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Barry Grant 6-pack Part two flow test

Posted By: Mopar Guy

Barry Grant 6-pack Part two flow test - 01/07/14 09:47 PM

There are some guy´s out here that say the BG six pack carbs flow whay less than the Holley`s but i whas surpriced today when i got the chans to flow test them at a well known head porting guy that have a flow bentch.

Whe started out whit flow testing a brand new out of the box Holley outboard carbs that Holley say 500cfm and it flowed 532,6 cfm

And a out of the box BG that whas stated at 355 cfm flowed 510,5 cfm at same underpresiure so i almost dropt my face

There is no way these are as smal as some say only about good for a 383 engine

If you consider al 3 carbs flow above 510 out of the box and compare that to a Holley set whit that smal center carb i would be very supriced if there not at least almost equal whit al 3 carbs on full throttel

The only modification i did on the center BG carbs whas that i milled of the choke tower and that cant make sutch a big difference !?
Posted By: tex013

Re: Barry Grant 6-pack Part two flow test - 01/07/14 10:50 PM

that's interesting . The BG is a annular isn't it ? I wonder how that will work . The only guy I know to have used them , I think on a Ford , was not thrilled performance wise . May pay to try and flow the carbs on manifold ?
I do like that they are mechanical not vacuum outers

Tex
Posted By: Mopar Guy

Re: Barry Grant 6-pack Part two flow test - 01/07/14 11:06 PM

Quote:

that's interesting . The BG is a annular isn't it ? I wonder how that will work . The only guy I know to have used them , I think on a Ford , was not thrilled performance wise . May pay to try and flow the carbs on manifold ?
I do like that they are mechanical not vacuum outers

Tex



Tex im totaly on the oposite side when it comes to a mecanical outer carbs as i whant to have control over when they open to avoid scary side ways rides on the road whit 4 speed trans and i hope that they will have a more square distributed acc pump fuel but mabee im wrong but i intend to tell the tale so to speak Yes they are annular boosters in those carbs !
Posted By: sshemi

Re: Barry Grant 6-pack Part two flow test - 01/07/14 11:10 PM

At what pressure where they flowed?
Posted By: Mopar Guy

Re: Barry Grant 6-pack Part two flow test - 01/07/14 11:26 PM

Quote:

At what pressure where they flowed?



28 ! Do that matter as whe compared at same
Posted By: 85_Ram_4speed

Re: Barry Grant 6-pack Part two flow test - 01/07/14 11:35 PM

I thought, and it was my understanding, that 2 barrel carbs were rated differently than 4 barrel carbs. And to figure the difference you take the 500 cfm rating and divide by 1.5 which gets you at 333 cfm. While not exact, it is supposed to get you close, to compare apples to apples.

So maybe that is why the BG carb is rated at 355, but actually flows similarly to the Holley when side by side. I mean, how can the beloved 4412 Holley 500 CFM 2 bbl carb that is essentially 1/2 of a 750 CFM 4 bbl flow almost 2/3 of the 4 bbl. But if you use the above formula, take that 333 CFM and double it (666 cfm), it sure comes alot closer to matching the 4 bbl value of 750 CFM.

EDIT: found this.....

The American Society of Engineers (ASE) decided to measure the flow of 2bbl carbs at one level of manifolcd vacuum (mercury/Hg) and rated 4bbl carbs at another level.
The conversion factor is 1.414.

soooo... 500 cfm / 1.414 = 353 cfm
Posted By: Mopar Guy

Re: Barry Grant 6-pack Part two flow test - 01/07/14 11:41 PM

Quote:

I thought, and it was my understanding, that 2 barrel carbs were rated differently than 4 barrel carbs. And to figure the difference you take the 500 cfm rating and divide by 1.5 which gets you at 333 cfm. While not exact, it is supposed to get you close, to compare apples to apples.

So maybe that is why the BG carb is rated at 355, but actually flows similarly to the Holley when side by side.



How ever you calulate they flow almost alike wouldent you say !? What i whas after in this realety test is that the BG dont flow as bad as some out there say ! BG are most likely flowed wet and Holley dry as i now did when compareing them
Posted By: 85_Ram_4speed

Re: Barry Grant 6-pack Part two flow test - 01/07/14 11:57 PM

Quote:


How ever you calulate they flow almost alike wouldent you say !? What i whas after in this realety test is that the BG dont flow as bad as some out there say ! BG are most likely flowed wet and Holley dry as i now did when compareing them



See my edit above
Posted By: ppmracing

Re: Barry Grant 6-pack Part two flow test - 01/13/14 12:16 AM

The right pressure to flow them at ( Holley 20,4cfm) as far as i know.
Then the so called 500cfm outbord carbs flow 434cfm on my Superflow digital bench.

Attached picture 7995253-PICT1472.JPG
Posted By: ademon

Re: Barry Grant 6-pack Part two flow test - 01/13/14 12:34 AM

Maybe BG all along had the right 2bbl flow rating on them.
Posted By: fast68plymouth

Re: Barry Grant 6-pack Part two flow test - 01/13/14 03:47 AM

Quote:

The right pressure to flow them at ( Holley 20,4cfm) as far as i know.
Then the so called 500cfm outbord carbs flow 434cfm on my Superflow digital bench.



2bbl carbs are rated 3"Hg, and 4bbl carbs at 1.5"Hg.
the 20.4"H2O equates to 1.5"Hg.
this is supposed to more accurately represent the pressure drop across the carburetor in operation(in an OEM type application).
as an example, a stock type 383 motor with a stock type 2bbl running at 5000rpm at WOT will have a higher pressure drop across the carb than the same engine with a stock type 4bbl on it.

this disparity in test pressures is why 6pak set ups are "1300cfm", but dont really have 53% more flow capacity than a std 850 4bbl.
the flow ratings were achieved at different pressure readings. 3.0"Hg for the 6pak, 1.5"Hg for the 4bbl.


also, carb flow ratings "should" be wet flow numbers.
for roughly 12.5 A/F ratio, i approximate the wet flow as 92% of the dry flow.
so, to my way of thinking, that 434cfm works out to 399cfm calculated wet flow @ 1.5"Hg.
Posted By: Mopar Guy

Re: Barry Grant 6-pack Part two flow test - 01/13/14 04:30 PM

Quote:

The right pressure to flow them at ( Holley 20,4cfm) as far as i know.
Then the so called 500cfm outbord carbs flow 434cfm on my Superflow digital bench.



Peter i whas manly whanting to show al that the BG flow more that the bad reputation say from some out there so how ever one bentch to another flow the BG´s will only flow about 23cfm under the Holley outboard carbs and that is out of the box brand new and al 3 of them witch Holley wount match as the center Holley is to smal ! I whas abel to pull out about 16-17 more of cfm on the BG outboards after i enlaged the venturis opening area if anyone needs to know.

Attached picture 7995933-venturi1.JPG
Posted By: ademon

Re: Barry Grant 6-pack Part two flow test - 01/13/14 05:44 PM

The real test will be back to back runs on the dyno to see what makes more HP. Then again BG is out of business.
Posted By: Mopar Guy

Re: Barry Grant 6-pack Part two flow test - 01/13/14 07:32 PM

Quote:

The real test will be back to back runs on the dyno to see what makes more HP. Then again BG is out of business.



I intend to dyno it in the car on the rear tires in spring whit the Holley´s on and then make the change to the BG´S carbs dial them in and tune them up the same whay on the rear tires to see if they work better but it is a few mounth´s away ! I beleve Indy still stock these Barry Grant Six Pack carbs if there not out of them now
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