Thinking about getting a Power Addiction head for my SB Assault Just strictly for riding out west. High altitude 8000-12000ft. Want it to be as "plug and play" as possible, Dont want to hassle with race gas, but 91 octane is available at every place we stay. Questions are: Will it be a hands down difference over all my stock friends running their comparable snowmobiles? i know with everything else equal you lose about 3% of your power to every 1000' of altitude due to oxygen levels and so on... What does this head reclaim for you at altitude? Obviously with the pro chassis the numbers dont always mean as much as the feel. Next question is, will i need to reclutch for the extra power? I run what polaris recommends (cant remember right now without digging out the paperwork) as far as clutch springs, and weights, i know i ran the 62's last year and changed both the primary and secondary spring. I would also consider a clutch kit to throw in with the head. I thought the sled ran good last year but want that extra edge. I was still getting beat by a 800 PRO RMK that was clutched awful and never saw above 7700 rpms, while mine was running flawlessly. I have heard great things about the Power Addiction head and would really like your input guys. I know im not going to win against a longer track pro thats stock and running good, but know i can do better.
PA Head Questions for those more experienced than I...
- Thread starter 06IQRMK
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M
add 2 grams to weights.
P
at that altitude brad is going to suggest getting the 13.6 head. you should notice a significant difference at altitude over the stock head. i'm trying the 12.5 head this year and from the numerous people i have talked with who have one i'm expecting an increase in performance (obviously). might have to add some weight, 1-2 grams, and should notice improvements in the low to mid range. i would expect it to be even more pronounced for your situation. as far as getting beat by a 155 pro, i would say that the difference between the skids is almost as much of a disadvantage as the track length. not that means you don't have a nice sled but there is a difference between the two. many have said that they were surprised with how well the 155 pro handled on trail compared to previous sleds. sorry, off topic. good luck
pv
pv
The primary difference that you guys will experience on the head is an increase in initial throttle response. That gradual application of power that the factory EFI map delivers is replaced by a much crisper felt throttle response from off to on and simply compression combustion design. Especially at such high altitudes. The stock compression is ridiculously low for a normally aspirated two stroke at those altitudes especially with 91 oct fuel. My experience is you won't det code a PRO map at 8000 feet even with 87 when properly clutched and set up. Maximum performance for the Polaris system is dead reliant on actual fuel octane versus the air condition of the situation. This is why you will continually get better crisper performance with this head starting at 5500 in normal western winter conditions with 91 oct fuel and it steadily progresses to about 7200 feet and then you'll get benefit in backing out octane and speeding up the burn without det. Obviously you to put in fuel that best correlates with the average of your conditions.
Of the several hundred guys that are requesting info on this application my standard is that it's a huge felt and experienced performance benefit. Once you dial in your clutching to your application and then find the spot on fuel it likes your sled becomes an absolute standout over the stock application at altitude. Head, clutching, track mod, has made the PRO I ride an awesome sled and far superior in performance to the other PRO's that we compare!@
Of the several hundred guys that are requesting info on this application my standard is that it's a huge felt and experienced performance benefit. Once you dial in your clutching to your application and then find the spot on fuel it likes your sled becomes an absolute standout over the stock application at altitude. Head, clutching, track mod, has made the PRO I ride an awesome sled and far superior in performance to the other PRO's that we compare!@
S
I'm getting the 13.1 head. I wish I could get the 13.6 cause we ride normally 6-8000' but during the middle of winter, we can start down at 2000' before we ride up which is way to low for the 13.6. I hope the 13.1 gives me a decent enough improvement over stock that its real noticeable switching back and forth from a stocker
F-Bomb how do you find out what fuel best correlates with your riding conditions? I'm interested because I just got my PA head and can combo last night and was just going to run 91 all the time. Are you saying that there is better performance to be had at high altitude with lower octane fuel or am I not understanding this correctly. I ride 8-11k.
I unload at about 3500. What do you do for the little bit I ride under 4000 to protect the engine from deto? Ride from there to about 7500 most of the time. I will be riding up to 11,000 this year but the bulk of my riding will be from 4 to 8. Do I go for the 13.6 and a couple of gallons of av gas when lower or just do the 13.1 and use non ethanol 92. I never run ethanol gas in my sleds.
I ride all of the time below 5000. We sometimes ride at 2700ft and one of our major starting spots is low. I just take it easy until I get to 5500 and then go crazy. If it codes stop shut it down and it seems to reboot the system and work fine. You guys will just have to experiment with fuel to find your sweet spot.
