PT425 with Robin Engine?

blackwell · Mar 5, 2004

I understand Power Trac is planing on building some PT425 machines with Robin 25HP engines. My understanding PT tests show the Robin has more torque under load than the Kohler. The Robin 18HP in the PT180 seems to have a lot of torque.
I also noticed PT was testing the Generac 30HP at the 2003 EXPO last fall. They indicated the test would be finished this fall.
Tell us what you think!!

duane · Mar 6, 2004

I like the Robin engine. (I also like the kohler engines). Robin parts and service are not quite as readily available, although I think the Robin network is still growing. A number of PT400 series owners are waiting for a small diesel in lieu of gas.

blackwell · Mar 6, 2004

Duane,
I ask Power Trac about a diesel in the 425 and they stated they have tried Acme, Kubota, Isuzu, and two others. Each required the frame to be lenthened up to 12" and some required wider frame up to 4". The results was a tractor too long or wide to fit the 425 profile and they felt was under powered over priced. They explained that most of these engines were as expensive as the Deutz 2 cyl. 1011 with some being longer and all less powerful than the Deutz. I suppose they are saying we already have the 425 diesel, the PT1430 at 4" wider and 8" longer frame.
Power Trac did say that if I or anyone could find a diesel engine 25hp or greater that was no longer or wider than the Kohler or Robin 25hp they will test it. I cant find one, so get out there and find that diesel that will fit.
EB

bubenberg · Mar 6, 2004

we did that last year. someone in this forum found one but has not been on for a long time. i will do some searching and will let everyone know. i would love to have a diesel, even though i have several commercial z turn mowers with the Kohler engine in it, i am not too fond of them.

MossRoad · Mar 7, 2004

At the time I purchased Power Trac offered the PT418, PT422 and PT425. They had Robin 18 and 22 HP engines and the Kohler Command 25HP engine, respectively. I opted for the Kohler over the Robin for a few reasons.

- I found several Kohler repair shops locally.

- Power Trac suggested the Kohler over the Robin for running the 60" finish mower.

- The Kohler has pressure lubrication. From everything I've read, the Robin has splash lubrication. I don't know if this will make any difference over the life of the engine. Does the Robin have an oil filter? I couldn"t find that information anywhere. EDIT: It has been pointed out that the Robin has pressure lubrication and an oil filter! 

- I never heard of a Robin engine at the time and my dad had good luck with Kohlers.

- At the time, I couldn't find any Robin repair shops locally.

- I really liked that the 400 series Power Tracs fit in the back of my pickup truck with an implement attached. I wanted the largest motor that was available in the 400 series frame. If there would have been a larger one in the same size frame, I would have paid for it. I have read but not investigated that Robin and Kohler measure their torque differently, so it is hard to compare apples to oranges. The 25 HP Kohler lists it's peak torque at 39.9 lbs. ft. (54.1) @ 2800 and the 22 HP Robin is listed as 33.6 lbs. ft. (45.5) @ 2500.

- bla bla bla /forums/images/graemlins/tongue.gif /forums/images/graemlins/smile.gif

If I have any facts incorrect here, someone please correct me. I could have missed something and I'd hate to give out bad information. Thanks, Duane 

With that said, no one here on TBN that owns a Robin seems to be complaining about any lack of power. They really seem to like them. There were some issues about the cold weather starting on the Robin, but apparently Robin has been addressing that to the owner's satisfaction. Jack Robin shows up on the board and now we have a factory rep that checks in once in a while and answers questions. I have yet to meet Joe Kohler /forums/images/graemlins/grin.gif That says something about Robin to me. Someone there is interested in customer feedback. That is really nice and I appreciate it as a consumer.

As for waiting to purchase... all I can say is that every year you wait, you will see improvements. If I had waited a year, I would have gotten a better laid out engine compartment, higher lift capacity and stronger wheel motors on our PT425. But I wouldn't of had my tractor, and I used the heck out of it in that year... I took about 2 years to make up my mind, but eventually took the plunge. I don't regret it one bit. If you can wait, then wait. Power Trac really seems to be developing the 400 series and my guess is it will only get better... more $$$, but probably worth it.

duane · Mar 7, 2004

MossRoad,

Just a clarification. The Robin engine has a pressure lube system with an oil filter.

Duane

MossRoad · Mar 7, 2004

That's good to know. I'll edit my post. Thanks. /forums/images/graemlins/smile.gif

JackRobin · Mar 10, 2004

Hello Guys,

It's really nice to read such good feedback regarding our engines, but I feel obligated to reply regarding complaints about the small Service network that we have/had to offer.

I'd tend to agree that a year or two ago our Service Center network was not as good as it should be. This was mostly caused by poor representation of our company by our distributors, however we've started cracking down on this and by today we have over 4200 Service Centers nationwide.

We're continuing to receive huge amount of new dealer contracts on the daily basis, so with every day our Service network is growing rapidly, and to me as a Tech Support/Warranty rep is a great news since it really hurts me sometimes to tell the customer that he or she has to travel over 30 miles to get their engine serviced.

Now we finally have a dealer locator on our new and improved web site, seems like everything is changing for the better, I'm really happy about it.

Regards,

Jack Gawecki
Robin America, Inc.
Technical Support Dept.
800-277-6246
http://www.robinamerica.com

MossRoad · Mar 11, 2004

Jack,
That is good to know.

For those of you who are interested, here's a link to the dealer locator.

There are now two in my area, one of which is my favorite small engine dealer /forums/images/graemlins/laugh.gif

duane · Mar 15, 2004

Interesting Note:

Worked with a guy over the week-end who owned a woodmizer portable lumber mill. It was powered by a Onan, 2 cyl, 22 Horsepower gas engine. Almost identical to the Robin 22 HP (I think Robin makes the Onan 22). The first engine lasted 4100 hours with only regular maint. He has 1300 hours on the second engine with no problems.

