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XP big bores - lets compare

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O
Aug 17, 2009
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BJ, without Kelseys head your BB kits would'nt do sqwat...There's just not much gain in porting alone.....Furthermore, A real BB kit will have Twin Pipes, Head, Porting, K&N Pods , V-Force Reeds, Race Crank, & Carb Bore. When you can make 25HP plus from your kit let me know.

BJ what kinda of power would your BB kit's make with the stock 12:1 head ? :eek:

FYI the 800R is a ported verison of the early day 800's :beer;:D


By the way BJ what kinda Torque # are you getting from your kit ?

It's always fun jawing with da bigguy. :heart::D

OT
 
C

cog

Member
Dec 7, 2007
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Wow, people looking for info and get a guy that never has anything good to say, and will stoop to anything to try and ruin a reputation, guess the saying "there is more hope for a fool than a guy that's wise in his own conceit", is true here,
I can tell you this, stock my machine was nowhere near what it is with the SHR BB.
 
D
Oct 13, 2008
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It'a pretty clear that you don't understand the relevance.....A well tuned & clutched 800R from the moment you stab the throttle "ENGAGEMENT" should have alot of "TORQUE"....If you don't feel the "TORQUE" every time you stab the throttle at 'ENGAGEMENT" you might want to have you 800R looked at because it's very likely your 800R has a few issues. :D

OT

I understand the relevance of torque plenty well. I had a 996 in a zx chassie a while back that could out run some bigger cc and hp sleds because it had a fair amount more torque. As far as the rest of your reply you once again missed the point.You asked what he feels @ 4000 rpm and made no mention of STABBING the throttle. So as far as my statement goes it was correct.I do for some crazy reason agree with your assesment of torque though:eek:. And my xrs runs strong and is extremly reliable.
 
F

Fack

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Nov 28, 2007
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Torque and horsepower seem to be a common topics on here. Lets clarify things a little. Torque=(horsepower X 5252) / RPM. You can take any dyno graph and plug in your given horsepower multiply that by 5252 then divide by your given RPM at which that horsepower was achieved and there is your torque. No more of this my sled didn't make very much horsepower but it made a lot of torque business. The only way that will happen is if your sled makes good horsepower at low RPM. This is why diesel motors make so much torque. They make a lot of horsepower at a low RPM. Torque can also be achieved through gear reduction, but again, that is simply transfering horsepower through a lower RPM, but in that transfer of enegy, energy is lost. If a sled is making more horsepower at the same RPM it will no doubt make more torque. I had a friend tell me a few years ago that the Apex was going to be the baddest thing on snow (stock) because four strokes make monster torque. Take it's 150 horse at 11,000 RPM and plug it into the equation. HMMMMM... I wonder why Yamaha thought the three cylinder lower RPM motor would be a better candidate for a snomobile motor.

-Fack
 
O
Aug 17, 2009
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At the end of the day it's what the rider feels while riding in there favorit terrain.....

While riding through "tree's" the rider rely's on the motor's torque to manage and control the sled through the tree's.

While riding "wide open bowls" peak horsepower works best to allow for the best trackspeed.

The rider feels torque. The rider does'nt feel the peak horsepower that much unless the rider is on a turbo.

OT
 

BIG JOHN

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Nov 26, 2007
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BJ, without Kelseys head your BB kits would'nt do sqwat...There's just not much gain in porting alone.....Furthermore, A real BB kit will have Twin Pipes, Head, Porting, K&N Pods , V-Force Reeds, Race Crank, & Carb Bore. When you can make 25HP plus from your kit let me know.

BJ- Hmmm I chose the RKT head cuz its the best...but since I have done a couple 860's with "other" heads and dyno'd them, they came up a little short but still better than "sqwat"...LOL:rolleyes:...I have 2 860/CS twin specific porting/RKT head/Boyeson/Bondi box mods going out this year...IMHO the LW crank is good for nothing short of a 660' drag race...148 + 24 hp = 172 thats what I get on my dyno... stock vs SHR860R...:)

BJ what kinda of power would your BB kit's make with the stock 12:1 head ? :eek:

BJ- I wouldnt waste my time with the stock head:eek:...if I did I would cut it for high elevation...and since stock is 12.25-1 and cutting for a BB would bump it to roughly 13-1...getting a lower 12-1 would be tough...but what do I know..LOL

FYI the 800R is a ported verison of the early day 800's :beer;:D

BJ- actually:eek:...you couldnt port a 800HO close to what the 800R comes stock at...but what do I know


By the way BJ what kinda Torque # are you getting from your kit ?

BJ- 172 hp at 8100 rpm (stock exhaust,reeds,air box,pump gas jetting)...do the math...more HP/TQ is available...it just starts there..

It's always fun jawing with da bigguy. :heart::D

OT

Ditto...:p-BJ
 

hobbes

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Nov 26, 2007
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Yep, but that's a whoooooole 'nother can of worms... lmao
 
O
Aug 17, 2009
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BJ, yes his head does work good. Have you tried trigstads 14:1 head. ? It workies pretty good 2 in head 2 head competition. We've got alot of Daves head running on XP's arond here.

