DynoTech on the Poo 800-Some thoughts
- Thread starter Ron
- Start date
Big John
( QUOTE FROM MY OTHER POST ) The triple will be a great lake racer or hill climber with gobs of track speed.
( if the builder does not try and make it something its not ) and the porting timing is in balance with crankshaft speed. What its never going to be >>> A stump pulling Boondocker. Should be built to run 8800 to 9200 RPM - It is what it is.
The best example I can think of off the top of my head for mountain guys....
The reason Big Johns 925 Ski Doo triple can give 1200 / 1325 Triples all they can handle...............Mind you Johns motor is about 200 hp max, and it runs better then, said 250hp + big bore triples.
Johns motor was built to be all it can be.........The triple part was completely utilized.>>>>>>>> Crankshaft speed >>>> RPM
Where as most of the Big Triples 1200 / 1325's all spin to slow and the triple feature was never utilized to spin fast enough.
A triple spinning to slow can never have enough clutch weight or enough gear in the chain case to off-set what was lost in crankshaft speed.
The same thing goes for the Price 1029 Ultras I use to built >>>> The reason there fast is becasue I spun the piss out of them.
( QUOTE FROM MY OTHER POST ) The triple will be a great lake racer or hill climber with gobs of track speed.
( if the builder does not try and make it something its not ) and the porting timing is in balance with crankshaft speed. What its never going to be >>> A stump pulling Boondocker. Should be built to run 8800 to 9200 RPM - It is what it is.
The best example I can think of off the top of my head for mountain guys....
The reason Big Johns 925 Ski Doo triple can give 1200 / 1325 Triples all they can handle...............Mind you Johns motor is about 200 hp max, and it runs better then, said 250hp + big bore triples.
Johns motor was built to be all it can be.........The triple part was completely utilized.>>>>>>>> Crankshaft speed >>>> RPM
Where as most of the Big Triples 1200 / 1325's all spin to slow and the triple feature was never utilized to spin fast enough.
A triple spinning to slow can never have enough clutch weight or enough gear in the chain case to off-set what was lost in crankshaft speed.
The same thing goes for the Price 1029 Ultras I use to built >>>> The reason there fast is becasue I spun the piss out of them.
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Bb 600
The main reason is how it was set up and tuned from the factory. Remember that the BB 600 twin was the replacement for the XLT piston port triple. It was never intended to be a "hot" motor, it was supposed to be mildly tuned and rider friendly. Now, if you gave it the same level of tuning the small-block 600 has, the results would be surprising. The BB 600 left plenty of performance potential "on the table" while you would be hard-pressed to find 5HP in the current 600 (and it would take careful tuning to even hit 120HP on a dyno run).
The main reason is how it was set up and tuned from the factory. Remember that the BB 600 twin was the replacement for the XLT piston port triple. It was never intended to be a "hot" motor, it was supposed to be mildly tuned and rider friendly. Now, if you gave it the same level of tuning the small-block 600 has, the results would be surprising. The BB 600 left plenty of performance potential "on the table" while you would be hard-pressed to find 5HP in the current 600 (and it would take careful tuning to even hit 120HP on a dyno run).
thanks Ron for getting this thread started. dynotechjim i loved reading the info and replys. And also thank you very much Indy Dan for for the tech info and explainations. I've learned alot from this thread and wish there were more threads with great info like this. They are too far and few between.
R
Ron
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I got my info from Polaris parts online-those were the temps for the PN's. They did show a 120 degree on the older 600, 05 or 06. Not even a PN on my 09 thermostat but it does have the larger bypass hole you mention.
Looks to me like 163 and 155 is the track length, not the opening temperature. Last years 155 and 163 length sleds took different thermostats due to one having a front bypass cooler.
R
Ron
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DTR report
I've been trying to understand dyno numbers and the disparity from different dyno sources. I read the full DynoTech report today and now I'm really confused. Anyone else?
If I read the report correctly the Polaris made 145.4 HP at 7900 RPM running 87 Octane (Ethanol?) fuel with the sled running the Ethanol fuel map. Really not bad performance considering the low grade fuel and rich fuel map. But power fell off rapidly after 7900 - we saw just the opposite in actual "in the snow results" at elevation. At 5-8000' the stock 8's were dogs unless R's were 8100 or more.
SLP shows "adjusted" peak HP of 154.4 at 8400 with non ethanol fuel of 91 octane for the 08 Dragon. Their chart shows higher readings above 7900 vs DTR shows lower readings. SLP is located at 4700' and DTR is about 900'.
Now along comes Xtreme dyno testing at 6500' and they show HP at 110 and adjusted HP of 138.4 for 08 and report similar results for 09. No comment about fuel type, ethanol, non ethanol, or octane rating.
All three are using the same method of adjusting dyno results to sea level, STD. Here we have three reputable firms with totally different results. There was a lot more info and also some dyno testing of AM products, but if there is this much difference with the stock dyno how does one make sense of the results with mods?
