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Just a guy with an SV1K
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If i was to do this would i need to get my PC re-mapped?

As DVS wrote, re-mapping could net you additional power. The neat thing is that my bike is otherwise very much stock, and I have not noticed any power losses during my commute to work (45 minutes these days). At least with the stock filter, I doubt the bike is running lean anywhere, or at least it certainly isn't pinging at all.

Next up is a TRE, and after that probably slip-on exhaust. I'll definitely get a PC III or a re-flash (TEKA etc...) for when I go beyond that.

I should probably snap a pic or two to show how all the parts went together for me. FWIW, I actually used a slightly smaller drill bit because on the first hole of the "2" of the 1-2-1 pattern. Only because I spaced the inside 5/16 hole a little too far from center. I don't think I hurt anything, since others have used smaller drill sizes to good effect as well.

It should be noted that the torque is pretty deceiving if you do all these mods straight from a stock airbox, or even if all you've done is yank the snorkel. In my commute I definitely had to restrain my urge to pass everything on the road, because early on I'd be flying up to cage bumpers before I realized how fast the SV was accelerating.

Prophet, Toronto is kind of on the other side of the country from where I'm at, but this time of year they seem to be enjoying much the same weather as we are out West. Just under 20 deg C and sunny for the most part. Good thing you're not going there in August though, the humidity from the great lakes is bad enough to kill LOL
 

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Moto-ST guys have already been instaling ram air on thair SV1000. There actualy was a modified tank for sale on ebay few months ago which I missed out on. It is a mod I will do eventualy because I'm not a big fan of all that real loud intake noise.
 

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Just a guy with an SV1K
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920 Posts
A quick update on these mods - my mpg went up from 32 to over 35 mi/us gal and I got over 120 miles to the fuel light instead of 105-ish. I didn't think I was playing nice most of the time, so it wasn't because I was babying it!
 

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Double Dumb Ass
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Sorry Prophet, I'm just getting caught up again. I have just read the whole thread again, and don't think these questions have been addressed, so here goes.....
With the dual length stacks:
I understand the theory that the longer stack helps bottom end and the shorter stack helps the top end but, if you have both stacks open at once why doesn't the engine just pull from the bottom "primary" stack? If it does that how could the variable lengths help the bottom end as the stack would only be working for the top end length?
Please answer these questions from an unworthy disciple, o great holy man!
 

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Discussion Starter · #225 ·
Ah, you must be refering to the zx6r type stacks. Where they are both open. Well the air at slower speeds (low rpm) will naturaly be less turbulant than air at higher speed. This will allow the longer stack to stabilize the incoming air and generate the air speed needed for that rpm. Air will flow from the lower portion as well at all rpm but it is not as great a flow until the intake air speed reaches (high rpm) the sweet spot and the air in the long path becomes to turbulent and unable to keep the demanded speed that the intake air will find the shortest path. That short path now becomes primary and has the needed speed to run the engine at optimum power. This is sort of a laymans terms explanation. I can go into more scientific detail if needed, but I think this is ok.
 

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Just a guy with an SV1K
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Nicely put, I thought. Question: how would these dual height velocity stacks work with the airfoils? Would they still be of benefit?
 

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Ah, you must be refering to the zx6r type stacks. Where they are both open. Well the air at slower speeds (low rpm) will naturaly be less turbulant than air at higher speed. This will allow the longer stack to stabilize the incoming air and generate the air speed needed for that rpm. Air will flow from the lower portion as well at all rpm but it is not as great a flow until the intake air speed reaches (high rpm) the sweet spot and the air in the long path becomes to turbulent and unable to keep the demanded speed that the intake air will find the shortest path. That short path now becomes primary and has the needed speed to run the engine at optimum power. This is sort of a laymans terms explanation. I can go into more scientific detail if needed, but I think this is ok.
Seeing as how I am a "layman" in this area, your answer was perfect for my needs.

Nicely put, I thought. Question: how would these dual height velocity stacks work with the airfoils? Would they still be of benefit?
Exactly what my next question was going to be.
Also, is there a reason for the non-concentric openings, or would the design benifit from having a tube inside a tube design, with the braces that hold the inside (smaller diameter, longer) tube forming the airfoil? (I know that sounds like gibberish, I'll try to get a drawing together to post up)
 

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Double Dumb Ass
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Ok so this is something like what I was thinking of.

