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| Ideal velocity stack development; Attempt at making the best velocity stack design | |
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| Tweet Topic Started: Apr 13 2014, 11:10 PM (1,410 Views) | |
| Sam_Q | Apr 13 2014, 11:10 PM Post #1 |
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Sam_Q
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Disclaimer: this is to do with my business and the development of a product I wish to sell, so if it's not meant to be here then a mod is welcome to delete it. Thought people would find it interesting to see what I have been doing regarding some development work on velocity stacks. Recently I for the first time had the option to get velocity stacks made by being machined out of a solid billet of aluminium instead of the current way of getting rolled and then fitted into flanges. Due to material costs this was only feasable on the shorter sizes, the first batch is 50mm which is ideal for the RHD Corolla and Sprinter owners who wish to run slide on filters. They will also fit inside a blacktop airbox with a light shave on #4 and work better than anything else out there. Right so being machined I have the liberty of choice in designing something new. From previous research I knew that the ideal design was a long taper to a parabolic opening and a full curved edge. This also known as a expodential, elliptical or variable radius curve. This gives the highest net airflow out of any of the designs. Most of the velocity stacks on the market have a fixed radius rolled edge, this has the highest velocity on the inside at the end of the rolled edge at the transition before slowing down again further down the tube. The parabolic design however lets the air keep speeding up all the way to the opening face. More about the technical side of that here: http://www.profblairandassociates.com/pdfs/Bellmouth.zip Knowing all that I came up with this: ![]() Which I then had 3D printed along with a different design and a prototype exhaust mount alternator mount: ![]() I sanded these smooth and had someone nice enough to put them on a flow bench for me. Here are the results in order worst to best, of note the OEM stacks where checked on a different day so the results might be a little off. - Blacktop OEM: 320 - Silvertop OEM: 342 - HRC: 445 - IMEC: 483 - SQ model #1: 483 - SQ model #2: 489 All tested at 28 inches of water. Two things really surprised me about this- first that silvertop flows better than black when to me they look terrible and second how bad both OEM designs flowed. This explains why people pick up power even when running short stacks in the OEM airbox. Picking the better of the two and taking the chance at making a small adjustment to improve it further I gave the go ahead for a batch of both silver and blacktop sets to be made. This is when I was last at the machinist and only the outside profile had been cut: ![]() Next up is them getting the flanges cut. Once done I shall have them back on the flow bench, this time all at once. This is the part of my job that I love, I really look forward to how they turn out not just in flow numbers but how they look with a little bit of a polish. If people are interested I can post updates I don't get notifications of replies for some reaosn on here so there may be delays in me responding. Edited by Sam_Q, Apr 13 2014, 11:13 PM.
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| ales_000 | Apr 14 2014, 01:57 AM Post #2 |
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Stage 6
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Interesting stuff! Did you test the flows inside a standard/modified plenum at all? |
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| Sam_Q | Apr 14 2014, 02:37 AM Post #3 |
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Sam_Q
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No I didn't, this may sound silly but it never crossed my mind. When I get these finalised I am not likely to though as it's out of the ordinary for me to have someone who wants them for that kind of install and I would have to send the whole airbox and the stacks to where the guy is located in another state. Unless I have a few people who specifically want it. That said though I don't think it would that easy to hook up to the flow bench with the way it's set up. Edited by Sam_Q, Apr 14 2014, 02:38 AM.
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| Levin BZR | Apr 18 2014, 05:38 PM Post #4 |
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Great work mate! |
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| bigshark | Apr 22 2014, 12:10 PM Post #5 |
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Stage 6
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very nice R&D work!! I take it those are the flow rates (in m³ / min??). i cant believe how restrictive those oem stacks are! |
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| Sam_Q | May 3 2014, 12:39 AM Post #6 |
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Sam_Q
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thanks, by memory it was CFM Here is the final product: ![]() Blacktop on the left and Silver on the right. Turned out really nice. I won't do the final flow test for a little while yet. Here is one I modified to suit a blacktop airbox: ![]() This also shows how the flange is shaped around the holes. I would of liked identical flange styles between the two types but the price difference was real big. I also hate the idea of slots as I think it's primitive and can need adjustment. With this though I think I have the best of both worlds, they still locate true but only need the smaller diameter bar to be machined. I had a customer do some back to back runs on the road against IMEC and to my surprise he reported an overall power increase, particularly in the mid range. I wasn't sure if there would be a difference because the IMECs are actually really pretty good on the bench. So far this has been both the single most interesting and rewarding job I have done with my business. Being able to try and design an ideal shape and then getting them made me really eager to see the final result. It was the first time ever I was looking foward to polishing something! -Sam Edited by Sam_Q, May 3 2014, 01:37 AM.
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2:34 PM Jul 11