Like someone said earlier, you can't ride a dyno.
I've been trying to understand dyno numbers and the disparity from different dyno sources. I read the full DynoTech report today and now I'm really confused. Anyone else?
If I read the report correctly the Polaris made 145.4 HP at 7900 RPM running 87 Octane (Ethanol?) fuel with the sled running the Ethanol fuel map. Really not bad performance considering the low grade fuel and rich fuel map. But power fell off rapidly after 7900 - we saw just the opposite in actual "in the snow results" at elevation. At 5-8000' the stock 8's were dogs unless R's were 8100 or more.
SLP shows "adjusted" peak HP of 154.4 at 8400 with non ethanol fuel of 91 octane for the 08 Dragon. Their chart shows higher readings above 7900 vs DTR shows lower readings. SLP is located at 4700' and DTR is about 900'.
Now along comes Xtreme dyno testing at 6500' and they show HP at 110 and adjusted HP of 138.4 for 08 and report similar results for 09. No comment about fuel type, ethanol, non ethanol, or octane rating.
All three are using the same method of adjusting dyno results to sea level, STD. Here we have three reputable firms with totally different results. There was a lot more info and also some dyno testing of AM products, but if there is this much difference with the stock dyno how does one make sense of the results with mods?
Like someone said earlier, you can't ride a dyno.
Ron something we used to do on our mud racers since we had to run coolant was to run a restrictor in place of the stat..it slows the coolant flow enough to allow it to absorb cylinder wall heat but flows freely enough to keep temps down..only problem I would see on a sled is you could conceiveably run into a cold seize in the right conditions..( long down hill off the power using engine braking followed by a uphill/full throttle carve....on a cold -0* day.)
Rich ( DYNOPORT ) will be playing around with temps - keeping updated over in the Fusion/IQ forum on HCS
they pulled 153HP today running 93 octane with the premium wires PLUGGED IN setting at approx 94-95 degree's with Power Commander
pulled 155-157 with SLP single and y pipe with stock silencer and Power Commander , testing tomorrow with SLP silencer added
they pulled 153HP today running 93 octane with the premium wires PLUGGED IN setting at approx 94-95 degree's with Power Commander
pulled 155-157 with SLP single and y pipe with stock silencer and Power Commander , testing tomorrow with SLP silencer added
Aside from the disparity in ECU mapping and sensitivity to detonation between the early 800's (slp test) and dynotech test (2009 mapping) , I believe two factors answer your question.
(1 )Pipe heat and (2)elevation of the dyno.
The dyno is probably not building pipe heat the way that we do in mountain riding. Look at the rpm where peak power is made. It is low compared to the rpm where you know you need to clutch for best performance. Hotter pipe means peak torque occurs at higher rpm. Fuel mixture correction from high to low elevation probably isn't perfect either, leading to changes in pipe temperature. Leaner mixture makes pipe hotter, again leading to peak torque ocurring at a higher rpm.
Elevation of the dyno. Yes, you can apply the correction factor, but this does not take into consideration that a pipe built for sea level is not going to perform the same as one built for higher elevation.
(1 )Pipe heat and (2)elevation of the dyno.
The dyno is probably not building pipe heat the way that we do in mountain riding. Look at the rpm where peak power is made. It is low compared to the rpm where you know you need to clutch for best performance. Hotter pipe means peak torque occurs at higher rpm. Fuel mixture correction from high to low elevation probably isn't perfect either, leading to changes in pipe temperature. Leaner mixture makes pipe hotter, again leading to peak torque ocurring at a higher rpm.
Elevation of the dyno. Yes, you can apply the correction factor, but this does not take into consideration that a pipe built for sea level is not going to perform the same as one built for higher elevation.
Just takes good premium fuel and someone else that knows his stuff to pull a good dyno run and show the real HP of any sled, way to go Rich at DP. Now DTR and SWR just need to stfu and keep their bad fuel and bashing dyno runs that turned alot of potential customers away from the 800 from the BS hype.
R
Ron
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It seems you are correct on the pipe heat. I looked back at DynoTech's report and he tested with 20-30 second runs with pipe temp beginning at 800 degrees and ending at pipe temp of 1000+. It's my understanding that the pipe sensor is looking for 1200 degrees, probably a normal temp riding a sled in the snow.
Write up is also incorrect on the ethanol fuel jumpers..."the connected ethanol wires apparently add 5% fuel flow during cold weather"...for ethanol the wires are unplugged adding fuel flow, probably just written up wrong. You plug them in for non ethanol fuel for best performance.
So if you aren't running the dyno tests with a hot pipe is it fair to assume that you are reporting low HP, wrong peak HP, wrong torque curve, & testing AM pipes goes out the window? Trying to clutch to these results won't work either. DTR Jim, how about your thoughts.
Also wonder if the engine wasn't developed for elevation more than the flatland? Introduced, tuned and tested at elevation & has good compression, hmmm?
