GC Series - 23 or 25 HP from the same size engine: How do they do that?

[daman1]

I would advise anyone without extensive knowledge of how injection timing, fuel shims, and injector pulse width works...to not adjust their fuel screw.

I agree, just saying.

 

[Berlock]

Hey all, new here, just ordered a gc1725m tlb.

Looks like the 23 develops peak torque earlier (65nm@2000rpm than the 25 (65nm@2200rpm)
At least in the Australian spec, pic attached.

That would suggest different valve timing to me. Given we’re naturally aspirated and they wouldn’t have a lot of wriggle room with air fuel ratios due to emissions, I wouldn’t think it’d be all in the fuel. What do you reckon?

 

[kenmbz]

Hey all, new here, just ordered a gc1725m tlb.

Looks like the 23 develops peak torque earlier (65nm@2000rpm than the 25 (65nm@2200rpm)
At least in the Australian spec, pic attached.

That would suggest different valve timing to me. Given we’re naturally aspirated and they wouldn’t have a lot of wriggle room with air fuel ratios due to emissions, I wouldn’t think it’d be all in the fuel. What do you reckon?

Welcome to TBN Berlock and congrats on the new tractor

 

[daman1]

Hey all, new here, just ordered a gc1725m tlb.

Looks like the 23 develops peak torque earlier (65nm@2000rpm than the 25 (65nm@2200rpm)
At least in the Australian spec, pic attached.

That would suggest different valve timing to me. Given we’re naturally aspirated and they wouldn’t have a lot of wriggle room with air fuel ratios due to emissions, I wouldn’t think it’d be all in the fuel. What do you reckon?

Is that taken at the tractor's PTO or the flywheel? that makes a big difference

 

[Berlock]

Thanks heaps kenmbz, glad to be here.

daman1, in the context of discussing at what RPM the engine develops peak torque, why does it make a difference where the torque is measured? I would have thought that the torque curve would be about the same shape regardless of where it's measured, perhaps incorrectly? Genuine question, I'm a massive noob.

With that said, I reckon it's measured at the flywheel. 2200rpm@65Nm is 14.3kW which sounds about right.
The PTO delivers 13.8kW@540rpm which is 244Nm so the 65Nm is probably too low.


Here's an extract from the manual which shows they're slightly different engine models (XB02 and XB03). I can't find Iseki's specs on those engines though sadly.
Does anyone have access to a parts catalogue? It'd be interesting to see if they use different camshafts.

 

[daman1]

Thanks heaps kenmbz, glad to be here.

daman1, in the context of discussing at what RPM the engine develops peak torque, why does it make a difference where the torque is measured? I would have thought that the torque curve would be about the same shape regardless of where it's measured, perhaps incorrectly? Genuine question, I'm a massive noob.

With that said, I reckon it's measured at the flywheel. 2200rpm@65Nm is 14.3kW which sounds about right.
The PTO delivers 13.8kW@540rpm which is 244Nm so the 65Nm is probably too low.


Here's an extract from the manual which shows they're slightly different engine models (XB02 and XB03). I can't find Iseki's specs on those engines though sadly.
Does anyone have access to a parts catalogue? It'd be interesting to see if they use different camshafts.

View attachment 690921

Yea,I seen that too, That's what a dealer will tell you and that's true workable horsepower when it comes to a tractor, you want to know what PTO horsepower is for future Implement purchases.

That's what's confusing I have the parts manual on hand and service manual neither one shows a different part number but I'm going to look again just in case I missed it.

 

[ProfJeff]

I can chime in on my brand new 1723E, it seems to run out of power over 2900-3000 or at least not increase in power so if there is a restriction of some kind some place, that might be removed to let the 25 make a bit more top end. Being around cars and bikes and boats for several decades, there is a 6.7% difference from 22.5 to 24 so that would be noticeable. It's not that it's "only" 1.5 hp, it's the % change. Having said all that, I have a lot to learn about my new tool---starting with ballast. I live on a very hilly lot leading down to a lake. My first day had visions of it rolling into the lake while hauling some rock in the FEL. More YouTube time, and more dollars out the door.

 

[JerryC999]

I can chime in on my brand new 1723E, it seems to run out of power over 2900-3000 or at least not increase in power so if there is a restriction of some kind some place, that might be removed to let the 25 make a bit more top end. Being around cars and bikes and boats for several decades, there is a 6.7% difference from 22.5 to 24 so that would be noticeable. It's not that it's "only" 1.5 hp, it's the % change. Having said all that, I have a lot to learn about my new tool---starting with ballast. I live on a very hilly lot leading down to a lake. My first day had visions of it rolling into the lake while hauling some rock in the FEL. More YouTube time, and more dollars out the door.

Yep, with my debris forks on and a few straw bales on the loader, I lost traction from my rear wheels on sorta wet grass. I had to switch to 4-wheel drive to keep moving. So, that ballast thing is a real issue.

 

[fxdb96]

For anyone saying that the addtl HP comes soley from RPM I have some words of wisdom. Correlation is not Causation.

 

[Snobdds]

I don't know where this notion of more RPM = more power comes from, but the last time I looked at Facebook...it was being repeated as common knowledge on the Massey group.

A perfect case of social media making people dumber instead of smarter.