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M1combat
| | Posted on Friday, June 11, 2004 - 04:51 pm: | 
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"Making the combustion chamber more efficient is a better way to go."
They're already extremely efficient. Hence the lack of a cat or air injection and the fact that it passes 2008 CA emissions standards. Personally, I think DOHC is more simple. At the moment we have ?five? gears and four cams in the lower end. Why not one pulley/sprocket and two more on the upper end. RPM's are a good thing, but only when they don't cost too much torque. As far as buying an imported V-Twin... I almost did. I bought this one because it's cooler and American and I knew that I could buy a Ninja 250 and not be able to extract everything from it. I still say that power is nearly unimportant to me... I like RPM's because they sound good  . Especially when they're coming out of a big bore engine .
In any case, I think our beloved air cooled twins have a lot of life left in them for our application. |
984_cc
| | Posted on Friday, June 11, 2004 - 04:54 pm: |
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No, BMW is still currently using their boxer twin. That engine came out in 1929. Originally an aircraft engine. They use it in a variety of models, most notably, the GS and Star Wars inspired look Rockster. Don't think like over-payed engineers do, by thinking that the more complex it is, the better it works (and the only way to do it). I have to deal with them everyday. |
984_cc
| | Posted on Friday, June 11, 2004 - 05:00 pm: |
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You're right M1, they do have a lot of life left.
And on the efficiency part too. They can always keep perfecting the design in the combustion chamber. It's not that perfect. But don't these engines utilize only 1 camshaft with four lobes? |
984_cc
| | Posted on Friday, June 11, 2004 - 05:05 pm: |
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By the way, I owned an Aprilia V-twin, and sold it to get my Buell. Much more flexibility and torque. Sounds better too (exhaust) without the whirring and clanking sounds the Aprilia made because of it's valve-train when I revved it up. And I don't have to put up with taking the thing apart to check/adjust the valves. |
M1combat
| | Posted on Friday, June 11, 2004 - 05:06 pm: |
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Well, with four valves you don't need to lift them as far and you can lift them more aggressively. As I recall there is less loss due to spring pressure and stuff (maybe Aaron can chime in here...).
edited by M1combat on June 11, 2004 |
M1combat
| | Posted on Friday, June 11, 2004 - 05:09 pm: |
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"But don't these engines utilize only 1 camshaft with four lobes?"
No. They may be twin cams like the big twins but I think they still have four cams. You'll notice the angle of the pushrods.... |
Socoken
| | Posted on Friday, June 11, 2004 - 05:17 pm: |
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its always been my theory that four valves means smaller runners and ports for higher AF velocity, which is really only worth it in high RPM where it can create a ramming effect.
i find it easier to relate the big twin to an American V-8. four valve SBC heads have been on and off the scene for years, but they have never really taken off. in big bore low rpm engines, two valves seems to be the way to go.
im probably wrong, so someone correct me so i can learn something |
Ingemar
| | Posted on Friday, June 11, 2004 - 05:23 pm: |
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984:
I really don't wanna fight over this but high velocity porting will restrict high end power because the ports get too small.
Here's a quote of someone I trust to know what he's talking about:
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Tilley HD roadraced Buells. The rules limited them to 90 hp, didnt say anything about torque numbers. They learned that they could make gobs of torque down low and set the rev limiter to kick in just under 90 hp. I heard they were making well over 100 lbs of torque. Rules committee put an end to the rev limiter trick.
American HD in AnnArbor, Michigan raced in the same class. I saw some of their ports. The floor(short side) was welded up big time. The long side looked like a crescent in cross section, couldn't hardly get a finger in there. Gobs of torque down low. These ports wouldnt flow at higher revs, effectivly rev limiting the engine before it got to 90 hp. But the velocity was so high at low revs that it worked very good.
=-=-=-=-=-
But then again, I'm qouting others I trust to know their stuff (and I have my reasons), but I really know jack about this stuff myself, so maybe you're right. Like I said, really not worth fighting over.
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984_cc
| | Posted on Friday, June 11, 2004 - 05:28 pm: |
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I'm not sure about the cam arrangement on them now, but I do know some Harley V-twins have only 1 cam. I've only owned mine for a week now. I don't think the loss is that great through pushrods. Belts and chains can stretch and wear causing a lot of slop and lost power. You experience this in American V8s when the timing chain gets worn-out. More valve area (more valves) equals more top-end. That's why I still think simple (pushrods, 4 valves total) with variable valve timing would be the best of both worlds. I know from building and racing American V8s that you can get very aggressive opening and closing camshafts. Do these engines have roller lifters and rockers? If not, that would be a huge improvement. Maybe 25-30 HP. |
Hogs
| | Posted on Friday, June 11, 2004 - 05:31 pm: |
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all sposters have four cams and probally always will... |
984_cc
| | Posted on Friday, June 11, 2004 - 05:37 pm: |
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Ingemar, what I meant was, high flow (as in very high engine speeds, where it is needed). Small ports are good for low-end power. If you can make the fuel /air mixture enter and exit quicker at lower engine speeds (high-velocity) that will improve your power down-low. So I guess when I saw 4 valve/cylinder, I thought you meant large ports for high velocity in the top-end. Sorry. |
984_cc
| | Posted on Friday, June 11, 2004 - 05:40 pm: |
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Thanks Hogs, I wasn't sure. What V-twin is it that I saw that has only 1 cam, like an American V8? |
M1combat
| | Posted on Friday, June 11, 2004 - 05:42 pm: |
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As I recall these engines have roller everything. They certainly don't get 25-30HP out of it though. You can only look at changes like that as a percentage. If it gives you 10 percent on a V8, it'll probably give you the same or similar on an HD engine.
