im out of money pretty much so the $400 flowmasters arnt lookn like a good deal right now ... i was wondering if i just put strait pipes and remove everything and just run a pipe out the side from the downpipe if it would mess up my engine at all... like backpressure problems or any hp or torque loss problems??? just let me know... thanks!

 

serious?? no one can take 2 seconds to answer this stupid question??

 

id say at least leave the cat's on for some back pressure .. i know my mustang ran ok with true str8's but it was a 89 336 stroker .. take a risk and give it hell

 

IF I LEFT THE CATS ON IT WOULDNT BE STRAIT PIPES THO....

 

there is no such thing as too little back pressure...
what size piping are you putting on?
as long as you keep your o2's where they belong, you'll be fine and loud

 

^-----What he said. Straight pipes baby, at least until you get tired of how loud its gonna be. You could run some $20 glasspacks if you want to smooth out the sound a little...

 

how do those glasspacks work???

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mmuller &raquo;</TD></TR><TR><TD CLASS="quote">there is no such thing as too little back pressure...
what size piping are you putting on?
as long as you keep your o2's where they belong, you'll be fine and loud</TD></TR></TABLE>

BUll fukin **** ahole!!!
Another guy that doesn't know what hes talkin about.

Quit fukin postin when u r guessing.

There is such a thing as 2 little backpressure.

No backpressure=No Power.

Thats why we don't run 3 inch exhaust w/o turbo.


Why is it that everytime someone post a question, there are a bucnh of know-nuthings that have to reply with either a wild-*** guess or a bunch of **** that confuses people. If u **** want to post just to post, then carry your slack-asses 2 the general discussion forum. Most of us don't have time to sit here and filter through all the bullshit replies that mean nothing. Some of us want to find a solution and move on.

Yea buddy, ummmmmmm, ahhhhhhhhhhwhy don't you just run 5 inch straight pipes, must be better than what u have now........bigger is better-right... What a bunch of ****.

Just search this site and learn.

 

I think you're coming off way too harsh here. Now just because some backpressure might benefit some motors, perticularly in low end torque which is needed most by very small engines i.e. honda motors, doesn't mean "no backpressure = no power". Take a look at top fuel dragsters for example: Giant open headers = ~ 6000 horsepower. I personally don't see anything wrong with running straight pipes off of a 5.9L dodge motor, but if you *really* want to find out what you're gaining / losing, you'll have to take it to the 1/4 or the dyno. Good luck.

Edit: I didn't see you're question up there, but glasspacks work just like most straight-thru design mufflers, that's essentially what they are. It's an inner pipe riddled with holes and enclosed by another bigger pipe. Between the outside of the inner pipe and the inside of the outer pipe is packed fiberglass. This muffles some sound, but as the inside pipe should be the same size as the rest of your exhaust, there should be very little if absolutely no restriction.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by racecar80 &raquo;</TD></TR><TR><TD CLASS="quote">

BUll fukin **** ahole!!!
Another guy that doesn't know what hes talkin about.

Quit fukin postin when u r guessing.

There is such a thing as 2 little backpressure.

No backpressure=No Power.

Thats why we don't run 3 inch exhaust w/o turbo.


Why is it that everytime someone post a question, there are a bucnh of know-nuthings that have to reply with either a wild-*** guess or a bunch of **** that confuses people. If u **** want to post just to post, then carry your slack-asses 2 the general discussion forum. Most of us don't have time to sit here and filter through all the bullshit replies that mean nothing. Some of us want to find a solution and move on.

Yea buddy, ummmmmmm, ahhhhhhhhhhwhy don't you just run 5 inch straight pipes, must be better than what u have now........bigger is better-right... What a bunch of ****.

Just search this site and learn.</TD></TR></TABLE>

Chill out dude. You should take your own advice and not spew a bunch of misinformation yourself. The way you went about doing it is gonna make you look especially stupid.

The other dude is right, the less backpressure the better. Backpressure does not give you torque, and backpressure does not give you power. It only takes it away, in every situation.

That does not mean that bigger pipes are better. Pipe size is not the same thing as backpressure. It controls other things, too, such as exhaust velocity. Backpressure is an unwanted byproduct of increasing exhaust velocity. It does not mean it's good. It's like saying that snapping an axle is good becasue it means you're making lots of power.

The only time I can think of backpressure being a good thing is to bypass exhaust through a wastegate around a turbo, but that's a whole other issue.

