The Ford Torino Page Homepage
Forum Home Forum Home > Model Specific Forum > Other Technical Discussion
  New Posts New Posts RSS Feed - back pressure,needed or not
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

back pressure,needed or not

 Post Reply Post Reply Page  12>
Author
Message
fordpower View Drop Down
Senior Member
Senior Member


Joined: 02-September-2010
Location: willseyville,ny
Status: Offline
Points: 1477
Post Options Post Options   Thanks (0) Thanks(0)   Quote fordpower Quote  Post ReplyReply Direct Link To This Post Topic: back pressure,needed or not
    Posted: 19-July-2017 at 5:31AM
Well thinking of replacing my cats.
tried to do some research on back pressure.I found it very confusing to say the least. does anyone have opinion . I like sound with cats and no mufflers.
Back to Top
GranTorinoSport View Drop Down
Admin Group
Admin Group
Avatar
Admin of "The Org"

Joined: 20-May-2003
Location: Seattle
Status: Offline
Points: 2262
Post Options Post Options   Thanks (0) Thanks(0)   Quote GranTorinoSport Quote  Post ReplyReply Direct Link To This Post Posted: 19-July-2017 at 7:12AM
Back pressure is needed for lower end power and driveability.

Lack of back pressure is desired for high RPM and race applications, however those vehicles don't have to worry about driving on the street.

The absence of your catalytic converters with the muffler(s) remaining will likely reduce some back pressure but not to an exceptional degree. I'm not sure how much back pressure the original factory cats provided, but like anything I would imagine the early ones were probably far worse than a more modern one.

If you want more sound, I would not remove the mufflers, rather choose a new muffler. There are several good offerings that will reduce back pressure and increase sound. I know many members here will have some strong opinions on good and bad mufflers. I think I used a Dynomax on mine (I'd have to look up which one). I got a higher flowing model that still was touted as "quiet", coupled with dual 2.5 inch exhaust (and an H-pipe) for my 521. I'm happy with it, but you can tell between the 600cfm carb and the 2.5 exhaust that it hits a wall when you are WOT. The 600 cfm carb is me just being cheap (it was laying around) until I get fuel injection, but the 2.5 inch was intentional because I've heard that quieting down 3 inch exhaust is nearly impossible.
Scott Eklund

Webmaster
Back to Top
Nuggets View Drop Down
Senior Member
Senior Member
Avatar

Joined: 07-November-2014
Location: UK
Status: Offline
Points: 869
Post Options Post Options   Thanks (0) Thanks(0)   Quote Nuggets Quote  Post ReplyReply Direct Link To This Post Posted: 19-July-2017 at 7:56AM
Its not back pressure! I hate this term......you are SO WRONG when you say back pressure.....or lack of etc etc

You want as close to ZERO back pressure as possible.

What you want in an exhaust is HIGH VELOCITY, this allows gas to escape quickly. This is not back pressure, has never been and will never be. It is a case of keeping exhaust gasses as hot as possible 

Its why if you run a full 3" system on a 289 it'll run worse and feel more gutless than a 289 on a twin 1.5" system. What you're doing is lowering gas velocity, in turn this can create back pressure as the gas slows down so much that you have a backup right at the end.

Run whatever the hell you want with regards to cats, no cats, mufflers.......just keep the pipe size in line with the engines requirements. 

If you create back pressure you harm performance. End of story. 



Barnaby

429 powered 73 Stripper.....no comfort, just noise!
Back to Top
72GTS351CJ View Drop Down
Senior Member
Senior Member
Avatar

Joined: 30-November-2010
Location: NY
Status: Offline
Points: 1323
Post Options Post Options   Thanks (0) Thanks(0)   Quote 72GTS351CJ Quote  Post ReplyReply Direct Link To This Post Posted: 19-July-2017 at 9:06AM
Take a breath and calm down. It a friendly forum.
72GTS Clint Eastwood Special                                     
Back to Top
Nuggets View Drop Down
Senior Member
Senior Member
Avatar

Joined: 07-November-2014
Location: UK
Status: Offline
Points: 869
Post Options Post Options   Thanks (0) Thanks(0)   Quote Nuggets Quote  Post ReplyReply Direct Link To This Post Posted: 19-July-2017 at 9:32AM
As far as I'm concerned there was nothing unfriendly about my post.....purely informative and not sugar coated.

