How much will I gain if I run open headers????

[JOEYMAN]

I'm headed to the track on slick night T&T this coming wednesday. I want to drop the exhaust and run open headers. The exhaust is not mandrel bent. I have flowmaster 40series 2 chamber. The car runs 12.40's with full exhaust. How much should I gain. It will be cooler out than what I have been running in (temps).

[BBLM23]

I took the 4 inch bullets off and gained nothing...

[JOEYMAN]

Well I have full exhaust with tail pipes all the way out to the bumper.

[Capt Jack]

Ive done the old "unbolt the collector and let them hang" thing before.  other than the teeth rattling increase in noise (and fumes) I noticed zero difference from a well built exhaust system.

[JOEYMAN]

I have reason to believe that I will gain because I don't have mandrel bent pipes. Just something put together from the exhaust shop down the street.

The bends look flat as it goes up and over the rearend

I should at least gain some MPH

[illfish]

Lose some weight or find it in the motor.

[JOEYMAN]

I've always heard that you can gain 2 tenth without mufflers. That is a restriction.

There is only one way to find out and that is take 6 bolts off and 

[abodyjoe]

think it depends alot on your exhaust.

have a friend that gains a solid 2 tenths in his cuda when he opens the cut outs...    he is running straight 3" pipes to flowmasters and dumps in front of the rear..


my car runs exactly the same open or close.. i'm running 3" pipes to a X-Pipe and 3" dynomax super turbo mufflers... was running tail pipes but now that they are off ther has been no difference.

[jamesdart]

when i had the 3" on my dart with flow techs, i picked up nothing but ringing ears when  i opened the exhuast. those arent even a strait through muffler. you might gains some, but you should also try jetting up a tad when you open it. what size is the motor and what size pipes? i say just build the right size exhuast with some strait through mufflers.

[496dart]

I PICKED UP .5  in e.t.  when i installed a 3" system on my car.

Leave it on.

[Joe-Dokes]

As someone with a real hearing loss, please protect your hearing.  Though my wife doesn't bother me as much, since its gotten worse. 

A modern well designed exhaust system has a negligible effect on hp.  I'd leave the system on.

Make sure you have mandrel bent with an x pipe and good mufflers.  Rather than pull your system off, simply upgrade the portions that need it.

By the way 496 Dart what were you running before the 3" mandrel bend setup 1" with a cork?  Half a second is a serious gain.  Good Job.

Regards

Joe Dokes

[Eats4dz64]

The reason most people do not gain power from removing there exhaust is that there exhaust allready flows very well, or the carb is well tuned to the motor in its current state. Try going up 2 jet sizes in the secondary then see if you gain some ET from it.

The exhaust on my dart is very porly done, so when I drop the exhaust it runs much better and allows me to jet up at the same time.

Just food for thought.

[MyCreation68]

I've always heard that you can gain 2 tenth without mufflers. That is a restriction.

There is only one way to find out and that is take 6 bolts off and 

from the way you sound your convinced already you will make gains from it. So as you said theres only one way to find out and thats taking the exhaust off and trying.

[Womanator]

I lose a tenth when I put my bullets on my 68 dart it's a 9.5 sec car.Maybe if I jetted down when I put the muff's on it would stay the same.I tune for open headers.

[496dart]

As someone with a real hearing loss, please protect your hearing.  Though my wife doesn't bother me as much, since its gotten worse. 

A modern well designed exhaust system has a negligible effect on hp.  I'd leave the system on.

Make sure you have mandrel bent with an x pipe and good mufflers.  Rather than pull your system off, simply upgrade the portions that need it.

By the way 496 Dart what were you running before the 3" mandrel bend setup 1" with a cork?  Half a second is a serious gain.  Good Job.

Regards

Joe Dokes

no b.s. brother.

its all in the engine and torque curve/combo --thats why you see guys bolting on 12"-16" header extensions.  I will have to dig out my logbook , but,  i ran  one weekend and then on wednesday the next, had my 3" exhaust put on (with $19 3" Summit glasspacks)  , and--no other changes.  same weather-- "almost"  a 10th  in ET.  My combo loved the back pressure.  Believe me-----I was suprised!

[dustymopar]

I gained nothing, but run a 3"  1/2 system with Flowmaster 40's

BUT, it does sound good and is a goos chance to make a lot of noise

[PureGTS]

Depending on your exh' system, maybe as much as two tenths to as little as nothing at all.

My 400 stroker, open header, went (1/8th mile) 6.80 @ 100.1 MPH without and 6.88 @ 101.19 MPH with 3 1/2 exh' w/ flowmasters. The exh also added about 50lbs (using the right arm curl scale method of weighing) to the overall weight of the car too.