You just have to test within known safe aspects and go from there. Fuel oct plays a huge performance roll in the current polaris system. Running the dialed in octane rate for your application is paramount for top performance. test test test
You just have to test within known safe aspects and go from there. Fuel oct plays a huge performance roll in the current polaris system. Running the dialed in octane rate for your application is paramount for top performance. test test test
Rob, you don't use the 13.6 head do you? I just got the head and I'm pumped to use it. I'll probably start out with 91 ethanol fuel with the ethanol plug. Then I'll go to using the non-ethanol plug. But I'm at 8,000' + so I think I'm good.
For those flirting with lower elevations, I would throw in a gallon or two of race/av fuel. If that works, run the next tank with a little less and so on. You could always carry a couple gallons of race/av fuel in your extra fuel caddy as insurance.
For those flirting with lower elevations, I would throw in a gallon or two of race/av fuel. If that works, run the next tank with a little less and so on. You could always carry a couple gallons of race/av fuel in your extra fuel caddy as insurance.
DET With 91?
So if im understanding this correctly, above 7200 ft. running the 13.6 head, i will benefit from backing off the octane from 91 a little? If i ride all day from 8-11k mostly, and have no option of lower than 91 on the mountain, will i have problems with DET. I really dont want my motor limping out on me midway through a climb. I understand the atmospheric conditions at the time will also have some affect on performance also. can i expect to have problems if all i have access to is 91? I mean. they dont really make a octane...decreaser? Suppose i could grab a 5 gal jug of 84 to mix and lower at the trailer...
So if im understanding this correctly, above 7200 ft. running the 13.6 head, i will benefit from backing off the octane from 91 a little? If i ride all day from 8-11k mostly, and have no option of lower than 91 on the mountain, will i have problems with DET. I really dont want my motor limping out on me midway through a climb. I understand the atmospheric conditions at the time will also have some affect on performance also. can i expect to have problems if all i have access to is 91? I mean. they dont really make a octane...decreaser? Suppose i could grab a 5 gal jug of 84 to mix and lower at the trailer...
P
if your octane is higher than necessary you won't have det and the sled will not go into limp mode. you just might not have the the absolute top performance from your sled. the lower the octane, as long as you don't get detonation, the better performance you will have, generally. i believe rob was speaking to those looking for the absolute peak performance out of their sled to adjust their fuel octane to the elevation they are riding for the day. that can be slightly dangerous for a motor, but with the sensitivity of the det system on the polaris it will pretty much cover for most octane mistakes. it at least gives you a little more leeway and margin of safety. if you don't want to worry about it just run 91 and you will be fine. for those that want to run on the edge, and for myself, i'm planning on carrying a bottle of the klotz octane booster so if i under estimate or get "bad" gas i can bump the octane enough to cover the issue.
pv
pv
Here's what I don't "get". Not trying to be a smart-a$$ of any sort, just looking for some debate and open dialogue.
Can anyone actually feel the 1-2 hp max difference between having "91" octane vs. "89.5" octance fuel at a specific elevation? I'm highly skeptical.
For my dollars ( and YMMV ) before I flirt with melting a $3k+ engine down to get every last possible half-horsepower out of my engine (which let's be honest, everyone on this thread I'd wager doesn't race and aren't sponsored to offset failures) I'd spend a few hundy on some gearing/clutching. And really, have ANY of us been in a particular jam, where you sat and said
" CRAP!! If only I had 1 or 2 more hp I coulda pulled that chute/sidehilled that gulley/got that extra 3' on the jump so I didn't case it" ?
So I guess I'm really asking why risk such a costly meltdown over what amounts to nothing? I'll be happy running my 92 or 94 (whatever pump/station I pull up to), pulling the rope, adding oil and riding.
Absolutely at some point when wty is off this engine I will be adding a head, most likely Brad's. But can bet it will be safe for the elevation range/octane fuel I run and leaning to the safe side.
Will someone eke me out on the hill? Most likely.. Will I be chuckling to myself when that same someone has burned a piston? Most likely.. Will I be getting him to pay me for a burned 115 belt when I need to tow him out? Most definitely!!
Feel free to flame now lol...
Can anyone actually feel the 1-2 hp max difference between having "91" octane vs. "89.5" octance fuel at a specific elevation? I'm highly skeptical.
For my dollars ( and YMMV ) before I flirt with melting a $3k+ engine down to get every last possible half-horsepower out of my engine (which let's be honest, everyone on this thread I'd wager doesn't race and aren't sponsored to offset failures) I'd spend a few hundy on some gearing/clutching. And really, have ANY of us been in a particular jam, where you sat and said
" CRAP!! If only I had 1 or 2 more hp I coulda pulled that chute/sidehilled that gulley/got that extra 3' on the jump so I didn't case it" ?
