| Author | Message | ||
     Buckinfubba |
well here ya go. Its a very spiffy looking piece. fit on perfect very easily. did the test on my bike at tilley's yesterday and heres the results. Nothing nada no change at all. the power curves mirror each other to the point where if posted you would have to squint your eyes to see the feww spots where is different at all. sorry all are plans were dashed. but there the balloon popping. but I will add this my airfilter had really gotten dirty as I hadn't cleaned it in about 8 thousand miles. so I dynoed it first with dirty air cleaner,drummer, race ecm, stock stack. 79.9 hp. then I cleaned it and re oiled it all that good stuff. then I did the first baseline dyno with the stock stack. 83 hp on a 9r. so yes normal maintance is a good thing. and air flow is a big thing. so now my nine has 83 hp at the wheel ....at least sunday it did. I had spooky here as a witness to all this if no one wants to believe me. He also got a lesson in how a manufacture of parts could manipulte a dyno run just so their products work better. what I mean by this is we could have used the dyno run with the dirty airfilter and stock stack and compared it to the dyno with the aluminium stack with the clean filter and it would have looked like the stack was good for 4 hp gain. same day same bike same dyno same guy running the dyno. so anyway long story short the design that I tested did not change a thing. Brian Tilley hd/buell buckinfubba@hotmail.com | ||
| Aaron |
You're absolutely right on the ability to manipulate dyno results to suit an agenda. I could show you 100 other ways to do it, too. It comes down to the honesty of the person doing the testing. Even when the operator is honest, repeatability often requires careful attention. Especially when you're looking for potentially very small differences. Things move around on their own, you get a heat soak effect, etc. Gotta control the variables as best you can and do a lot of A-B-A kind of stuff. | ||
| Buckinfubba |
yep...and yeah you probably could show me a bunch of other ways. and your right honesty is everything in this kinda stuff. | ||
| M1combat |
So.... What's the next design Jerseyguy?? BTW Brian... Did it SOUND cool? | ||
| Bads1 |
So I wonder what Cory's stack will do.Seeing some guy said Jersey stole the idea and used it to his benefit.But who cares really.Jersey made a nice piece and I wonder if he changed some things on it,it may work better.It certainly didn't hurt the performance any. | ||
| Buckinfubba |
m1 what do you mean did it sound cool. I wouldn't know I ride with ear plugs and in the dyno room I have on hearing protection also. | ||
| M1combat |
I was just trying to keep the glass half-full instead of completely empty. What I meant though is - Did it sound cool? Any difference? If not, cool. If so, great. If you can't tell, neat. Just curious. | ||
| Buckinfubba |
couldn't tell... | ||
| Bads1 |
Bubba I think M1 means did it sound like a V8 when you take the air cleaner lid and put it back on up side down | ||
| Aaron |
I once read an article once wherein the author tried to show a small improvement on the dyno from a snake oil device. But he made a critical mistake: he detailed his procedures in the article. I could tell from reading them that he didn't understand how a motor changes and responds differently as it heats up and and how it shows up on the instrument, because his testing procedures set up the ideal conditions to get fooled by the heat soak effect. And then he didn't go back and retest the baseline configuration, so he didn't catch his mistake. Another time, a guy wrote to me claiming how he found some power with a Krank Vent device. I asked him about his test procedures, and he told me he tested the bike, then unhooked the breather from the air cleaner and put the Krank Vent on it and tested it again and voila, 2 more hp. He had inadvertently changed 3 things: removed the blow-by from the intake stream, created a new path for air to go into the airbox, and attached a Krank Vent. His conclusion was totally invalid, but he had no clue. Sigh. I've gotten to the point where I get really skeptical anytime anyone tries to show me an improvement on a dyno sheet from some device. Unless I stood there and watched how it was done. Pipes, cams, carbs, heads, sure, they all show up on a dyno sheet bigtime, although they can sure as hell move you backwards if the system isn't matched. But gimmick devices, virtually never. Anytime I see a minor improvement from something that I don't expect to do anything, I'm so skeptical that I'll sit there and go back and forth between them to prove it to myself. But it happens rarely. Last time it happened was with single-fire, I was shocked because I had tested single fire numerous times and never seen a thing. But this bike had set up the conditions to allow the single fire to help. I had to go back and forth four or five times before I convinced myself. Not saying any of this relates to this velocity stack. Intake tract length and shape most certainly does affect the dyno sheet. But as I understand it, this one mimicked the stock piece? If so, I wouldn't expect it to do much just because it's a different material. Change the length, then you'll see a difference. Pressure waves travel back and forth in the intake system and when you change the length, you change the timing of those waves. | ||
