Another chainsaw dyno...

[MustangMike]

The important part of the curve (9 - 11,000) looked fine, so if it were me I would not be spending the time to change things.

What happens at RPMs above that level is not terribly important, you will not be at those RPMs in the cut.

 

[Red97]

Here are probably my 2 worst/questionable runs to date.

Both ported Makita 7900.

High power one was leaned way out. Seen over 16k

Lower power one was way rich 11.5k

Didn't have the DD screwdriver with us to tune at the same working rpm

Being only 14 seconds of load and plenty of idle time, customer gave the go ahead on the pull for the lean saw.

The ripples on the far right, I know is me on the load valve, trying to get a nice smooth run on the first shot.

May be ok for racing, but I don't think the 16k saw would make it through 1 load of firewood.

I would expect about
.2 max hp drop and about that in ftlb gain with a proper 14k work tune.

Would be close, but without a good work tune in not 100% confident in these numbers. But, from peak power to the low end, looks great.

Lean saw is unlimited coil low top filter.
Rich saw is he filter limited coil.

Believe they are the same porting, and close to same muffler mods.

 

[Red97]

3 cube fun...

Stock cs501p
Ported 550mk2
Ported cs510

Any guesses?

 

[Armbru84]

 

[MustangMike]

Ported 510.

 

[Bigmac]

3 cube fun...

Stock cs501p
Ported 550mk2
Ported cs510

Any guesses?View attachment 246322

550 5.75 hp
Cs501 5 hp
Cs510 5.5 hp

 

[cuinrearview]

550 5.75 hp
Cs501 5 hp
Cs510 5.5 hp

I've ran a 501, might even be this 501. I'm pretty sure the one I ran was bone stock. I would put that one around 3.75.

 

[Bigmac]

I've ran a 501, might even be this 501. I'm pretty sure the one I ran was bone stock. I would put that one around 3.75.

I have never ran any of them...but joe asked...so I guessed! Lol

 

[Red97]

I'll graph them later,

550 gained close to 18% peak to peak. Most gains in the 10k+ range.

 

[Duane(Pa)]

550 pretty much tied 261. And the brand wars rage on

 

[cuinrearview]

I wasn't too far off. I'm gonna claim it was because there was more O2 in the air that day

 

[Johnmn]

I'd kinda like to see a dolmar 421......

 

[cuinrearview]

I'd kinda like to see a dolmar 421......

I have a 420. I can add it to the four I want to take up there.

 

[titanman6100]

What 4 do you want to take to him

 

[cuinrearview]

Bone stock 2171
034S KS
XS365
XS357
Betting the last two have curves so flat they'll make Big Gretch stand up and applaud.

 

[Johnmn]

It would be neat to see some progressive dynoing. Take saw x and dyno it stock then muffler mod, then timing advance, base delete and then porting. A guy could see most bang for the buck that way

 

[MustangMike]

OK, but the order of the upgrades will make a difference! For example, a timing advance will do more after a muff mod, etc. If you do the timing advance first, it may not do any good!

 

[MustangMike]

Well, the ported 510 did not have the most Hp, but it did have the most Torque!!!

 

[Red97]

Well, the ported 510 did not have the most Hp, but it did have the most Torque!!!

Nope,

That is where the graphs pay off.

The 550 was still out performing the 510 in hp/tq at the 510 peak hp rpm.

 

[MustangMike]

OK, I was just going by the pics you posted!