OT
 
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Insaneboltrounder/sjohns

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Nov 26, 2007
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Remove user from ignore listOriginal OT
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Thing works like a charm.... no more BS , misleading , ignorant claims by a midget brained loud mouth. Those who dont use it , dont know what they are missing:beer;
 
O
Aug 17, 2009
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Dude,you have not uttered 1 word that has anything to do with the subject or RU remotely even close....Who give a F:)CK about pressing the "Ignor-ant Button".

On the way out don't let the door hit you in the ars.

OT
 
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Insaneboltrounder/sjohns

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Nov 26, 2007
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hisssssssssssssssssssssssss.... sounds like gas..........out of a slow leaking ,giant , fat and stupid balloon. Thats all I hear.:beer;
 
M
Sep 21, 2002
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Remove user from ignore listOriginal OT
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Thing works like a charm.... no more BS , misleading , ignorant claims by a midget brained loud mouth. Those who dont use it , dont know what they are missing:beer;

Yes but those who do are dying to know what they are missing////so they undo it... LOL
 
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Insaneboltrounder/sjohns

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Nov 26, 2007
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That would be true if the one being ignored had ever posted one brain phart of useful info. That is not the case with the origonal windbag.
 
F

frog

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Feb 16, 2009
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Frog, with all due respect.. this is simply not true..
don't feel singled out... this is a HUGE misconception among most people..

I will try and explain, and I will generalize and keep it very simple..

1) Given 2 engines running at the same rpm.. if one engine has more HP, it automatically has more torque.. ALWAYS!! Torque is measured and HP is calculated via mathematical formula using TORQUE as one factor.

2)HP and torque can NOT be separated in terms of what is doing what with respect to how your engine runs (see #1).. They are connected ALWAYS and can not be separated..

3)Stating that torque is what is accelerating you down the track is simply incorrect.. Why? See #1 and #2 above..

Now, here is where the "FUN" begins...and hopefully, I can related to this Big Bore topic..

1st.. a few basics... Engines need to be clutched ALWAYS at peak HP rpms..

ANY good engine will have a peak torque output rpm 2-500 rpm LOWER than the peak HP output rpm. WHY.. Because you clutch for peak HP.. NOT peak Torque..

So, when your engine is heavily loaded and it begins to drop a few hundred rpms.. It will fall into its PEAK Torque realm and have a much easier time at recovering and returning back to peak HP rpms... Hence, the reason for having the engine' speak torque rpms lower than its peak HP rpms.. Without this relationship.. the engine would be VERY hard to clutch in a full load situation. Make sense?

When people talk about engines, they like to quote and cite peak HP numbers..For example.. RK Tek 860R makes 180HP at 8300 rpms. Peak torque is closer to 7900/8000 rpms.. OK, so, those are the peak numbers.. What MANY fail to realize is that the area under the torque curve is what really makes one engine stand out over another.

Different engines builds build TORQUE at different rates.. Some build torque rather rapidly and then hold the torque across a very wide rpm band.. This is a good engine and one that will accelerate very hard and will be very easy to clutch.. The area under this torque curve would look like a bumpy straight line with very little upward slope.
Some engine builds do not build torque quite as fast but can get to the same torque numbers as another engine.. This engine's torque curve will look like a side of a mountain.. So, while the 2 engines can make roughly the same torque and HP, their torque curve can look completely different. So, the area under the curve really tells you how the engine will "perform" under real-world operation.

In flat land racing, this curve is not so important (note: I did NOT say NOT important. just not as:confused:).. because you come out of the gate and immediately hit the desired rpms and stay there for the duration of the race. so, what the curve looks like BELOW the rpms you are running are inconsequential.

Now, boon docking and mountain riding.. Different story.. It is very common to have your engine quickly lose rpms because you are on and off the throttle. So, the flatness of the torque curve becomes a big player..

This is where the Big Bores really shine... I will speak to my BB, because it is , obviously, the one I know the most about...:D:beer;

The 860R builds torque at a very rapid rate when compared to the stock engine. It builds it faster and builds much more of it.. So, you have a very broad and very flat torque curve.. So, when on and off the throttle OR when your sled hits a super "Deep" spot and drops some rpms.. The BB is MUCH less effected and can recover much faster than the stock engine.. WHY?? Much more TORQUE AND HP at ALL rpms.... Simple as that.. Where the stock engine will get overloaded.. the Big Bore will be much less effected by it and continue to pull...

The RKT 860R has massive torque and HP increases in the 6500-8000 rpm band. So, it has a much easier time handling anything "HIGH LOAD" situation it encounters. This becomes very apparent when banging a steep hill with 3ft of fresh and deep powder.. There is no comparison between the Big Bore and the stock engine.

Kelsey

No offense taken by any means I have no problem being corrected.

I should have been more clear, I guess I was using the 800R in the rev chassis for an example in which doo wanted this engine spun up to 8500 r's for peak power where the 860 only needs to spin up to 8100-8300 for peak power. More power at a lower rpm will generate more usuable "power" or torque and like brew stated this would be a simple fact of math.

I guess I was not comparing properly but that is what I was trying to get at.

I won't pretend to know everything because I definately do not as you can see. :eek:

I dunno if I make sense but from here it does.:confused:
 
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