Duane

JackRobin · Mar 15, 2004

We did private label the V-Twin for Onan for the past couple of years.

Jack Gawecki
Robin America, Inc.
Technical Support Dept.

ernemats · Mar 15, 2004

Jack:
What is Robins opinion in using synthetic oil such as amsoil in your 22 hp engine and if ok what weight. My pt422 has about 560 hours on it and does not require any oil added between oil changes. I have thought about trying a synthetic but I am a little hesitant about changing .

Schultz · Mar 16, 2004

Hi Jack
Did you ever get a reply from your engineers about testing the Robin engines to the same specification or testing method as the Kohler? As I said before it could only add power to the 22hp specifications if it were tested the same way as the Kohler.

Tim

MossRoad · Mar 16, 2004

We've heard this subject mentioned before. What are the two methods used by these two companies and how do they differ? Just want to know. /forums/images/graemlins/smile.gif

JackRobin · Mar 16, 2004

( Jack:
What is Robins opinion in using synthetic oil such as amsoil in your 22 hp engine and if ok what weight. My pt422 has about 560 hours on it and does not require any oil added between oil changes. I have thought about trying a synthetic but I am a little hesitant about changing . )

I have been looking for as much info regarding synthetic oil used in our engines as possible. I was always under the impression that synthetic oil would damage the cylinder sleeve in the longer run, however this is not true what so ever.
I have been advised by the japanese engineers that use of synthetic oils in our engines is allowed, as long as the weight is the same as non-detergent oil (10W30-Summer, 5W30-Winter)
They've also said that there is no advantage in using the synthetic oil, the only significant operation difference is noticible in extreme cold conditions such they have in Alaska.

I hope this helps.

Jack Gawecki
Robin America, Inc.
Technical Support Dept.
800-277-6246

Rip · Mar 16, 2004

Different brand and model gas or diesel engines produce their peak rated HP and Torque at different RPMs, so these " @ xxxx RPM" number will most always be different. A chart showing the HP and Torque curves will provide much more usefull information since you can see how the HP and Torque are related over a range of RPMs.

Industrial engines are also often shown with several HP and Torque curves for the same engine with designations such as Intermittant, Continous, and Peak. This information is useful for those applications where the engine is run at near constant speed with constant load or variable load. A hydrostatic machine such as a PT or CUT with HST puts quite different demands on an engine than a gear unit for example.

Advertising literature aimed at non-engineers most often lists the highest value for both HP and Torque that the engineering data will support even if it can be misleading in reallity. Most all engines within a general type class are "tested" in the same manner, it is that the data is often selectively presented in "technical" specs provided to the general public that can cause confusion.

So, look for those curves!

Rip

Schultz · Mar 22, 2004

We've heard this subject mentioned before. What are the two methods used by these two companies and how do they differ? Just want to know.

Kohler's method of testing is J1995, which is SAE Gross Horsepower, below is a definition of the term:
SAE Gross Horsepower
This is the old process that American manufacturers used as a guide for rating their cars. It was in place until 1971. SAE gross also measures horsepower at the flywheel, but with no accessories to bog it down. This is the bare engine with nothing but the absolute essentials attached to it; little more than a carb, fuel pump, oil pump, and water pump. Because the test equipment on the engine is not the same as in SAE net, it is impossible to provide a mathematical calculation between SAE net and SAE gross. As a general rule, however, SAE net tends to be approximately 80% of the value of SAE gross. SAE J245 and J1995 define this measurement.

Koehler's Disclaimer:
Horsepower ratings (shown as gross) are in accordance with Society of Automotive Engineers Small Engine Test Code J1995. Actual engine horsepower is lower and affected by, but not limited to, accessories (air cleaner, exhaust, charging, cooling, fuel pump, etc.), application, engine speed and ambient operating conditions (temperature, humidity and altitude).

I wasn't able to find Kohler's power curves, if anyone has them, please post.

Robin's method of power measurement is SAE Net Horsepower, below is a definition for that:
SAE Net Horsepower
In 1972, American manufacturers phased in SAE net horsepower. This is the standard on which current American ratings are based. This rating is measured at the flywheel, on an engine dyno, but the engine is tested with all accessories installed, including a full exhaust system, all pumps, the alternator, the starter, and emissions controls. Both SAE net and SAE gross horsepower test procedures are documented in Society of Automotive Engineers standard J1349. Because SAE net is so common, this is the standard we will use to compare all others.

Attached is Robin's power curve and disclaimer for the 18-22hp engines. The 22hp is the EH65.

So if you look at the two methods of power measurement the net provides a more realistic number for the end user. As mentioned in the above definitions gross horsepower rating will out do net horsepower by about 20% in typical automotive applications, I don't think that difference is that great in a small air cooled engine, so maybe I'm splitting hairs.

Web site that explains HP and measurement a little more:
HP definitions

Schultz · Mar 22, 2004

Yes RIP your exactly right hp and torque aren't everything and the power curves along with actual usage will complete the story and prove that all engines rated at the same HP are not equal.

Attached is an extreme example of torque rise, serious torque rise....

This is from a Case/Challenger/CAT track type Ag tractor. This engine creates some serious HP/torque just about anywhere you put the RPM, it's HP doesn't peak at peak rpm like the air cooled engines discussed above, it peaks at mid range rpm. So, you won't bog this tractor down if your working it beyond 2000 rpm. A 550 hp race car's engine power curve probably looks like the robin engine curve where it's peak power is developed at peak RPM. Compare these two engines and the only thing they have in common is they both make 550 hp.

Tim