GC2400/2600 and GC1705/1715

[dnw64]

From all I can see, the only difference is power output. Anyone figured out what changes they made to generate the additional 2.5HP and try it? I'm guessing injectors and/or pump pressure. Seems like it should be relatively easy to add over 10% if the basic mechanicals are the same.

 

[AxleHub]

Between a gc1705 and a GC1715 the differences are (assuming each has a dl95 fel ) :

1. Engine has rpm range change of 2600 to 3000 rpm
2. Hydraulic pump flow is slightly greater
3. H. P. Of 2.5 as you mentioned
4. Rear light
5. An entirely different seat and spring suspension for the seat added

From personal use and testing, I can tell you that the lifting strength is more than you might imagine with the gel. I've tested payload size at 2600 rpm and at 3000 rpm on my gc1715. I can imagine that will also show up on the 3ph side too.

But the seat and seat spring suspension alone is worth the price difference Imo. It is noticeable on wasboard-like lawns.

 

[plowhog]

Another difference is a bracket/guard around the signal lights.

 

[AxleHub]

Another difference is a bracket/guard around the signal lights.

Good catch plowhog I forgot that one. And judging by other threads I've read, those guards on lights are more important than I figured. Apparently quite a number of gc1705 and gc1710 users have knocked off or broken their lights on branches and fence posts.

 

[dnw64]

Interesting to know the other differences.

I was mostly interested in how they increased the power using the same block. It sounds like they just turned up the governor*. In fact I did read on another thread that someone had just gotten their GC back after having the RPM increased to 3000 but didn't think much about it. I will have to check into that option. I had already thought about running a higher RPM to make my snow blower throw further.

*A 15% increase in RPM past the peak of the torque curve resulting in an 11% increase in HP sounds about right.

 

[AxleHub]

Interesting to know the other differences.

I was mostly interested in how they increased the power using the same block. It sounds like they just turned up the governor*. In fact I did read on another thread that someone had just gotten their GC back after having the RPM increased to 3000 but didn't think much about it. I will have to check into that option. I had already thought about running a higher RPM to make my snow blower throw further.

*A 15% increase in RPM past the peak of the torque curve resulting in an 11% increase in HP sounds about right.

Over the last few years I've read quite a few stories about manufacturers using the same blocks with considerably different power curves produced. The rpm is typically the smallest but most visible difference. The more likely things are porting changes and timing changes. It would not seem possible to just speed up the rpm and still have the same safety tolerances. Pump output increases are a fair amount and to move a 22.5 HP engine and increase it to 25 hp is meaningful.

If just changing a governor was all it took. . There would be no point in Massey having 2 engine choices in my opinion.

 

[dnw64]

The rpm is typically the smallest but most visible difference.

If an engine continues to produce similar torque, RPM is all it takes to increase HP. BTW I haven't seen a torque curve for both engines, but from anecdotal reports I've seen I'd be pretty certain that they both perform identically up to 2600 RPM.

Pump output increases are a fair amount

The pump output increase is no more than the RPM increase. With rare exceptions, a pump produces a fixed amount per revolution, so increasing a pump RPM by 11% (2600 to 3000) should result in an increase of 11% in flow. 4.3 GPM + 11% = 4.8 GPM*, which numbers coincide with published figures.

If just changing a governor was all it took. . There would be no point in Massey having 2 engine choices in my opinion.

I guess you have more faith in "the system" than I do. I have seen far too many companies do things just to gain market share, profits, consumer awareness, etc. with no regard for logic, fairness or actual value.

FWIW, since making the original post I have done a lot of searching. I came across one post by a guy that got both parts sheets and compared them line by line. The only performance related difference was the injector pump, which does make sense; in order to put out more HP you need more fuel.

The other interesting thing is that the 2600/1715s have their PTOs run at a different ratio, so that they put out 540/2000 at 3000 engine RPM. This means that if one were to increase the RPM on a 2400/1705 from 2600 to 3000, the PTO outputs would be 600/2220. Which could be good, or bad, depending what you're doing.

Long story short, it appears it would be possible to get the higher output from the "smaller" engine without too much trouble, but the relatively small increase in real world usage makes it infeasible for most applications. Or, as I was told when looking for ways to increase the HP of my 3.2L V6 Mercedes "If you want more power the best way to do so is just get a car that has a bigger engine". So for now I will wait and see if I actually need/want more power, and if so, most likely trade the whole thing.

*Edit: I was using numbers from a 3rd party site that must have a typo. According to the M-F produced brochure the pump outputs are 6.3 and 6.8 GPM
(or more accurately 24 and 26.3 LPM), which is a 9.5% increase.

 

[AxleHub]

Dnw64. You have an interesting set of information regarding your idea. However there was another point that I made that you didn't respond to if everything was the same except governor settings. Here it is:

"It would not seem possible to just speed up the rpm and still have the same safety tolerances."

An rpm change from 2600 to 3000 is almost a 15% change. Without some reason for that possibility to exist . . the engineering safety factors and mean-time-to-failure numbers would be greatly effected. And that would impact several issues for warranty costs etc.. If the engines were identical in all ways. . . and if the GC1715 meets all safety factors. . . I fail to see what would be a motivation to sell a de-tuned gc1705 at a lower price and higher volume .

I'm not saying you are wrong. . . I'm just not seeing any manufacturer's motivation. . . Unless there are differences besides rpm speed and performance results.

 

[dnw64]

Dnw64. You have an interesting set of information regarding your idea. However there was another point that I made that you didn't respond to if everything was the same except governor settings. Here it is:

"It would not seem possible to just speed up the rpm and still have the same safety tolerances."

I guess I didn't respond directly, but the "evidence" I mentioned covered that. Again, it's hearsay, but another poster claimed that he compared the parts lists for both motors and all the part numbers were identical except the injector pump. IOW, no matter which engine you have, if you need, say, new rod bearings and pistons, you order the exact same part.

Additionally, another poster said (again, hearsay) that he wanted a 1715 but the dealer didn't have any on the lot, but offered to adjust the governor and replace the injection pump on a 1705 to make the sale.

Admittedly, this is "internet chatter" and I have no idea if these things are actually true. But based on my personal experience with performance related items (and you don't know me from Adam so I don't expect you to "trust" me, but it still influences my personal opinion), an 11% increase in RPM/HP seems very doable on this type of engine with no discernible consequences.

I fail to see what would be a motivation to sell a de-tuned gc1705 at a lower price and higher volume .

This happens all the time in many industries*.

Exactly what M-F's motivation was, I don't know. I can guess, but don't see any point in that.

*one example. My brother is an over-the-road truck driver. When he drove for CR England they bought new trucks (Freightliner IIRC) on a two year rotation. They were governed by the factory to a top speed of 60 (or maybe 62?) mph and all PMs had to be done on strict schedule. In return they were guaranteed a high trade-in value because the company knew they could sell them for top dollar with a guarantee.

 

[piercedtiger]

Seems like it would benefit them to build both to handle 3,000 RPM, sell one lower for lower budget buyers and the other for higher budget buyers. No change in manufacturing, just slap a different fuel pump, governor setting and stickers on the higher output one then top off with a higher price tag. Wouldn't be the first marketing gimmick to get people to pay a higher price for the same thing.