2000Firehawk

iTrader: (248)

Looking for flow at 28 if you got um. Pipe sizes 2.25" , 2.5" , 2.75" , 3" , & 3.5".
I tryed install university with no luck either <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />
Thanks,
Dave

Cody Brooks

iTrader: (2)

i think that i heard 3in flows over 2200 cfm. 2200 is as high as the flow tester will go. or so i'm told.

2000Firehawk

iTrader: (248)

2200 cfm... <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />
I found a thread where someone stated that 3" flowed 904 cfm... <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

Does anyone know... <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

Cody Brooks

iTrader: (2)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by 2000Firehawk:
<strong>2200 cfm... <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" />
I found a thread where someone stated that 3" flowed 904 cfm... <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />

Does anyone know... <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" /> </strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">i remeber seeing a thread stating that a 3in. dynomax bullet flowed 2200 cfm and that it was the same as a 3in. straight pipe. 2200 is as high as the flow tester goes so the exact number on it hasn't been found yet.

2000Firehawk

iTrader: (248)

I don't know about how Dynomax gets their flow numbers <img border="0" title="" alt="[Confused]" src="images/icons/confused.gif" />
They also claim that there mufflers with only 2.25" inlet/outlet flows 1100cfm... <img border="0" title="" alt="[Eek!]" src="gr_eek2.gif" /> If that was so, we would only need a single 2.25" pipe for our cars... <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />

Dave

2000Firehawk

iTrader: (248)

Ackattack,
Cool... <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />
Looking forward to your findings <img border="0" alt="[Fluffy]" title="" src="graemlins/fluffy.gif" />

Thanks,
Dave

jimmyblue

iTrader: (11)

I don't see any of these "flow numbers"
referenced to their pressure drop, so they
are pretty meaningless. Huff 100PSI at
the inlet and they'll all flow a shitload.

Ackattack

Using fluid mechanics, you could come up with a theoretical value, which would be pretty close to actual. I'd do it, but it's been awhile, and I don't have any references on hand right now.

2000Firehawk

iTrader: (248)

ttt <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

2000Firehawk

iTrader: (248)

ttt <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

LS1derfull

Dynomax flow tests at 20.4" of water the standard of industry that 4 barrel carbs are flown at.
I dont know what vehicle flow requirements should be for modded LS1 though.

Old SStroker

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by 2000Firehawk:
<strong>Looking for flow at 28 if you got um. Pipe sizes 2.25" , 2.5" , 2.75" , 3" , & 3.5".
I tryed install university with no luck either <img border="0" title="" alt="[Sad]" src="gr_sad.gif" />
Thanks,
Dave</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">The best number I found was 560 cfm for a 2.5 Outside Diameter (OD) tube about the length of a muffler flowed at 1.5 in-Hg (20.3 in H20)

A number of points:

1)converting flow at one depression to another is failrly straight forward. Take the square root of the pressure ratio. Example: (28/20.3)^1/2 or the sq. rt. of 28 divided by 20.3 = 1.174. That would make 560 cfm = 658 CFM

2) you need to relate flow to the Inside Diameter (ID) of the tube, of course. You can assume .060 wall thickness and be close. A 2.5 OD then has a 2.38 ID and 4.45 square inches of flow area.

3) In the range of sizes you mentioned, flow should be fairly proportional to cross sectional area fo the ID. Just comparing the square of the IDs will give you the ratios. Here's what I got. Numbers are rounded a bit.

OD-ID square-CFM---% of 2.5 OD
2.25 (4.54)= 527 CFM 80%
2.50 (5.66)= 658 CFM 100%
2.75 (6.92)= 804 CFM 122%
3.00 (8.29)= 964 CFM 147%
3.25 (9.80)= 1139 CFM 173%
3.50 (11.42)=1328 CFM 202%

4) remember the flow is for a short, straight length. Longer lengths reduce flow, and bends reduce it considerably. If you find different flow numbers, you still should be able to relate sizes by the square of the ID as shown above.

My $.02

<small>[ December 09, 2002, 08:14 AM: Message edited by: Old SStroker ]</small>

2000Firehawk

iTrader: (248)

Cool... <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

Thanks Old SStroker, that's the info I've been looking for... <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

I bought Random Techs new #702500 high-flow cats
that flow 560cfm... to install in 2.5" pipe...
so it looks like I'll be aok...

These new cats are 4" diameter & as tall as a can of coke, 4.75" flow 560cfm & are made of a metal substrate, not ceramic , & won't melt down like a ceramic cat if you cook it to hot with over rich mixture... <img border="0" alt="[Fluffy]" title="" src="graemlins/fluffy.gif" />

Dave

BurnOut

iTrader: (1)

An online calculator for converting airflow from one depression to another: http://www.csgnetwork.com/airflowcalc.html (all manners of neat converters there).

As for airflow of an open pipe, I looked up an old ad for Hooker Max Flow mufflers: "...flows 595 cfm, only 5% less than a plain 2.5" diameter open pipe...".

From looking at Hooker's website (at another airflow chart), it seems as if they use 28" of water (the same as most cylinder heads porters/manufacturers) as their standard pressure drop. Check the caption on the chart below (notice also that the chart has the Aero Chamber listed but not the Max Flow, which is the one that the above ad mentions as flowing 595 cfm).

<img src="http://www.holley.com/HiOctn/ProdLine/Products/ES/ES_pics/fAFAC.gif" alt=" - " />

ratio411

The 2200 cfm number for the DynoMax bullet was done at 28" in an independent test that pitted several different brand F-body muffers against each other. It was not done by any manufacturer. It was published, although I am not sure where. XTrooper, mod on LS1.com, has that info and posts it there.
The 2200 cfm figure is not correct for the bullet either. It is just the max that the flowbench could measure. The bullets were still flowing at 2200 cfm. The bullets in question are the short 3" (24222) and the long 3" (24219).
Some other numbers from this test (as close as I remember off top of my head):
Borla ~900 cfm
Magnaflow crossflow 1100 cfm
Flowmaster 80 series ~350 cfm
Hooker crossflow ~900 cfm
DynoMax 3" bullet 2200+ cfm

Some things that you could presume from these numbers are that 3" pipe flows at least as well as a bullet. SLP LMs flow as well as a bullet. The Borla was probably tested with the plate closed. I am sure it would read higher with the plate open.
FWIW
Dave