| Author |
Message |
    
Easyrider
| | Posted on Monday, March 07, 2011 - 01:58 am: | 
|
Fresnobuell, that depends on the type of exhaust |
Ratsmc
| | Posted on Monday, March 07, 2011 - 12:26 pm: |
|
/quote{stacks provide a smoother passageway for air, particularly at high volumes. The 'pinch point' (air entry) is wider and further removed from the throttle bodies, offering better flow characteristics (at high volume). In theory, you get more air faster to the throttle bodies}
Actually, velocity stacks are intended to lengthen the intake tract to take advantage of the positive and negative intake pulses caused by the opening and closing of the valves. At specific lengths the negative pulses "suck air into the tract increasing the volume of the intake charge. More air=more gas=more power.
It is similar to scavenging on the exhaust side.
It should be noted that velocity stacks only provide a boost within a specific RPM range. You can alter where that range is with the length of the stacks but it isn't very broad.
That said, well-tuned velocity stacks generally make the whole range feel stronger. |
Fresnobuell
| | Posted on Monday, March 07, 2011 - 03:48 pm: |
|
Easy,stock exhaust. |
Easyrider
| | Posted on Tuesday, March 08, 2011 - 12:12 am: |
|
Fresno,
You can see in the graph above, what happens, when using our tune and Intake stacks.. Blue line is stock, red line is with tune and stacks. This is the minimum gain, when having a engine that is maintained well, and is in a good condition. |
Ratsmc
| | Posted on Tuesday, March 08, 2011 - 12:22 am: |
|
I think what he is asking is what are the stacks alone worth in hp?
Essentially, is this a $140 (stacks only) upgrade or is it $590 upgrade (stacks plus tune) |
Trider
| | Posted on Tuesday, March 08, 2011 - 09:49 pm: |
|
Ratsmc- Actually, no. And yes. Just not here. These stacks are short. 'Tuning' them to intake pulse frequencies (that's a fairly narrow rpm band also) would most certainly require stacks longer than what would fit in the air box.
Like with most all aftermarket stacks designed to go into an OEM airbox, all these likely do for our purposes is provide better air flow characteristics. |
Ratsmc
| | Posted on Tuesday, March 08, 2011 - 11:11 pm: |
|
quote:Ratsmc- Actually, no. And yes. Just not here. These stacks are short. 'Tuning' them to intake pulse frequencies (that's a fairly narrow rpm band also) would most certainly require stacks longer than what would fit in the air box.
Right, I actually asked about that when these were announce. The shortest length I could come up with that would make any usable increase in power was a little over 3 inches while the biggest usable increase came at something like 6-7 inches which is, of course, impractical given the size of the airbox and filter.
Improving airflow sound a little suspect. I could imagine that maybe this could be the result controlling turbulence but I'm still not sure how much benefit there would be.
All of this supports the request for dyno charts with and without the stacks which, t this point, I don;t believe we've seen.
I'm not going to say I don't believe there is some value in the stacks as I believe Twin knows what they are doing. However, I'm not willing to drop that kind of coin on something without any evidence (even theoretical) that they can provide some value.
It might be a matter of exchange rates but a pair of velocity stacks are usually half the price. |
Easyrider
| | Posted on Tuesday, March 08, 2011 - 11:18 pm: |
|
Read this article careful, and you find all our sheets dyno's before, after and different lenght and data: http://www.twinmotorcycles.nl/artikelen.asp?cid=6& aid=76 |
Trider
| | Posted on Tuesday, March 08, 2011 - 11:31 pm: |
|
Yes, at least 3" sounds right, but likely longer like you said. The air flow question is not about controlling turbulence so much, but more about providing a smooth entry and hopefully a better opportunity for a flow stream to develop. It's the pressure created by that flow stream you are hoping to tune by adjusting the length (more length = more even flow pressure- to a point).
I plan on doing before and after dyno pulls when I put on the pair I bought. I'll do it on the same day, same dyno. I know someone else that is planning to do this also, so hang in there. We'll hopefully have some numbers soon.
As far as the cost... yup. Exchange rate does not help... |
Trider
| | Posted on Tuesday, March 08, 2011 - 11:38 pm: |
|
Easy- you guys obviously did some testing with some good controls. I'm looking forward to trying them out soon! |
Ratsmc
| | Posted on Wednesday, March 09, 2011 - 12:58 am: |
|
Easy, I think I'm trying to get the answer to my first question: are the stacks just a component of a $590 upgrade or do they provide some value on their own?
