| Author |
Message |
    
Phillyblast
| | Posted on Friday, November 19, 2004 - 09:42 am: | 
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Tripp,
Stock S2s are down a wee bit on power vs. say an M2. The fairing helps, but a bone stock S2 probably won't do 130, especially on the salt, at 4300 feet. Most I've ever gotten out of the S2 indicated was about 120. It was running out of breath, and I was running out of road, so I didn't push it.
It was really comfy and stable at that speed, however.  |
Firemanjim
| | Posted on Friday, November 19, 2004 - 10:46 am: |
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Tripp,you are working against several factors at Bonneville--elevation is 4300' so you have lost power,and then the salts consistency adds another power sucking factor(somewhere between 5% and 10%) and lack of traction to the equation.It's not nearly as easy as it sounds. |
Jmartz
| | Posted on Friday, November 19, 2004 - 12:31 pm: |
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Never heard of an SE 551 cam. Is this new? |
Blake
| | Posted on Friday, November 19, 2004 - 11:00 pm: |
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FMJ,
I think that the loss of power at altitude is exactly offset by reduced aerodynamic drag at altitude. It's why jets fly as high as they can, same speed, less power required, less fuel burned.
The salt wheel spin factor is a whole 'nother matter though.
Bodingtons Pub Ale, get some, drink it. |
Lornce
| | Posted on Friday, November 19, 2004 - 11:58 pm: |
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Blake,
Is that true? Aerodynamic HP requirements drop off at EXACTLY the same rate as altitude induced power loss?!?
Wind resistance and ambient pressure are in perfect co-relation? And this perfect co-relation is in perfect co-relation to the stociometric efficiency of hydrocarbon based fuels?
I'm not doubting you, I'm just amazed.
Bushmills 10 yr old Irish single malt. Even if you don't drink you'll love sniffing the cork. |
Tripp
| | Posted on Saturday, November 20, 2004 - 12:47 am: |
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thanks for the education fellas! i've read about the salt flats it sounds fun! |
Blake
| | Posted on Saturday, November 20, 2004 - 12:50 am: |
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I dunno about "perfect correlation", considering humidity and other effects that are secondary but yes, within any measure considered significant the effect is darn near exactly offsetting. "Exactly" was a probably a poor choice of wording though. I should just have said "offsetting."
But look at the basics...
Drag is inversely proportional to air density.
Power is proportional to air density.
Yep, offsetting.
I'll try the 10yr old Bushmills. |
Unibear12r
| | Posted on Saturday, November 20, 2004 - 02:06 am: |
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Blake your right about offsetting proportions but I'm pretty sure the rates are different with H.P. falling off faster.
Jets fly at high altitude because they are actually more efficient there than at lower altitudes. Unlike internal combustion engines & props. |
Lornce
| | Posted on Saturday, November 20, 2004 - 02:14 am: |
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"Drag is inversely proportional to air density.
Power is proportional to air density."
Yes, but the two are not directly proportional to one another.
Jets fly at high altitude to take advantage of reduced air density and thus wind resistance. They're able to exploit this advantage because jet turbine or turbofan engine technology permits them to operate efficiently over a broad range of altitude densities.
"I think that the loss of power at altitude is exactly offset by reduced aerodynamic drag at altitude. It's why jets fly as high as they can, same speed, less power required, less fuel burned."
As relates to a standard motorcycle's internal combustion engine and relatively simple mixture control, your claim is incorrect. Significant modification: ie turbo, supercharger would be needed to provide the charge density required to overcome altitude related power losses. |
Firemanjim
| | Posted on Saturday, November 20, 2004 - 03:36 am: |
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Blake,---NOT!!!
I cannot remember rule of thumb for loss per 1000 feet in elevation,might have been 10%.Even if its less you are not going to see that much gain from lowered air density---especially if you are running in a small displacement class where speeds are lower and HP loss more noticable. |
Lornce
| | Posted on Saturday, November 20, 2004 - 09:26 am: |
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BTW Firemanjim,
Congratulations on your results at Bonneville. Was perusing the Nallin site the other day when I stumbled upon this:
You go, Jim! |
Tripp
| | Posted on Tuesday, November 23, 2004 - 01:05 pm: |
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alright what's the opinion on money well spent
stage 1 thunderstorms or new xb heads?
seems about the same cash for either or |
Rick_a
| | Posted on Tuesday, November 23, 2004 - 01:22 pm: |
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How about Stage 1 XB heads? |
Tripp
| | Posted on Tuesday, November 23, 2004 - 02:30 pm: |
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lol, they would be around $1200 vs $700 to get my thunderstorms done or buy stock xb new |
Phillyblast
| | Posted on Tuesday, November 23, 2004 - 06:23 pm: |
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Tripp,
I'm thinkin' best bang for your buck is the Stage II work on T-storms. Bigger valves, better springs, let you head on up the the 585 cams if you decide to in the future.
