| Author | Message | ||
     Ralph |
Okay Blake, I figured it would be best to seperate this from the other boards. Lets get one thing straight from the very beginning, I don't know squat  Hm, where to start....how about the at the bottom and work up? Rods, knife and fork. I don't know what else to say. The weakness inherent in this design is obvious. Single crank pin. At "high" rpm the single crank pin allows the fly wheels to seperate. Not a big deal until you realize that as the fly wheel "tilts" it is no longer running true in the bearings. I'm looking forward to seeing how the new motor copes with that problem. Mostly I would think by dropping weight. Will that solve the problem? I doubt it. With this motor being pushed as a "rever" it will be reved without mercy. We'll see in a year or so. Piston length is very limited. Pistons are very short, otherwise they will hit each other at the bottom of their travel. Intake, oh lordy. There isn't enough room to shove anything in there! The intake runner (in a perfect world) should be as straight as possible. Ain't gonna happen with the current set up. Sorry, the Firebolt suffers from the same deal. Only difference is from the top rather than the side. Valve train. "Train" is a damn good word for it! The only thing missing is the kitchen sink. Four, count 'em, four cams. All driven by gears which are not only loud unless fitted precisely (two words that do not mean easy assembly for the manufacturer) but a drag on the motors energy simply driving all that extra mass. Now think about it this way, four times as many things to go wrong, cams, bearings, gears.... Loooooonnnngggg push rods. Almost as if designed to be heavy and flexible all at the same time. Could a guy put the cams and the valves any further apart and still think they have anything to do with each other? I believe that over head cams have proven them selves to be more effecient (slight sarcasm can be noted in that last statement). Seemingly the only thing holding Buell away from OHCs is the weight of history (Harleys history at that). In an all new bike like the Firebolt history is nothing more than a mill stone around it's neck. Two big ass valves is certainly the easy way to work things and see some performance. Problem is the larger your valve is the more "shadow" you have from it. Law of dimishing returns. Only way to beat it is to go with more valves with more efficient sizes. Witness Riviara's four valve heads. If a guy had to have a push rod air cooled motor, just absolutly had to, why not use Sputhes motor? Just as narrow, only slightly longer. Valve train is lightend by having a single cam in the valley of the cylinders. Geometry is kept realistic by turning the heads so that the lifters and pushrods are inbetween the cylinders. You have a push rod that is half the length so much easier to make it stiff but be really light in comparison to the ones in your motor. Better yet, ditch the crap and put the cams overhead. Intakes are kept straight as you want because the runners are not inbetween the cylinders but on the outside. Lastly (for now) vibration. You ain't gonna get rid of it in a 45. Pistons are both doing their thing on a common pin. Chain driven dampers? Sure. Just more power shoot to ••••. The name of the game is putting that power to the rear wheel, not making your ass feel good. Don't worry Blake, I'm not done. Just had to get that out. Not to bad for one short ride on my archaic motor'd Buell. Before anyone tells me I'm an ••••••• (that's fine, I can be) and should take a hike if I don't like these motors, you should understand I do. Tough. Just 'cause I like 'em doesn't mean I am blind to their shortcomings. Quite the opposite, the more time I spend looking at these motors the more challanges I see. At the same time I see how strong other motors can be. Strong both in power and reliability because they have dispenced with the weaknesses of this motor and moved on to platforms with less inherint weakness. Devoloping them rather than sticking with a motor simply because they are most familiar with that design. I have no doubt Harley/Buell engineers could spend a lifetime (many have) improving these motors. That may make the motor better than the last revision but means nothing compared to it's real competition - other motorcycle manufacturers. Please by all means tell me I'm wrong. I look forward to it. bighairyralph | ||
| Knutz1 |
Amen brother Ralph jeff | ||
| Blake |
