no mufflers cause less throttle response??

[Foxfan88]

lately since i have had no mufflers. there seems to be a drop in throttle response. could it have anything to do with it??

 

[srothfuss]

Less back pressure can lead to slugishness...

 

[302RollinHard]

Agreed. Most engines require back pressure to function properly. Too much back pressure is a bad thing and to little can be as well.

 

[Grn92LX]

You do NOT want backpressure!

 

[mike myrick]

no back pressure

If you take all the back pressure off of the exhaust it will do that depending on the car and what you have done to it .Put the mufflers back on when you do it should be up and running also temp change was it cold the day before I know here it has gotten hot in the past two days and that will play a big role in performance.

 

[vikingpower]

scavenging, not backpressure. backpressure bad, like teenie-tiny E7 exhaust ports

 

[onefstsnake]

so if my headers are leaking would that cause a surging idle?

 

[Racerjoey1]

I think no mufflers may cause a little lack of throttle response. At least on my car I think it does. I have Motorsport shorties, a upr offroad x, and thats it. I am waiting to order mufflers after I get some other stuff done (its not a daily driver). It has less response and doesn't run as good. Of course it may just be a p.o.s.

 

[DeadLifter]

You'll probably lose a little low end torque and gain more up top with no mufflers.

 

[blackstangt]

i was running with no tailpipes for a little while(had 3.08's then now 3.73 which changes things a little) and when i added tailpipes, it was better all around, I didn't really lose top end, but i gained a lot down low, so without mufflers, you are definately losing a lot of power, and this may also cause a surging idle because there is nothing to hold back the power(not the best way of saying). IF you have some reason to run without mufflers, you can probably fix your idle with a proper throttle body adjustment procedure.

 

[vristang]

If anything the decrease in backpressure would improve the motors ability to breathe, increasing throttle response.

There is a huge difference between backpressure and scavenging, as eluded to a few posts up. Scavenging has to due with an exhaust pulse in one tube causing a negative presure in second tube, which helps pull the second exhaust pulse out of the head. The reason larger than necessary headers should not be used is that if not enough exhaust is pulsing through tube #1, then the affect on tube #2 will be minimal. Too large of an header primary does not allow the exhaust pulse to maintain velocity, and create the negative pressure in the other primaries.
Backpressure has to do with how restrictive the exhaust system is.

Most likely the difference is in your head OR you have something else going on that just happened to start causing problems when you removed the mufflers.
As always pull the codes, check tps, fuel pressure, and timing.

jason

 

[CRASH7772]

Unless your running over 1000hp why would you ditch the mufflers?

"OPEN EXHAUST MAKES LESS HP AND TQ THEN MUFFLERS"

Results based on 5.0 Mustang Magazine December 2002 issue (page 55). Test car is a ’90 Coupe with 370 HP and 11 second potential. A number of 66 pulls were made to compile this information. Where does your muffler stack up?

The results in HP order:

1.Flowtech Warlock (open) 374.2 hp/ 333.1 tq
2.Bassani Real Street 373.7 hp/ 333.8 tq
3.Hooker Maxflow 373.5 hp/ 333 tq
4.Borla XS 373.3 hp/ 332.6 tq
5.Magnaflow 372.8 / 332.5 tq
6.MAC 372.3 hp / 331.5 tq
7.Flowtech Afterburner 372.3 hp/ 330.1 tq
8.Hooker Aerochamber 372.1 hp/ 330.4 tq
9.Bassani 372 hp/ 333.5 tq
10.Spintech 371.6 hp/ 332.2 tq
11.Edelbrock Performer RPM 370.9 hp / 331.3 tq
12.Borla XR1 370 hp/ 334 tq
13.Flowtech Terminator 369.5 hp / 331.3 tq
14.Dynomax Ultra Flo 369.4 / 333.2 tq
15.Flowmaster 369.4 hp / 331.8 tq
16.Flowtech Warlock 366.3 hp / 325.3 tq
17.No muffs 365.2 hp / 330.1 tq

Not sure if anybody remembers but when the noise levels from oval racing (500-700 hp range) became a issue and mufflers had to be run the engine builders found more power with the mufflers on.

 

[bluevenom867]

If your EFI,you need to tune it for use with open exhaust.

In other words cause a set program will only hold an injector open for a certian period,when you take off your mufflers to reduce backpressure it can over scaveng and pull some fuel out of the port,causing a slight lean condition.

vristang,the exhaust "pulse" from one primare will pull the "pulse" charge of another port/primary also,once it reaches the collector.The collector becomes useless above peak torque though,as the velocitys are high enough to pull the a/f through its own primary.

You got to tune for open exhuast/headers....so dont just say that mufflers make more power.

 

[onefstsnake]

so if my headers are leaking would that cause a surging idle?

anyone?

 

[Roland69]

probly not .

 

[onefstsnake]

cuz a buddy of mine gave me his old O/R H pipe and O2 sensors and idle is terrible...

Sometimes the car will cut off...

He did run a little C16 through it though, could have messed up the 02's?

 

[vristang]

vristang,the exhaust "pulse" from one primare will pull the "pulse" charge of another port/primary also,once it reaches the collector.The collector becomes useless above peak torque though,as the velocitys are high enough to pull the a/f through its own primary.
.

So how does exhaust tuning affect peak hp then?

I developed the thoughts I posted above by just "thinking things through," so if I have something wrong please let me know.

This subject seems to be a mystery to many

jason

 

[5spd GT]

Since back pressure isn't what we want...I'm not even going to put headers on...see how it runs...

Disclaimer:

You do want some form of backpressure...saying you don't want any at all is ludacris...

Velocity and backpressure intersect at some point...if our cars didn't have any "pressure" at all...we would know it...

They aren't the same thing...but they are needed to a varying degree...

 

[Mavrick]

I think everyone needs a lesson on the difference between exhaust velocity (efficiency) and back pressure. Back pressure is not good.

 

[CRASH7772]

If your EFI,you need to tune it for use with open exhaust.

In other words cause a set program will only hold an injector open for a certian period,when you take off your mufflers to reduce backpressure it can over scaveng and pull some fuel out of the port,causing a slight lean condition.

vristang,the exhaust "pulse" from one primare will pull the "pulse" charge of another port/primary also,once it reaches the collector.The collector becomes useless above peak torque though,as the velocitys are high enough to pull the a/f through its own primary.

You got to tune for open exhuast/headers....so dont just say that mufflers make more power.

Well after reading this article http://superchevy.com/technical/engines_drivetrain/exhaust/0505phr_exh/index1.html I guess it's claimed that the power levels can be equal with properly tuned open exhaust and the right mufflers. It just seems that unless your making big power it's not worth it IMO. I still wouldn't recommend anybody to run open exhaust unless it's a strip car with big power. I think we all know that the right size pipe and location has effect on engine performance. I would recommend that anybody that has questions about exhaust read the article (even though it's from Super Chevy).