Found Actual engine torque/hp/sfc GC1710 vs GC1720. Also actual hydraulic flow to the

[GC1710]

Found these in the engine service manual and thought they were worth posting. A lot of conclusions can be drawn from this data!

My simple conclusion if your stuck between the 1705/10 vs 1715/20: If you are mainly using PTO attachments at 540rpm you will see just about the same power and much better fuel consumption with the less output engine. If hydraulic flow is critical and you are already thinking of a log splitter or other heavy GPM flow needs then going for the higher output engine may be best. (13% more flow for attachments on the higher output models 4.9 vs 4.4 gpm at the attachments). Why doesn't Massey make the dealers more aware of this data, the multiple dealers I spoke with were all knowledgeable but when asked the difference they all said, better seat, light guards, and just a bit more power. Really I think for anyone considering it's about PTO vs hydraulic flow use. Also for mowing the SFCs are much better on the smaller output motor. Just my 2 cents and a little contribution from a newbie member. Have a great Labor Day weekend!

 

[AxleHub]

Found these in the engine service manual and thought they were worth posting. A lot of conclusions can be drawn from this data!

My simple conclusion if your stuck between the 1705/10 vs 1715/20: If you are mainly using PTO attachments at 540rpm you will see just about the same power and much better fuel consumption with the less output engine. If hydraulic flow is critical and you are already thinking of a log splitter or other heavy GPM flow needs then going for the higher output engine may be best. (13% more flow for attachments on the higher output models 4.9 vs 4.4 gpm at the attachments). Why doesn't Massey make the dealers more aware of this data, the multiple dealers I spoke with were all knowledgeable but when asked the difference they all said, better seat, light guards, and just a bit more power. Really I think for anyone considering it's about PTO vs hydraulic flow use. Also for mowing the SFCs are much better on the smaller output motor. Just my 2 cents and a little contribution from a newbie member. Have a great Labor Day weekend!

How would you know that a GC1705 would be "much better fuel consumption" than a GC1715?

Also - more horsepower output will show up at any hydraulic using port - whether its drive wheels or FEL or MMM or rear PTO.

 

[GC1710]

How would you know that a GC1705 would be "much better fuel consumption" than a GC1715?

Also - more horsepower output will show up at any hydraulic using port - whether its drive wheels or FEL or MMM or rear PTO.

Comparing the SFC (specific fuel consumption) charts to one another was my simple conclusion, depending on what throttle % you use on what application the lesser power GC has better fuel economy. To get that extra power in the higher power GC takes up quite a bit more fuel, not just at the higher RPM it can obtain but throughout the rev range....at least according to the data. If you are running a PTO implement at 540rpm (per most implements), the high power GC makes 18.7hp at the PTO the lower power GC makes 18.5hp at the PTO additionally the lower power GC makes 540rpm at the PTO at 2532rpm, the ladder at 2829rpm (quite a bit more fuel used on the higher GC for 0.2 hp. To me this equates to the lower GC cost and fuel savings being the better deal for most PTO driven implements (if you run recommended implement rpm). Now if you are going to be running compact tractor implements on a SCUT...then please get all the power you can.....

I was just trying to add some data points to the forum as I saw so many posts asking about the power difference and the two dealers I dealt with couldn't answer what that power difference really meant....and I couldn't find it myself until I read the Iseki Engine Service Manual.


Not sure I don't disagree with your 2nd statement, however the PTO if ran at recommended RPM has better fuel economy on the lesser engine (as mentioned above). Higher HP shows up at the hydraulic port by the measurement of more flow at the same given pressure. Which is why you do see a pretty significant jump in flow at full RPM in the higher output engine at full throttle where the power difference is greatest.

I think if users are stuck between the two one question to help decide is PTO vs hydraulic implement use. Now if you are going to bushhog all day and run max throttle then yes the more output motor will give you that extra boost....but if you run at 540rpm I just don't see the reasoning.

If I have this all wrong please keep the discussion going I don't want to misinform!

 

[Snobdds]

How would you know that a GC1705 would be "much better fuel consumption" than a GC1715?

Also - more horsepower output will show up at any hydraulic using port - whether its drive wheels or FEL or MMM or rear PTO.

It's one of the graphs he posted. More power has a cost and that is more fuel.

Also, a pump output is not a product of horsepower. Pump output is a product of how fast the pump is spun, accounting for equal flow rates. To change a pumps output, more horsepower is not need, just a change in pulley diameter, usually a smaller pulley, is all that is needed.

The gc1715/1720 makes it's extra power with more RPM and more fuel. It's the same engine and same fuel pump, just adjusted for more fuel flow in the pump.

