2.75" vs 3" pipe on supercharged vehicles.

SS_Firehawk

Bringing this back again as I was doing a bit more research on it.
I was trying to determine the maximum flow rate of different exhaust diameters as well as HFC diameters.

Found somewhere in the internets that a good estimate for flow rate per diameter of tubing is 115 x sq in. Not sure how truly accurate it is, but cross referencing with what manufacturers are quoting, it's within .05%. I included dual 2.5" results because I know that it can support the power requirement.

So some quick number crunching gave me this info
dual 2.5"= 1128CFM
single 2.75"=683CFM
single 3"= 812CFM

Now with regards to the flow rate of the Motordyne HFC that I have... It's 3" going in, expands to 4", then back to 3" and is 200 CPI. I found one test with an Xforce 200 CPI 3" cat with a 4" body that hit 750 CFM. XForce HFC. I've seen lower numbers on other cats but there isn't as much info about the testing methods, most between 478 & 596 CFM. Motordyne claims very minimal difference in power output between their straight pipe and HFC, maybe 2-3whp. So I'm leaning towards the 750 number.

So with this information, is the 3" HFC the larger restriction or the 2.75" mid pipe?
The more and more I think about it, I question if this exhaust can handle the 500whp I'm hoping the car will make. The only thing that gives me a glimmer of hope are the results GTM achieved with the stock exhaust and their SC kits. If it doesn't, I'll probably jump in that Fast Intentions line, add mini cats to the Y pipes and 12" resonators. Hate selling parts tho...

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