPM and my question actually is so what? The fact is the BX is relatively overpowered any way in some respects and most guys mow at about 2600 anyway--I did and do, but with the govenor on the BX set for a higher engine speed it is like having extra horses on standby. I use about 2200-2400 on the 2410 for mowing. J

 

[kyoders]

Not to fan the flames, but somebody over in the owning group just posted a link to Kubota engine specs. Unless I'm reading it wrong, the D905-E engine makes about 19.5HP at 2600, 22HP at a tad over 3000, and 23.5 at 3600. Peak torque is at 2600. At 3200, it appears to be doing about 22.5HP. The D722-E has peak torque at about 2600 at 16HP. It reaches 18HP at a tad over 3000, and at 3600 still falls a bit short of 19HP. At 3200, it might be making 18.4HP or there abouts.

Buzst, I can kind of see what you mean by the disservice of rating the D905-E at 17HP at 2600RPM. It appears that it should really be 19.5 /forums/images/graemlins/tongue.gif. I don't know how long ago they stopped making B1700's, but is it possible that they have made other improvements to the engine that has boosted output since then? In any event, you apparently "found out" about the rating chicanery and decided against the BX, largely because of it. In the end, no matter whether it was engineering or marketing that made the decision, the governor is set at 3200RPM, so it wouldn't make any sense to give HP ratings at any other RPM.

Kevin

 

[kyoders]

Peter,

Thanks for cleaning it up. I forgot that spacing doesn't come out the way you might think using markup. I couldn't find any specs on just what the maximum tread width is on the B7500 or B2410. pcmem's comment on "seat-o-pants" pucker check indicated that the B7500 was set at max width. And TresCrows' later comment about the B2410 indicates the same.

Kevin

 

[TresCrows]

Looking at Kubota engine specs from the site from another thread it is apparent that Kuobta specs the D905 engine at both a standard speed off 3000 RPM and a High speed of 3600 therefore it is apprent that the engine was designed for operation up to and including 3600 RPM. Several other engines were given both high speed and standard ratings. Since the govenor for the BX is set at about 3300 or is 3200 it is apparent it is well within it's design limits. I guess if I had a choice I would put the same engine in the BX as the 7500 gets but limit the RPM to approx 3000. The D905 engine is very smooth and fuel stingy and I think this is a big ta-doo over nothing. J

 

[Anonymous Poster]

I have read in other threads that one of the factors that seem to make diesel engines last longer compared to gasoline engines is the relatively low operating RPM.

Is there a concern that running the engine faster in order to obtain a higher power output in a BX-22 might shorten its life relative to running at a lower speed? (From what I have seen in other similar threads, there are as many answers to this as there are people to give them! /forums/images/graemlins/tongue.gif)

Would the additional mechanical load on the engine's components be expected to have a bearing? (Couldn't resist the pun /forums/images/graemlins/laugh.gif)

How do other driveline components of a B1700 compare to a BX22? (If I recall correctly the B1700 is a gear drive vs HS for BX22, so this may be a meaningless question /forums/images/graemlins/confused.gif)

 

[TresCrows]

The B1700, B2100 and B2400 were all deluxe tractors--the same size and features as the current B2410. The B1700 was HST and was available I think with bi-speed turning. I think they dropped the 1700 and 2100 when they came out with the BX and 7500. The previous 7400 did not have power steering. When I first went to get a tractor it was the B1700 I went to get. I rode one around the lot and worked a dirt pile with it and they put a box on it so I could tug that around. The tractor performed very well. I was still shopping and by the time I came back to take a second look they had the BX units on the lot and a nearly new 7500 which I took home for a weekend trial. I wound up with the BX. The engine in the BX is plenty stout. It is after all a Kubota diesel engine.
My limited experience with engines suggest that the greatest wear occurs during start up or during improper operation such as overheating or lugging the engine. I guess some of you guys set your throttles wide arse open all the time but I typically use 1800-2200 for FEL work per the manual with the BX and about 3/4 throttle for most mowing per my ears. I run my 2410 about the same way. I am not sure the 2410 has ever been opened up to full throttle. I know it has quite a bit of grunt when it comes to FEL work and makes quick work of heavy gravel. J