I have read about head flow for years,But?????

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Re: I have read about head flow for years,But?????

Post by Warp Speed » Thu May 03, 2018 7:45 pm

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Last edited by Warp Speed on Thu May 03, 2018 7:47 pm, edited 1 time in total.

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Re: I have read about head flow for years,But?????

Post by Warp Speed » Thu May 03, 2018 7:45 pm

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Re: I have read about head flow for years,But?????

Post by Abbottracingheads » Thu May 03, 2018 7:57 pm

Airflow is not the be all end all in making power. You need air flow sure, but the runner size and shape and fuel handling is just as important.
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Re: I have read about head flow for years,But?????

Post by PackardV8 » Thu May 03, 2018 8:56 pm

cgarb wrote:
Thu May 03, 2018 7:00 pm
Different inches of vacuum....heads are flowed at 28" and I believe a carb is flowed at only 10" or less.
IIRC, 4-bbl carbs are rated at 1.5 inches of vacuum and 2-bbls at 3".
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Re: I have read about head flow for years,But?????

Post by Carnut1 » Thu May 03, 2018 9:01 pm

PackardV8 wrote:
Thu May 03, 2018 8:56 pm
cgarb wrote:
Thu May 03, 2018 7:00 pm
Different inches of vacuum....heads are flowed at 28" and I believe a carb is flowed at only 10" or less.
IIRC, 4-bbl carbs are rated at 1.5 inches of vacuum and 2-bbls at 3".
What do they flow a single throttle body at? Thanks, Charlie
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Re: I have read about head flow for years,But?????

Post by cgarb » Thu May 03, 2018 9:09 pm

I'm just saying that if you rated a carb at 28" the cfms would be a lot more than what they are rated at. What would the 300 cfm intake port flow at 1.5" of vacuum? The restriction is not at the carb because the intake isn't drawing all 8 cylinders at the same time. I didn't quite understand the point you were getting at regarding a 300cfm intake port and 800 cfm's at wide open. Not arguing I'm just trying to understand.

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Re: I have read about head flow for years,But?????

Post by modok » Thu May 03, 2018 9:55 pm

Sinc he has a supercharger it should be real simple.
The runners are short enough you can just go by size. The carb needs to match the draw of the supercharger.
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Re: I have read about head flow for years,But?????

Post by MadBill » Thu May 03, 2018 10:21 pm

Carnut1 wrote:
Thu May 03, 2018 9:01 pm
PackardV8 wrote:
Thu May 03, 2018 8:56 pm
cgarb wrote:
Thu May 03, 2018 7:00 pm
Different inches of vacuum....heads are flowed at 28" and I believe a carb is flowed at only 10" or less.
IIRC, 4-bbl carbs are rated at 1.5 inches of vacuum and 2-bbls at 3".
What do they flow a single throttle body at? Thanks, Charlie
1 bbls carbs were also rated at 3.0" Hg.
EFI throttle bodies are a relatively recent development (compared to 1 or 2 bbls.) and with no fuel mixing duties, can be sized for less WOT restriction, so regardless of barrel count (3 on the 1990-95 Corvette ZR1...) an aftermarket manufacturer would almost certainly rate them at 1.5" Hg.(20.4 H2O).
OEMs? Who knows unless they list it...
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Re: I have read about head flow for years,But?????

Post by Stan Weiss » Fri May 04, 2018 12:01 am

Warp Speed wrote:
Thu May 03, 2018 6:39 pm
Why does a port need to flow 300cfm, when the engine running full song doesn't pull 800 total?!?
Jay,
How much will that port flow in 3 Milliseconds?

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Re: I have read about head flow for years,But?????

Post by Warp Speed » Fri May 04, 2018 4:24 am

Stan Weiss wrote:
Fri May 04, 2018 12:01 am
Warp Speed wrote:
Thu May 03, 2018 6:39 pm
Why does a port need to flow 300cfm, when the engine running full song doesn't pull 800 total?!?
Jay,
How much will that port flow in 3 Milliseconds?

Stan
Kinda my point...........I think?!? Lol

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Re: I have read about head flow for years,But?????

Post by digger » Fri May 04, 2018 4:27 am

What's the size of the hole ...

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Re: I have read about head flow for years,But?????

Post by JohnsnsFord2@aol.com » Wed May 09, 2018 1:37 am

You need velocity
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Re: I have read about head flow for years,But?????

Post by user-23911 » Wed May 09, 2018 2:44 am

The CFM that an engine consumes at X RPM is one thing.

The CFM that a head flows at a certain no of inches water is something completely different.

As is the no of CFM that a carburettor flows at x inches Hg,

3 completely different things with nothing in common apart from "CFM".

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Re: I have read about head flow for years,But?????

Post by barnym17 » Wed May 09, 2018 6:39 am

Isn't the carb rated in inches of mercury vs cyl heads in inches of water (i.e. using manometer) the numbers would all have to be taken at the same depression, using the same measuring device to in any way correlate the cfm of the carb vs the port.

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Re: I have read about head flow for years,But?????

Post by barnym17 » Wed May 09, 2018 6:40 am

Sorry I just saw Joe mentioned the same thing I did.

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