Okay, my brain is now sore. You sure know alot for someone who don't know squat; not that knowing squat is a big advantage these days. I don't know squat myself, so I guess this discussion may end up being full of squat and we won't even know it. I guess we can only hope that the curious onlookers have been sufficiently warned. Maybe once we have hashed this topic to our satisfaction, we can get Mr. Dickey to review and comment on it's merrits. That'd be nice anyway. Okay, to your list of problems inherent in the HD 45 deg V-Twin XL engine configuration. What about the knife and fork rods is a problem? Not a significant reliabilty problem that I know. Likewise for the common crank pin. Actually shortening the crankshaft by using a common crank pin may significantly reduce the crankshaft length and as a result the deflection you refer to (as opposed to an offset, dual crank pin configuration). Intake runner length could be increased a' la Jap ram intakes. Is this really a constraining factor specific to the HD 45 deg V-Twin? The inline fours have the same problem don't they? Plus, I diasagree; I think the XB9R intake will be extremely efective. Piston height could be increased simply by using longer rods/cylinders. Like all piston engines, the piston/rod/cyl geometry is chosen for optimum compactness and reliability. So this isn't an issue specific to the HD 45 deg twin is it? I've always understood that the multiple cams are a significant advantage due to optimum/most efficient geometry wrt rocker arms and valves (no off axis angle, pushrods are parallel to valve stems). And gear driven cams versus belt/chain are surely no less efficient, especially versus the belt a' la Duc. Think about this... What is the real benefit of having OHC's driven by a relativiely flimsy/stretchy chain or belt compared to std cams driving the valves via relatively stiff hydraulic lifter roller-ended pushrods? I mean if your design intent (goal) is for a long stroking high torque engine that is thus rev limited more by piston speed than anything else, why would you want to add complexity and height where it is not required? It doesn't make sense to do so. How much HP is really lost flinging the pushrods around? Not much. I'm sadly not familiar with the Sputhe's engine. Is it a proven reliable and powerful engine configuration? Vibration is also a problem for thumpers, but I agree, it is a problem inherent in the 45 deg V-Twin powerplant. Not an insurmountable one though. It justs adds one more challenge for the engineers/designers to consider when they are designing/specifying components/connections that will be susceptible to vibration induced problems. I think some of the so-called weakness that you've listed are actually necessary compromises in support of the designers' governing intent, a simple, compact, torque laden engine. This is great stuff. My laptop battery is near dead, so I'll check back tomorrow and continue. Looking foreward to a successful web search of the Sputhe engine. Hey, look at that! Jeff has found religion! heheheh God bless you Knutz. Glad to see you joining in on the fun. You in NJ aren't you? You ever ride with TST? We're hoping to have one more ride before I leave the Garden State at the end of the month. You should join us. Blake (pleasedontmakemebringoutthemath!!!) | ||
| Tripper |
The OHC REVOLUTION motor (what a hokey monikor) is actuating 8 valves to 9K rpm. A 2200 rpm improvement over the current motor, 1500 more than the TwinBlast (EvolvedEvo?) which is using the latest "Nascar" spring technology. Why would you defend pushrods? That's crazy, I don't care to see any math thank you. By the way, did anyone notice that if you do the math on the Firebolt's engine, with ONLY 68 Ft Lbs Torque, that the new heads must breathe much better than the current engine, as it appears the torque does not taper off from a 3500 rpm peak as in current 1203 motors (stock ones anyway). Did Court put his test bike on Aarons dyno this weekend? | ||
| Ralph |
What about the knife and fork rods is a problem? Not a significant reliabilty problem that I know. At the current RPM range of Buells the knife and fork is okay. That's it, mere "okay". Spin the motor fast enough to make competetive power and the "fork" rod will show its weakness pretty quick. The current fix for this weakness is a beefy, stronger rod such as the S&S's I have in my S3. Don't forget though, that beef is more reciprocating weight. Exactly what's trying to break it in the first place. Likewise for the common crank pin. Actually shortening the crankshaft by using a common crank pin may significantly reduce the crankshaft length and as a result the deflection you refer to (as opposed to an offset, dual crank pin configuration). An offset pin crank could be cast as one piece. Hence use automotive type rods. Yes, the crank would be longer but it