When we design exhausts in an engineering environment we design mufflers, cats, bends and the entirety of the system to have as close to zero back pressure as possible whilst in keeping with the given constraints both dimensionally and budget wise. 
Barnaby

429 powered 73 Stripper.....no comfort, just noise!
Back to Top
fordpower View Drop Down
Senior Member
Senior Member


Joined: 02-September-2010
Location: willseyville,ny
Status: Offline
Points: 1477
Post Options Post Options   Thanks (0) Thanks(0)   Quote fordpower Quote  Post ReplyReply Direct Link To This Post Posted: 19-July-2017 at 9:35AM
Could be a difference in meaning is all. I run only my cats. I like the sound so have a lot of others. I just wondered if by not running mufflers I create the velocity problem
Back to Top
Nuggets View Drop Down
Senior Member
Senior Member
Avatar

Joined: 07-November-2014
Location: UK
Status: Offline
Points: 869
Post Options Post Options   Thanks (0) Thanks(0)   Quote Nuggets Quote  Post ReplyReply Direct Link To This Post Posted: 19-July-2017 at 9:54AM
Back pressure in an exhaust sense is essentially a restriction, thats its only definition. Not what you want on any car.

Yes you potentially create a velocity problem, will you notice it? Probably not. 

Its hardly a performance car you're toying with, if you enjoy the noise just do it
Barnaby

429 powered 73 Stripper.....no comfort, just noise!
Back to Top
Big Bird View Drop Down
Senior Member
Senior Member
Avatar

Joined: 25-August-2013
Location: New York
Status: Offline
Points: 3339
Post Options Post Options   Thanks (0) Thanks(0)   Quote Big Bird Quote  Post ReplyReply Direct Link To This Post Posted: 19-July-2017 at 10:27AM
You need to find a balance. Exhaust that's overly restrictive hurts performance, but enormous pipes cause the exhaust gasses to move too slowly, which reduces scavenging and forces the engine to "push" to get the exhaust gasses out. If the engine is a stock engine with a factory tune, EGR will not function correctly with no back pressure, for example. On a non-stock setup, keeping the exhaust moving at proper speed will help scavenging and increase intake charge flow.
The above post should be read in a "Grumpy Old Man" voice.
Almost forgot: "Get off my lawn!!!"
Randy
1979 T-Bird
2005 F-150 STX 4.6, 3.55 LSD
Back to Top
Nuggets View Drop Down
Senior Member
Senior Member
Avatar

Joined: 07-November-2014
Location: UK
Status: Offline
Points: 869
Post Options Post Options   Thanks (0) Thanks(0)   Quote Nuggets Quote  Post ReplyReply Direct Link To This Post Posted: 19-July-2017 at 10:44AM
You have to compromise. However.....given all design restrictions in a full under car system you will never eliminate all back pressure anyway so the EGR should always function. 

I cant remember the figures on the GT3-R exhaust or stock W12 system on the Continental but even with the optimum routing you still get it and thats with super high flowing cats, mufflers and pipework routed in such a way to minimise kinks as well as being of optimum size. 

The only way is to essentially run it like a drag car with zoomie headers, but given this is a full system car having the positive or negative pressure valve in the system it should not make a difference to its operation. 

They want deleting anyway. Horrid things.


Edited by Nuggets - 19-July-2017 at 10:45AM
Barnaby

429 powered 73 Stripper.....no comfort, just noise!
Back to Top
lynchster View Drop Down
Senior Member
Senior Member
Avatar

Joined: 07-January-2006
Location: Pennsylvania
Status: Offline
Points: 1737
Post Options Post Options   Thanks (0) Thanks(0)   Quote lynchster Quote  Post ReplyReply Direct Link To This Post Posted: 19-July-2017 at 1:42PM
[QUOTE=Nuggets]

Since you seem to be an expert on the subject............

I'm guessing that having my manifolds with four or five feet of pipe is not optimal.

