DynoTech on the Poo 800-Some thoughts

[dynotechjim]

Dtubbs SkiDoo does a similar deal w/ Mach Z low, mid, and high altitude maps changeable by dealers. We find here in the flatlands the mid-altitude map is most desirable for performance riding, because they make more HP.

Do Yamaha or Cat have different cals for altitude? I must ask my Cat friends.

My Chevy truck EFI is dandy at 1000 ft and I don't need a different ECU to drive in CO. Sean Ray is coming to test/ tune Pol SnoX engines this weekend. He runs a calibration dyno at Delphi, and I will ask him how GM can calibrate one ECU for all altitudes and the sled people have trouble doing that.

 

[penguinpoo]

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Dtubbs SkiDoo does a similar deal w/ Mach Z low, mid, and high altitude maps changeable by dealers. We find here in the flatlands the mid-altitude map is most desirable for performance riding, because they make more HP.

Do Yamaha or Cat have different cals for altitude? I must ask my Cat friends.

My Chevy truck EFI is dandy at 1000 ft and I don't need a different ECU to drive in CO. Sean Ray is coming to test/ tune Pol SnoX engines this weekend. He runs a calibration dyno at Delphi, and I will ask him how GM can calibrate one ECU for all altitudes and the sled people have trouble doing that.

I would guess it has to do with automotive engines being a close loop system and snowmobiles an open loop feedback system (no oxygen sensor), but I am very interested to hear more.

 

[Ron]

To clutch for maximum acceleration in good traction conditions, you should be shifting at the engine's HP peak from 400 degrees CS temp (maybe 7600) at clutch engagement to maybe 1250 on the longest run (maybe 8300) (steel turns red at 1250). Knowing exactly where the HP peak occurs makes that possible.

We used to think that we were getting best acceleration shifting at torque peak (a few hundred revs lower than HP peak on a typical 20 second dyno run). But eventually, after 20 years of doing this dyno testing and converting that data to best possible field/ track performance we realized that we were really shifting at cool pipe HP peak.

Jim things are starting to clear up a little here. This is mostly a Western forum and perfromance in snow & climbing is likely the goal for most of us. A drag race clutch setup just doesn't work well for us....the clutch needs to backshift in different snow conditions. Actually most clutching setups are likely the result of trial and error in the field so clutching to torque or HP may be just theory to most of us.

The HP peak RPM is a constantly moving target, moving up and down as pipe gases heat up and cool down. That's why I thought it would be good to create a pipe CS temp/ peak HP RPM chart or map, to be useful for hotrodders to achieve best possible acceleration by measuring their own CS temp.

Now for revelation #2, today we dyno tuned our first Dragon 800 Switchback. This was a whole new ballgame--instead of 110 lb/hr peak HP fuel flow this one was in the mid-nineties lb/hr! With cool coolant to eliminate midrange knock we made exactly the same peak HP as the Dragon 800 SP with PCIII yanking a pile of fuel, 152-153 A/F in the 11's and mid .60s BSFC. According to Polaris-savvy people the Switchback has the same ECU programming as the RMK. If that's the case, then the question that must be answered is how does the Switchback/ RMK ECU calibrate at high altitude? For you mountain guys that information may be provided by Bill and Donavan at Xtreme. And for mountain guys, the fuel flow/ HP/ coolant temp graph I posted here is useless for you, and only needs to be an eye opener for the flatlanders who own D8 SPs.

In order to use the BMP pipe mod on the Switchback, we had to add fuel heavily in the midrange to keep it knock-free, and some on top end, whereas with the SP we were able to reduce fuel flow for max HP. Everyone needs a wideband.

Are you under the assumption that there are different fuel maps for each sled? What if the maps are the same, yet you got different results? Did Hedland tell you that there were different maps? Don't see how they could control mapping by model since some of all models will be used at different altitudes. In 08 the initial map seemed lacking at very low or very high elevations but it was all part of one map, one ECU in the Dragon RMK 8's. Didn't see anything different in heads, pistons or cyclinders. Maybe I missed something but you seem to infer there is a difference in the fuel map of these different models, please elaborate!
Still trying to understand,
Ron

 

[steepndeep]

Switchback vs. SP

Please clarify a little for me but did you say the switchback makes that 152-153 HP and 20 lbs of fuel per hour less with no controller (out of box stock) and leaner in the mid and up top, or that is what you did with the controller on the switchback and it turned out the same as the SP? If thats the case something is different with ecu, pipe, something.

