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XP big bores - lets compare

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trinitypowder

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Nov 26, 2007
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I've been absent for a few months and can't believe this thread is still cooking!!!! Everybody that's on the fence quit talking and pony up the dough for and 860 so we can move on:rolleyes:
 
D
Jul 4, 2001
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Central Alberta, Canada
Recieved my top end back from Big John the other day....hmmm....looks slightly lighter than it was when it went out! Along with this, also recieved a RKT head. This had to be custom made due to the way that "the other guys" did the 880...Thanks Kelsey and John!

IMG_0409 (Small).JPG IMG_0410 (Small).JPG IMG_0404 (Medium).JPG IMG_0408 (Medium).JPG
 
O
Aug 17, 2009
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Hmmm not much comparing going on just the same old SW forum members claiming there stuff is best.......

At the end of the day when you recalculate the actaul HP gained at 9000' feet or higher your gaining approx 8 to 10 HP maybe. Remember you lose approx. 30% of the rated HP at high elevations.....At 9000' and above the a good 860 or 880 big bore does have a slight edge over a well setup XP with Head mod, Clutch kit & exhaust package, but not by very much @ 9000'

AIR + FUEL = HP

OT
 
O
Aug 17, 2009
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You would sure think so i agree.... However in chest deep snow @ 9000' sleds are working really hard regardless of setup and often times it's the heat soak that occures during deep deep days that equals out the playing field......In the spring time or setup snow @ 9000' the big bores will scream but in the deep deep stuff only by a slight edge..... I have them both and i ride chest deep snow 1500 miles a season I and Others compare all the time.

OT
 
N
Nov 26, 2007
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CowTown
You would sure think so i agree.... However in chest deep snow @ 9000' sleds are working really hard regardless of setup and often times it's the heat soak that occures during deep deep days that equals out the playing field......In the spring time or setup snow @ 9000' the big bores will scream but in the deep deep stuff only by a slight edge..... I have them both and i ride chest deep snow 1500 miles a season I and Others compare all the time.

OT

Easy math

151 HP stock
173 (average) HP in BB form

Basically a 15% increase in HP (corrected).

All things being equal, both sleds will loose 3% rated HP at that elevation per 1000 ft, not 30% total from original factory rating. You have to factor in the loss of HP per 1000 ft as rated HP.

15% is 15%, at the bottom of the hill or at the top. Maybe its only 10 HP at 9000 ft like you say, but that means your stock sled is 70 HP (70 HP X 115% = 80.5 HP) so its still making 15% more HP. However this math doesn't work because your loss of 30% HP (which is actually less but regardless...) equates to 45 HP loss off the 150 HP stock is still 105 HP. Add 15% to this and its 120.75 HP. 120.75 - 105 = 15.75 HP

At 9000 ft the equated HP difference is still almost 16 HP (and will probably be slightly more with the corrected calculation).

If you're not seeing a difference between your big bore and a stocker, maybe you should have BJ and Winter Brew help you out.

NSC
 

BIG JOHN

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Nov 26, 2007
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Minnesoooota
Easy math

151 HP stock
173 (average) HP in BB form

Basically a 15% increase in HP (corrected).

All things being equal, both sleds will loose 3% rated HP at that elevation per 1000 ft, not 30% total from original factory rating. You have to factor in the loss of HP per 1000 ft as rated HP.

15% is 15%, at the bottom of the hill or at the top. Maybe its only 10 HP at 9000 ft like you say, but that means your stock sled is 70 HP (70 HP X 115% = 80.5 HP) so its still making 15% more HP. However this math doesn't work because your loss of 30% HP (which is actually less but regardless...) equates to 45 HP loss off the 150 HP stock is still 105 HP. Add 15% to this and its 120.75 HP. 120.75 - 105 = 15.75 HP

At 9000 ft the equated HP difference is still almost 16 HP (and will probably be slightly more with the corrected calculation).

If you're not seeing a difference between your big bore and a stocker, maybe you should have BJ and Winter Brew help you out.

NSC


whats wit all duh the numbers???

