HP numbers

Ratchit · Sep 30, 2018

Daag44 said:
Below are the numbers closest to160Hp for the 3 dyno runs done back to back with pipe/muffler temps increasing for each run.

MAX Power Engine RPM changes very little by only 50 rpm.

MAX Power drop changes very little by only 1.4 Hp.

@ 8100 rpm (blue lines). As the pipe/muffler temps increase for each run it causes the engine management to run richer in fuel for a safer running engine.

The Polaris Powertrain engineering team appear to have done an awesome job in Engine Management to bring consistency to a high strung two stroke.

1st run
7750 160.8
7800 162.1
7900 164.6
8000 166.6
8100 167.6 Hp 12.84 a/f 258 scfm 93.5 lbs/hr 0.562 BSFC
8200 167.1
8300 164.7
8350 162.2

2nd run
7850 160.9
7900 162.2
8000 164.8
8100 166.8 Hp 12.45 a/f 253 scfm 94.9 lbs/hr 0.573 BSFC
8150 167.3 Hp 12.39 a/f 255 scfm 96.0 lbs/hr 0.579 BSFC
8200 167.2
8300 165.1
8400 160.9

3rd run
7900 160.7
8000 164.3
8100 166.0 Hp 12.29 a/f 253 scfm 96.0 lbs/hr 0.583 BSFC
8150 166.2 Hp 12.21 a/f 253 scfm 96.5 lbs/hr 0.586 BSFC
8200 165.9
8300 163.8
8350 162.0
8400 159.9

That’s very fat in Polaris land. We had many at dtr and leaned them out to a safe 13.2:1 or 13.5:1 and gained 5-6 hp and 2-4 tq with a pcv.

Look at the test Darrin H from Polaris did @13:1 afr. It was 173 hp.
Lots left on the table here which is good .

m1kflyingtiger · Sep 30, 2018

Is this still on the break in map? I’m thinking if so it could still lean out an but, peak may even move a bit once fully broken in.

damx · Sep 30, 2018

No break in was done on this sled. Also if the ecu is played with, like adding a fuel controller polaris can tell.

m1kflyingtiger · Sep 30, 2018

Do we know what changes in the map once break in is done? I don’t know, but am assuming oil rate slows slightly and fuel map leans out a bit?

Daag44 · Sep 30, 2018

Ratchit said:
That’s very fat in Polaris land. We had many at dtr and leaned them out to a safe 13.2:1 or 13.5:1 and gained 5-6 hp and 2-4 tq with a pcv.

Look at the test Darrin H from Polaris did @13:1 afr. It was 173 hp.
Lots left on the table here which is good .

That was an impressive gain @ 13:1 .

I removed most numbers from my post, so please remove them from your quote. Thanks.

Sheetmetalfab · Sep 30, 2018

kanedog said:
The dyno sheets tell you what rpm your engine makes the most power and hence, what rpm to calibrate for.

If max hp is at 8000 rpm and max torque is also at 8000 rpm, calibrate your sled to run at 8000 rpm.

If your max power is at 8000 and it's only revving to 7800, its losing speed and power and your buddies are beating you and your probs getting stuck more often.

I like to calibrate rpms a little past the hp/tq peak so when the sled encounters a heavy load like spring snow, extra weight, steep hill or warmer weather the rpms will drop down to(but actually up to) peak hp/tq. I hope that makes sense.

There's other small tips but that's the jist of it.

True, honest Dyno sheets are an invaluble tuning tool. It's not possible to tune properly without them.

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You are correct, that’s what dyno graphs are for.

Unfortunately since i’m in Alaska it seems none of the engines i’ve atte To clutch according to DTR have responded in the same way in the field as on his dyno. (Some having peak power higher slightly and some lower)

So i end up ignoring the numbers and doing side by side testing.

RHODESIE · Sep 30, 2018

who provided the sled that is at dynotech?

summ8rmk · Sep 30, 2018

I think its pretty clear, this year, just like 2008, polaris will come out as the most powerfull '800'.

Hopefully that is the only similarity to 2008.... u all know what i am referring to.

kanedog · Sep 30, 2018

Sheetmetalfab said:
You are correct, that’s what dyno graphs are for.
Unfortunately since i’m in Alaska it seems none of the engines i’ve atte To clutch according to DTR have responded in the same way in the field as on his dyno. (Some having peak power higher slightly and some lower)
So i end up ignoring the numbers and doing side by side testing.

Did you use dynotech's pcv maps for your sled?

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dragonfire · Sep 30, 2018

patriot 850

RHODESIE said:
who provided the sled that is at dynotech?

