Re: At what point (CID/HP) do you need a 3" exhaust?
[Re: quickd100]
#2291316
04/20/17 11:41 PM
04/20/17 11:41 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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People... what you need to consider when talking exhaust on a car is back pressure.. how much back pressure do you have.. I know MOST of you have NEVER measured it.. try it and see what it is... then try to reduce it.. its simple to do but MOST dont do it
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Re: At what point (CID/HP) do you need a 3" exhaust?
[Re: Pale_Roader]
#2291401
04/21/17 02:07 AM
04/21/17 02:07 AM
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Joined: Nov 2003
Posts: 1,890 Pittsburgh,PA
RTSrunner
top fuel
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top fuel
Joined: Nov 2003
Posts: 1,890
Pittsburgh,PA
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What about a 2 into 1 system like a Magnum truck exhaust? Using headers of course and 3" piping/muffler . RT
Last edited by RTSrunner; 04/21/17 02:08 AM.
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Re: At what point (CID/HP) do you need a 3" exhaust?
[Re: quickd100]
#2291438
04/21/17 07:02 AM
04/21/17 07:02 AM
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Joined: Jan 2005
Posts: 4,862 the frozen wastes...
Pale_Roader
OP
Swears too much
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OP
Swears too much
Joined: Jan 2005
Posts: 4,862
the frozen wastes...
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Here is my $.02 for what it's worth; I have my own dyno, 605ci street hemi, through open headers and collectors it made 853hp and 818ftlbs. Back to back pulls 15 minutes apart, engine and oil at same temps. With the full exhaust hooked up,(3-1/2" pipes, X-pipe and 3-1/2" Ultra-Flows that dump right after the mufflers. It made 117hp and 97ftbls. LESS.Dave 605cid Hemi...??? Hahahahahaha... Dave... i do not think you and i live on the same planet. HALF ov what you're making will be music to my ears in this roach... Hahahahahahahahaa
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Re: At what point (CID/HP) do you need a 3" exhaust?
[Re: Pale_Roader]
#2291637
04/21/17 04:07 PM
04/21/17 04:07 PM
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Joined: Nov 2010
Posts: 3,698 jersey
Spaceman Spiff
master
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master
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Posts: 3,698
jersey
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I went from a 2 1/2 system with x pipe and bullet mufflers, to a 3 inch system, with x pipe and ultra flows.... I saw a bigger gain switching to a 1000cfm Hp series carb, then I did from the exhaust change. This is on a 550hp 526 stroker.
526 cubes of angry wedge, pushbutton shifted, 9 passenger killer!
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Re: At what point (CID/HP) do you need a 3" exhaust?
[Re: Spaceman Spiff]
#2291680
04/21/17 05:49 PM
04/21/17 05:49 PM
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Joined: Jul 2004
Posts: 19,318 State of confusion
Thumperdart
I Live Here
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I Live Here
Joined: Jul 2004
Posts: 19,318
State of confusion
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Close to 700 hp and have ran a 3 1/2" side exit exhaust forever and never a problem w/the police not even w/slicks on the street.............They are a bit loud but I don't buy the idea that small pipes make hp in a big motor, just not true and I know of a few 8 second and quicker NOS cars w/some BIG exhaust...........
Last edited by Thumperdart; 04/21/17 05:49 PM.
72 Dart 470 n/a BB stroker street car `THUMPER`...Check me out on FB Dominic Thumper for videos and lots of carb pics......760-900-3895.....
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Re: At what point (CID/HP) do you need a 3" exhaust?
[Re: Thumperdart]
#2291691
04/21/17 06:03 PM
04/21/17 06:03 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
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Posts: 52,972
Romeo MI
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Again.. I will ask what is your back pressure... we still dont know crap yet.. if you can say what your REAL back pressure is we would have a clue to what the flow of the system is.. everyone wants to throw out HP numbers but if system X is this much back pressure and system Y is this much it will say A LOT.. I measure mine so I do have a clue to what it is.. a simple gauge hook up will tell you EDIT And state at what RPM
Last edited by MR_P_BODY; 04/21/17 06:06 PM.
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Re: At what point (CID/HP) do you need a 3" exhaust?
[Re: Pale_Roader]
#2291737
04/21/17 07:16 PM
04/21/17 07:16 PM
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Joined: Jan 2003
Posts: 8,225 Plymouth, MI
Blusmbl
master
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master
Joined: Jan 2003
Posts: 8,225
Plymouth, MI
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You're supposed to use piezometer rings to measure the pressure around the pipe, but a simple tap with a pressure gauge is good enough.
For a horsepower reference, the 2013-14 GT500 made 662 hp out of a supercharged 351" V8. It has 2.75" exhaust to the cats, and 2.5" pipe to the mufflers mounted at the back of the car. The Hellcat is the same- 2.75" exhaust, 707 hp from less than 400 cubes.
'18 Ford Raptor, random motorcycles, 1968 Plymouth Fury III - 11.37 @ 118
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Re: At what point (CID/HP) do you need a 3" exhaust?
[Re: hudsonhornet7x]
#2291741
04/21/17 07:19 PM
04/21/17 07:19 PM
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Joined: Jun 2003
Posts: 52,972 Romeo MI
MR_P_BODY
Master
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Master
Joined: Jun 2003
Posts: 52,972
Romeo MI
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Mr. P Body, What do you use to measure back pressure? I would love to learn this. Very simple.. a inch of vac gauge( its inches of merc,HG).. drill it into the exhaust.. I just use a tap thats 1/8 pipe ad that way I can screw is a 1/8" pipe fitting.. once your done I just usually weld it close.. unless I need more readings.. very simple.. I did a few hundred of these at work
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Re: At what point (CID/HP) do you need a 3" exhaust?
[Re: Pale_Roader]
#2291745
04/21/17 07:27 PM
04/21/17 07:27 PM
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Joined: Jan 2003
Posts: 2,787 541 slobovia
A990
master
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master
Joined: Jan 2003
Posts: 2,787
541 slobovia
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A local dealer tech told me to put a pressure gauge ahead of the catalytic converter and as long as pressure was below 3psi the convertor was good. Will this work on a converterless exhaust?
Last edited by A990; 04/21/17 07:29 PM.
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Re: At what point (CID/HP) do you need a 3" exhaust?
[Re: MR_P_BODY]
#2291754
04/21/17 07:46 PM
04/21/17 07:46 PM
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Joined: Jan 2012
Posts: 1,552 USA
hudsonhornet7x
pro stock
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pro stock
Joined: Jan 2012
Posts: 1,552
USA
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Mr. P Body, What do you use to measure back pressure? I would love to learn this. Very simple.. a inch of vac gauge( its inches of merc,HG).. drill it into the exhaust.. I just use a tap thats 1/8 pipe ad that way I can screw is a 1/8" pipe fitting.. once your done I just usually weld it close.. unless I need more readings.. very simple.. I did a few hundred of these at work Thank you! Simple and easy I will be doing this.
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Re: At what point (CID/HP) do you need a 3" exhaust?
[Re: Pale_Roader]
#2291766
04/21/17 08:24 PM
04/21/17 08:24 PM
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Joined: Jan 2003
Posts: 20,335 Park Forest, IL
slantzilla
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 20,335
Park Forest, IL
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I had 3" put on my Duster with turn downs in front of the axle. Why? Because that is what I wanted.
"Everybody funny, now you funny too."
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