dolmar?

[glens]

Originally posted by bwalker
How does a decomp valve lessin HP if its not leaking?

I can't answer that, I'm only observating that they're providing data and qualifying it by the exclusion statement.  Maybe while they can be a bit creative with the weight claims, they have tighter regulation on the power-production statements?  I'd assume they're publishing the most attractive power figure they can muster.

What sprocket did the 7900 have?

Can't say for sure.  Assume it was a 7 pin, although my feeling is that the particular saw would fall on it's face with an 8 pin if it were wearing a 7.  So maybe it was an 8...  My saw was pulling 8 drivers each time around.

Also who built the saw?

I don't want to disparage anyone here, and I'll talk with the builder about it before naming him because that's certainly not where I'm trying to go with this.  He's relatively famous around here, but it may have been one of his early jobs; and it may have suffered a bit in the mean-time.  I recall there was somewhere in the vicinity of 20% difference in cutting times.  I filed both chains myself and I wasn't unfair about it so I'm quite confident that wasn't the basis for such difference.

The builder was not present, and this was an incidental, informal test during a removal.

Again, I'm impressed with the Dolmar, and if I didn't already have the (that particular?) 066 I'd certainly be in the market for a red saw.  Don't forget that this was in a 25" bar-full of fresh and sound maple.  Also, my saw is wearing a magnum front cover and it must have been a faulty muffler because the baffle basket just fell out one day...

Glen

 

[RandD]

Originally posted by glens
I apologize.  I'm only going by the specs available here in the US, which differ, evidently, from yours. ...

Hi glen,

in the US is a difference in calculating horsepower from the measured kilowatt. Determining is the measured power output in kilowatt. In Europe the horsepower ist calculated by multiplication th kW with 1,36. In the US the factor is 1,34.

Seems that the guys from stihl took the european values for horsepower.

Here are the official specs for the MS460 from the german website (www.stihl.de):

(diplacement) Hubraum 76,5 cm³
(power output) Leistung 4,4/6,0 kW/PS
(Weight ower head) Gewicht ohne Schiene/Kette 6,5 kg
(power to weigth ratio) Leistungsgewicht 1,5 kg/kW


and for the PS-7900 (www.dolmar.de):

(diplacement) Hubraum (cm3): 79
(power output) Leistung (kW): 4,6
(Weight ower head) Motorgewicht (kg): 6,3
(power to weigth ratio) Leistungsgewicht (kg/kW): 1,37

 

[RandD]

Originally posted by glens
....
Do you know exactly what it is they remove from the saw to achieve the 13.6 lb dry weight?  We weighed one on a digital scale and got 14.4 lb and I believe removing the clutch cover was too much; taking it below 13.6 lb.
...
Glen [/B]

It's the weight of the dry(!) motorhead without spike and bar.

Originally posted by glens
....
Do you have a ready reference to the EWG standards?
...
Glen [/B]

The EWG-Standard defines standard conditions during the measurement on the test bench. It takes the influence of temperature, air pressure and humdity on the power output into account.

It's the same standard, which is used in the automotive industrie.

 

[glens]

It's the weight of the dry(!) motorhead without spike and bar.

Yeah, we had a brand-new, fresh out of the box powerhead with no bar/chain.&nbsp; 14.4 lb <i>dry</i> for the 7900.&nbsp; We did not remove the bucking spikes from the saw/cover but I have a hard time believing they're .4 lb each on average, even though they resemble Klingon batleths.&nbsp; I remember weighing two Stihls that evening, an MS460 and an MS660, both brand new, dry, with spikes and all, just no bar/chain, and they both weighed as claimed (actually the 660 was 0.1 lb less than rated).

The specs I used in my calculations are from the US publications.&nbsp; The German "horsepower" (PS) is a metric equivalent to the actual horsepower and is remarkably close in correlation, though providing slightly larger figures.&nbsp; The Stihl figures translate back and forth between kW and HP quite well.&nbsp; The Dolmar figures do not give the kW rating, so there's no way to tell if they're using HP or PS in their publication.

The reason I asked about the standards you referred to is because I'm curious.&nbsp; I doubt anybody could buy a saw and, placing it on a dyno, measure the same amount of power as these manufacturers are claiming.&nbsp; I was just wondering if you had any inside information about exactly what is is they're doing.

Glen

 

[RandD]

Originally posted by glens
... The Dolmar figures do not give the kW rating, so there's no way to tell if they're using HP or PS in their publication.

The reason I asked about the standards you referred to is because I'm curious.&nbsp; I doubt anybody could buy a saw and, placing it on a dyno, measure the same amount of power as these manufacturers are claiming.&nbsp; I was just wondering if you had any inside information about exactly what is is they're doing.

Glen

The power output in the catloque is 4,6 kW / 6,3 hp.

Generally the power output of every product should be after breakin time within +/-5% of the rated value.

The Dolmar PS-7900 achieved in the Test carried out by the DLG (http://www.dlg-test.de/pbdocs/5050.pdf) with 4,7 kW more than the rated power output.

 

[RandD]

Dyno testing

Originally posted by glens
... The Dolmar figures do not give the kW rating, so there's no way to tell if they're using HP or PS in their publication.

The reason I asked about the standards you referred to is because I'm curious.&nbsp; I doubt anybody could buy a saw and, placing it on a dyno, measure the same amount of power as these manufacturers are claiming.&nbsp; I was just wondering if you had any inside information about exactly what is is they're doing.

Glen

The power output in the catloque is 4,6 kW / 6,3 hp.

Generally the power output of every product should be after breakin time within +/-5% of the rated value.

