How much does a stock 20V blacktop head flows?

onnaj
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How much does a stock 20V blacktop head flows?

Postby onnaj » Wed Jan 29, 2014 5:52 am

Hello,

I'm wondering (also for my exhaust choice) how much (in CFM) a stock blacktop head flows. Only mod i did to the head i have is a very light polish on the exhaust side, but nothing serious.

thanks.
Check my 4AGE 20V BT teardown, rebuild and transplantation over here --> http://club4ag.com/forums/viewtopic.php?f=7&t=3382

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yoshimitsuspeed
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Re: How much does a stock 20V blacktop head flows?

Postby yoshimitsuspeed » Wed Jan 29, 2014 10:38 am

That's kinda like asking how much a garden hose flows.
It totally depends on the water pressure of the water source, the size of the piping leading to the valve, whether there are any restrictions after the hose and so on.
We could guess with some degree of accuracy.
The 20v is pretty efficient in the higher RPM so let's guess a VE of 95%. .8L/rev x 8000 RPM = 6400 L/M x .95 = 6080 L/M.

onnaj
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Re: How much does a stock 20V blacktop head flows?

Postby onnaj » Wed Jan 29, 2014 11:22 am

I'm more looking for the flow in cfm. I thought that's a value that isn't depended on anything, it's just a fact about how much it could flow. I thought it was around 170cfm but don't know for sure.
Check my 4AGE 20V BT teardown, rebuild and transplantation over here --> http://club4ag.com/forums/viewtopic.php?f=7&t=3382

yoshimitsuspeed
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Re: How much does a stock 20V blacktop head flows?

Postby yoshimitsuspeed » Wed Jan 29, 2014 12:01 pm

onnaj wrote:I'm more looking for the flow in cfm. I thought that's a value that isn't depended on anything, it's just a fact about how much it could flow. I thought it was around 170cfm but don't know for sure.


No there are no such absolutes like that. CFM is cubic feet per minute. My calculation of 6080 L/M comes out to about 215 CFM.
Although that is just a guess the moral of the story is that there are plenty of variables that could change it even with the stock ECU and internals. Intake and exhaust will change the VE and that will change how much air your particular motor flows. A dirty air filter or clogged cat will limit how much the the motor can flow.
What exactly are you trying to figure out?

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onnaj
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Re: How much does a stock 20V blacktop head flows?

Postby onnaj » Thu Jan 30, 2014 12:36 am

I wanted to know to be sure if my custom exhaust would flow enough, but if i look over here: http://www.exhaustvideos.com/faq/how-to ... e-diameter then my setup will be sufficient for the stock flow.

I'm using only an OEM AE111 Apexi intake and have no other mods.
Check my 4AGE 20V BT teardown, rebuild and transplantation over here --> http://club4ag.com/forums/viewtopic.php?f=7&t=3382

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Re: How much does a stock 20V blacktop head flows?

Postby yoshimitsuspeed » Thu Jan 30, 2014 3:07 pm

I believe I said something along these lines in your last thread. If I remember right you are going with 2".
On a dyno you might be able to notice some loss in the low end and some gain in the high end going up to 2.25 or 2.5 however I think you would be lucky to notice it on a dyno. I definitely don't think it's worthy enough to fret over.
I don't know any forumlas off the top of my head but this comes from seeing various peoples experiences, reading and being involved in many discussions over the years. I think 2 or 2.25 would work great for your goals.

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Re: How much does a stock 20V blacktop head flows?

Postby LongGrain » Thu Jan 30, 2014 5:12 pm

onnaj wrote:How much does a stock 20V blacktop head flows?


all of them

burdickjp
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Re: How much does a stock 20V blacktop head flows?

Postby burdickjp » Thu Jan 30, 2014 9:28 pm

there was a graph here, but it was the wrong graph.
sorry.
:(
Last edited by burdickjp on Sat Feb 01, 2014 7:30 am, edited 1 time in total.
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onnaj
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Re: How much does a stock 20V blacktop head flows?

Postby onnaj » Fri Jan 31, 2014 12:49 am

yoshimitsuspeed wrote:I believe I said something along these lines in your last thread. If I remember right you are going with 2".
On a dyno you might be able to notice some loss in the low end and some gain in the high end going up to 2.25 or 2.5 however I think you would be lucky to notice it on a dyno. I definitely don't think it's worthy enough to fret over.
I don't know any forumlas off the top of my head but this comes from seeing various peoples experiences, reading and being involved in many discussions over the years. I think 2 or 2.25 would work great for your goals.


Thanks! I've read this ofcourse but i was just curious about the estimated flow so i could check it with the charts on exhaustvideos.com

@burdickjp: thanks for the graph!
Check my 4AGE 20V BT teardown, rebuild and transplantation over here --> http://club4ag.com/forums/viewtopic.php?f=7&t=3382

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oldeskewltoy
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Re: How much does a stock 20V blacktop head flows?

Postby oldeskewltoy » Fri Jan 31, 2014 5:49 pm

onnaj wrote:I'm more looking for the flow in cfm. I thought that's a value that isn't depended on anything, it's just a fact about how much it could flow. I thought it was around 170cfm but don't know for sure.


@ 28" probably closer to 160 cfm then 170
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Re: How much does a stock 20V blacktop head flows?

Postby burdickjp » Sat Feb 01, 2014 7:31 am

oldeskewltoy wrote:
onnaj wrote:I'm more looking for the flow in cfm. I thought that's a value that isn't depended on anything, it's just a fact about how much it could flow. I thought it was around 170cfm but don't know for sure.


@ 28" probably closer to 160 cfm then 170


At what lift and with what intake configuration? I haven't seen one top out under 170CFM.
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Jimmee1990
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Re: How much does a stock 20V blacktop head flows?

Postby Jimmee1990 » Sun Feb 09, 2014 4:08 am

At what valve lift though? Anyone with a spare blacktop head and access to a flowbench will be able to tell you.

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