Solo goood

[Tony Snyder]

The Solo 650; power to weight to price, stands out in the 50cc class.

When I get a new model in, all I want do is gas it up and try it. Over half my stock has been run.

Now I have complimented Solo I'll stick my neck out on something else. You have to take these advertised horsepower ratings with a grain of salt. A 3.0 rated 2149 Jonsered will hold it's own against a 4.0 rated 651 Solo.

I have also noted the saw builders commenting on advertised vs real world horsepower.

We need a Nebraska Tractor Test for chainsaws.

 

[tundraotto]

Originally posted by Tony Snyder

We need a Nebraska Tractor Test for chainsaws.

LOL, I have a feeling its the same test as here, or maybe backwards (pulling vs. pushing). Anyway - as you said there seems to be a gaping lack of empirical data regarding true power output of all the new saws out there. I am certain that all the manufacturers err "on the high side" - but it would be interesting to know who is outright lying.

 

[dbabcock]

I looked at Walker's dyno runs on their site a couple of weeks ago. They're running a calibrated, corrected Land and Sea water brake dyno that I know to be very accurate and nearly foolproof in operation. They have the 346XP at something like 2.2 HP stock, which is very believable. Having said that, they also show a plot of the saw after Walkerizing, that has it at about 4.2 HP! Not only that, but the power peak is at 10,000 RPM! After looking at the stock reading, I was overjoyed that someone had finally put a damper on manufacturers' gross overrating of HP. This zealousness faded quickly when I looked at the modified HP and RPM. I also wish that they'd plot the curves versus RPM rather than the time of the pull. The Land and Sea dynos are both reliable and accurate, so I don't know what to think about Walkers' results.The dyno uses a shear beam load cell to measure torque and has correction lookup tables built into the firmware of the microprocessor that runs it. For 4 grand, you can own one too!

 

[tundraotto]

Yes, walkers has probably the most comprehensive dyno data on saws available that I have seen. I am somewhat sceptical with you Doug, regarding the accuracy of the postings. While I obviously would not accuse a shop with a reputation such as walkers of "doctoring the results", I would certainly love to see an independent study.

What always comes to my mind is the mopeds we used to have when we were growing up. 2 stroke suzukis, 50cc, 0.5hp stock advertised. They all got up to 30mph, after a new 80cc pot and a new pipe they would go over 65mph. I dont see my 2.2hp 136 husky motor moving my butt at 30mph - however it might be geared. I guess like the old riding (lawn) tractors with 4hp that do not bog when the new ex. 17hp tractors bog. Why dont you buy one of those dynos Doug? I know you would tell us the truth! maybe we could put your M5 on it too, and see if Dinan comes up with the goods! LOL

 

[dbabcock]

As a rule of thumb, doubling the speed of a vehicle at relatively low speeds requires at least 4 times the HP. I have a couple of theories about HP and torque versus cutting speed through a log, but I have yet to convince the big guns around here that they hold any water.

I've designed and built several dynos over the years, just for fun. They were made for marine applications such as stern drives and outboards, but the principles are the same. I actually did the prototype design for the front end strain gauge intrumentation amplifier in the original Land and Sea Dynomite a few years ago. Land and Sea is about 15 miles from me. I got to know Bob Bergeron, the founder of the company, quite well during my high performance boating days.

There's a place here in Manchester that has a nice eddy current chassis dyno that I could take the M5 to, but why bother when so many others have done it and the HP and torque are usually within 5%. I visited Steve Dinan last year and we talked about M5 mods, but even though it would be fully warrantied, I think I'll leave well enough alone. 394 HP is close enough to Dinan's 470 HP that it's not worth the $40,000 including S3 mods, or the aggravation, not to mention the lack of return on investment. I'm number one on the list at my dealer for a new E60 M5 when they come out in a couple of years. That one will supposedly have a 550 HP V10 in it. They'll have to do something of this order to compete with the new Mercedes E55 AMG Kompressor (465 HP) and the Audi RS6 (not really a contender, but it does have a 450 HP twin turbo V8 under the hood). I miss the 996 TT.

If I had the time to actually make money with the dyno, I would consider buying it. Unfortunately, like the $2700 Stalker ATS radar gun that I bought several years ago to horse around with, it would probably spend most of its time collecting dust.

I'll see if I can get in touch with John Walker by phone tomorrow.

