Dyno tested......... Mastermind ported 660 vs Stock 660 vs Dual port 660

Using two saws is problematic to good numbers. I realize it is hard/more costly to do it any other way but there is a standard deviation in terms of power from stock saw to stock saw. The Nissan GTR engines are built in a clean room environment and individually dynoed and there is a 10% deviation in HP in those engines. Add into that wear and tear and your numbers could possibly be even more skewed. I am not saying that is the case or the numbers are not useful but two saws opens the door.

Now if Chad sent you his 660 and he put that on the dyno you would have unquestionable numbers. But it would need to just be ported no parts replaced.

I am not saying I would expect a big change but it would represent a true incremental advance.

 

Please reread my post, I think you missed a number of important qualifications to my statements.

Please correct me if I am wrong but the dual port muffler was standard equipment on the 660 in Europe and if so Stihl would have tested the HP on the saw in that configuration. I think you can throw out the lower single port muffler numbers when comparing the stated and actual HP. That gets you to slightly more than .5 hp difference.

You are correct about weather conditions and such but would seem to be doing so only to be pedantic.

 

Yep.......I believe you are spot on.

Something else to consider is the differences in cylinders. I've seen 6 - 8 different cylinders for the 066/660 in respect to port timing.

 

Randy, after you received my 660 I remember you telling me mine had a "good jug".

 

Yes......I was able to get the exhaust down without the intake going way too far.

It should get decent fuel mileage......at least for a 660.

 

Heh, heh, Ron has good jugs, heh, heh

 

I believe I read where you have a formula that you have worked up for every saw and once you have settled on what seems to work best you don't stray from it. Does the difference in port timing mean you have 6-8 formulas for the 066/660? Even if it is just tweeking.

Have you seen another production saw with that many changes during its production lifespan in terms of cylinders?

I know this would be speculation; but do you think the changes were just to make governments happy or was it to reduce breakage problems without a major rework to the design or maybe both? Like when Dodge put the Cummins in its truck for the first time and there were significant driveline problems their response was to detune the engine by something like 100 HP.

 

They have used three different cylinder manufacturers over the years, so that is some of it. They have also reworked the jug to help with EPA emissions.

They aren't worried that the saw will be so powerful that parts breakage will be an issue. The ones that I turn the wick way up on last just fine.

I have a single "recipe" for the 066/660. Some jugs allow me to hit it better than others though.

 

Fascinating, do you or someone else have production date ranges for the good ones? Or is it as simple as older is better. Or so screwy you don't know till you look.

 

Non decomp jugs are good usually. Mahle or the early Kolbenschmidt that were on the flat tops are good. I can't remember who made the red light cylinders but they'll have a thinner base compared to the later ones.

 

That last one there.

 

The stock 660 I tested is new. Purchased a couple months ago and has had more than three gallons run through it.

Let me clear this up. I ran lots of saws on this dyno and have come up with a number as far as a loss from the slight drag of the dyno components. I multiply all the HP #s by that # to put the HP #s more realistic. I have no idea how Stihl dyno tests there saws but Im thinking there a bit inflated.
I built the dyno to pick up gains and losses. The true HP isn't as important to me as the increase. I tested two 660's and found both to be low in HP compared to what Stihl advertised. All other saws have come pretty close to Stihls #'s advertised #'s after I do the loss math.

 

10% on a six banger maybe but not on a chainsaw that was built the same time as the other. I've been impressed at how close saws timing #s are to the other. The 660 may have many changes but most likely not these two. Maybe Randy has the stock timing #s for Ronn's 660. My 660
Is
Ex...95° atdc
Tr...123° atdc
In...80° btdc
Bd...28°
Squish...038"

 

I think you intake number is off Chad......should be 80*

 

I had 100 aBdc or 80 Btdc
Tomato.... Tomoto?