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D
dynotechjim
Well-known member
When we did our dyno testing it was in the mid fifties F, and the enthanol wires had no measurable effect on fuel flow, plugged or unplugged. According to our Polaris tech support, with the temp we were testing at we were in the lean mode. In cold winter weather it's 5% added or thereabouts in ethanol mode. I think I had that backwards. We ran the pipe center section temp as hot as 1100-1150 degrees F. The question is how hot is everyone's pipe center section temp when you ride? Everyone who is into performance sledding would benefit from knowing that, and knowing where his HP peaks at from cool, on takeoff to as hot as it ever gets on your longest period at WOT.
During dyno testing we have the advantage of holding the engine WOT steady state at lower revs where leaner 13/1 A/F ratio occurrs, allowing CS temp to climb quickly to 850ish to begin each test, with the idea of being well over 1000 at peak revs which was our target.
From our charts you can see how stock fuel flow peaks at 113 lb/hr and close to 10/1 around the torque peak creating that camel-hump in the HP curve, and the higher you rev it the lower the fuel flow drops. The PCIII map we created flattens out the fuel curve, and drops it at peak HP to below 100 lb/hr, then remains fairly flat beyond that. By eliminating that huge pile of fuel, we get the pipe hotter, quicker which combined with two points leaner A/F ratio adds 5-10 HP depending on pipe temp that we're operating at.
Next time we test Casey's stocker I'll try to put together a chart of just where peak HP occurs, from 500 to 1200 deg F (I don't think it's possible to exceed 1200 in the field, even mountain climbing). Then all you guys can know exactly where to clutch to for max HP in any condition. The change in the speed of sound has nothing to do with altitude, just temperature so the CS temp/ HP peak RPM chart we create here at 1000 ft should apply at 10,000.
As Donovan suggests, and as you see in our test data, we surely make more HP at lower coolant/ engine temps (100 vs 125) but the main benefit of 100deg F coolant for low altitude riders is avoiding detonation, keeping peak combustion chamber temps low enough to prevent the formation of those nasty active radicals even with leaner more powerful A/F ratio that we created with the PCIII. And this also prevents the very protective 09 ECU from sensing the slightest knock, pulling timing, adding fuel and further reducing HP.
For now, the only ones I know of who have ridden hard in the field while measuring the pipe CS is Bill and Donovan from Xtreme, on last years RMK800s. No sense guessing and arguing about what it is, just measure it and hopefully the temp/ HP peak RPM data we create will be extremely useful.
During dyno testing we have the advantage of holding the engine WOT steady state at lower revs where leaner 13/1 A/F ratio occurrs, allowing CS temp to climb quickly to 850ish to begin each test, with the idea of being well over 1000 at peak revs which was our target.
From our charts you can see how stock fuel flow peaks at 113 lb/hr and close to 10/1 around the torque peak creating that camel-hump in the HP curve, and the higher you rev it the lower the fuel flow drops. The PCIII map we created flattens out the fuel curve, and drops it at peak HP to below 100 lb/hr, then remains fairly flat beyond that. By eliminating that huge pile of fuel, we get the pipe hotter, quicker which combined with two points leaner A/F ratio adds 5-10 HP depending on pipe temp that we're operating at.
Next time we test Casey's stocker I'll try to put together a chart of just where peak HP occurs, from 500 to 1200 deg F (I don't think it's possible to exceed 1200 in the field, even mountain climbing). Then all you guys can know exactly where to clutch to for max HP in any condition. The change in the speed of sound has nothing to do with altitude, just temperature so the CS temp/ HP peak RPM chart we create here at 1000 ft should apply at 10,000.
As Donovan suggests, and as you see in our test data, we surely make more HP at lower coolant/ engine temps (100 vs 125) but the main benefit of 100deg F coolant for low altitude riders is avoiding detonation, keeping peak combustion chamber temps low enough to prevent the formation of those nasty active radicals even with leaner more powerful A/F ratio that we created with the PCIII. And this also prevents the very protective 09 ECU from sensing the slightest knock, pulling timing, adding fuel and further reducing HP.
For now, the only ones I know of who have ridden hard in the field while measuring the pipe CS is Bill and Donovan from Xtreme, on last years RMK800s. No sense guessing and arguing about what it is, just measure it and hopefully the temp/ HP peak RPM data we create will be extremely useful.
The speed of sound may not change, but the density of air changes with altitude and therefore the need for low elevation pipes and high elevation pipes, if you want the best performance.
Hmmm, I have a slp ported carbed 797 in a ves case with two separate cylinders, and a big block struthers ported 800. I'll keep my small block.
I created a thread on hcs on my thoughs on cooling the 800 down some that does not require removing the t-stat or hose reconfigure. It's along the lines of the washes in place of the t-stat that was talked about in this thread. Read it and let me know what you think or have another idea.
http://www.hardcoresledder.com/forums/index.php?showtopic=356243
http://www.hardcoresledder.com/forums/index.php?showtopic=356243
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