 

has anyone ever seen an engine run with no headers or exhaust manifolds. Runs like ****. All engines need a certain amount of back pressure. Even 6000HP dragsters. That why they have headers in the first place. Oh and if your thinking deisel, that a whole nother story. Why are we arguing about a Dodge in this forum anyway. My rant wasn't about back pressure anyway, it was a general rant.

Everyone have a great weekend.
L8r

 

Like I said, headers and exhasut manifold don't only control backpressure, they also control many other variables. Backpressure happens to rise proportionally with some of those variables.

Here's something posted in another discussion on backpressure, found by doing a quick search as per your advice:

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
quote:
--------------------------------------------------------------------------------


"from 21st Century Performance Book

Few tests have been done that clearly show the effect of changing back pressure. Most muffler and exhaust comparison tests change more than one parameter simultaneously, making the identification of exhaust back pressure as a culprit difficult.

However, Wollongong (Australia) mechanic Kevin Davis has done extensive testing of varying back-pressure on a number of performance engines.

These range from turbocharged Subaru Legacy RS flat fours to full-house traditional pushrod V8s. In not one case has he found any improvement in any engine performance parameter with increased exhaust back pressure.

The tests came about because Kevin has developed a patented
variable-flow exhaust that uses a butterfly within the exhaust pipe. He initially expected to use the system to cause some back pressure at low loads 'to help torque.'

However, he soon changed his mind when any increase in back pressure proved to decrease torque on a properly tuned engine. What increasing the back pressure does do is dramatically quieten the exhaust.

One of the engine dyno tests carried out by Kevin was on a modified 351 4V Cleveland V8. Following the extractors he fitted a huge exhaust that gave a measured zero back pressure. Torque peaked at 573Nm (423 ft-lbs) at 4700 rpm, with power a rousing 329 kW (441 hp) at 6300 rpm. He then dialed-in 1.5 psi (10.4 kpa) back pressure.

As you'll see later, very few exhausts are capable of delivering such a low back pressure on a road car. Even with this small amount of back pressure, peak torque dropped by 4 per cent and peak power by 5 per cent. He then changed the exhaust to give 2.5 psi back pressure. Torque and power decreased again, both dropping by 7 per cent over having zero back pressure. These results were achieved on a large engine with a large overlap cam - one of the type some people suggest is 'supposed' to like back pressure.


If, in fact, power does increase with increased exhaust back pressure, it is most likely the air/fuel ratio and/or ignition timing that are no longer optimal for the altered state of engine tune."

Larry Widmer comments on the above textbook quote:

At less than WOT and peak power rpm, the diameter of the tubing should change in ID. Just as with intake ports (unless we're just running off port volume), cross sectional area should be only sufficient to supply the flow rate necessary to feed the engine.

High velocities, that don't incur pumping losses are the rule.

The exhaust system is much the same. Just changing back pressure is a bogus way of trying to create the "ideal" pressure in the system. The exhaust system should work like a correctly conceived header. It should extract the exhaust from the header, to minimize pumping pressures.

The only way to create a system that will serve as an extractor is to properly size the tubing to allow the flow velocity to create a sort of "vacuum" behind it.

Just as with headers, creating a system that will provide the best of all worlds at all throttle positions and rpm ranges is impossible. It's all going to be a trade-off. You can tune for the throttle positions and rpm ranges where you desire the greatest performance, but you'll sacrifice performance at the other end of the rpm range.


Building a system to divert the flow into a smaller system can help bolster lower rpm power, just as with today dual runner intake manifolds, but you'll never find a dual runner intake on any engine that's targeting the greatest performance potential possible. I should also add that such systems are inefficient from a standpoint of weight and surface area.

For mid-performance applications, these type systems will be as popular as their costs will allow.


In our quest for "more", we seldom work to achieve mid-level (mid rpm range) performance, so just as the gentleman who wrote the book in the post from above, we prefer to tune with the least amount of backpressure possible. We do have to observe rules and regulations (noise levels and EPA regulated emissions) and the systems must fit the vehicle in question without dragging the ground, so there will always be compromises.

I suppose that I should mention that cost is another consideration. If it wasn't, a lot of our street systems would have greater area and they wouldn't necessarily be circular in configuration either.

In the stock ITR, backpressure becomes a power "liability" by the time the engine's making 210 flywheel HP. Relative to wheel HP, if you're making more than about 11 HP more than "stock", the system's costing you....and yes, detonation can be caused by excessive back pressure.

