2 1/2 or 3 inch exhaust

[Glew]

I know there are discussions on this evrywhere and there is no definitive answer. Anyway i just got my 470 stroker motor installed with summit racing 1 7/8 long tube headers with a 3" header collector. now i need mufflers and exhaust. Shop who installed my motor said a need a 3'' system and the exhaust shop said i need a 2 1/2 because a 3'' will be hard to fit. as far as mufflers i think im going with the dynomax ultra flows

 

[RoadWarrior]

Engine Masters did a show 2 1/2 vs. 3" exhaust. The 3" made like 20 something more horsepower.

People argue about back pressure but its a myth. Look at all these record breaking cars with open headers. I just wish I went with 3 inch on mine. Oh well.

Go with the 3 inch. Not like you have to fuss with it, it is the exhaust shops problem not yours, your job is enjoying it.

 

[Mike67]

X2 on the 3"... 3" sound deeper to me as well....You could use youtube for hearing the difference...

Good looking engine bay!

 

[rumblefish360]

View the. Engine masters video. It's worth a view.

The 2-1/2 will be quite vs. the 3 inch.
And a few missing hp. Your call. Do you need every last hp on the street or are the ears hearing worth it?

 

[Car Nut]

I have 3" now with wide open mufflers, too quiet for my liking. I had 2.5" with the same muffler that sounded a bit louder. The 2.3" that came on the car had a more muscle car sound. I thought the 3" would be louder, nope, not what I was hoping for. Buy a TTi system and install it yourself in three to five hours.

 

[multimopes]

I would go with the 3" for sure. I have them on mine. As for sound, a lot depends on the muffler itself and what's either inside it or not. I think my mufflers are cherry bombs and they are barely quiet enough for the street. If I am passing by a cop, I always go easy on the gas. Besides, ask your collectors what size they would like to bolt up to, as they are 3", I'm sure they would like to mate up with another 3". Keeps everything in the same scale. I think your exhaust shop just want's to make it easy for themselves. What is the difference in price? That might be a factor for you to consider as well. Are you going stainless? Lasts a lot longer even though it's pricey! Good luck what ever you decide!
Got any more pics of your car? You didn't mention what year and body you have. I'm sure many of us would like to take a gander!

 

[Patrick Gresham]

Engine Masters did a show 2 1/2 vs. 3" exhaust. The 3" made like 20 something more horsepower.

People argue about back pressure but its a myth. Look at all these record breaking cars with open headers. I just wish I went with 3 inch on mine. Oh well.

Go with the 3 inch. Not like you have to fuss with it, it is the exhaust shops problem not yours, your job is enjoying it.

I can verify this, I saw that episode too. I was blown away.

 

[Lazerwolf]

Watched that Engine Masters video myself and really respect their opinion.



I probably had a different take away from that video as others though. With a 600+ HP engine, the HP and torque was less than a 3% difference from the 2 1/2" to the 3" exhaust. I'm don't race my car so not sure, but for racing that might be huge. For street driving, doesn't seem to me you would notice a difference. I don't think I would lose sleep about using 2 1/2" because 3" don't fit.

 

[rumblefish360]

And there you have it. Only missing the decibel ratings. LOL!

So, is 600hp good enough for the street or do you need the total 620hp?

 

[Glew]

I ended up going with the 3" exhaust and dynomax ultra flow mufflers. It definitely sounds a lot more tame with the full exhaust. But when you get on the throttle the sound gets meaner. I did like the sound of the open headers but after 15 minutes of driving it I couldn't take it anymore haha. I think once the engine gets dialed in it'll sound a lot better though.

 

[Car Nut]

Awesome, gorgeous RR!

 

[rumblefish360]

Glew;

How much power are you making ?

 

[polywideblock]

so what about the oval exhausts that were being pushed a couple of years ago ,the benefits of the 3" system with the clearance of the 2 1/2 "

 

[dvw]

A 3" is only 1/4" closer than a 2 1/2". One half the diameter. Find a better exhaust guy.
Doug

 

[Glew]

Glew;

How much power are you making ?

620 at the crank. Haven't chassis dynoed it yet

 

[Glew]

Awesome, gorgeous RR!

Thanks!

 

[Carcinogen]

Most of the mufflers for 3 in are are actually 2.5 internally.

3 in pipes are louder with the same muffler.

Problem I have with the 3 is it is a tight fit and occasionally rattles against the frame or shocks as it goes over the axle. Using flowmaster tailpipes on 72 B body.

 

[rumblefish360]

I have gone through just a few mufflers that are not the same size on the inside. And those were 2-1/2 pipe sized!

For surely, don't settle on that crap!

 

[Kern Dog]

A 3" is only 1/4" closer than a 2 1/2". One half the diameter. Find a better exhaust guy.
Doug

Absolutely. Some exhaust guys are NO talent hacks that don't have any interest in performance. This one shop I use had a lazy assclown that would do whatever he could to convince customers to go smaller. I wanted 2 1/2" pipes over the axle and under the bumper. He said...I'll have to do in in a few sections, no way I could get all those bends in one piece. I was fine with that.
Years later I went to a 3" system from headers to the mufflers. I still kept the 2 1/2" tailpipes though.

 

[moparedtn]

Most of the mufflers for 3 in are are actually 2.5 internally.

3 in pipes are louder with the same muffler.

Problem I have with the 3 is it is a tight fit and occasionally rattles against the frame or shocks as it goes over the axle. Using flowmaster tailpipes on 72 B body.

Yep. I have 3" all the way back on mine as well; it came that way when I bought it.
It's obvious some exhaust shop made it up; it has the single chamber Flowmasters on it as well.
Is it loud? Depends on how old you are, I suppose.
Yes, it's rather obnoxious when you're tromping on it and even when you're just coasting between buildings going through town.
My wife says she can hear it coming for about a block away.

No crossover on it. That would help some with the noise level.

I have been under there more than once, tweaking on it here and there. Exhaust systems do move a little while going down the road and yes, the bigger pipes find ways of vibrating off something, especially the over the axle area, where things get really congested under there.

Something not yet mentioned is that larger pipes don't sound like the original stuff, either. I know that's nothing tangible, but Mopars always had a distinctive sound to them when new; you could spot one from a ways off because of it.
Some of that distinctive sound is the exhaust system, of course, including pipe sizing and muffler types. Even the exhaust tips make a difference on some Mopars.
Just saying.