Edited by lynchster - 19-July-2017 at 1:45PM
Chuck
72 Gran Torino Sport
91 F-150
Back to Top
72FordGTS View Drop Down
Admin Group
Admin Group
Avatar

Joined: 06-September-2005
Location: Ontario, Canada
Status: Offline
Points: 2620
Post Options Post Options   Thanks (0) Thanks(0)   Quote 72FordGTS Quote  Post ReplyReply Direct Link To This Post Posted: 19-July-2017 at 3:07PM
The modern hi-flow cats don't really seem to have much restriction.  We've come a long way from the old restrictive 1970's cats.   My brother bought a set from a speed shop for one of his cars.  It did muffle the sound slightly, but the exhaust also stinks way less than a car without cats.  I'd stick with mufflers, just stick to small ones for more sound (if that's what you want).
Vince

1972 Ford GTS Sportsroof - Survivor, One Family car
Back to Top
Nuggets View Drop Down
Senior Member
Senior Member
Avatar

Joined: 07-November-2014
Location: UK
Status: Offline
Points: 869
Post Options Post Options   Thanks (0) Thanks(0)   Quote Nuggets Quote  Post ReplyReply Direct Link To This Post Posted: 19-July-2017 at 10:55PM
Originally posted by lynchster lynchster wrote:



Since you seem to be an expert on the subject............

I'm guessing that having my manifolds with four or five feet of pipe is not optimal.



Probably not. But that's how I run too. I like the sound and look of true duals....could I gain more with an X or H set up. Yes.
Do I want to. No?


You have to weigh up, cost of making your exhaust, sound quality which is always subjective and performance. Could you gain something with the tuning of the system through pipe sizing and bend radius etc. Yes.

Would it be worth it. Doubt it.

Exhaust tubing and optimisation is only generally worth it on high performance motors or where you're being stifled by emissions to start with so the tuning of the system post cat becomes even more critical in order to keep power high. It's how a Bentley still makes 500+ hp with pre and post cats, giant mufflers and emissions regs.
Barnaby

429 powered 73 Stripper.....no comfort, just noise!
Back to Top
Don V. View Drop Down
Member
Member


Joined: 07-July-2017
Location: Michigan
Status: Offline
Points: 173
Post Options Post Options   Thanks (0) Thanks(0)   Quote Don V. Quote  Post ReplyReply Direct Link To This Post Posted: 25-July-2017 at 6:50AM
When it comes to IC engines an interesting debate is what term is more misused and misunderstood, back pressure or torque?
 
 
Unless the laws of physics have been recently rewritten backpressure is absolutely necessary for an engine to run. I suppose it's possible to get an engine to idle poorly for a while without backpressure because the 3 requirements for ignition are present but a load would stall it.
 
The basic analogy might be a syphon hose. What happens when a syphon hose loses back pressure? Flow stops. An IC engine is defined as an air pump and this is basic fluid dynamics. BTW, fluid is not the same as liquid in fluid dynamics.


Edited by Don V. - 25-July-2017 at 6:50AM
Back to Top
aquartlow View Drop Down
Senior Member
Senior Member
Avatar

Joined: 19-December-2011
Location: Summerfield, Fl
Status: Offline
Points: 1795
Post Options Post Options   Thanks (0) Thanks(0)   Quote aquartlow Quote  Post ReplyReply Direct Link To This Post Posted: 25-July-2017 at 9:08AM
Originally posted by Don V. Don V. wrote:

When it comes to IC engines an interesting debate is what term is more misused and misunderstood, back pressure or torque?
 
 
Unless the laws of physics have been recently rewritten backpressure is absolutely necessary for an engine to run. I suppose it's possible to get an engine to idle poorly for a while without backpressure because the 3 requirements for ignition are present but a load would stall it.
 
The basic analogy might be a syphon hose. What happens when a syphon hose loses back pressure? Flow stops. An IC engine is defined as an air pump and this is basic fluid dynamics. BTW, fluid is not the same as liquid in fluid dynamics.
 
Not trying to be an ass here, but how does a top fuel dragster/funny car make 10K horsepower with just zoomie headers if back pressure is absolutely necessary for an IC engine to run well. In another IC example I have also seen numerous turbo diesel engines with little more than a 18" piece of 4" pipe for an exhaust ran up through the hood and those ran "real" well. Please explain.
www.supermotors.net/22468
Yeah, It's a Hybrid...It burns gas and tires.

No matter how good she looks, somebody, somewhere, is tired of her sh*t.