Like I said, I don't question you guys and your ability to tune these bike, I'm just trying to figure out who should buy these things? The guy with the stock bike or the guy with an aftermarket exhaust and E-B_R ecu or only for someone with your tune? |
Fresnobuell
| | Posted on Wednesday, March 09, 2011 - 01:01 am: |
|
This is the minimum gain, when having a engine that is maintained well, and is in a good condition.
Ok so give us an idea of what a "minimum gain" is in numbers. I don't know how many times or different ways this question can be asked? Please don't refer to the dyno charts as I think those are suspect. From everything I have learned about stacks, you might get a pickup over a narrow rpm band, but not all over the rev range as your chart suggests. |
Easyrider
| | Posted on Wednesday, March 09, 2011 - 01:10 am: |
|
Rat,
That all depends how you want to look at it.
There are people who already have our tune, they can get a free online update for the stacks from us.
There are people that have already a good Erik Buell Racing tune
There are people that will tune there own bike
There are people they have nothing yet and YES in that case it is a perfect moment to buy the stacks and our tune.
Fresno,
there will be some dyno results soon posted i understand from other buyers, lets wait on that and see what they say. A big part of your question is depending on filter, exhaust and tune. Whatever I say, can be different then the upcoming dyno results.. |
Ratsmc
| | Posted on Wednesday, March 09, 2011 - 01:55 am: |
|
Easy, I'm really not trying to put you on the spot here but your site isn't really clear. Or maybe it is but I am looking for a different answer.
It might be a language issue but your site doesn't really "sell" the products you offer. You definitely make a strong case for buying your complete package but not many owners are going to do that. You might want to consider publishing the value of each component and whether it is a good purchase on its own.
Just my thoughts. |
Fresnobuell
| | Posted on Wednesday, March 09, 2011 - 03:42 pm: |
|
To add on that, unless it's been revised relatively recently, I saw several discrepancies as well. It would start off with a tune, then a few lines or paragraphs later it wouldn't have a tune. Very confusing and hopefully a language thing as Rat wrote. |
Trider
| | Posted on Wednesday, March 09, 2011 - 09:52 pm: |
|
Tonight I asked my local Harley/Buell shop about a couple before and after pulls for my Buell stack install. They're going to strap up the bike (Barker Exhaust & Erik Buell Racing Barker ECM), get a base dyno pull, install the stacks right then and there, and then pull it again. The owner is a well versed and experienced Bueller who is very seasoned in making real power, and I think he is looking forward to trying out the stacks as much as I am.
More importantly, he can ride the bike and help discern if the the increase is more visceral and seat-of-the-pants-feel than it looks on paper (that's my guess and more important to me than a curve of ink on paper). Since a dyno does not measure time, I'm wondering if any increase may actually feel greater than it looks. He's a retired road racer and FT bike mechanic with a great shop and state of the art dyno booth, so I'm thinking he'll do a solid job eliminating as many variables as possible.
I'll take it over there in a couple weeks and start a new thread. |
Cowboytutt
| | Posted on Wednesday, March 09, 2011 - 10:04 pm: |
|
Fireman Jim has asked me to come down to JTS Performance in Sonoma with my stacks where we will also put it on a dyno and hopefully do some ride comparisons as well. Just waiting to get my new stator on. The "seat of the pants" feel is QUITE noticeable if you ask me. My understanding is that the 'stacks increase laminar air flow. -Tutt |
Trider
| | Posted on Wednesday, March 09, 2011 - 10:14 pm: |
|
Yes- that's the idea. If a flowing stream of air has a straighter path, laminar flow increases do to lack of friction nearer the middle of the stream. |
Blake
| | Posted on Wednesday, March 09, 2011 - 11:01 pm: |
|
>>> Since a dyno does not measure time
That is the one thing that a dyno does indeed must measure. It measures the elapsed time for each rotation of the drum.
Intake optimization can make a difference, but don't expect the same magnitude as with a performance exhaust.
The only thing that won't show up well on the dyno is throttle transition performance and part throttle performance. But at WOT, if it doesn't show on the dyno, it ain't there. |
Easyrider
| | Posted on Wednesday, March 09, 2011 - 11:11 pm: |
|
Blake, What do you excatly mean when you say does not measure time ?.
Do you mean how fast it is taking to go at wot from 2000 until 11000 RPM?.
Oke Rat and freso..
You guys want to see.