"its always been my theory that four valves means smaller runners and ports for higher AF velocity, which is really only worth it in high RPM where it can create a ramming effect."
There is always a "ramming" effect. The RPM range at which this ramming effect is most efficient is what you play with. Not only do you have a ramming effect though, you also have a scavenging effect (that is worth more I think, again, maybe Aaron can chime in here) that is based on exhaust gas velocity and cam overlap and exhaust pipe/port size/shape. In any case, torque is the king of the street and HP is the king of the track. |
R1DynaSquid
| | Posted on Friday, June 11, 2004 - 05:42 pm: |
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Do these engines have roller lifters and rockers? If not, that would be a huge improvement. Maybe 25-30 HP.
Thanks for making me spill my pepsi from laughing so hard. 25-30 hp from roller lifters & rockers? You arent Corey by any chance are you? |
Hogs
| | Posted on Friday, June 11, 2004 - 05:44 pm: |
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yup all big twin quote the name "big Twin" had one cam for almost a 100 years then just in the past few years they went to two cams... but Sporsters since they arived in the 50`s and the buells since the gee not sure on the buells I think the eighties or nintys had four cams as well since they are based on the sposter engines... :-) |
Hogs
| | Posted on Friday, June 11, 2004 - 05:50 pm: |
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I don`t think you would can 1 hp with roller rockers but you might get one hp. but it will run smooth maybe rev a little bit more just a hair though :-) |
984_cc
| | Posted on Friday, June 11, 2004 - 05:51 pm: |
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Well, I don't know for sure if the 1200 Sportster has 'Roller everthing' but they only put out about 50-55 HP. Considering they have four cams, and with it friction, rollers alone could add more power. I said 'maybe' 25-30, especially near redline. I was only guessing. You can get up to 30+ HP in a V8 just by adding roller-rockers and not anything down below. Friction takes a lot of power. A clutch fan in a V8 takes up to 17 horsepower. |
984_cc
| | Posted on Friday, June 11, 2004 - 06:01 pm: |
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You could get a few HP in the R1. Especially since it revs real high and has 20 valves. |
984_cc
| | Posted on Friday, June 11, 2004 - 06:09 pm: |
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Here is a thought- How 'bout having both Horsepower and torque (152 HP+ and 100 lb. ft. at the wheel)? Hayabusa!  |
M1combat
| | Posted on Friday, June 11, 2004 - 06:16 pm: |
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"I don't know for sure if the 1200 Sportster has 'Roller everthing'"
I was unaware that we were including the sporty in our conversation. I don't think they have roller everything like the XB's do. Yes, you can get 30HP by adding roller rockers to a V8, but only if you are already making 500. It's a percentage that you add. If you are making 100 and add rollers and get 105, you can only assume (and you would be assuming pretty closely) that if you add rollers to a 300HP engine you might make 315. The same with a fan. I can assure you that I can add ANY type of fan to my 351C and I will NOT get anything like 17HP. I wouldn't even get that much if I removed the fan or replaced it with an electric. Maybe 8 but it's a percentage of what you already have. You could get a couple hundred HP out of roller parts on a 6000HP top fuel dragster I suppose...
"maybe" 25-30 is way too much. If you start with 50-55 and add roller everything you might end up with 55-60. I think that's even stretching it a little. I have heard roller rockers, cams and lifters in a pushrod V8 are good for about 5-7%. In any case, the XB's are already roller engines so it's a moot point.
The gains to be had on an XB engine are in the head design combined with cams, valves and exhaust. I still think they can be revved to 7500-8000 (the 12's) with their stock stroke occasionaly and still be perfectly reliable. The reason the factory doesn't do this is because they know that some dorks would run 95 miles an hour in third all the time just because they can. I think it sucks that I have to suffer because of these people. Of course I would rev it out there every once in a while but most of the time I try to stay as close to 2K or a little above as I can when I'm cruising around town. I always run the highest gear I can and stay above 2K.
You would almost certainly get more than one HP out of a non roller sporty 1200 by going to roller everything. Just rockers... That sounds about right. |
984_cc
| | Posted on Friday, June 11, 2004 - 06:31 pm: |
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What I meant on the fan was, a clutch fan, which is more efficient than just a fixed fan. Clutch fans can take as much as 17 HP from your V8 (high average). So if you took the fan off completely, and did not put anything in it's place (not even an electric unit), you could possibly get up to 17 free HP. I've experienced 10 percent increases in power with roller kit. So you were right when you said 10 percent earlier. So a 400 HP V8 would get 40 HP with roller rockers (one built for higher RPM) and 40 more with the roller lifter kit (very possible if not always accomplished). Because I did not know if they had 'roller everything' at 92 HP, the XB9 could possibly, theoretically, make nearly 20 extra HP if it didn't already have this kit. You know that this is all just theoretical Buellshite, don't you? |
Socoken
| | Posted on Friday, June 11, 2004 - 06:43 pm: |
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pretty sure Harley has been using roller lifters and roller tip rockers for ages. buells have roller lifters and roller tip rockers, so do XBs. aside from frictional loss, roller lifters allow for steeper cam lobes, and quieter operation. |
M1combat
| | Posted on Friday, June 11, 2004 - 06:44 pm: |
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Yes .