would also have two "pins" in different positions holding the fly wheels together. The "pins" would also be shorter, hence stronger, than current because of only needing to hold one rod rather than two. Intake runner length could be increased a' la Jap ram intakes. Is this really a constraining factor specific to the HD 45 deg V-Twin? The inline fours have the same problem don't they? Plus, I diasagree; I think the XB9R intake will be extremely efective. The main problem is not length (although that is a problem) it's shape. The intake manifold is bent at a ninety degree angle. Air is resistant to moving like that, for air/fuel mix it's just bad juju. Exactly how do the jap bikes suffer in the intake side, Blake? The inline fours have a carb (or injector) sitting at the very mouth of the head, there is no bend the air has to take after mixing. The length of their intake is also right, high rpm motors need a short length. It's our low rpm motors that suffer from a short intake. At five thousand rpm the intake length on motor should be nineteen inches. Lower rpm, like where the motor lives all day, would be massivly longer. Exactly how will the intake be different? The only difference I see is that the air moves down rather than sideways. Same path for all the air/fuel mixture cares. The ram air the japs use (and now Buell) is not a fix for intake length but rather a shot at pressurizing the intake charge for more power. Piston height could be increased simply by using longer rods/cylinders. Like all piston engines, the piston/rod/cyl geometry is chosen for optimum compactness and reliability. So this isn't an issue specific to the HD 45 deg twin is it? Longer rods would add to their mass, making them heavier and weaker all at the same time. A sixty degree or more motor has more room between the pistons making it a non issue. I've always understood that the multiple cams are a significant advantage due to optimum/most efficient geometry wrt rocker arms and valves (no off axis angle, pushrods are parallel to valve stems). And gear driven cams versus belt/chain are surely no less efficient, especially versus the belt a' la Duc. Four cams an advantage? C'mon man, where's the engineer in you? That's a massive waste. The four cams in this type of motor make for the best geometry in all Harley motors. But Blake, why does that make it the best? Do the cams have to lay on the side of the motor? A single cam placed in the valley would have the same superior geometry, less mass, less parts coupled with shorter pushrods, making them lighter twice over. Twice because by having a shorter rod it weighs less. Then to top it off it wouldn't have to be so thick because by virtue of being shorter it's stiffer. How much HP is really lost flinging the pushrods around? Not much. Bet? Okay, lose of HP directly? Virtually none. Indirectly because of the inability to rev, ya sure you betcha. As soon as you float the valves you loose HP. Bigtime. And once you do the springs are shot. A performance motor built on this platform will float the valves by the time the Duc is singing or the jap bike lopping around. Think 16,000 rpm, not 6,000. I'm sadly not familiar with the Sputhe's engine. Is it a proven reliable and powerful engine configuration? It's very cool. Sputhe has built what I think is the perfect pushrod air cooled twin. It is not very popular. The Harley guys are not interested because it's not a clone. Performance guys are not interested because compared to jap bikes, it doesn't, only when compared to a harley motor. Add to that the expense of a custom motor and you've pretty much got a motor that won't move massive numbers. As far as problems go, haven't heard of any. But then again Sputhe hasn't had the luxery of the number of beta testers Buell has had to learn from I think some of the so-called weakness that you've listed are actually necessary compromises in support of the designers' governing intent, a simple, compact, torque laden engine. I don't. bighairyralph | ||
| Ralph |
Trip, I'm lookin' for a set of those new heads to end up on my S1 soon as they come available. I don't doubt they'll bolt on. Mr. Buells penchant for things having more than one use has reared it's wonderful head once again. bighairyralph | ||
| Loki |