 

[dbabcock]

I've just been looking over the Walkers 346XP dyno run and there looks to be correlatable truth to it. I have no reason to doubt Walkers evidence and as I said before, these dynos are really accurate. The problem with reading the graph is that RPM is plotted as a dependent variable (along with HP and torque), versus the independant variable, dyno pull time on the X axis. This makes quick comparisons of data cumbersome. HP and torque should be plotted versus RPM. Also notice the "corrected" flag in the upper left corner of the graph. This indicates that temperature, barometric pressure and humidity are used to normalize the torque numbers by the dyno software if these values were put in. What this means is that you could make a run at another time with different atmospheric conditions and the corrected values would be directly comparable.

Nonetheless, the stock 346XP makes it's peak HP of about 2.5 at 10,000 RPM. It's peak torque of about 1.7 ft. lb. occurs at about 7,000 RPM. What I don't understand is why the HP and torque curves don't intersect at 5252 RPM. They should always be equal at this RPM, given the HP=T X RPM/5252. This could be because the throttle was closed near the end of the run, so it's no biggie. The dashed, Walkerized curves show a peak HP of about 3.8 at about 11,000 RPM which seems to make sense, in that the peak power has moved up by 1000 RPM. The peak torque has also moved up to about 2.3 ft. lb. at an also higher RPM of about 8,000. What Walkers has done to make a 50% increase in HP is to build in a lot more torque in the higher RPM range. I find it amazing that they can get this kind of power increase with such a small increase in RPM over stock, but what do I know? Note that the modified torque curve is also much more peaky than the stock one, although this is somewhat deceiving due to the use of two separate RPM curves. A quick check of a couple of points says that the dyno is correct mathematically in deriving HP from torque and RPM.

In regard toward the X Axis, which is in seconds: The sequence of events that happened here is that the dyno is initially set to a minimum load condition at time=0 sec. The saw throttle is then opened fully, then the dyno load (restriction valve for the water) is increased (valve closed) gradually and the computer takes RPM and torque readings over a period of 12 or 18 seconds here. Note that the load was backed off momentarily in the stock test at about t=14 seconds causing the HP and RPM to rise and the torque to fall as they should under this condition.

If I get a chance tomorrow, I'll plot the stock and modified HP and torque curves versus a single RPM scale as they should be and post it up here. The results are at least in the ballpark and seem to indicate that, at least in this case, Husky's 3.4 HP factory claim is very inflated.

Sorry for the verbosity, but I'm sober tonight.

 

[tundraotto]

Originally posted by dbabcock
Sorry for the verbosity, but I'm sober tonight.

well darn, are you still recovering from the other week Very interesting points!! Please, do post your graph with the power and torque in relation to rpm when you get a chance - this is the only way I will be able to really relate to it. Just shows for stock figures though doesn't it...

 

[dbabcock]

Yeah, for sure on the factory BS. All I can say is that if Walkers is getting a 50% increase in HP with what they do, one can be assured that Dennis and Ken are getting substantially more than that. That is, of course, if Walkers tested a "production sample"..lol

 

[tundraotto]

We do know that Den and Ken get more out than walkers. You're right, what is there to say that this is an example of what is put out there to the customer! ???? you are making this issue more complicated by the post Doug!

 

[rbtree]

I'l have to agree with you Tony, my Solo 651SP, even after Greffardizing, doesn't cut the mustard. It is still a bit slower than an 036, and quite a bit slower than my 346XP-G. Just got my Shin. 488 from Dennis today, so will have that to use for comparison also.

 

[dbabcock]

I could always uncomplicate things by making my posts only two or three words long, thus proving to people that I believed stupidity was a virtue.:Monkey:

 

[tony marks]

this all has to do with things way over my head. having said that . it would sure be great to have one that improved a saw to the drgree ,weve heard of.
just think how much faster bucking etc would be. some day.

 

[seesaw]

RB, I'm surprised to hear that about your 651SP-G. I wonder if it had something to do w/some saws responding better to Dennis' mods.
I've run my 651PRO against two different 026PRO's and one 346XP. The Solo out ran all of them. All the saws were stock and we switched up saws to eliminate the difference in operator skill. I know those Stihl and Husky boys had their saws tuned and sharp when they came to "fight it out". Go figure. I need to run against a stock 2149.
I've found my 651PRO (stock) to be somewhere between an 026PRO and an 036PRO. Also between a 346XP and a 357XP.

 

[WOLF_RIVER_MIKE]

making my posts only two or three words long

Your post would probably be deleted.

 

[rbtree]

Hi seesaw. As you know, the SP is rated 0.4 hp less than the Pro. And it is open port design, one reason the modified 346 gains are larger. What will be interesting will be comparing both with the 488-G, also open port, and rated 3.5 hp stock.