Beauty is skin deep, ugliness goes clear to the bone.
Back to Top
californiajohnny View Drop Down
Senior Member
Senior Member
Avatar

Joined: 05-October-2013
Location: winlock, wa
Status: Offline
Points: 9512
Post Options Post Options   Thanks (0) Thanks(0)   Quote californiajohnny Quote  Post ReplyReply Direct Link To This Post Posted: 25-July-2017 at 12:18PM
slight amount of back pressure works better on most street engines.

todd, to answer your question about the top fuel engines... they breath by help of the big belt driven blower!Big smileThumbs Up
JOHN
74 GRAN TORINO S&H CLONE
74 VETTE CUSTOM
90 S10 BLAZER 4X4 LIFTED
77 CELICA CUSTOM
75 V8 MONZA SUPERCHARGED
79 COURIER VERT. SLAMMED
75 VEGA V6 5 SPD
70 CHEV C10 P/U
68 MUSTANG FB CONVERSION
Back to Top
aquartlow View Drop Down
Senior Member
Senior Member
Avatar

Joined: 19-December-2011
Location: Summerfield, Fl
Status: Offline
Points: 1795
Post Options Post Options   Thanks (0) Thanks(0)   Quote aquartlow Quote  Post ReplyReply Direct Link To This Post Posted: 25-July-2017 at 12:51PM
Originally posted by californiajohnny californiajohnny wrote:

slight amount of back pressure works better on most street engines.

todd, to answer your question about the top fuel engines... they breath by help of the big belt driven blower!Big smileThumbs Up
 
Definitely agree about street engines liking a bit of back pressure and the TF cars with blowers, but I also see pulling trucks with zoomies through the hood and they run tunnel rams with 2-4's(and they run pretty "fair" Wink).
   It seems on a street car engine, the exhaust system doesn't necessarily need to introduce back pressure to help the engine run better, but rather be tuned to some extent to help keep exhaust pulse velocities up so the exhaust flow itself will help or aid in scavenging or pulling the exhaust volume before it cools enough to slow down the exhaust pulse(which would equal back pressure). I believe exhaust back pressure, unto itself, is generally thought of as a bad thing for performance and/or efficiency.  
www.supermotors.net/22468
Yeah, It's a Hybrid...It burns gas and tires.

No matter how good she looks, somebody, somewhere, is tired of her sh*t.

Beauty is skin deep, ugliness goes clear to the bone.
Back to Top
californiajohnny View Drop Down
Senior Member
Senior Member
Avatar

Joined: 05-October-2013
Location: winlock, wa
Status: Offline
Points: 9512
Post Options Post Options   Thanks (0) Thanks(0)   Quote californiajohnny Quote  Post ReplyReply Direct Link To This Post Posted: 25-July-2017 at 1:12PM
very true!
JOHN
74 GRAN TORINO S&H CLONE
74 VETTE CUSTOM
90 S10 BLAZER 4X4 LIFTED
77 CELICA CUSTOM
75 V8 MONZA SUPERCHARGED
79 COURIER VERT. SLAMMED
75 VEGA V6 5 SPD
70 CHEV C10 P/U
68 MUSTANG FB CONVERSION
Back to Top
aquartlow View Drop Down
Senior Member
Senior Member
Avatar

Joined: 19-December-2011
Location: Summerfield, Fl
Status: Offline
Points: 1795
Post Options Post Options   Thanks (0) Thanks(0)   Quote aquartlow Quote  Post ReplyReply Direct Link To This Post Posted: 25-July-2017 at 1:26PM
Originally posted by californiajohnny californiajohnny wrote:

very true!
 
I kinda figured it had to be, it was on the back of a Cracker Jack box LOL. Unfortunately, I will now be sued for plagiarism. On a lighter note: those caramel covered peanuts are the bomb and the little book of tattoos inside the box was a bonus Big smile, they kept me busy for a while WinkLOL.   
www.supermotors.net/22468
Yeah, It's a Hybrid...It burns gas and tires.

No matter how good she looks, somebody, somewhere, is tired of her sh*t.

Beauty is skin deep, ugliness goes clear to the bone.
Back to Top
Rockatansky View Drop Down
Senior Member
Senior Member


Joined: 30-July-2010
Location: On The Road
Status: Offline
Points: 4129
Post Options Post Options   Thanks (0) Thanks(0)   Quote Rockatansky Quote  Post ReplyReply Direct Link To This Post Posted: 25-July-2017 at 1:35PM
72 GT Ute
   
Back to Top
Don V. View Drop Down
Member
Member


Joined: 07-July-2017
Location: Michigan
Status: Offline
Points: 173
Post Options Post Options   Thanks (0) Thanks(0)   Quote Don V. Quote  Post ReplyReply Direct Link To This Post Posted: 25-July-2017 at 3:46PM
Originally posted by aquartlow aquartlow wrote:

 
Not trying to be an ass here, but how does a top fuel dragster/funny car make 10K horsepower with just zoomie headers if back pressure is absolutely necessary for an IC engine to run well. In another IC example I have also seen numerous turbo diesel engines with little more than a 18" piece of 4" pipe for an exhaust ran up through the hood and those ran "real" well. Please explain.
 