Just think of the positives.... -three fewer carbs to deal with(for those who still have one) I always hated synch time... -have you priced a bare head for the latest and greatest sportbike. WOW! -I can still work on/with this archaic thing hung in my bike. HD didn't miss the evolution train, they just fast forwarded it. All things travel in a big circle don't they.... -it does not take an engineering degree(or the entire weekend) to disasseble my bike to change the plugs. -some things I would like to see..... --three valve heads(Hnip did it with the VLX) --downdraft carbs(see the afore mentioned VLX) and stuffed between the cyls. Thanks BHR, you reminded me why I liked the set-up in the first place. I have nothing against the cookie cutter riders. I still own another archaic engined bike, an 82 GPz(KZ750R1). Loki | ||
| Ralph |
Loki, you'll notice at no point in time have I said the single carb on these motors is a weakness. When it comes to top power it would be. But when you consider ease of maintainence and the stunning mileage....it ain't no weakness. At the same time, I think there is room for a dual carb model that offers more perfomance. I don't think it would take an engineering degree to change sparkplugs on any bike. Why three valves? Just as easy to have four. Have you priced an after market head for your Buell or having them ported? WOW!!! HD didn't miss the evolution train, dude, it's more like a horse drawn cart Blake, here's a lousy picture of the Sputhe motor. This is from Dec '98 Hot Rod Bikes.  Sixty degrees. Semi-down draft carbs (what do ya think of that Loki?). The shiney thing where the timing cover would be is the oil pump. The heads are stock Sportster heads. bighairyralph | ||
| Jmartz |
Ralph and Tripper: With only a brief look a the Fireblast heads I can tell you they are one and the same as what is in our bikes. Yes the chamber has been reshaped and the breather bosses are undrilled (more unnecessary weight to carry) but if you look closely at the intake manifold and the intake ports, these are still pointing sideways and not up. The manifold while vertical is the same old "Y" units with an additional upward bend. This motor does not impress me, in fact, it is only a weaker form of the old motor with oiling and breathing improvements. I don't know what Buell is thinking but this twin Blast when its comes to power and acceleration will be blasted by the most other bikes with 1/2 its diplacement. Sorry Blake I feel your pain, I'm also a dedicated Harley and Buell man but frankly I'm sick of this poorly performing technology the company is trying to get us excited about. | ||
| Buellzebub |
i have to agree with Jmartz on this one... but i'm going to wait a while and see what the high performance version of the blasthead's numbers looks like [not gonna pass final judgement until AFTER i test ride this new beast]. worst case i spend big bux on my s1 engine [shorter stroke, bigger bore and maybe the fabled dual carb heads] i love my S1 | ||
| Ralph |
Jmartz, over all they may be the same old heads but I have a feeling they will perform even better than Thunderstorms. I have no doubt they'll hook right up. I disagree that it is a weaker form of the old motor. I have no doubt its been worked over seven ways from Sunday and many more improvements made than just breathing and oiling. For all of that, I feel it was a waste of time and effort. Improvement is not the same as updating. By the way dude, if you think the two undrilled breather holes make that much of a weight difference I'll drill 'em out for ya. Buellzebub (you devil you), I'm going to make a dual carb set up for the S1 this winter. I can't afford that high dollar stuff. Luckily I can afford a little time in front of the milling machine bighairyralph | ||
| Jmartz |
BHR: I meant weaker in the HP sense. And this distortion of the lower end that takes place at "higher" rpm can be improved with a lighter (but expensive) reciprocating assembly (Ti rods, tapered pins and rocky pistons). Buellzebub: A motor such as you describe (4 x 3.5) with Ti rods to allow 8500 rpm could produce as much 150 HP (rear wheel) providing those individual runner heads become available (and affordable) and a suitable cam can be found. NASCAR spins their motors to 9000 rpm with a similar valve train although they use short lived Ti valves. On a street motor Manley tells me they can go 30000 miles. Not too bad since we have to open these motors at around 25000 anyway to clean up the heads and get sustain peak performanc. Jose | ||
| Jmartz |
Ralph: Remember that the Blast displacement is 450 cc (vs 600 for a Sportster) and that its cyclider head(s) likely has smaller valves than the T-Storms. Jose | ||
| Tripper |
Jose, same bore, shorter stroke. Nallin has bolted TStorm heads to the Blast single. I think when we see the valve sizes we will not be disappointed. | ||
| Jmartz |
What could possibly make them flow better? Larger valves? We don't know.. CNC porting and seat blending? Not likely... Straighter intake ports? Definitely not... |