The Dolmar PS-7900 achieved in the test carried out by the DLG (http://www.dlg-test.de/pbdocs/5050.pdf) with 4,7 kW even more than the rated power output.

 

[Dolmar_Tech_Mgr]

Power Rating/BHP : 4.6kW/6.3 This Data is pulled straight off of the Dolmar USA website for the PS7900. We always list the kW first followed by the PS. The kW factor comes from the factory and the PS factor is calculated.

 

[Saw Man]

Perhaps some readers don't know that power ratings can be different due to final shipping & usage destination.

Some countries have different specifications, thus mufflers, and carbureators, etc. can be different.
All of which will affect performance.

When doing 'on paper' comparisons best to do it with current sales literature for that country, and even check publishing dates.


Quite sometime ago when I started to post info on the new Dolmar "Bubble Saws", there was quite a few guys taking me to task over the weight, and power. A "Search" should bring up a couple different Topics, and lots, and lots of posts on Dolmar.

Just a side bar on weight, some companies that suffer from,
"Pinnochioitis" (remember why Pinochios nose grew) started to weigh equipment like string trimmers w/o the line head, guard, strap, and even the strap bracket.

Chain saws w/o clutch cover, w/o bucking spikes. One big 'orange' company even had to remove the right front anti vibe spring because it's attached to the bucking spike to make advertised weight

That made their models falsely appear lighter.
Deliberate misleading. Personally think that WILLFULL misleading is an advertising lie, and goes to company marketing ethics.

Now other companies have to follow suit to level the playing field, but only a few list the true "dry weight", and the "stripped weight" with printing large or easy enough to read.

Which they all listed exact 'dry weight' w/all normal items included.

 

[bwalker]

I don't want to disparage anyone here, and I'll talk with the builder about

Sounds like a case of another botched 7900 mod job. I assure you my stock 7900 will pull a 8 pin all day long and This is in real hardwood, not 8" basswood.

 

[glens]

Originally posted by Dolmar_Tech_Mgr
Power Rating/BHP : 4.6kW/6.3 This Data is pulled straight off of the Dolmar USA website for the PS7900. We always list the kW first followed by the PS. The kW factor comes from the factory and the PS factor is calculated.

Hi Jeff. [edit: sorry about that, I mean Terry!]

You've got it right when you say the 6.3 is PS; but their US website says it's BHP, which value for 4600W is 6.17 HP (the seven is rounded up from a 6 followed by an 8).&nbsp; The page of the manual I posted a partial image of shows 6.2 which is probably okay to say based on 4600 Watts.&nbsp; Hell, the 4.6 kW is probably rounded up from 4550 Watts; I doubt it's an exact figure or rounded down from 4649!

I really don't want to quibble over a couple tenths of a HP.&nbsp; I don't mind saying that the Dolmar 7900 and Stihl MS460 are comparable saws that would probably make within a paint can or two worth of chips difference in a work day (as a guess).&nbsp; I guess what gets my goat about all this (beyond marketeering in general) is that the comparisons seem to be always set on saws out of the class.&nbsp; If you need a saw that really does what the 066 will, you won't be happy in the long run with the 7900 unless you've got a slightly bad back and have some time to spare.&nbsp; That's all I'm really trying to say, I guess.&nbsp; (I'm not forgetting that Ed has posted some eye-opening times as compared to the 066 here in the past)

Glen

 

[glens]

Originally posted by bwalker

I don't want to disparage anyone here, and I'll talk with the builder about

Sounds like a case of another botched 7900 mod job. I assure you my stock 7900 will pull a 8 pin all day long and This is in real hardwood, not 8" basswood.

I'm sorry for even bringing this up.&nbsp; The owner of the saw is quite happy with it and I believe has plans to get another like it.&nbsp; I like it, too, except for the two factors of not using the same bars I currently have and the nose-heavier-ness-than-I'm-used-to handling characteristics.

Glen

 

[geofore]

nose heavier

For about $180 you can get the new 32" or 36" Oregon bar with the alloy insert that is lighter than the Oregon 24" Power Match bar without the insert. For those of us with a bad back, we would like to see a light weight Oregon bar in the 24" range not just the 32" & 36" bars. I did ask the Oregon rep at the Pittsburgh show to let me know when they come out with the light bar in 24".

 

[ehp]

Come on now Ben , of all people here you should know that in 8 inch basswood you use a 9 pin on a stock 7900, lol

 

[166]

The weight of a Dolmar PS-7900 Setup 1 of 3

Here is a picture of a 7900 with a 20" Bar & Chain

This saw weighs 18 Lbs or 8.2 KG

 

[166]

The weight of a Dolmar PS-7900 Setup 2 of 3

Here is a picture of a 7900 no B&C with side cover

This saw weighs 14.8 Lbs or 6.7 KG

 

[166]

The weight of a Dolmar PS-7900 Setup 3 of 3

Here is a picture of a 7900 with no side cover

This saw weighs 13.8 Lbs or 6.3 KG


The 7900's sold in the us are listed at 13.8 Lbs
The 7900's sold in Germany are listed at 13.6 Lbs

The difference between the German Spec & the US Spec is the Spike Bars.

The US Spec Saws get two large spike bars
The German Spec gets one small spike bar

Maybe this will make it clear how these saws are weighed!

 

[ehp]

I also weighted a 7900 with spikes on it at 2 places to day and both scales said the same 6.630 kg's, now the scales are legal store scales so are very accurate. the saw was used a bit and may of had a little dirt in it but pretty clean

 

[166]

I used a Digital Scale used for UPS shipments

 

[ehp]

the 2 i used were the post office and the meat counter at Eagle Lake food town store , both said the same 6.630 kg's

 

[166]

EHP,

Did you have the side cover on or off to get that weight?