The other problem you face with excessive back pressure is one of reversion. The higher the back pressure, the more inert exhaust components re-enter the cylinder. A few of these bad-guys can really steal big hunks of power in a hurry. If you don't believe me, just run a pipe from your exhaust tip up near the air cleaner on your next trip to the dyno. A little sniff of the exhaust will absolutely kill your power.


--------------------------------------------------------------------------------


2. Calculations and Comments by Dave Stadulis of SMSP Exhausts Relating Flywheel HP to Exhaust Cross-Sectional Area (Diameter):


quote:
--------------------------------------------------------------------------------


Here are the numbers for 16g tubing:

OD (in.)....ID (in.)...Area....%Increase......HP.......HP/in^2

2.25........2.120.......3.53.....0%............... 200.......56.66

2.50........2.370.......4.41.....25%.............. 275.......62.34

2.75........2.620.......5.39.....22%.............. 318.......59.00

3.00........2.870.......6.47.....20%.............. 400.......61.83

OD is exhaust outer diameter, ID is inner diameter, Area is tube cross-sectional area, % Increase is increase from the prior OD, HP is Flywheel hp, and HP/in^2 is hp per square inch cross-sectional area.


For the 2.75 in. tube, I assumed 59 HP per square inch of flow area, I used Larry's numbers for the others....you are talking HP at the crank :

2-1/4" for up to 200HP @ the crank, 2-1/2" for 275HP, 2-3/4 for 320HP...

or 60HP (at the crank) per square inch of (cross-sectional) flow area.

This 60HP/in^2 is to get you in the general vicinity. It also is based on the inside diameter of the tubing not the OD (ie. 2" in your example). The ID for 2' 16g tubing is 1.87" and this will yield a limit of 165 crank HP. 2-1/4" 16g (212 HP), 2-1/2" (265 HP). Now you can get different sized tubing such as 2-1/8" and 2-3/8" to fine tune a vehicle but you can't get cats and mufflers in those sizes so you should go up a size when building an exhaust in those cases.

The stock ITR exhaust is 2-1/4" but not everywhere. At the B pipe flange, the tubing actually necks down to 1.9" OD or 1.75" ID and then opens up to 2-1/4". It again necks down (not as bad) around the flex joint prior to the axle.

--------------------

Question: Do you have an opinion concerning the best choice for harnessing exhaust pressure waves when a catalytic converter is present at the manifold? ... I'm just curious at a theoretical level. : Here are the possible choices:

1. Gut the manifold mounted converter, so it acts like a pressure wave plenum, and replace the smaller converter downstream with a larger converter (coating the exhaust to encourage light off). As with the intake manifold, there should be some pressure wave tuning occuring somewhere in the rpm band.


2. Use a manifold/header which does not have a converter mounted to it, and install a pressure wave plenum immediately in front of a larger manifold type converter downstream (once again coating the exhaust to encourage light off). Same benefit as above, but allows some tuning flexibility since the plenum location can vary.


3. Ignore exhaust pressure wave tuning; it's not a significant issue with a stock valvetrain.

SMSP replies:

I believe you can effect the overall peformance of your system by the placement of the cat, since you have a volume change when the exhaust gases enter the cat. But then temperature does become an issue for the emissions performance of the cat.

Same goes for running an open header versus a header with a short tuned tail pipe. Tail pipe length is very important, it just takes a lot of testing to determine what is right. I know of a guy who played with different length tail pipes and picked up 5-6 HP on a 190+ WHP engine.

To take full advantage of the system you have test and tune, many many times. I believe a tuned length tailpipe will get you the most power, versus running the header open (nothing after the collector)
--------------------------------------------------------------------------------


3. John Grudinsky at HyTech Exhausts comments on the usefulness of backpressure:


quote:
--------------------------------------------------------------------------------


I have seen where a little back pressure, helped out the very low end of a 4 cycle engine because it had a lot of valve timing and it stopped some of the scavenging of the cylinder and (therefore) helped the power. But as the motor revved up, the gains were diminished and it lost power on top (in the upper rpms). There have been exhaust systems designed to actually reverse feed the cylinder through the exhaust port, before the valve closes on overlap. It actually has worked, but it didn't seem to work over a large rpm band but in a short (rpm) one, it worked quite well.

</TD></TR></TABLE>

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by racecar80 &raquo;</TD></TR><TR><TD CLASS="quote">

BUll fukin **** ahole!!!
Another guy that doesn't know what hes talkin about.

Quit fukin postin when u r guessing.

There is such a thing as 2 little backpressure.

No backpressure=No Power.

Thats why we don't run 3 inch exhaust w/o turbo.


