At what point (CID/HP) do you need a 3" exhaust? - Moparts Forums

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Re: At what point (CID/HP) do you need a 3" exhaust? [Re: hudsonhornet7x] #2291782 04/21/17 09:16 PM 04/21/17 09:16 PM
Joined: Jan 2003 Posts: 27,421 Balt. Md 3 383man Too Many Posts
383man Too Many Posts 3 Joined: Jan 2003 Posts: 27,421 Balt. Md	Originally Posted By hudsonhornet7x Mr. P Body, What do you use to measure back pressure? I would love to learn this. I had a great tool at the Dodge dealer when I worked there. We had a lab Scope adapter setup for the DRBIII and part of it was an adapter/transducer that screwed in where the 02 sensor went. Then as long as the DRBIII had the Pep module on it it had a spot where you could read pressure and it worked great. It also had a transducer to read fuel pressure and an Inclinometer. But basically the transducer to read pressure screwed right into the 02 sensor bung. Ron

Re: At what point (CID/HP) do you need a 3" exhaust? [Re: Pale_Roader] #2291788 04/21/17 09:30 PM 04/21/17 09:30 PM
Joined: Apr 2006 Posts: 4,220 West Plains, MO DrCharles master
DrCharles master Joined: Apr 2006 Posts: 4,220 West Plains, MO	I tried that with an X-pipe but it was way loud inside the car... also MO requires tailpipes to exit from underneath the body.

Re: At what point (CID/HP) do you need a 3" exhaust? [Re: 383man] #2291806 04/21/17 10:15 PM 04/21/17 10:15 PM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	Originally Posted By 383man Originally Posted By hudsonhornet7x Mr. P Body, What do you use to measure back pressure? I would love to learn this. I had a great tool at the Dodge dealer when I worked there. We had a lab Scope adapter setup for the DRBIII and part of it was an adapter/transducer that screwed in where the 02 sensor went. Then as long as the DRBIII had the Pep module on it it had a spot where you could read pressure and it worked great. It also had a transducer to read fuel pressure and an Inclinometer. But basically the transducer to read pressure screwed right into the 02 sensor bung. Ron Yeah we did the same thing but just on exhaust.. the tap works well and very simple.. we did a lot of pressure testing in exhaust and ran hundreds of taps on the systems.. I normally had about 50 pressure taps on each car EDIT pressure taps were easy and we ran a ton of temp readings per car.. about 200 readings per car was normal... but took up to about 500 readings per cars Last edited by MR_P_BODY; 04/21/17 10:23 PM.

Re: At what point (CID/HP) do you need a 3" exhaust? [Re: Spaceman Spiff] #2291813 04/21/17 10:32 PM 04/21/17 10:32 PM
Joined: Mar 2009 Posts: 890 Oh P parksr5 super stock
parksr5 super stock P Joined: Mar 2009 Posts: 890 Oh	Originally Posted By Spaceman Spiff FAST class cars are required to run 2 1/2..... And look how much power they make. Some run 130+mph Excuse me sir, some of them run 140+mph. (Shameless plug for Mr. Dudek who broke the 140mph barrier last year).

Re: At what point (CID/HP) do you need a 3" exhaust? [Re: MR_P_BODY] #2291830 04/21/17 11:04 PM 04/21/17 11:04 PM
Joined: Jul 2004 Posts: 19,318 State of confusion T Thumperdart I Live Here
Thumperdart I Live Here T Joined: Jul 2004 Posts: 19,318 State of confusion	Originally Posted By MR_P_BODY 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 Never measured and my math on my dart has been bigger heads, cams comp etc, like a bigger exhaust but it would be interesting to test some time but still would change it unless it WAS a restriction............ 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.....

Re: At what point (CID/HP) do you need a 3" exhaust? [Re: Thumperdart] #2291855 04/21/17 11:44 PM 04/21/17 11:44 PM
Joined: Jun 2003 Posts: 52,972 Romeo MI MR_P_BODY Master
MR_P_BODY Master Joined: Jun 2003 Posts: 52,972 Romeo MI	Originally Posted By Thumperdart Originally Posted By MR_P_BODY 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 Never measured and my math on my dart has been bigger heads, cams comp etc, like a bigger exhaust but it would be interesting to test some time but still would change it unless it WAS a restriction............ With out a back pressure reading you have NO clue what your exhaust is doing.. try taking a reading and see where your at

Re: At what point (CID/HP) do you need a 3" exhaust? [Re: Pale_Roader] #2291891 04/22/17 01:02 AM 04/22/17 01:02 AM
Joined: Nov 2013 Posts: 728 Southern Alberta Uberpube super stock
Uberpube super stock Joined: Nov 2013 Posts: 728 Southern Alberta	4" inch on my 2 litre turbo car... With turbo, its basically as big as you can fit on the car...

Re: At what point (CID/HP) do you need a 3" exhaust? [Re: Pale_Roader] #2292055 04/22/17 12:55 PM 04/22/17 12:55 PM
Joined: Feb 2003 Posts: 1,942 Metro Detroit OUTLAWD top fuel
OUTLAWD top fuel Joined: Feb 2003 Posts: 1,942 Metro Detroit	I pick up 0.1 in the 1/4 on my 3"/H-pipe TTI system when I open the dumps on my iron head 493" The weight is the same, and this is back to back, EFI keeps the AFR consistent. Faster, Faster until the thrill of speed overcomes the fear of death... 71 Swinger - slowly collecting dust/parts 66 Belv. II - just a streetcar 88 Mustang - turbo LS beater

Re: At what point (CID/HP) do you need a 3" exhaust? [Re: OUTLAWD] #2292144 04/22/17 03:37 PM 04/22/17 03:37 PM
Joined: Aug 2003 Posts: 43,359 Bend,OR USA C Cab_Burge I Win
Cab_Burge I Win C Joined: Aug 2003 Posts: 43,359 Bend,OR USA	Originally Posted By OUTLAWD I pick up 0.1 in the 1/4 on my 3"/H-pipe TTI system when I open the dumps on my iron head 493" The weight is the same, and this is back to back, EFI keeps the AFR consistent. Real world results Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)

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