I don't think you're being an ass at all. It's a great question. I don't have the time right now to answer your question but I will quickly address Zoomies.
 
First and foremost, zoomies are cool.
 
A top fueler engine is designed for zoomies. I've seen more people use zoomies and destroy their heads than I've seen people successfully use them. Zoomies aren't something the average garage mechanic should be screwing with.
 
Back pressure is an important engine design parameter that involves the entire engine. It's often seen as an exhaust only parameter by a lot of people so they don't consider the effects inside of the engine from whatever they are doing with an exhaust. A lot of engines have been detrimentally effected because of this. For example, CATS require specific exhaust temperatures to perform their designed emission function. People remove CATS and alter their exhaust system but that doesn't change the engines design parameters like exhaust temperature. There is a measure of adaptability designed in to an engine but when the optimum performance requirements of an exhaust system exceed the engines adaptability to deliver the demanded performance requirement either performance is reduced, more often then not because of insufficient exhaust velocity, or money has been wasted on something with an engine that can't deliver the necessary performance to meet the exhaust systems potential. This example has more to do with modern engines than the engines that came in the cars that are the topic of this website.
Back to Top
MrSmog View Drop Down
Senior Member
Senior Member
Avatar

Joined: 21-January-2016
Location: Ky
Status: Offline
Points: 1088
Post Options Post Options   Thanks (0) Thanks(0)   Quote MrSmog Quote  Post ReplyReply Direct Link To This Post Posted: 25-July-2017 at 4:38PM
I love when engineers talk, you know, the ones that bury oil filters behind things so you remove all flesh on your hand gettin it out, require truck cab removal to work on a engine and all sorts of other glorious things. I recall a whole forum of engineers told me I couldn't swap a inboard jet drive to a bracketed outboard (I did it easily), another half dozen told me I couldn't swap a v10 in place of a 318 without massive frame damage/suspension failure ( I did it easily), and a few other things they said was impossible. Some people over think things. To the original poster, many people run cats with no mufflers, you'll be fine. As for the zoomies destroy engines, tell that to all the rat rod/street rod guys who run them and have run them for years with no ill effects.
Past 1974 Ranchero GT Q code

Present 1973 Q code formal roof base model Torino with ralleye equpiment package and 4spd.
Back to Top
fordpower View Drop Down
Senior Member
Senior Member


Joined: 02-September-2010
Location: willseyville,ny
Status: Offline
Points: 1477
Post Options Post Options   Thanks (0) Thanks(0)   Quote fordpower Quote  Post ReplyReply Direct Link To This Post Posted: 26-July-2017 at 12:57AM
Who would have though my question would make such a topic. All I know is remove all smog s plug the egr valve and the car ran worse. Gas millage went down car vapor locked seemed t less power. Everyone had said get rid of all that sh*t it will run 100% better wrong.
Back to Top
Don V. View Drop Down
Member
Member


Joined: 07-July-2017
Location: Michigan
Status: Offline
Points: 173
Post Options Post Options   Thanks (0) Thanks(0)   Quote Don V. Quote  Post ReplyReply Direct Link To This Post Posted: 26-July-2017 at 3:01AM

Originally posted by MrSmog MrSmog wrote:

I love when engineers talk, you know, the ones that bury oil filters behind things so you remove all flesh on your hand gettin it out, require truck cab removal to work on a engine and all sorts of other glorious things. I recall a whole forum of engineers told me I couldn't swap a inboard jet drive to a bracketed outboard (I did it easily), another half dozen told me I couldn't swap a v10 in place of a 318 without massive frame damage/suspension failure ( I did it easily), and a few other things they said was impossible. Some people over think things. To the original poster, many people run cats with no mufflers, you'll be fine. As for the zoomies destroy engines, tell that to all the rat rod/street rod guys who run them and have run them for years with no ill effects.

I'd like to know what forum of engineers told you this and the circumstances of your question. Attitude can make a difference too. Maybe the information you got was about something other than your question?

