Exhaust concept for the truck(drawing).....

[moregrip]

I'm running a pair of 3" high flow cats on my truck.  They use a corrugated metallic substrate instead of the stock ceramic brick.  Benefits = much better flow and a higher thermal breakdown temp.  The stainless baffles inside withstand heat much better, which in our forced induction setups is a big benefit.  There are a few manufacutrers, but as Ben said, they are costly.  The powercat brand is cheaper than the random tech brand.

 

My experience with them:  I had a dyno done with my full exhaust.  ASM headers, 3" pipes into an X then duals out through the cats and into a muffler.  I went back to the same dyno on the same week, but this time I removed the exhaust from the X pipe back.  So no muffler and no cats.  No changes in the tuning were made between dyno pulls.  The end result was 4 more peak rwhp without the exhaust.

 

My take on it - I don't think my cats are causing any real loss of power.

<{POST_SNAPBACK}>

 

What cfm are your cats rated at? and how much fwhp do you estimate your making? maybe I can compute a tolerance with that data.

[BenKey]

Powercats flow close to 400cfm, according to the Dynatech website.

[deezel]

2.2cfm for every 1 fwhp, based on 625fwhp = 1375cfm needed.

 

not sure how exact that estimate is...

 

by my calculations, using intake manifold pressure, engine displacement, and rpm, the air flow of a hypothetical 408 c.i. engine would be:

 

732cfm at 6200rpm and 1atm (N/A)

1098cfm at 6200rpm and 1.5atm (~7.5psi boost)

1464cfm at 6200rpm and 2.0atm (~15psi boost)

 

[FuelSlut]

big tex - if you dont mind... what is the part number(s) cats you used?

 

thanks in advance\

George