So I guess I'm really asking why risk such a costly meltdown over what amounts to nothing? I'll be happy running my 92 or 94 (whatever pump/station I pull up to), pulling the rope, adding oil and riding.
Absolutely at some point when wty is off this engine I will be adding a head, most likely Brad's. But can bet it will be safe for the elevation range/octane fuel I run and leaning to the safe side.
Will someone eke me out on the hill? Most likely.. Will I be chuckling to myself when that same someone has burned a piston? Most likely.. Will I be getting him to pay me for a burned 115 belt when I need to tow him out? Most definitely!!
Feel free to flame now lol...
G-Force I don't think they are talking about the 1-2 HP. I think they are talking about getting lazy throttle response when at elevation using gas with a high octane. You can definitely feel that. Not the loss of power alone, more the loss of snap when you thumb it. Turbos can be even worse from what i have heard. More a bobble or burp and that would be frustrating especially when it's followed by way too much power because you pinned it when it was popping.
MM.. I can sort of see where you're coming from, but on my M7 with RKT and stock head, my '10 Dragon with stock head, my '01 Doo with Eng Tech and stock head.. I can't say I've ever noticed a difference in all out performance/throttle response when filling up with 91 oct at the Shell vs. 94 octane at the Chevron...
hahah perhaps I have too much cushion in the cushion drive on my butt-dyno?:face-icon-small-ton
I get that more (and more effiecient with good chamber design) compression will definitely give you more power and snappier throttle response, no arguement here. But run that same "brand-X" head or setup on 91 vs 87 octane at a particular elevation? Minimal difference at best IMO...
hahah perhaps I have too much cushion in the cushion drive on my butt-dyno?:face-icon-small-ton
I get that more (and more effiecient with good chamber design) compression will definitely give you more power and snappier throttle response, no arguement here. But run that same "brand-X" head or setup on 91 vs 87 octane at a particular elevation? Minimal difference at best IMO...
Octane questions
PV, F-bomb, and everyone else... I appreciate the info! Big help in my decision making. Honestly carrying klotz at all times might be the best, as you never know whats actually in the pumps up there, last year we met a group of guys (7 sleds) that all filled up in the mountains at a big name lodge and 5 of 7 were dead on the trail. Met them back at the bar later, and it turned out they all had a bunch of water in their fuel. Not that klotz can save you from that, but just goes to show things happen... whether its intentional or not. I know the ol' 144" isnt exactly a PRO RMK but its going to have to do me for now. I ride more than half my miles on groomed hard pack trails most of the year. Lived in laramie up until i was 21 so adjusting to flat land has been a little hard for me. Hoping to get a stock 155 setup that someone is swapping out of theirs to stuff in my sled for next year... But that will have to wait for now.
PV, F-bomb, and everyone else... I appreciate the info! Big help in my decision making. Honestly carrying klotz at all times might be the best, as you never know whats actually in the pumps up there, last year we met a group of guys (7 sleds) that all filled up in the mountains at a big name lodge and 5 of 7 were dead on the trail. Met them back at the bar later, and it turned out they all had a bunch of water in their fuel. Not that klotz can save you from that, but just goes to show things happen... whether its intentional or not. I know the ol' 144" isnt exactly a PRO RMK but its going to have to do me for now. I ride more than half my miles on groomed hard pack trails most of the year. Lived in laramie up until i was 21 so adjusting to flat land has been a little hard for me. Hoping to get a stock 155 setup that someone is swapping out of theirs to stuff in my sled for next year... But that will have to wait for now.
Yes I run the 13.6 head on 91 MAVERICK FUEL mostly or what ever gas station I stumble upon with up to 10% eth and without the 5% handicap of the eth plug. Most of my riding starts at 5000 and up. We don't get much snow below that on average but we often have to put in at low elevation and go up from there. As posted before I have ridden this sled aggressively at lower alts and it did fine. BUT...run it as instructed by the vendor! Brad can assist you in your application.
Also FYI G-Force I do ride professionally as my JOB. My sleds generally run good if not great and are used as examples for consumers to test and decide if they would like those performance parts on their sleds. Of the many after market parts that I have been offered to test and use only a portion of those make the grade and get my endorsement. For guys that ride Polaris in the mtns on this particular sled I highly endorse this product.
BugIto you are good to go with 91 to start and then you can either be satisfied with that or you can start to fine tune there after. Obviously not everyone rides the same sled setup exactly in the same manner. Remember it's a combo of all things that makes excellent performance.