Stock exhaust mounted, stock ecm?.
stock exhaust with tune
----
----
----
---
stock exhaust stacks mounted with the TM tune
what is in between. |
Father_of_an_era
| | Posted on Wednesday, March 09, 2011 - 11:16 pm: |
|
Yup, the seat of the pants is where the fun lies (huh, not in the sexual sense. lol)! Hopefully I will have my stacks in a few days (thanks to Andy and Tym) and I will feel the difference first hand. I will post the results either way and let you all know. |
Trider
| | Posted on Wednesday, March 09, 2011 - 11:17 pm: |
|
{The only thing that won't show up well on the dyno is throttle transition performance and part throttle performance}
I guess that's what I meant- thanks for clarifying. The transition time between roll-on and WOT is not measured, but that's where you'll feel it nonetheless. |
Blake
| | Posted on Wednesday, March 09, 2011 - 11:36 pm: |
|
Dris,
That was Trider. I was quoting him. He was meaning the throttle transition performance is tough to see on a typical dyno. |
Ratsmc
| | Posted on Wednesday, March 09, 2011 - 11:36 pm: |
|
Easy, thanks for not being annoyed by my responses and questions.
I guess what would help most people is a simple 'before and after'. Essentially, a couple of different set ups with an without the stacks. In particular, a stock with and without the stacks would be helpful.
BTW, I am sending you a message on a different topic. |
Easyrider
| | Posted on Wednesday, March 09, 2011 - 11:43 pm: |
|
Oke Blake,
rat,
It is important to get this wright also for other tuners.. do the runs from 1500 RPM. till redline. NOT HIGHER RPM.
'before and after'
stock bike stock exhaust, no stack no tunes
then compared to
stock bike stock exhaust, WITH stacks no tune.
That is 1, what else... |
Ratsmc
| | Posted on Thursday, March 10, 2011 - 12:04 am: |
|
Dris,
I think that and before and after with the whole stage 1 setup would be plenty for people to make decisions on. |
Easyrider
| | Posted on Thursday, March 10, 2011 - 12:14 am: |
|
oke, i need to wait until a customer brings the bike then... |
Kinder
| | Posted on Thursday, March 10, 2011 - 01:05 am: |
|
Dries, can you also post what type of fuel/ octane you are running these bikes on?
I think people forget that you have access to much higher octane fuel over there. I mean isn't 93 low grade there?
Also I think this was one of the first posts on this topic.
http://badweatherbikers.com/buell/messages/290431/531402.html?1263947812
(Message edited by kinder on March 10, 2011) |
Easyrider
| | Posted on Thursday, March 10, 2011 - 01:17 am: |
|
always the lowest i can get 95 octane.. |
Blake
| | Posted on Thursday, March 10, 2011 - 11:38 am: |
|
That being the "research" octane number (RON), where here in the States we see the "pump" octane number (PON). Then there is the "motor" octane number (MON)
The USA and Canada use PON = (RON + MON)/2, which is an average of research and motor octane numbers. Europe uses the research octane number; to clarify, Dris' 95 RON is equal to the USA's 91 PON.
Octane Ratings Comparison| USA (PON) | Euro (RON) | | | | 87 | 91 | | 89 | 93 | | 91 | 95 | | 93 | 98 |
|
Fresnobuell
| | Posted on Thursday, March 10, 2011 - 11:55 am: |
|
Not sure why octane would be a factor here unless the stacks raise compression. If they do, sign me up for at least one pair!
The transition time between roll-on and WOT is not measured, but that's where you'll feel it nonetheless.
Now this makes sense. So where is the tradeoff? Usually in these scenarios if you improve something, it comes at an expense elsewhere. Variable length intake stacks were all the rage for a while. |
Kinder
| | Posted on Thursday, March 10, 2011 - 12:03 pm: |
|
Maybe its different for bikes but with cars octane can affect how much you can push timing with affects power production. Just want to be sure we are all on same page. 
Fresno; You are right that stack length will affect when and where power will be. The thread I posted talks about how length of the stacks moved power around. They settled on the size that Dris sells because the low end loss was minor and made up for in the curve as I recall. |
Fresnobuell
| | Posted on Thursday, March 10, 2011 - 01:00 pm: |
|
Maybe its different for bikes but with cars octane can affect how much you can push timing with affects power production.
Good point about the tuning aspect, but I have the Erik Buell Racing tune and don't plan to change...just trying to get an straight up evaluation of these stacks.
Again, I had a source we would all consider reliable indicate after testing 3 variations of intake stacks the best they could do is add 1-2 HP on top at the expense of narrowing the power band. Just didn't make sense...maybe Easy is doing something different and if he has indeed found something, I am all in! |
|