If you want to blame engineers for putting 10 pounds in a five pound bag, feel free too. It's really ignorant but if you need someone to blame. . . .

I decided to leave the NHRA rules about top fuel cars and the time they get between races used to rebuild the engine out of my last response. What does anyone know about the effect of zoomies when the engine they are using has a quarter mile lifetime? The blocks? Maybe a 3 mile lifetime.

This is from Jim Thorton who the NHRA recognizes as the inventor of the funny car. Paraphrased, "Nitro burning cars are no different from any other car when evaluating exhaust. Power is forfeited with straight pipes but the cars run so rich headers become a pipe bomb halfway down the track. Choosing between the advantage of headers or nitro with straight pipes didn't take a lot of thought. There's also no doubt straight pipes are the better crowd pleaser." 

Mixing street cars and track cars about zoomies? OK I guess? The effect of zoomies on engine life and power I thought was pretty well understood since the 50's. Typically the same engine on a dyno with both zoomies and tuned headers creates more power with headers. It didn't take much searching of hot rod websites to verify this. The earliest versions of the Merlin engine in the P-51 Mustang engine is a good place to start to learn about the effect zoomies have on engine life. There's not much to compare between an engine designed to operate at ground level to 25,000+ feet but it is a good place to start. On the street, the effect zoomies have on engine life I thought was pretty much taken for granted.

On the street zoomies are about some combination of looks and sound and have little to do with performance. The few places where you might get away with running zoomies legally on the street usually at least require zoomie baffles. I don't know this for sure but I imagine true, straight pipe zoomies are pretty rare on the street. Legally anyways.

If anyone wants to limit back pressure to the purvue of exhaust then I agree, back pressure restricts exhaust potential. If anyone wants to consider the exhaust as part of the balance of the entire system then the answer begins to look a bit different.

I would like an explanation though of why of the two common header designs, restriction and velocity, velocity is the better performer? Restrictions increase back pressure in the exhaust system so why are designs aimed at restriction reduction the poorer performer?

Don V.

Back to Top
fordpower View Drop Down
Senior Member
Senior Member


Joined: 02-September-2010
Location: willseyville,ny
Status: Offline
Points: 1477
Post Options Post Options   Thanks (0) Thanks(0)   Quote fordpower Quote  Post ReplyReply Direct Link To This Post Posted: 26-July-2017 at 3:21AM
Please do.
Back to Top
Don V. View Drop Down
Member
Member


Joined: 07-July-2017
Location: Michigan
Status: Offline
Points: 173
Post Options Post Options   Thanks (0) Thanks(0)   Quote Don V. Quote  Post ReplyReply Direct Link To This Post Posted: 26-July-2017 at 3:23AM
Originally posted by fordpower fordpower wrote:

Who would have though my question would make such a topic. All I know is remove all smog s plug the egr valve and the car ran worse. Gas millage went down car vapor locked seemed t less power. Everyone had said get rid of all that sh*t it will run 100% better wrong.
The early days of emission control involved taking existing designs and adapting the emission controls to them. It was fairly simple to remove the controls and return the engines to their original designs. As the engines evolved and became more sophisticated there was no original design to revert to. Unfortunately a lot of people held on to their "engine lore," when it was just foolish to do so. Specific built, high performance engines aside, the typical engine today gets better gas mileage while producing substantially more power than it's predecessor. Why would anyone try to change it by removing\deleting components that are integral to its performance? Still. a lot of people believe they can improve an engine while having zip knowledge of ECU programming which would be required for any chance of succeeding. Bear in mind the "Tuners" mentality is often to refer to tuning as programming which it isn't. Tuning is akin to changing the font on your word processor. That's not programming and has nothing to do with what would be required to remove the emission controls on a modern engine.
Back to Top
Rockatansky View Drop Down
Senior Member
Senior Member


Joined: 30-July-2010
Location: On The Road
Status: Offline
Points: 4129
Post Options Post Options   Thanks (0) Thanks(0)   Quote Rockatansky Quote  Post ReplyReply Direct Link To This Post Posted: 26-July-2017 at 3:47AM
Originally posted by fordpower fordpower wrote:

Everyone had said get rid of all that sh*t it will run 100% better wrong.
 
Originally posted by Don V. Don V. wrote:

I'd like to know what forum of engineers told you this and the circumstances of your question. Attitude can make a difference too. Maybe the information you got was about something other than your question?
 
