mower advice please (Briggs&Stratton power charts)

[efc1978]

Hello,
Looking to buy a lawnmower, 18" push mower with 4 blades, catching grass about 1" to 1.5" (some areas grow longer than others), about 1 hour job in Melbourne.
I have attached a power chart of Briggs and Stratton 625EX / 150cc and also 675EX / 190cc, I believe the 625EX is OHV and 675EX is not OHV, I don't know much about engines and I can see the power charts show peak torque at a different RPM level for each.
Would there really be much difference in cutting torque between these 2 mowers?
I actually like the look and colour of the mower with the 625EX engine better, but that's irrelevant when it comes to getting the job done!, would it really be worthwhile getting the 675EX?, or should the 625EX be enough for the job?

Thanks in advance for any advice.

Here's the 2 power charts:

625EX
http://postimg.org/image/9xa32ki8d/

675EX
http://postimg.org/image/vzzip56xd/

 

[jhellwig]

The 625ex is an ohv engine that replaces the old Briggs flathead engine with the vacuum lift carb. The 675ex is a flathead and is what they are calling the quantum engines now and is a tank of an engine.

Look at the power curves and you will see that the higher displacement has a flater power curve. It is going to go through thick grass easier but be heavier.

 

[JR]

The flatheads make torque with a diesel loco. They make a nice flat power curve, they can lug and still make grunt power. The ohv make there power late in the rpm range, they drop in rpm's and they don't have any grunt.


-harvey

 

[Rolla07]

If you dont let your grass get too tall and thick the 150cc should be plenty. I have an old used 140cc and it cuts very well with ease unless grass gets really tall and thick. Make sure to keep the mower blade nice and sharpened regularly and you should be fine with the 150 cc.

 

[mech_tech]

Something to remember, the torque curves show up to a governed speed of 3600 rpm, and if I remember correctly most engines on push mowers run somewhere around 2200 to 2600 rpm...but I could be wrong on the exact number. I have the 675 on a 21' push mower and I surely notice the weight in the thick grass. I believe these engines are overkill for anything but a large self propelled mower. If I had to do it over, I would be looking for something lighter.

 

[efc1978]

Thanks for the info and opinions!
Going by the power chart for the 625EX what horsepower would that equal?
The website says 8.5Nm / 150cc.
Thanks again!

 

[efc1978]

Well that's interesting, unless I got something wrong....
If you read the fine print at the bottom of those power charts I posted from the Briggs and Stratton website, it says HP is measured at 3600 RPM, so looking at the charts I posted the 625EX 8.5Nm 150cc is a bit above 7.6Nm at 3600, and the 675EX 9.1Nm 190cc is about 7.8Nm at 3600, so when I used the converter at the below link to convert 7.6Nm and 7.8Nm at 3600 RPM to HP the 625EX is 3.84 HP and the 675EX is 3.94 HP, just 1 tenth of a % difference between the 2, according to the B&S website if I correctly understood......
http://www.wentec.com/unipower/calculators/power_torque.asp

 

[efc1978]

Originally Posted By: efc1978
Well that's interesting, unless I got something wrong....
If you read the fine print at the bottom of those power charts I posted from the Briggs and Stratton website, it says HP is measured at 3600 RPM, so looking at the charts I posted the 625EX 8.5Nm 150cc is a bit above 7.6Nm at 3600, and the 675EX 9.1Nm 190cc is about 7.8Nm at 3600, so when I used the converter at the below link to convert 7.6Nm and 7.8Nm at 3600 RPM to HP the 625EX is 3.84 HP and the 675EX is 3.94 HP, just 1 tenth of a % difference between the 2, according to the B&S website if I correctly understood......
http://www.wentec.com/unipower/calculators/power_torque.asp


Sorry I mean 1 tenth of 1 horsepower difference, not 1 tenth of a % difference.

 

[efc1978]

How would the torque compare of the Briggs and Stratton 625EX / 8.5Nm / OHV 150cc compared to a Power Torque 160cc from a 1994 Victa Mustang?
Anyone know what the Nm for the Power Torque would be on the same scale as the B&S being 8.5Nm? Would the RPM at peak torque be about the same?
Basically just wanting to compare old engine to new engine..., is either engine going to be superior when it comes to patches of 2 inch wet grass?
Thanks for any info!

 

[efc1978]

Originally Posted By: efc1978
How would the torque compare of the Briggs and Stratton 625EX / 8.5Nm / OHV 150cc compared to a Power Torque 160cc from a 1994 Victa Mustang?
Anyone know what the Nm for the Power Torque would be on the same scale as the B&S being 8.5Nm? Would the RPM at peak torque be about the same?
Basically just wanting to compare old engine to new engine..., is either engine going to be superior when it comes to patches of 2 inch wet grass?
Thanks for any info!

Sorry tried to delete this...