LOOONG post and flow data for AWE's cats, lots of info...Stop the Insanity!
12-19-2001, 06:01 PM
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LOOONG post and flow data for AWE's cats, lots of info...Stop the Insanity!
There has been quite a stir these last few months on the flow rates of various cats, and why certain cats are $400 or more better than those used on the AWE downpipe system, this post is meant to educate you guys on the basic flow rates and capacities of the S4 engine , as well as to quell the ration of BS some have been spouting on here with no background nor scientific fact on the actual flow rates of the cats used on "their" system of choice! follow the link to see the flow rates of the AWE 2.5 inch high flow cats-series 400 **400 cells inch** in 2.5 inch flow 380cfm each and 760 cfm combined!
lets start our lesson on the 2.7 engine and the airflow its capable of on the engine alone(no boost)
The 2.7 liter is 165ci in displacement it has a redline when chipped of 7050 rpm, it is a 4 stroke engine that only fills its cylinder on half of it revolution, and for scientific purposes it has a 85% volumetric efficiency(this is the general default for a high perf street going car)
Airflow Rate= cid x rpm x .5(4 stroke) x .85(vol efficiency)/1728(converts cubic inches to cubic feet) so on the S4 we have:
165 x 7050rpm x .5 x .85/1728 = 286cfm of airflow
with this rate of airflow established we can now move onto boosted max airflows that the AWE cats can handle!
Airflow rate=pressure ratio x basic engine cfm
2.65bar x 286cfm= 757cfm
So to max out the AWE cats( with a max airflow of 760cfm) you would need to run 2.65+ bar absolute(38.95psi) or 1.65+ bar(24.25+psi of actual boost) at redline!!
Now how much power is this(760 cfm)?
Most turbocharged cars make between .052bhp/ci and .077bhp/ci, this is due to the basic designs variances of the engine and this is taken in a wide range of different cars dyno results, so lets play around with this figure on the S4 configuration at 2.65bar of absolute pressure shall we?
The equation to determine power levels is:
Power variance x ci x boost(absolute pressure in psi-in this case 24.25 psi+ 14.7 ** 1 atmosphere = 38.95)
Low ball power figure for the S4
.052 x 165 x 38.95= 334.2 hp on a low efficiency engine
.077 x 165 x 38.95= 494hp on a high efficiency engine- so this is the upper power limit that the AWE S4 cats will flow without restriction at 760cfm!!!
so the moral of the story is if you want give away $400 dollars for higher theoretical flow, AWE will happily add a set of 2.5 inch 100 cell cats to their downpipes(2.5 inch does flow better than 2.25) for $350 extra, but its really not neccesary in power levels below 494hp and the the AWE cats are gauranteed to pass federal emissions tests!
Hope this alleviates any confusion on this matter,and I am anxiously awaiting the flow data figures of the 2 ¼ inch 100 cell cats and downpipes!
BTW i have these cats on my car and i plan to hit the 500hp+ power figure!<ul><li><a href="http://www.morflow.com/converters/cat-techdata.htm#flowdata">series 400 flow data in 2.5 inch!</a></li></ul>
lets start our lesson on the 2.7 engine and the airflow its capable of on the engine alone(no boost)
The 2.7 liter is 165ci in displacement it has a redline when chipped of 7050 rpm, it is a 4 stroke engine that only fills its cylinder on half of it revolution, and for scientific purposes it has a 85% volumetric efficiency(this is the general default for a high perf street going car)
Airflow Rate= cid x rpm x .5(4 stroke) x .85(vol efficiency)/1728(converts cubic inches to cubic feet) so on the S4 we have:
165 x 7050rpm x .5 x .85/1728 = 286cfm of airflow
with this rate of airflow established we can now move onto boosted max airflows that the AWE cats can handle!
Airflow rate=pressure ratio x basic engine cfm
2.65bar x 286cfm= 757cfm
So to max out the AWE cats( with a max airflow of 760cfm) you would need to run 2.65+ bar absolute(38.95psi) or 1.65+ bar(24.25+psi of actual boost) at redline!!
Now how much power is this(760 cfm)?
Most turbocharged cars make between .052bhp/ci and .077bhp/ci, this is due to the basic designs variances of the engine and this is taken in a wide range of different cars dyno results, so lets play around with this figure on the S4 configuration at 2.65bar of absolute pressure shall we?
The equation to determine power levels is:
Power variance x ci x boost(absolute pressure in psi-in this case 24.25 psi+ 14.7 ** 1 atmosphere = 38.95)
Low ball power figure for the S4
.052 x 165 x 38.95= 334.2 hp on a low efficiency engine
.077 x 165 x 38.95= 494hp on a high efficiency engine- so this is the upper power limit that the AWE S4 cats will flow without restriction at 760cfm!!!
so the moral of the story is if you want give away $400 dollars for higher theoretical flow, AWE will happily add a set of 2.5 inch 100 cell cats to their downpipes(2.5 inch does flow better than 2.25) for $350 extra, but its really not neccesary in power levels below 494hp and the the AWE cats are gauranteed to pass federal emissions tests!
Hope this alleviates any confusion on this matter,and I am anxiously awaiting the flow data figures of the 2 ¼ inch 100 cell cats and downpipes!
BTW i have these cats on my car and i plan to hit the 500hp+ power figure!<ul><li><a href="http://www.morflow.com/converters/cat-techdata.htm#flowdata">series 400 flow data in 2.5 inch!</a></li></ul>
12-19-2001, 06:24 PM
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Its at the top of AWE's priority list!
hang with me man you will thouroughly enjoy it, and it will be well worth the wait in every respect- the perfect complement to the downpipes, in sound and performance!
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12-19-2001, 08:35 PM
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which fine is that?