I've seen those charts, but good to share non the less.

 

[AxleHub]

It's one of the graphs he posted. More power has a cost and that is more fuel.

Also, a pump output is not a product of horsepower. Pump output is a product of how fast the pump is spun, accounting for equal flow rates. To change a pumps output, more horsepower is not need, just a change in pulley diameter, usually a smaller pulley, is all that is needed.

The gc1715/1720 makes it's extra power with more RPM and more fuel. It's the same engine and same fuel pump, just adjusted for more fuel flow in the pump.

I've seen those charts, but good to share non the less.

So here is the logical question. Given the gc1705 at 2600 rpm and the gc1715 at the same 2600 rpm . . . Does one use less fuel than the other or produce more power than the other at the identical same rpm ?

Now supposedly you're saying the charts will show the answers.

 

[Bremse]

According to the charts, at 2600 rpm the 1705 makes a bit less power with a bit less consumption than the 1715. The difference between the engines must be more than just having a raised max speed since the curves are different at same speed points. It's still probably all in the tuning though. The 1715 appears to be fueling a bit more at same rpm plus it has a larger rpm range.
Keep in mind that the gearing for the PTO is different so 1715 runs at higher engine speed compared to 1705 for the same PTO speed so the consumption difference is more than just the slight difference noted above in the 2600 rpm example.

 

[Snobdds]

So here is the logical question. Given the gc1705 at 2600 rpm and the gc1715 at the same 2600 rpm . . . Does one use less fuel than the other or produce more power than the other at the identical same rpm ?

Now supposedly you're saying the charts will show the answers.

No, they wouldn't use the same amount of fuel. The 1715/20 are set up to flow more fuel in the pump for any given rpm. That is one of the physical differences between the two. The fuel pumps do not have the same flow rates. Yes, the charts confirm this...

 

[GC1710]

According to the charts, at 2600 rpm the 1705 makes a bit less power with a bit less consumption than the 1715. The difference between the engines must be more than just having a raised max speed since the curves are different at same speed points. It's still probably all in the tuning though. The 1715 appears to be fueling a bit more at same rpm plus it has a larger rpm range.
Keep in mind that the gearing for the PTO is different so 1715 runs at higher engine speed compared to 1705 for the same PTO speed so the consumption difference is more than just the slight difference noted above in the 2600 rpm example.

You really had my mind wondering...."you are right since the PTO is gear driven and to obtain 540 rpm at the PTO takes different RPM on each model....something in the gearcase is different! (which most people have never mentioned at least in my research....) ......So I went and looked at the parts book.....low and behold two gear shafts are different in the gear box between the two models.....Here is the real odd part....usually when you increase engine hp you increase torque and thus you can gear "up" the transmission (meaning go down in ratio)....however on the 1715/20 they actually gear down and make it so you run higher RPM to obtain the 540 PTO RPM.....alright this was my 10 minute review....when I have time this weekend I will look into this further.....pretty interesting!



...and gearing different on hydraulic pump, which explains the different flow and not just being about the greater RPM.....

 

[AxleHub]

See thats my point. At the same rpm in each unit the hydraulic pumps are producing differently, hence there is more being done at the same rate of rpm and not a requiement to look at the 3000 rpm fuel burn number compared to the gc1705s 2600 rpm fuel burn.

Or . . . .

 

[Langanobob]

According to the charts, at 2600 rpm the 1705 makes a bit less power with a bit less consumption than the 1715. The difference between the engines must be more than just having a raised max speed since the curves are different at same speed points. It's still probably all in the tuning though. The 1715 appears to be fueling a bit more at same rpm plus it has a larger rpm range.
Keep in mind that the gearing for the PTO is different so 1715 runs at higher engine speed compared to 1705 for the same PTO speed so the consumption difference is more than just the slight difference noted above in the 2600 rpm example.

I notice that the tachometer on my new GC1720 has a mark for 540 PTO RPM exactly at 2600 RPM. If the gears are different between the GC1710 and GC1720 PTO's that mark should be about 3000 RPM. It looks to me like MF cheaped out and used the same dashboard graphics for the two models. If that's the case many GC1720 owners are going to be running their PTO at lower than rated speed, assuming they use the tach needle as a reference.

Or, the gears are really the same between the two models. I think I'll try calling MF tomorrow and see if anyone will talk to me about what looks like a discrepancy.

Edit: The info above is wrong. Turns out I can't properly read a tach scale. I'm doing real good, only 12 posts and already spreading false information. The marker on the tach for the PTO RPM's is on the right spot.