Guys I'm not saying DO IT (back off octane) I am saying that my testing shows that you can do this and experience an improvement in performance. Follow the spec's provided by Power Addiction and you'll be fine. For those that want more just know that some of us have experimented beyond and WE know there is performance to be had. THAT IS ALL
Also FYI G-Force I do ride professionally as my JOB. My sleds generally run good if not great and are used as examples for consumers to test and decide if they would like those performance parts on their sleds. Of the many after market parts that I have been offered to test and use only a portion of those make the grade and get my endorsement. For guys that ride Polaris in the mtns on this particular sled I highly endorse this product.
BugIto you are good to go with 91 to start and then you can either be satisfied with that or you can start to fine tune there after. Obviously not everyone rides the same sled setup exactly in the same manner. Remember it's a combo of all things that makes excellent performance.
Guys I'm not saying DO IT (back off octane) I am saying that my testing shows that you can do this and experience an improvement in performance. Follow the spec's provided by Power Addiction and you'll be fine. For those that want more just know that some of us have experimented beyond and WE know there is performance to be had. THAT IS ALL
Thanks guys, this is a good thread...
So basically what I'm getting out of this is instead of having a fixed head and adjusting your octane to compensate for performance due changes in compression caused by changes in altitude, you can run at a fixed fuel (assuming all 91 octane fuel is actually 91 octane and "good fuel" which may or may not be true 100% of the time) and change the head to bring the compression of your cylinder back to where it was and runs optimally on 91 octane correct?
For example if you're running at sea level and your cylinder has 130psi, then at 10000ft your cylinder has 70% of that because thats the pressure difference between the altitudes, so 91psi. If you buy the correct head to bring it back to 130psi then your motor should run like a top just like at sea level. This is the idea right?
So basically what I'm getting out of this is instead of having a fixed head and adjusting your octane to compensate for performance due changes in compression caused by changes in altitude, you can run at a fixed fuel (assuming all 91 octane fuel is actually 91 octane and "good fuel" which may or may not be true 100% of the time) and change the head to bring the compression of your cylinder back to where it was and runs optimally on 91 octane correct?
For example if you're running at sea level and your cylinder has 130psi, then at 10000ft your cylinder has 70% of that because thats the pressure difference between the altitudes, so 91psi. If you buy the correct head to bring it back to 130psi then your motor should run like a top just like at sea level. This is the idea right?
P
yes, mostly. you will get back some of the lost performance by changing out the head but regardless of your compression there is still less oxygen in the air mixture at altitude so you will still have less power. to actually make up the difference you have to do more than just get your compression back up to stock readings. even the turbo guys have to continually increase their boost to achieve the same hp levels at as elevation increases. the loss is even more so on N/A sleds.
g-force, i was pretty much saying what you were. for most i really probably isn't worth the effort to "adjust" the octane based on your elevation. like you and rob said, it is not any one thing that makes the difference, it is a combination of everything and messing with octane is only something to even start considering after everything else is at its peak.
pv
Ya it just seems to me if I try and mess with clutching and something doesn't quite work how I thought, I'm out the cost of a few springs and weights maybe.. If I try and "fine tune" with octane I run the risk of melting and engine, which means pistons and gaskets if lucky, or whole top end if not.
For myself I'll take the safe route and run the best fuel available to me and not try for every single last hp.
Tuned my bike the same way. Ya there's hotter cams/flat top pistons/ported heads to make more power, but for me I'll take "awful close" to the same performance with all the longevity vs. a faster motor that's a ticking time bomb one bad snort of fuel away from demolition.
Again, others like F-Bomb are paid/make a living selling performance products, so of course the state of tune on their personal sleds will be maxed out. Just helps them sell more products. But for the average weekend warrior? Do we REALLY need to worry about that last 1 or 2 hp? Hey some will, that's just the makeup of their personalities, I get that.
Mine is a touch more conservative is all lol. :face-icon-small-ton
Safe riding to everyone this season!!
For myself I'll take the safe route and run the best fuel available to me and not try for every single last hp.
Tuned my bike the same way. Ya there's hotter cams/flat top pistons/ported heads to make more power, but for me I'll take "awful close" to the same performance with all the longevity vs. a faster motor that's a ticking time bomb one bad snort of fuel away from demolition.
Again, others like F-Bomb are paid/make a living selling performance products, so of course the state of tune on their personal sleds will be maxed out. Just helps them sell more products. But for the average weekend warrior? Do we REALLY need to worry about that last 1 or 2 hp? Hey some will, that's just the makeup of their personalities, I get that.
Mine is a touch more conservative is all lol. :face-icon-small-ton
Safe riding to everyone this season!!
O
I agree with your view. How many times have you seen a guy with all the performace mods who can't ride? Most of the time the difference in who is at the top of the mountain, isn't which head is on the engine... but the one above the bars.
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