Polaris had a production sled shipped to a dealer near dynotech and they delivered it to DTR. Darren Hedlund provided an ECU that was out of breakin mode. So this sled is making max hp already, Hedlund made 6 more hp leaning it down with his laptop. You need a fuel controller to lean it down. Dynojet does not have a PCV available as of now. Bullydog not available, ECU is different with this motor.

1Mike900 · Sep 30, 2018

Just doing a little math peak torque is still 200 rpm. below peak BHP. Average of the 3 runs is 108.6, not too shabby for a 51 cid. engine. Max. torque 1st run is 109.45 and lowest is 107.86 on the 3rd pull. I would clutch at peak BHP and let pull down to peak torque in heavy load situations! roughly 2.15 ft.lbs. per CID, probably 2.25 to 2.30 with head and twin pipes would be 182 + BHP depending on RPM at which it is most efficient and proper fuel ratio. Hell of a engine polaris produced, gotta give them a high five for that! Hopefully it is as durable as they say? Mike

XCaSSAULT · Sep 30, 2018

dragonfire said:
Polaris had a production sled shipped to a dealer near dynotech and they delivered it to DTR. Darren Hedlund provided an ECU that was out of breakin mode. So this sled is making max hp already, Hedlund made 6 more hp leaning it down with his laptop. You need a fuel controller to lean it down. Dynojet does not have a PCV available as of now. Bullydog not available, ECU is different with this motor.

So motor is not broke-in but is hooked to a ecu that’s running out of break in mode?

If motor is not broke in and rings not seated I’m guessing they probably did a heat soak or two before 1st run. Either way I’d think hp numbers would improve with a couple hundred real world miles?

Sheetmetalfab · Sep 30, 2018

kanedog said:
Did you use dynotech's pcv maps for your sled?

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They were carb sleds.

damx · Sep 30, 2018

Dynotech did 35-40 dyno runs to seat the rings before he posted the 3 back to back runs that are posted on there site.

Daag44 · Sep 30, 2018

XCaSSAULT said:
So motor is not broke-in but is hooked to a ecu that’s running out of break in mode?

If motor is not broke in and rings not seated I’m guessing they probably did a heat soak or two before 1st run. Either way I’d think hp numbers would improve with a couple hundred real world miles?

On an engine or track dyno you can see the Hp rise with each wot run. When the increase tapers off the rings are considered broken-in and you can disable the break-in. Real world miles doesn't load the engine enough to seat the rings as quickly as on a dyno making wot runs, so it takes a lot longer, hence the longer break-in period.

For the heat soak, I don't think it would do anything to prep for a dyno run. The manufacturer has already done this by running the engine up to temp to ensure all the connections have no leaks and to bleed the oil and cooling system.

revrider07 · Sep 30, 2018

Motor is not broke in on 30 to 40 runs. One other thing to consider is oil makes rings seal better. Break a motor in correctly with original Ecm. Not much adds up in this thread that many runs not same ecm. Looks like a troll to me. How long on runs 20 seconds or 30 or what ever post some videos. Any heat sinks on motor who knows.

SRXSRULE · Sep 30, 2018

The way some people "break-in" engines takes for ever, and they can even end up glazing the rings before the take a seat.

When you have a brand new engine on a dyno you can seat the rings very quick.

I buy / dyno a couple brand new crate engines (not 2 strokes) every year and put them on the dyno, run them at 1/2 load at 3500 rpm until engine temp is at 190*. Then we make full, wide open throttle pulls. They will make MAX hp in less then 6 pulls, most of the time its 3-4 pulls.

1Mike900 · Sep 30, 2018

Really would need 3 to 6 engines in sleds mfg'd 1 week apart ea. to really get a base line? They have to be broke in properly as per Polaris recommendations. Then what temp is the outside air they are breathing? 10 -30 deg. will make a difference I would assume unless the ECM re-calculates/Dyno computer etc. does it's job? But otherwise what does it really make on the hill at different temps/humidity etc.... I would not accept a replaced ECM from what is std. equipped and properly broke in? Would like to see what differences between engines in real world assembly/part parameters/clearances/temps etc... could create? I would bet 2% roughly? Otherwise still a nice little compact powerplant!! Mike

kanedog · Sep 30, 2018

Sheetmetalfab said:
They were carb sleds.

Your old.

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Daag44 · Sep 30, 2018

revrider07 said:
Motor is not broke in on 30 to 40 runs. One other thing to consider is oil makes rings seal better. Break a motor in correctly with original Ecm. Not much adds up in this thread that many runs not same ecm. Looks like a troll to me. How long on runs 20 seconds or 30 or what ever post some videos. Any heat sinks on motor who knows.

There are several of us on this thread who are paying members to Dynotech Research, so it would be trolls with an s. Sounds like you have discovered a big conspiracy theory.

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