1) Does it make sense?
2) What adjustments would be needed to make it work?
3) Is there a way (mathmatical or otherwise) to come up with the correct length for each diameter of velocity stack? or Is it just a matter of trial and error with lots of dyno runs?
 

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So if I am hearing this right the optimal modifaction would be 8 3/8" holes with some going across the center. I am struggling to get through all of this post and dealing with new and older info. I was wondering prophet if you could update the first post with a lower section of what would be the most recommended set up with one of the pics.
 

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Double Dumb Ass
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So if I am hearing this right the optimal modifaction would be 8 3/8" holes with some going across the center. I am struggling to get through all of this post and dealing with new and older info. I was wondering prophet if you could update the first post with a lower section of what would be the most recommended set up with one of the pics.
Having read through the whole thread, the pattern you want to use is the one pictured in post #196.
 

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Just a guy with an SV1K
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Also, FWIW, 3/8 will seem pretty big. In my case I ended up using a 5/16 bit as it was easier for me to space them out.
 

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Discussion Starter · #232 ·
Ok, so I am on a flight back from Toronto, Canada right now and thought I would answer some of the questions. First, the air foils would work in any aplication (even the K&N pods if I can get them in just the right spot). The best size and pattern for the STV drilling is 5/16 or one (32nds) size smaller, in the 1-2-1 pattern as mentioned above. Now the tube inside a tube technique was actualy tried by the F1 community (toyota to be exact) back in there first F1 appereance. They had the longer tube of smaller diameter inside the lager tube at 1.5 inches past the bell mouth. The stopped using this design halfway thru the season because, while it generated mass torque, the air become too turbulant and unpredictable. They tried to reposition the the two tubes, and the result was the same however. The dual stack set-up was later banned and deemed unfair for the cars that didn't have it. The two diameter tubes need to share most of the wall surface area in order to stabalize the air properly. The ideal set up is two have a single diameter with two bell mouth openings at different heights. So that is what I am after. I went to micheals before I left for canada and bought some styra-foam cylinders to shape my idea and then lay fiberglass over that to create my first test set. We'll see how that goes........
 

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So the height is more the issue than the diameter. That makes sense when trying to alter the velocity. I will work on another drawing and see if that is more like what we should be after. I realise that a simple drawing will not have all of the subtlety needed to truely get the most out of aerodynamics, but I have to feel like I'm contributing something to the thread.
 

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Just a guy with an SV1K
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Most definitely! I imagine the stack set Prophet is working out will look somewhat like the dual height fixed stacks you find on the 09 ZX-6R, but tuned to the SV of course.

2009
 

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Double Dumb Ass
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Ok, here is the new sketch.
Upper right = top view
Bottom right = cut away

So will that work better? I calculated the total area of opening for the cylinder, then spaced the stacks the right distance to maintain that same ammount of area between the upper and lower stack. Is that correct, or is there some funky airflow math that needs to be applied?
 

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Drat I hate it when I do that. HERE is the sketch
 

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Discussion Starter · #237 ·
yup, thats it. there is some more math involved in the hieght bit of it all, but basicly you've got it. its just slightly over the area of the throttle body on the bottom stack, and the same area on the top stack. i will get you the math soon.
 

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I don't know that I got everything right any way. I just went off of memory for the TB diameter and then used that for the height of each of the stacks. Looking forward to the exact numbers. Thanks for your efforts and expertise.:niceone:
 

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Well, finally got around to drilling the STV's. I didnt notice a big improvement, not that I was expecting to, but maybe some improvements. Then again, I didnt ride the bike much after the mod, just a jaunt to work and a little out and about. It didnt help me at the drag strip though, my best time was a couple tenths slower than my previous best time, then again, my previous best was my first time ever at the strip and today was lots of crap launches :lol: , so no real comparison there either.

Looking forward to getting a set of DL stacks and making some chambers though, I have high hopes for that mod.

Thanks for all the hard work Prophet!
 

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Prophet, I have done some more research, but almost everything I can find is about cars. I assume (yeah, yeah, yeah) that the principle is the same. If so from what I have found you would want the bell shape to be longer and gradual to cover a larger RPM range. Is that correct?
Also I have read a bunch about resonance and how that allows a greater amount of air to fill the cylinder. What I haven't been able to find is, ideally do you want the first harmonic, second, third, ect.... to be the one that hits in the RPM range you want the gain in? It seems like if you went a bit low with the first harmonic, you would still get benefit with the second, third, and maybe the fourth (although not as strong) in the rest of the RPM range. Is that the case?
 
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