Like I said, I only went with the XB heads because my choice was buy T-storms or buy XB heads.
notice how i slipped in the prod to spend more money on cams . . . seemed only appropriate since this thread made me open the wallet even wider. |
Tripper
| | Posted on Tuesday, November 23, 2004 - 08:13 pm: |
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advice from a guy who will stick his head where it don't belong. that ain't natural! |
Aesquire
| | Posted on Tuesday, November 23, 2004 - 08:52 pm: |
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The Bushmills is great, though it's a less complex taste than a good highland single malt scotch. The Irish sometimes regret teaching the Scot's how to make uisgebaugh while they were bringing them christianity.
Drag goes down with altitude, as does combustion engine power. not exact, but close enough. ( funny curves at the extremes ) The 15,000 lbs thrust ( sea level ) turbine engine is only pushing 400 lbs at 45 thousand feet. That 400 lbs is enough to keep the jet doing mach .9. The non turbo'd piston engine has stopped.
Power production on your Buell is limited by the most restrictive bit. I, for example, don't want the noise of a Force exhaust, so with the same mods as another ( except the Force ) I'd get less power. I'm saving up for more power, stage 2 heads, cams with more lift, but "M2 like" timing to keep the power curve like it is now, but bigger. Roller rockers, maybe hydrosolid lifters. I say, go for breathing mods & the cams & valvetrain to keep it going, then big bore kits etc. later, as funds allow. If you get just the heads, you will be disapointed without the cams. IMHO YMMV
(Message edited by aesquire on November 23, 2004) |
Tripp
| | Posted on Wednesday, November 24, 2004 - 12:04 am: |
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woohoo, open the wallet! if you're gonna do it, might as well do it big! so far the biggest mistake on my on going project was to not have the heads done at the same time as cylinders, oh well step by step it'll have to be... therefore, for me it'll be full exhaust, heads, cams and at some point in there when money will allow, mikuni--- there is no end though because one of my projects in the performance/repair department is going to have to be "back cutting the dogs on my first gear", sounds like lyrics from a rap song. i'm not really sure what that means but come tranny project time i'll be on here finding out! thanks for valued opinions fellow buellers! |
Racerx1
| | Posted on Wednesday, November 24, 2004 - 04:02 pm: |
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Way back to the 550 lift SE cam vs the .536....I've run both. the .550 lift cam is an XB cam with excellant high speed cam dynamics. Peak hp is similar to a stock X1 'B' cam with a slight loss of torque everywhere else. Excellant cam choice for a road racer or engine you plan on spinning over 7000 rpm, very easy on the valvetrain with great top end power potential. Awesome sounding idle too if your into that.
.536 cam has a bunch more 'area under the curve' makes more power/torque through 7000rpm then the 550 lift cam. Requires a spring upgrade.
My experience has been with road race 1200cc engines with the normal hot rod hop ups. All my road race bikes run the XB cam, my drag bike runs the .536 cam. I wouldn't hesitate recomending either, depending on what you are shooting for. |
Tripp
| | Posted on Saturday, November 27, 2004 - 10:47 am: |
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that's interesting racer i would have thought it the other way around the 536 in the road bikes and the higher lift 550 in the race bike. is it the duration figures that made you choose these setups? |
Racerx1
| | Posted on Monday, November 29, 2004 - 12:12 pm: |
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Hey Tripp,
Picked the .550's for road racing mainly for survival (you must first finish to win). My goal for my road race program is to have a competitive engine who's maintenence needs over a season consist of fuel and oil, not necessarily the last 1/1000th of power i can get. The road race motors spend their entire life between 5000 and 7000rpm with occasional excursions to 7500. The .550 make good high rpm power with the added benefit of good valvetrain dynamics. I'm a big believer in lighter is righter when operating at high rpm continously, and I can get away with light XB springs/valves with the .550 lift cams, get good valvetrain dynamics, and make good top end hp. I'll give away low end or a couple of horsepower any day in exchange for a bulletproof top end.
The .536 cams have more 'area under the curve' (and duration) than the .550's thanks to more aggressive opening and closing ramps. They take a lot of spring to control, especially at the constant high rpm a road race motor sees. I like them for a drag bike where it is important to make as much hp as possible and the duty cycle is strictly high rpm excursions (not steady state). Good choice for a streetbike for the same reason |
Phat_j
| | Posted on Monday, November 29, 2004 - 04:08 pm: |
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exactly why i chose the 536's over the other options.... must be doin something right... 103hp |
Phillyblast
| | Posted on Monday, November 29, 2004 - 06:12 pm: |
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quote:I'll give away low end or a couple of horsepower any day in exchange for a bulletproof top end.
Wes,
Pretty much why I went with the .550
Curious, though - the XB12 dynos I've seen are pretty flat as far as torque curve. When you say you lose low end, is that just in comparison to the .536?