| M1combat |
BadS1 - That's pretty much what I was asking. I don't think I'd spend any money for the change in sound anyway, but was just curious. | ||
| Azfirebolt |
The stock stack is soft rubber and flexes easily. Thinking that a solid stack might be an improvement for air flow is something that buellsandblondes and I talked about. You still out there Ed? Anyway, nice attempt Jersey. Bubba, you are the Buell God! 65 f getting ready to ride home! | ||
| Jerseyguy |
OK guys, there you have it: "fair balanced and unafraid". I completely trust Bubba's ability to do the test properly and to be objective - that's why I asked HIM to do it. Thanks Brian. Its quite conclusive that the ovality and lack of flatness of the stock rubber stack do not hurt the performance of that design. I also mirror polished the inside of the aluminum stack to make the boundary layer as small as possible. Alas, to no avail. Congrats to the Buell engineer who decided to use rubber for the stack. Well, it's back to the drawing board as we geek engineers say. I have another design which I'll post tomorrow from my office when I get a moment. You can all offer your ideas if you like. I'll probably go through a few iterations but I have to add that at $300 to $400 a pop for a one off it gets kind of pricey. Aww, what the hell, I love this $h1t! Steve  | ||
| Rocketman |
Aaron is your offer of dynoing my 'boat anchor' still open if I bring it across? Rocket | ||
| Court |
I will say one thing, if you want to keep that "glass half full" thing going. CONGRATULATIONS Jersey Guy! You did as well as Buell. Trust me on this one, the STOCK STACK was no a random hit & miss choice. You produced a stack that equalled what some pretty fart smellers, who were being paid to do it, produced. Buell doesn't just slap parts together, cross their collectice fingers and hope for the best. I would also like to add that your attention to detail, insatiable curiousity, willing do take action and workmandship make you a true ELF. Besides, regardless of what the stack does, I enjoy the honesty and candor of this conversation. Pal here in NYC just got an XB this weekend....he's anal retentive and I'll bet he'd be a candidate for an aluminum stack.  Thanks Bubba! | ||
| Spooky |
Steve, I have one thing to say, You did one hell of a job on your stack. Fit and finish is top notch. Eric  | ||
| Dynarider |
You will se BS dyno shootouts all the time in the mags. They will have a headline screaming something like "Dyno tested drag pipes!!" Or maybe an ignition or maybe even Nology wires They will take a bone stock bike, & throw on a carb, some heads, a cam & then they will make some goofy assed claim how the pipes or whatever was good for X amount of hp, when the truth is they have no clue where the hp gain came from. Hell they could have punched out the stock baffles & added a different filter & gotten the same numbers. | ||
| Bads1 |
Jersey is there anyway you could put some type of a spacer at the bottom of the stack to change its height???Or maybe a couple different sized spacers to try.Maybe that wouldn't be so expensive then to start all over again.Modify the part you made.I don't know just my 2 cents worth. | ||
| Bads1 |
I know that you can put spacers intakes of cars and get results why not your stack??? | ||
| Dynarider |
Those intake spacers for cars actually go under the carbs & increase the manifold length, you can go with a 4 hole version or an open one for different applications. On a car that might be putting out 300hp those stacks actually add very little hp. On a bike thats doing 70-80-90 hp the results would be negligable at best. Adding a spacer to that stack most likely wont do a damn thing. | ||
| Bads1 |
Dyna,Aaron just posted that changing the height of the stack would in fact change the dyno.Whether it would be good or bad that remains to be seen. | ||
| M1combat |
Another reason to add a spacer under the carb of a car is to keep the carb temp lower thereby cooling the A/F mixture a little creating a better/more dense charge... You can polish the underside of an intake manifold for a bit of a gain as well. I would imagine that one could find intake manifold to head gaskets that are both gaskets and insulators. Granted, all this is worth extremely little until you are already pushing say 700HP out of say a 351-427 cubic inch engine, and even then, you might get 5-6HP. It all adds up though... Cold intake = good hot exhaust = good | ||
| Aaron |
Intake tract tuning is the process of timing pressure waves such that they help cylinder fill. Pressure waves are travelling up and down the intake tract and the idea is to hit the chamber with a positive pressure wave as the intake valve is preparing to close. Hitting overlap with a positive wave can help too. The waves travel at a pretty constant speed regardless of the engine's rpm, so they're only going to be timed right during an rpm window. There are ways to calculate intake tract length but there are some variables that are very difficult to characterize. So the simple rule-of-thumb formulas have some error. The most accurate way to figure it out is empirically. I use cardboard and duct tape  | ||