I've seen that response here several times fairly recently, sometimes w/o regard to inspection regs
and certainly with no plan to recalibrate the tune after removing 'all that sh*t'
 
FWIW the laws regarding emissions systems are still alive, and the board here needs to be respected
concerning careless shooting off at the keyboard with 'get rid of all that sh*t it' replies
 
=======================
to the OP, not sure if you've seen my comments regarding reduced  ~backpressure~ for a daily street driven car but I've been shocked at the difference between a 2>1 single pipe to the rear bumper and a simple dual dumping before the rear axle. night and day would be an understatement it was more like an equatorial eclipse. the gas pedal went from a very sensitive throttle control to an old beat up work boot stuck in a bucket of 1/2 cured concrete. a previously nimble 350-2bbl lost all it's off idle finesse and required a significant amount of throttle angle just to get out of it's own way
 
it was not a Win Win Win
 
 


Edited by Rockatansky - 26-July-2017 at 3:48AM
72 GT Ute
   
Back to Top
stanman View Drop Down
Senior Member
Senior Member


Joined: 23-March-2007
Location: Nova Scotia, Ca
Status: Offline
Points: 1369
Post Options Post Options   Thanks (0) Thanks(0)   Quote stanman Quote  Post ReplyReply Direct Link To This Post Posted: 26-July-2017 at 4:08AM
Rock.....so going from single to dual exhaust made performance worse?
Back to Top
Rockatansky View Drop Down
Senior Member
Senior Member


Joined: 30-July-2010
Location: On The Road
Status: Offline
Points: 4129
Post Options Post Options   Thanks (0) Thanks(0)   Quote Rockatansky Quote  Post ReplyReply Direct Link To This Post Posted: 26-July-2017 at 4:41AM
pretty much that sums it up. as a daily driver 350-2bbl there was nothing to gain in the mid or on the top end that it didn't already do as a single exhaust. throttle response and driveability were in the toilet compared to before the exhaust system 'upgrade'
 
tailpipes would've probably helped get some back but those benders are proud of their work and demand to be paid accordingly, at that time an appointment with the fancy pipe machine wasn't in the budget
 
the exhaust system is certainly a deal maker / breaker for sure
 
 
72 GT Ute
   
Back to Top
fordpower View Drop Down
Senior Member
Senior Member


Joined: 02-September-2010
Location: willseyville,ny
Status: Offline
Points: 1477
Post Options Post Options   Thanks (0) Thanks(0)   Quote fordpower Quote  Post ReplyReply Direct Link To This Post Posted: 26-July-2017 at 5:12AM
I in know way am advising removing smog or emission system. In NY car is old enough that it makes no difference though. My exhaust system uses the cats because 15yrs ago they could not legally remove them.
Back to Top
MrSmog View Drop Down
Senior Member
Senior Member
Avatar

Joined: 21-January-2016
Location: Ky
Status: Offline
Points: 1088
Post Options Post Options   Thanks (0) Thanks(0)   Quote MrSmog Quote  Post ReplyReply Direct Link To This Post Posted: 26-July-2017 at 5:28AM
Originally posted by fordpower fordpower wrote:

Well thinking of replacing my cats.
tried to do some research on back pressure.I found it very confusing to say the least. does anyone have opinion . I like sound with cats and no mufflers.


my reply was in my own personal experience with the engineer types online, the reply to don who said zoomies destroy cylinder heads and the OP's question above. There is no reason a properly sized dual exhaust with just cats should hurt performance, in fact it should help. The same could be said for a stock 350 2bbl, can't imagine a set of properly run 2" duals on that engine would do anything but good. I think some people read too much of others opinions and then second guess themselves. I am about to put a set of 2" duals with 2.5" mufflers/tailpipes on my blue stock 302 car, I'll report back just how badly it runs, loses power and mpg afterwards. LOL
I have put duals on just about every V8 powered vehicle I had had for almost 30 years now, never had anything but positive results from it. Power always went up, mpg always went up if drove normally and the only negative I can think of is there was never enough tunnels to go through to hear it when I stomped on it.




Edited by MrSmog - 26-July-2017 at 5:28AM
Past 1974 Ranchero GT Q code

Present 1973 Q code formal roof base model Torino with ralleye equpiment package and 4spd.
Back to Top
 Post Reply Post Reply Page  12>
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 11.10
Copyright ©2001-2017 Web Wiz Ltd.

This page was generated in 0.094 seconds.