(remember I'm coming from the land of D cams, here)
David |
Racerx1
| | Posted on Tuesday, November 30, 2004 - 09:07 am: |
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Hey Dave,
XB12 torque curve is very flat! Yes, when i was refferring to the low end loss, it was the .550 vs the .536. The XB/.550 cams have a pretty advanced exhaust and intake centerlines to get a decent amount of overlap with relatively short duration numbers. this makes them a bit more sensitive to exhaust/intake tuning vs. the .536 cams, which has more traditional centerlines and gets its overlap via large duration numbers, especially the exhaust. The XB exhaust/intake is a very well designed system and really makes the most of the XB cam profile. In a carburated tube frame application with a Buell pro-pipe, the XB cams still maintain a flat torque curve and make excellant hp, but give away mid range torque to the .536 and a slight bit of peak hp (103 with XB cams vs 105 with .536 cams in my case). I have no doubt some exhaust/intake tuning work would change those numbers. Again, as you know, cams are just 1 piece in the tuning puzzle and you have to take a system approach when looking at this stuff. you can generalize to some degree, but my results should be taken in the context of a carburated, race kitted tube framer. throw in a different pipe design, intake, carb, heads, etc, and your results will vary! |
Phillyblast
| | Posted on Tuesday, November 30, 2004 - 11:08 am: |
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Wes,
Cool, thanks for the clarification. I figured that's what you meant, just wanted to be sure.
I'm keeping the stock 2" header, the Supertrapp, and the CV for now, so I'll have some tuning work to do but at least I can fiddle with the discs on the 'trapp.
That exhaust valve on the 12s is pretty trick from what I've seen. Going to pick up the S2 service manual I ordered last week at the dealer this Sat. - if the weather holds maybe I'll see if I can wrangle a demo ride.
BTW I started out with the idea I'd be happy to see say, 90rwhp on the S2 and keep it usable throughout the powerband, when it was all done, so if I don't get near the 103-5 range you guys are pulling I won't be tooo disappointed  |
Tripp
| | Posted on Tuesday, November 30, 2004 - 12:04 pm: |
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it seems that happiness comes at around a hundred horses! i think i'll probably do the .536 cams after i get my heads done, hopefully i can afford a full exhaust come february, then i can move on to having the heads done maybe in spring but probably next fall. that'll put me into new cams by this time next year! a long and slow progress for me, but i expect it'll be worth it! |
Phillyblast
| | Posted on Thursday, January 13, 2005 - 10:35 pm: |
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UPS delivered a set of heads today. waiting on the rest of the goodies (pistons, cylinders, cams). |
Tripp
| | Posted on Friday, January 14, 2005 - 12:20 pm: |
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you must be tapping your foot, ready to get started! |
Phillyblast
| | Posted on Saturday, January 15, 2005 - 11:15 am: |
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box two arrived last night. Heading over to the shop to see about available time/space to start work, and stopping by the HD/Buell dealer to see about some misc. parts (front iso. mount bolts, front iso., etc.) |
Lornce
| | Posted on Saturday, January 15, 2005 - 11:54 am: |
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Now, how about those XB heads?
I'm looking for answers as I'm planning to order
some Stage III Nallin heads, (possibly two sets) but I don't
know which type to plan for in my project(s).
I'm a little confused as one of the primary
advantages of the XB heads appears to be lighter valves with 7mm stems
and lighter "bee-hive" taper wound valve springs.
However, NHRS installs valves with 8mm stems and heavier,
conventionally wound springs when they build Stage II and Stage III
heads (just like T-Storm heads). At that point the advantage must
simply be in the shape of the XB's ports and combustion chambers. Or
is it? That's what I need to know.
In stock form the XB head outperforms the T-Storm head, that's
understood. How about the difference in performance by the Stage III
level of modification with larger unshrouded valves, squish band cut
to 15 degrees to match T-Storm type pistons and ports suited
to breath best for 88" applications?
I'd call Nallin and ask them directly, but my phone access is limited
during business (read working!) hours.
best,
Lornce |
Spiderman
| | Posted on Saturday, January 15, 2005 - 07:23 pm: |
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Well the upside of the XB heads in stage three areas would be the larger fin area.
Blanks in place of the breather holes so you can put smaller screws in to use the XB rocker tops.
The heads are also a little shorter, which gave me a little more clearnce while putting in rockers and rocker covers.
You would have to Ask Aaron the specifics when you are doin that extensive head work specially cutting the chamber.
If you were to do a stage three and leave the chamber stock I would use the XB heads cause the combustion chamber has a better design for better flame front and complete fuel burn. |
Loki
| | Posted on Sunday, January 16, 2005 - 05:37 pm: |
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The S1 now sits with the XB heads and cyls(cosmetics and added cooling) on top of stock S1 pistons. Well into the break in before I left on my trip in mid october. The seat-o-pants meter had the needle bent over the stop. Now to drop on a 42 and find a nearby dyno for some fine tuning.
The 42 became a low priority till the season really starts back up.
-cruising the real world on my S1X and the web on a P4 3.0HT in a sff FIC VL67 |
Not_purple_s2
| | Posted on Thursday, October 26, 2006 - 02:15 pm: |
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Happened across this thread from a search.
Thought I'd pull it from the dead.
Since the XB has little advantage over the TS when both have stage 3 work, what disadvantages would stock s2/sporty heads have if they were taken to the same level (stage3)? |
Blake
| | Posted on Thursday, October 26, 2006 - 08:22 pm: |
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I think your premise is not quite accurate. The XB heads are a significant improvement over the TS version. It's just that at 120 RWHP, the cylinder heads are likely no longer the limiting link in the chain. |
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