| Dynarider |
Aaron, when you refer to intake tract, are you simply talking about the length of the actual intake manifold...ie the area directly under the carb or FI & attached to the heads, or are you also including the air cleaner setup, velocity stack, etc etc? In Buells case the velocity stack was designed with air flow & hp in mind so I doubt..but cant dismiss entirely...that increasing the velocity stacks height & keeping it within the cover would gain any appreciable numbers. | ||
| Easyflier |
Dyna, I'm thinking that changes to the intake tract might not [have a great] effect [on] max HP but can affect driveability. Personally I'd give up 1 or 2hp at the top end for a mid range that pulled like a freight train. This has gotten me to thinking about Brians perforated airbox mod. Initially I thought that it was all about getting more needed air for more power but in hindsight the 3/8 holes probably had an influence on the pulse so it was more than just making more air available. edited by easyflier on February 03, 2004 | ||
| Aaron |
 The effect of changing intake tract length. The Forcewinder adds a little to the intake length compared to an open carb throat and the window where you get some ram effect moves down slightly. Easier to see in the torque curve than the hp curve because a torque curve is a picture of the cylinder fill. | ||
| Martin |
so why not have a moving-length stack? You could use the redundant motor from your disconnected exup valve on 12s. I's like to think that it would even 'actuate' at the right time. MV (I think) have a system where there are two velocity stacks inside one another. the inner stack gives a longer tuned length and then slides out completely to leave a shorter stack for top-end. Naturally only a completely variable length system can better this. Once again you are looking for the best compromise for your chosen application, hence the duct tape and bits of tube, which I bet have a place in Erik's own workshop, even after all the computer modelling. The intake charge-heat discussion explains the Hillbilly FAST mat, but the spacer under the carb mod on big V8s also increases volume in the plenum chamber which is not really a feature of bike engines on the downside of the 'Butterfly'. Now bring the V-Max into the equation and the phenomenon of 'stand-off' contained in airboxes with big cylinders and the way a four-cylinder engine resonates at twice the frequency of a 45degree twin, not to mention the out of phase nature of the uneven firing pulses and this thread couls run and run, even without the Atkins diet effect on HP. | ||
| Buckinfubba |
aaron Thanks for jumping in on this you know alot more on this than I do.It is greatly appreciated. azfirebolt I am far from a buell god. Just a guy willing to see if something works. and I work somewhere where I can test some stuff. easyflier That hole thing in the airbox was not my Idea. I don't know whose it was but I got the info from skully. now the 12 airbox lid....I will take credit for that since I kept getting in trouble at the factory on the tour for crossing the big yellow lines and diving into a box that had the lids. and then pestering henry duga and anybody else to see if it would work. and them not be able to tell me because they are not allowed to say. so I think maybe I am just a Buell disciple.... | ||
| Jerseyguy |
Now we are getting somewhere. You men have alot of collective knowledge. If we can come up with a design that has scientific merit and some empirical art, I can make it happen. I'm not just talking about some guesswork like: some guy said shorter is better or my cousin Vinny said a rolled edge will flow more. It seems obvious that there is much more here than a velocity stack, but it is one of the things that we can rework to possibly flow better with the rest of the intake system. Aaron - I've read about intake tract length tuning on car sites. You can measure the length from the intake valve through the stack and also calculate a theoretical length, but it seems much more complex than that. Its an area where experimentation and art come into play. Bads - The height of the stack could actually be raised around .25" by clamping it not fully seated in the throttle body. This pushes the trumpet end up too close to the airbox lid I think. Here's an issue to consider. Imagine the area of a cylinder created by the top if the stack and the inside of the lid. This is how the air enters the stack. That area is only around one half of the area of the circle created by the OD of the top of the stack (7.87 in^2 vs 14.2 in^2). I don't get this. The closeness of the lid creates a restriction, yet the 12's airbox lid improved HP. Maybe someone can explain this. I can also cut the stack a little shorter if there is any real reason to do so. Martin - interesting idea but difficult to implement, especially on a 9. Steve | ||
| Jerseyguy |
I solid modeled the gasket and K&N to show how this all fits together. Notice how Buell made a concerted effort to stuff the tit down the mouth of the stack (sorry ladies) which restricts the airflow. My bad - see the next post Steve\ edited by jerseyguy on February 03, 2004 |
