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Old 07-15-2009, 03:26 AM   #1
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Default Gains from a velocity stack on a turbo Honda

blox 4" velocity stack gains - Honda-Tech

He was using no filter and the stack (Blox 4") was directly mounted to the turbo.

It'd be interesting to see gains/losses w/ an arm/stack/filter.
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Old 07-15-2009, 08:55 AM   #2
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so you get like 5whp over 2000rpm from lets say $300 in fab work? Awesome.
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Old 07-15-2009, 10:25 AM   #3
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took the words right out of my mouth
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Old 07-15-2009, 10:44 AM   #4
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I cant zoom the graph to actually see wtf is going on, but it looks like there are only gain from 7.5-9K, doesn't help me much.
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Old 07-15-2009, 11:07 AM   #5
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Quoted from the thread
Quote:
Is there any speculation as to exactly what causes this bell make more power up top?
Clearly not an engineer.

Not sure why the guy had to spend $300 on it. With some creativity it should have been possible to do it for less.
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Old 07-15-2009, 12:00 PM   #6
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Quote:
Originally Posted by Braineack View Post
I cant zoom the graph to actually see wtf is going on, but it looks like there are only gain from 7.5-9K, doesn't help me much.
I don't think it's a function of the RPM but the stock piping diameter and the peak power.
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Old 07-15-2009, 12:14 PM   #7
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Yeah it has more to do with air flow rate and less to do with RPM. But for a given engine and tune, at WOT those two are tied closely together of course.
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Old 07-15-2009, 05:31 PM   #8
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Originally Posted by hustler View Post
so you get like 5whp over 2000rpm from lets say $300 in fab work? Awesome.
The Blox 4" stack is $30 on ebay.
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Old 07-15-2009, 11:41 PM   #9
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Quote:
Originally Posted by kenzo42 View Post
The Blox 4" stack is $30 on ebay.
so, the fab work on the bells is free?
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Old 07-15-2009, 11:53 PM   #10
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What fab work? It seems he just bolted the stack to the turbo inlet.
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Old 07-16-2009, 07:48 AM   #11
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Something about seeing the acronym Vtec, even if legitimate, makes my skin crawl.
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Old 07-16-2009, 09:18 AM   #12
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so are these idiots taking of the air filter and replacing it with the bell? In for "lol".
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Old 07-16-2009, 10:44 AM   #13
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Yeah I would not use one unless I put a large air filter on the inlet of the nozzle aka 'velocity stack'. They work, no doubt about it, but I am not about to rearrange my entire CAI setup for that small of a gain.
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Old 07-16-2009, 11:09 AM   #14
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there is merit to the bell inlet. air doesn't turn sharp corners.

but

no filter = dragster

and filter = reduced bell function

so ... draw your own conclusions.
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Old 07-16-2009, 11:14 AM   #15
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What you really have to do is make sure that the filter is atleast 1 Diameter away from the edge of the bell, and your surface area of filter media to inlet area is rediculously large. So a proper setup would be around 10 inches in diamater, and maybe 4 inches deep. Like a big carb filter. Maybe one of those extreme flows withe the filter media on top as well. Then imagine ducting?
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Old 07-16-2009, 11:34 AM   #16
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^^ Yeah exactly. No thanks, at least not on a street car.

There is no real magic to these bells. They are basically just nozzles with tapered reduction sections. The decrease in head loss (pressure drop loosely speaking) is well understood in the world of fluid mechanics and can be calculated.
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Old 07-16-2009, 11:54 AM   #17
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I had considered one of these Turbohoses AirRam & Velocity Stacks, Velocity Stack, Air Ram, Intake, Airram Intake, Turbohoses Intake because I "think" my current filter may be a restriction. I haven't hooked a vacuum gauge up between the filter and throttle body yet to see though.
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Old 07-16-2009, 12:55 PM   #18
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Quote:
Originally Posted by TravisR View Post
What you really have to do is make sure that the filter is atleast 1 Diameter away from the edge of the bell, and your surface area of filter media to inlet area is rediculously large. So a proper setup would be around 10 inches in diamater, and maybe 4 inches deep. Like a big carb filter. Maybe one of those extreme flows withe the filter media on top as well. Then imagine ducting?
I've always thought you could run an airbox with filter and that bell doo-dad on the inlet to the airbox and get more benefits.. never tested this theory though.
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Old 07-16-2009, 09:30 PM   #19
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Quote:
Originally Posted by y8s View Post
I've always thought you could run an airbox with filter and that bell doo-dad on the inlet to the airbox and get more benefits.. never tested this theory though.
I don't know on that, but if your trying to increase the discharge coefficient you can't choke the edge of your bell with flat edges, or your not going to accomplish anything. The purpose of the bell is to dramatically decrease pressure gradient DX,DY,DZ spherically away from the entry so that entrance velocity is decreased, and smaller eddys form around the neck point of the flow in the front of the pipe..
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Old 07-16-2009, 10:09 PM   #20
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Quote:
Originally Posted by TravisR View Post
I don't know on that, but if your trying to increase the discharge coefficient you can't choke the edge of your bell with flat edges, or your not going to accomplish anything. The purpose of the bell is to dramatically decrease pressure gradient DX,DY,DZ spherically away from the entry so that entrance velocity is decreased, and smaller eddys form around the neck point of the flow in the front of the pipe..
WTF? Can we get that in English please?
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