 

[Stewy]

This could be very bad for people who allready purchased and installed new fuel flow w/ the pcIII controller. Jim you really need to clarify this for us.
Thanks

 

[sgrady]

The 800 has 2mm longer stroke than the 700. The monoblock design has a lot of flow up top. The engine pulls better with more R's....that's a fact at 5-8000'.
The leader in aftermarket engine mod for the 800 is SLP....by a huge margin, yet their dyno numbers are not taken seriously??? Like I said to start with....most dyno numbers are almost always from someone wanting to sell you something. Why doesn't SLP claim low numbers and a bigger gain from their mod's? We are all in the same boat here, just some seem real hung up on dyno numbers as the answer. I didn't need a Power Commander on my 08! These discussions can be healthy but they don't prove a thing until dyno tests are supported by real world "in the snow" results.
I'm beginning to see why some mod shops like Carl's Cycle don't play the dyno game. They just get it done in the snow.

Agreed, great post

 

[thefullmonte]

I will admit I'm not very fuel injection savvy, but didn't someone suggest last year that different sled production runs had different injectors installed?
Regardless, this hp comparison could start to explain the variances we are seeing between sled fuel usage, peak rpm and HP.
This thread just keeps getting better and better.

 

[dynotechjim]

our experience is the four 09 D8SP ECUs tested that I know of (two here, one at DynoPort, and one in Quebec) all were low HP, big on fuel flow.

This is our first Switchback and it's definitely a completely different fuel map, but just as sensitive to knock as the SP. Was this an early build, but could it have been a factory goof? Next time Casey comes with his SP, I will get another Switchback ECU to be sure. And if that's lean as the one yesterday, I'll email everyone who has acquired a PCIII to catch any Switchback owners. If they bought a PCIII just to lean down and run powerfully stock I will buy them back. But if they have pipe mods or aftermarket pipes they will need new PCIII SB maps with fuel added instead of being reduced like the SPs require for best HP.

 

[BigBoreManiac]

Jim,

Will you be posting the SB dyno charts on your website? Do you have results for the BMP without PCIII? Thanks.

 

[dynotechjim]

We had to add substantial midrange fuel to get the BMP pipe mod to be happy. I plan to post those preliminary SB numbers on DTR tonight.

 

[Stewy]

Jim, was the fuel flow similiar to what your reprogram was? I do subscribe but I thought I'd ask. Is there any chance cooler air did this or could you call your guy at Polaris to find out what the deal is?
Thanks

 

[klj]

Are you under the assumption that there are different fuel maps for each sled? What if the maps are the same, yet you got different results? Did Hedland tell you that there were different maps? Don't see how they could control mapping by model since some of all models will be used at different altitudes. In 08 the initial map seemed lacking at very low or very high elevations but it was all part of one map, one ECU in the Dragon RMK 8's. Didn't see anything different in heads, pistons or cyclinders. Maybe I missed something but you seem to infer there is a difference in the fuel map of these different models, please elaborate!
Still trying to understand,
Ron

According to SLP the SP, Switchback and RMK all use the same fuel map.

 

[dynotechjim]

I just got an email from a subscriber in Norway, who indicated that they must pay a HP tax on sleds. Anyone heard of that? He said for tax purposes Polaris rates the SP at 140, the RMK at 154. He's got one of each coming this week, will dyno both and report his results.

 

[rab]

I just got an email from a subscriber in Norway, who indicated that they must pay a HP tax on sleds. Anyone heard of that? He said for tax purposes Polaris rates the SP at 140, the RMK at 154. He's got one of each coming this week, will dyno both and report his results.

I wonder if that somehow slipped through the cracks and is affecting the output here in North America

 

[steepndeep]

Dyno tech

Can you switch and run a ecu off of a switchback on the SP please. I am just wondering, there is nothing different in the two motors like compresion,pipe or anything is there? Otherwise the only difference would be the ecu fuel and timing curve. I am going to put a call into polaris about this but couldn't a guy then have the ecu reflashed for a switchback 800 and make everything much better? The other question is have you checked on a regular shorty non SP d8 Ecu or sled to see those results. This is really weird.

