Would going from 2 1/2 to 3'' exhaust be worth it???

[69wannabe]

I'm running a mild cammed 493 cubic inch stroker in my charger. It's a street driven weekend driver with mild 9.8 or so dish pistons and a XE285 comp cam. Got cast iron 346 heads with 214/181 valves and mild port work and the RPM intake and 850 DP holley carb. The headers are the hedman 1 3/4 headers with 2 1/2 pipe out the back. I have other mopar guys tell me the car needs 3'' exhaust since its a stroked 440. I am wanting to change the tips and put some more correct ones on there but would like input on the 3'' recommendation. Thanks

[green69rt]

Just to get the discussion started....  A bigger exhaust will only help when running at the top RPM with a big cam.   Correct that...it will help MOST running at top RPM and a big cam.  Otherwise it's mostly bragging rights.   I doubt if you could tell in day-to-day driving or even at the stop light.   It might show up on a dyno but not much, only at the top end.   With a fairly mild cam you need to enhance the low end torque, which translates to seat-of-the-pats kick.   For that you need to keep the exhaust velocity up at low RPM.  With a 3" exhaust, you will reduce the low RPM velocity. 

[JB400]

I would have to agree.  Since it's just a street car, 2 1/2 is enough.   If it's going to spend quite a bit of time on the track, then the 3 inch would be more justifiable and necessary.

[68X426]

Ron will hopefully post on this topic, with way more knowledge than I have. But as I understand the science of this, the point to headers and the big exhaust is to not restrict the flow of the heads (in the final analysis).

The heads are not large enough flow to call for 3". In other words, 2.5" is not restricting the flow, so it's not worth the expense.

[Cooter]

OP, you sure they ain't 1 7/8" headers?
I think you'll benefit from a free flowing 3" exhaust if for nothing more than to change the sound of the car and free up a few ponies up top. plus, if you go with aluminum heads later, you have the pipe.

[tan top]

yeah stroker motor ,  3inch pipe  & its all ready there should you feel the need to ad more speed parts 
stock 383 or 440   , with no plans  of looking for more power !!   2 1/2 inch   

[Ghoste]

I think in your case the 3 inch will make a difference given the cubic inches you are moving.  It's going to set off car alarms driving around town but that can be amusing in its own way too.

[1974dodgecharger]

If u have da money I say do it...I have 3 inch exhaust myself love tye sound

[Back N Black]

I think a 2.5'' exhaust would be go up to 500 hp. Anymoe than 500 hp go with the 3'' exhaust.  

[John_Kunkel]

My '62 Dart Max Wedge car had the original 2 1/2"/2 1/4" exhaust, replaced it with a 3" system from TTI. Starting the motor after the new exhaust install it idled 200 rpm faster and had noticeable better throttle response.

Downside...very noisy (to my taste).

[firefighter3931]

A 3in mandrel bent system with an X-pipe and straight-thru style mufflers would be a nice improvement. The welded UltraFlow mufflers would be my first choice. 


Ron

[Mopar Nut]

A 3in mandrel bent system with an X-pipe and straight-thru style mufflers would be a nice improvement. The welded UltraFlow mufflers would be my first choice. 


Ron

Mine too with a 493 cubic inch stroker.

[ACUDANUT]

 I never did find a Muffler shop around me who could give me a 3inch exhaust.  Their systems could only bend 2 1/2.  It works for me.

[BSB67]

Do those of you that believe that 3" is better also think that hp level is not pertinent?

Do you believe that the OP is making more than 500 hp?

Do you believe that a 440 with the same hardware (cam, heads etc.) should have a 3" system too?

Do you believe that there would be and increase in 1/4 mile mph (i.e. average power)?

Do you believe that there would be more than 10 hp increase at max power (5000 rpm or so)?

Do you believe that there will not be a degradation of throttle response below 3000 rpm?

Just curious

[69wannabe]

If u have da money I say do it...I have 3 inch exhaust myself love tye sound

What mufflers are you running? I am currently running super turbo's and they have been on the car for years and I like the way they sound. They are very noticeable at idle and smooth and mellow down the road. I had 3 chamber flow masters a long time ago on there but they resonated through the car and I didn't like that at all. Guess i'm getting old and don't like the noise!