Why is it that everytime someone post a question, there are a bucnh of know-nuthings that have to reply with either a wild-*** guess or a bunch of **** that confuses people. If u **** want to post just to post, then carry your slack-asses 2 the general discussion forum. Most of us don't have time to sit here and filter through all the bullshit replies that mean nothing. Some of us want to find a solution and move on.

Yea buddy, ummmmmmm, ahhhhhhhhhhwhy don't you just run 5 inch straight pipes, must be better than what u have now........bigger is better-right... What a bunch of ****.

Just search this site and learn.</TD></TR></TABLE>


dude, your a complete idiot and you should be banned from this site.
before mouthing off learn your facts. backpressure is a myth.
you need to keep exhaust velocity, not pressure.

Im not even going to waste my time on you since Lsos already OWNED you
look at my avatar and smile

what a tool...

 

has anyone ever seen an engine run with no headers or exhaust manifolds. Runs like ****. All engines need a certain amount of back pressure. Even 6000HP dragsters. That why they have headers in the first place. Oh and if your thinking deisel, that a whole nother story. Why are we arguing about a Dodge in this forum anyway. My rant wasn't about back pressure anyway, it was a general rant.

Everyone have a great weekend.
L8r

 

Whatevr, you already wasted your time, & mine. And about your Avatar, it is as GAY as u r. Ha

And another thing, with strait pipes that Dodge will sound like ***. Bwahhhhhh, bawahhhhhhh.

 

it looks like you learned something about exhaust from reading LSOS post... Congratulations........

You gave that guy bad advice about running just strait pipes. Why should he waste his time and money running strait pipes. All its gonna do is get him tickets and sound like ****. Not to mention what he is doing to the Atmoshere with-out cats on. There are posts here about that also. You can find them by searching.

Now
I'm done with U.

 

it looks like you learned something about exhaust from reading LSOS post... Congratulations........

You gave that guy bad advice about running just strait pipes. Why should he waste his time and money running strait pipes. All its gonna do is get him tickets and sound like ****. Not to mention what he is doing to the Atmoshere with-out cats on. There are posts here about that also. You can find them by searching.

Now
I'm done with U.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by racecar80 &raquo;</TD></TR><TR><TD CLASS="quote">

BUll fukin **** ahole!!!
Another guy that doesn't know what hes talkin about.

Quit fukin postin when u r guessing.

There is such a thing as 2 little backpressure.

No backpressure=No Power.

Thats why we don't run 3 inch exhaust w/o turbo. dude dont u think ur a little too new here to be goin off like that there is no need for that kind of response chill a bit before a mod locks this thread and this guy dont get the info he needs


Why is it that everytime someone post a question, there are a bucnh of know-nuthings that have to reply with either a wild-*** guess or a bunch of **** that confuses people. If u **** want to post just to post, then carry your slack-asses 2 the general discussion forum. Most of us don't have time to sit here and filter through all the bullshit replies that mean nothing. Some of us want to find a solution and move on.

Yea buddy, ummmmmmm, ahhhhhhhhhhwhy don't you just run 5 inch straight pipes, must be better than what u have now........bigger is better-right... What a bunch of ****.

Just search this site and learn.</TD></TR></TABLE> hey man dont u think ur a little new here to be going off like that, there is no need to respond like that just calm down before a mod locks this thread and this guy dont get the help he is looking for..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by b18c5-EM1 &raquo;</TD></TR><TR><TD CLASS="quote">im out of money pretty much so the $400 flowmasters arnt lookn like a good deal right now ... i was wondering if i just put strait pipes and remove everything and just run a pipe out the side from the downpipe if it would mess up my engine at all... like backpressure problems or any hp or torque loss problems??? just let me know... thanks!</TD></TR></TABLE>

No, it will not mess up your engine nor will it make you lose power. You will probably gain some, in fact. However, it will sound lound and/or terrible and if you take the cat off you might want to think about the effects that it will have on the environment (although I'm not one to talk).

 

I like how you get much more activity in a thread when people are busy insulting and arguing with each other than you do when you post a very technical question seeking advice. Thanks lsos, and to the thread creator, I hope you got enough info to make a decision.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by racecar80 &raquo;</TD></TR><TR><TD CLASS="quote">

Just search this site and learn.</TD></TR></TABLE>

HELLO FUCKFACE DO YOU THINK IM GOING TO FIND IF I NEED BACK PRESSURE FOR A 5.9 LITER DODGE RAM ON A HONDA FORUM BY SEARCHING? HAH WOW WE GOTA ****** IDIOTTTTTT