 

[Ron]

140 HP is the 700. Anyone holding out hope that any of the Poo 800 engines are different is going to be disappointed. Remember big brother EPA, lots of bucks & time involved for every new map. That's why the new flash for the 08's went international and CA, not USA yet.
Only 2 possibilities, IMO, dyno process or the sled(setup or sensor malfunction).

 

[hilinerider]

polaris poured the fuel to em to make em last for the warranty period, leaned out they make power, flooded they don't, or they might if you can get the pipe up to temp, if there is that much fuel goin through the pipe temp can't rise,

just my 02 from what i've heard here and my own observations,



question is if you can get the air/fuel right to make power will it last?

 

[AKSNOWRIDER]

140 HP is the 700. Anyone holding out hope that any of the Poo 800 engines are different is going to be disappointed. Remember big brother EPA, lots of bucks & time involved for every new map. That's why the new flash for the 08's went international and CA, not USA yet.
Only 2 possibilities, IMO, dyno process or the sled(setup or sensor malfunction).

My guess ron would be the TPS switch..it has a major factor on fuel flow...my dealer used it last year to lean up a pig rich sled, the adjustment was minute to make a big difference.....

 

[shortstop20]

Dtubbs SkiDoo does a similar deal w/ Mach Z low, mid, and high altitude maps changeable by dealers. We find here in the flatlands the mid-altitude map is most desirable for performance riding, because they make more HP.

Do Yamaha or Cat have different cals for altitude? I must ask my Cat friends.

My Chevy truck EFI is dandy at 1000 ft and I don't need a different ECU to drive in CO. Sean Ray is coming to test/ tune Pol SnoX engines this weekend. He runs a calibration dyno at Delphi, and I will ask him how GM can calibrate one ECU for all altitudes and the sled people have trouble doing that.

I think it's just the fact that the EFI on car motors is more sophisticated and they've had many years to fine tune it. 4 strokes running better with rich settings vs. a 2 stroke probably has something to do with it as well. You never hear anybody comment that the EFI mapping is bad on the 4 stroke Yami's. I think Yami has the same EFI calibration whether it be in a short tracker or mountain sled. I'm not sure if Cat has different ECU calibrations depending on altitude or not. Cat had different "coded" injectors on their F-7's. Each injector flows a little different and the ECU is matched to whatever style injector. It's not dependent on altitude though as F7's with all three "codes" can be found all over the flatlands. Polaris' CFI system is supposidly setup this way too?

I would think each fuel map(RMK/Switchback and SP) has to have a "baseline" or something that is uses to calculate the preferred A/F ratio off of. Whether it be at 5000 ft and 10 degrees, etc., etc. You have to have somewhere to start off at. Then the mapping would be changed dynamically(using parameters that are programmed into the ECU) and delivered to the injectors resulting in a different A/F ratio. Maybe Polaris set the SP up with a different baseline and the programming parameters don't reflect what is needed at low elevation for a good A/F ratio, BSCF's, etc? People have had good luck with their RMK's across all ranges of elevations it seems so this is all i can think of at the moment.

On a side note, is the coolant setup any different on the Switchback vs. Dragon SP 121"?

 

[Ron]

Racemen

Junior Member
Join Date: Oct 2008
Location: Quebec
Posts: 6

Problem Dragon 800
After testing 5 Dragons 800 , we discovered a problem with the exhaust valves . The solenoid who controls the valves opening begins to work only at 120 F . So the exhaust valves wont open if the engine doesn't reach this temperature . We have to fine a way so the solenoid open the valves at a lower temperature around 90F . I'm sceptic that the guys were able to get 154 hp with a so cold engine(110-115F).

I don't have the solution but if you find it before me , tell us please so we can modify so we can get the maximum out of it.

If i find the solution before you , I'll tell you pretty fast.

Thanks

Might as well copy this post over here. Hope this isn't true, it's the one thing I "bought" from the DTR tests, glad I saved my stock thermostat!