[69wannabe]

A 3in mandrel bent system with an X-pipe and straight-thru style mufflers would be a nice improvement. The welded UltraFlow mufflers would be my first choice. 


Ron

Hey Ron, are these mufflers rather quiet?? I like the sound of the regular turbo's that are on it rite now verses it being loud.  I want the performance without the noise!! 

[ACUDANUT]

BSB....Nice car. 
Get the rear in the air.

[69wannabe]

BSB....Nice car. 
Get the rear in the air.

Thanks!! It actually sat a lil higher in the rear right after I put the new leaf springs on it but its been about 8 years ago and they are starting to slouch a little bit now. It is actually kinda aiming uphill in this pic so it looks even lower in the rear. If you look at some of the other pic's I posted it looks better on level ground. It has a decent stance but could use some new springs again I suppose.

[ACUDANUT]

Are BSB and 69 wannabe the same...?

[Ghoste]

Do those of you that believe that 3" is better also think that hp level is not pertinent?

Do you believe that the OP is making more than 500 hp?

Do you believe that a 440 with the same hardware (cam, heads etc.) should have a 3" system too?

Do you believe that there would be and increase in 1/4 mile mph (i.e. average power)?

Do you believe that there would be more than 10 hp increase at max power (5000 rpm or so)?

Do you believe that there will not be a degradation of throttle response below 3000 rpm?

Just curious

Absolutely great questions and clearly your car runs strong with manifolds and 2.5 exhaust.  Do you ever wonder how much you left on the table with the more restrictive exhaust? 

[green69rt]

No one will ever know unless its on a dyno or at the strip in a heads up comparison..  Again I say the bigger exhaust matters at the top end.  Am I wrong??

[Cooter]

No one will ever know unless its on a dyno or at the strip in a heads up comparison..  Again I say the bigger exhaust matters at the top end.  Am I wrong??

all depends on how the engine's built if you wanna get all the way into specifics.....

[green69rt]

No one will ever know unless its on a dyno or at the strip in a heads up comparison..  Again I say the bigger exhaust matters at the top end.  Am I wrong??

all depends on how the engine's built if you wanna get all the way into specifics.....

Nah, lets not go that far.  Too many possible scenerios and I don't want to hijack the thread.  

[BSB67]

BSB....Nice car. 
Get the rear in the air.

Thank you.  That aint the only rear end I have that seems to be getting lower to the ground.   

[BSB67]

Do those of you that believe that 3" is better also think that hp level is not pertinent?

Do you believe that the OP is making more than 500 hp?

Do you believe that a 440 with the same hardware (cam, heads etc.) should have a 3" system too?

Do you believe that there would be and increase in 1/4 mile mph (i.e. average power)?

Do you believe that there would be more than 10 hp increase at max power (5000 rpm or so)?

Do you believe that there will not be a degradation of throttle response below 3000 rpm?

Just curious

Absolutely great questions and clearly your car runs strong with manifolds and 2.5 exhaust.  Do you ever wonder how much you left on the table with the more restrictive exhaust?  

The cam was selected with the exhaust manifolds in mind, so I suspect that I'm probably not leaving as much on the table as you would think.  If it had a similar cam lobe sizes but designed for headers, it would probably make a bunch more power.  But then it probably would not run on pump gas.    

I know a guy making nearly 800 hp and trapping at 136 mph with 2 1/2" exhaust system.  Obviously it is a very specialized situation, but it is demonstrated as doable, by several people actually.  So it does make me wonder the real in the car performance difference on a 450 to 500 hp motor between 2 1/2" and 3".  My guess is that unless you are a techie working the tune base on regular track tuning, the average guy won't even find the potential power difference if there is one.  But that is just an opinion, I've never tested it.  And that is the problem, Who is going to buy two new exhaust systems and test them back to back ( adjusted for atmospheric conditions if not tested on the same day)?  Results from testing a used exhaust system to a new system is not indicative of the power increase from just the pipe size difference.