From what I've learned the entire roller setup is worth about 10%. Cams, lifters and rockers. On the XB's I think that even the cam bearings are rollers. The only ones I'm not sure about are the crank bearings but I think they are rollers as well. In any case, I wouldn't add rollers with HP in mind. I would add rollers with RPM's in mind. Too bad we have a rev limiter... |
984_cc
| | Posted on Friday, June 11, 2004 - 06:46 pm: |
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BTW- You shouldn't be so pessimistic on the power gainsThe XB12 already has a 50 percent increase over the 1200 Sportster. |
984_cc
| | Posted on Friday, June 11, 2004 - 06:52 pm: |
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Plain bearings are better for the crankshaft because they create a fluid wedge of oil at high speed between the mating surfaces. They will also last longer. But I don't know what these engines have. |
M1combat
| | Posted on Friday, June 11, 2004 - 06:55 pm: |
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nearly 100%... But it has different cams, exhaust, heads, pistons, DDFI and ECM as well. Or at least most of those things... and more. |
984_cc
| | Posted on Friday, June 11, 2004 - 06:59 pm: |
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You're right- 100%- it's time for me to go home. Not thinking clearly anymore. I've a headache from thinking so much on this theory. |
M1combat
| | Posted on Friday, June 11, 2004 - 07:21 pm: |
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. Me too . I think it's about time Aaron pops in here and sets us BOTH straight . |
Johncr250
| | Posted on Sunday, June 13, 2004 - 11:24 am: |
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I think there is still room to get more out of the air cooled motors but you`ll have to invest some money.
Options:
Nickel Silicon Carbide Cylinders
Lightweight forged piston
Ceramic Bearing for the Motor
Lightned crank
Roller Rockers
Or better yet Overhead Cams and 4 valves per cylinder like the Moto Guzzi MGS-01, and still aircooled.
They claim 122hp and 83tq from 1225cc in stock tune. Not bad!
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Anonymous
| | Posted on Sunday, June 13, 2004 - 11:59 am: |
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Well, when the Guzzis actually show up to race we'll see how they do. It's amazing how much press they got from something that virtually doesn't exist... BTW, 122 crank HP out of a race motor (which is what the MGS-01 is, not street legal) is really easy guys with two valves and pushrods. 120 RWHP is an every day thing out of under 1200cc race Buells running today. 135 RWHP out of 1350cc is no problem for a Buell race motor either, with better reliability than a 749 race Ducati, too! DOHC and 4 valves only help when the rpm's get high which can't happen with the stroke we are running. It would be too long to go into all the issues that surround DOHC on v-twins, but suffice it to say that if you aren't after huge rpm, or your engine can't attain high rpm due to its configuration, you definitely don't want DOHC. The four separate cams were developed for racing by H-D years ago because they had better pushrod angles, and they allowed easier individual degreeing and changing of cams in race conditions. Still works, doesn't it?! |
Outrider
| | Posted on Sunday, June 13, 2004 - 01:29 pm: |
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It's amazing how much press they got from something that virtually doesn't exist...
Just like the rumor mills only with a press release. Looks like nobody is safe from speculation and conjecture. LOL
Actually, strategically placed "leaks" from time to time work well concerning market research to support the decisions to proceed with the production and or geographic distribution of new products.
In Guzzi's case, if they don't introduce it or sell it here, no big deal as they have little to lose and lots to gain.
On the other hand, Buell has an overabundance of consumer input to analyze and has has the luxury of time to decide what does and does not fit their strategic planning. Sounds like an ideal situation to me. |
Sshbsn
| | Posted on Sunday, June 13, 2004 - 08:02 pm: |
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I was daydreaming wishfully that with DOHC, four valves, and some lightening of piston/crank, we'd see a higher redline. I don't know what stroke the race bikes are running, just assumed it was same as the 9 and they'd bored the tar out of it! Either way, to get too much more power on the street bike they're going to have to spin it faster aren't they? |
Sammigs
| | Posted on Sunday, June 13, 2004 - 09:02 pm: |
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XB's have roller lifters, but don't have roller rockers.(stock that is) |
Johncr250
| | Posted on Sunday, June 13, 2004 - 09:22 pm: |
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Well that is true about the guzzi`s.
I have been hearing and seeing pictures about the MGS-01 for about 2 years now, with no sign of a road going model yet.
Well, when the Guzzis actually show up to race we'll see how they do.
But just because Moto Guzzi doesn`t race a motorcycles doesn`t mean they don`t produce a good performance bike. |
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