I think the elevation gremlins take MORE from a BB than a stocker...elevation does that ya know...its not linear like one would think...the more power ya make, the more ya lose until at 9000' your back to stock...:rolleyes:

from what I have read from others...:D

adding a head = more power = better than stock
add porting = more power = better than stock
adding head and porting = more power - way better than stock
adding a head, porting and bigger 2 ring cast pistons = ?? power and = stock power...at 9000':face-icon-small-sho

That there is some funny chit...LOL-BJ
 
S
Nov 26, 2007
1,664
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Helena, MT
Hmmm not much comparing going on just the same old SW forum members claiming there stuff is best.......

At the end of the day when you recalculate the actaul HP gained at 9000' feet or higher your gaining approx 8 to 10 HP maybe. Remember you lose approx. 30% of the rated HP at high elevations.....At 9000' and above the a good 860 or 880 big bore does have a slight edge over a well setup XP with Head mod, Clutch kit & exhaust package, but not by very much @ 9000'

AIR + FUEL = HP

OT

Same old SW forum members claiming they know it all.....something about a kettle and calling it black pops in my head.
 

winter brew

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I hate to even bring this up....but the painkillers are talking.... OT, maybe when you click up for altitude your ramps aren't moving? :confused::beer;
And JFYI there will be some comparing going on this year, I just did one of John's 860's....I hope you approve.
 
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diamonddave

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I hate to even bring this up....but the painkillers are talking.... OT, maybe when you click up for altitude your ramps aren't moving? :confused::beer;
And JFYI there will be some comparing going on this year, I just did one of John's 860's....I hope you approve.

Who doesn't love painkillers? Is that a personal BJ 860? My final ride was setting up an XP and I finally started to maybe like the chassis.
 
O
Aug 17, 2009
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What can't show the math.........

151 HP Stocker

@1000' = 146 HP
@2000' = 142 HP
@3000' = 137 HP
@4000' = 133 HP
@5000' = 129 HP
@6000' = 125 HP
@7000' = 122 HP
@8000' = 118 HP
@9000' = 114 HP

173 HP Big Bore

@1000' = 167 HP
@2000' = 162 HP
@3000' = 157 HP
@4000' = 153 HP
@5000' = 148 HP
@6000' = 144 HP
@7000' = 139 HP
@8000' = 135 HP
@9000' = 131 HP

At 9000' the BB has approx. 12.5% more power in optimun conditions " Hard Pack or Trail conditions..... IMHO, a 12.5 HP gain in chest deep snow isn't anything to be proud of :D

This was calculated at @3% and rounded off... Depending on the atmosphere/temps/conditions @ 9000' you can easily expect even less HP than posted.


OT
 
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winter brew

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What can't show the math.........

151 HP Stocker

@1000' = 146 HP
@2000' = 142 HP
@3000' = 137 HP
@4000' = 133 HP
@5000' = 129 HP
@6000' = 125 HP
@7000' = 122 HP
@8000' = 118 HP
@9000' = 114 HP

173 HP Big Bore

@1000' = 167 HP
@2000' = 162 HP
@3000' = 157 HP
@4000' = 153 HP
@5000' = 148 HP
@6000' = 144 HP
@7000' = 139 HP
@8000' = 135 HP
@9000' = 131 HP

At 9000' the BB has approx. 12.5% more power in optimun conditions " Hard Pack or Trail conditions..... IMHO, a 12.5 HP gain in chest deep snow isn't anything to be proud of :D

PS, depending on the atmosphere/temps @ 9000' you can easily expect even less HP than posted.

OT



What do you think of the 17 HP gain at 9Kft as shown above? Pretty substantial for nothing but a small overbore. :beer;:)
 
O
Aug 17, 2009
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Brew, like i've stated in chest deep snow like we ride here in Wyo., 17 HP isn't sqwat to be proud of until you run on "hard pack" or "trail" conditions.


OT
 
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winter brew

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What does a Dyno measure? And the formula for HP derived from this measurement is ???
You know that you don't get more HP with more torque...HP is mathematically calculated from measuring torque.
By the way, we have chest deep snow here too...but not that light fluffy girly stuff....we have "MAN SNOW"....LOL :beer;
I'm just hoping the 860 gives me "a little more" that's alll that is claimed and all I expect.
 
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