3" or 2 1/2"??

[Kenflo]

I am trying to decide on my exhaust system.
Engine is a fresh 340 stroker (422) makes 470hp and 500tq.
I am thinking of going with the pypes system with x pipe and race pro mufflers or for a bit less cash I am considering the summit 3" dual system with summit dul chamber mufflers with no x pipe. Will the 3" be better or worse? My thinking is because of the larger siZe I will not need the crossover? (Plus the price is nice!)w
Any thoughts?

 

[halifaxhops]

I am trying to decide on my exhaust system.
Ringing is a fresh 340 stroker (422) makes 470hp and 500tq.
I am thinking of going with the pypes system with x pipe and race pro mufflers or for a bit less cash I am considering the summit 3" dual system with summit dul chamber mufflers with no x pipe. Will the 3" be better or worse? My thinking is because of the larger siZe I will not need the crossover? (Plus the price is nice!)
Any thoughts?

I have the summit 2.5 on my 440 and really like it great bang for the buck.

 

[ProStocker273]

3 inch all The way.

 

[69_340_GTS]

3" tailpipes often have a real hard time fitting between the gas tank, rear axle, frame, and shocks. Hell, a 2.25" system is real tight in spots! I seriously doubt if a 422 cu in motor needs the 3" pipes. I'd lean towards the 2.50" system myself. It'll be a much easier install.

 

[grimreaper]

http://www.exhaustvideos.com/faq/how-to-calculate-muffler-size-pipe-diameter/

 

[halifaxhops]

3" tailpipes often have a real hard time fitting between the gas tank, rear axle, frame, and shocks. Hell, a 2.25" system is real tight in spots! I seriously doubt if a 422 cu in motor needs the 3" pipes. I'd lean towards the 2.50" system myself. It'll be a much easier install.

That's why I went 2.5, it is tight between the frame and tank

 

[340doc]

I had a 2 1/2" system with turbo mufflers on my Duster running 11.70's. I got a 3" system from a buddy with flowmasters and thought for sure I'd see a difference. I did, it was louder...

 

[rumblefish360]

Flow Master used to have (And may still have somewhere) a chart for approx. exhaust sizing. The above link has a chart that will help. Just remember it is an approx. size suggestion.

While max power will be realized with a larger pipe size, it is not really the best solution for a street driver. To large of a exhaust pipe will cause power to drop off (Torque) on the lower side of the RPM scale, where you drive most. For a street car, it is better to be slightly under sized rather than oversized. The reason being is the exhaust gas tumbles through and out of the pipe. To small is obviously a restriction. The balance is a high velocity exhaust gas that doesn't hurt the cars performance or mileage. Below is a copy and paste of the above link for you all.

( Edit! The 2 posts below I like a lot and agree with!)

Quick and Dirty Exhaust System Math
Easy Way To Estimate: Your intake system needs to flow 1.5 CFM per engine horsepower, and your exhaust system needs to flow 2.2 CFM per engine horsepower.

Good Way To Estimate: Take engine RPM x engine displacement, then divide by two. This is the intake volume. Use this same volume of air for the exhaust system, but then correct for thermal expansion (you need to know exhaust temps to figure things out).

Exhaust Pipe Size Estimate: A good section of straight pipe will flow about 115 CFM per square inch of area. Here’s a quick table that shows how many CFM each common pipe size will flow, as well as the estimated max horsepower for each pipe size:

Pipe Diameter - Pipe Area - Total CFM - Max HP ......Max HP For A
(inches)..........(in2) .............(est.)......(Per pipe) ...dual exhaust

1 1/2 ............1.48 ...171 ..........................78 .......155
1 5/8.............1.77....203...........................92........185
1 3/4.............2.07....239..........................108.......217
2...................2.76....318..........................144.......289
2 1/4.............3.55....408...........................185.......371
2 1/2.............4.43....509...........................232.......463
2 3/4.............5.41....622............................283......566
3...................6.49....747...........................339.......679
3 1/4.............7.67....882............................401......802
3 1/2.............8.95....1029..........................468......935
NOTE: These numbers are just estimates. All pipes are assumed to be 16 gauge steel.

The table above is probably over-estimating pipe size, but you can see that a 400 hp vehicle with a dual exhaust system only needs 2 1/4 – 2 1/2 inch pipes. Anything larger is overkill.

 

[Abodybomber]

ISummit's/Jeg's Hearttrob's 2.5 mandrel bent system tubes,possibly 450-475 HP & quieter than 3" of the same caliber. Cam duration ,actual compression, are needed information.

 

[BlueDream]

It just depends on what you want..

If you don't want to be obnoxious, and you want to run tail pipes, then 2.5" fits your needs quite well.

If you're the obnoxious type (I mean c'mon, you have a 470HP stroked 340!!) and you want it to be loud, then I'd go 3". If you go 3" I would add a resonated X pipe because it'll shut it up a bit, help on the top end, and it'll aid in reducing drone. Or you could add an H pipe.

 

[FredS]

The right muffler will keep the 3 inch tame too. Do you foresee upping the power if what you have just isn't enough? Then do the 3inch.

 

[abodyjoe]

go 3" with 2 1/2" tail piupes

 

[72Duster440]

go 3" with 2 1/2" tail piupes

That's what I wish I did. I went 3" all the way, it took me about 40 hours to fabricate a pair of tail pipes. Now that I have changed my suspension/ride height slightly, the 3" rattles. 2.5" would be much easier to package.

 

[abodyjoe]

they also say going with smaller tail pipes keep the gasses flowing better because by the tail pipe its cooled quite a bit.

 

[roccodart440]

3 inch all The way.

x2

 

[ScampMike]

if you can fit it - 3" with the X

 

[stroked340]

I have a custom made exhaust system 3" aluminized H- pipe w/dumps into 3" stainless Magnaflos with 2 1/2" tailpipes factory like stainless tips..

 

[d1970]

Smaller diameter pipes will usually produce better low- to mid-rpm torque. Larger diameter pipes usually produce more mid- to high-rpm, so it's up to you what you want from your motor.

 

[ir3333]

rumblefish's attachment show's 2 1/4 - 2 1/2 for 400 hp.
..that would probably be 500 hp + on a dyno.
..3" would overkill and may hurt performance

 

[EL5DEMON340]

go 3" with 2 1/2" tail piupes

thats what i would do 3" into X to mufflers, then 2.5" out to bumper

 

[AJ/FormS]

I have TTI's dual 3" all the way and Dynomaxers on my 68 Barracuda-367 cuber. It goes 93 in the 1/8th.
It's tight to install the TPs all right but wasn't bad at all. I had to bend the lip of the gastank is all.Offset springs and narrowed rear.
Car is also lowered. I think my sills are at 8 inches at;just in front of the rear wheels.
When I put the GearVendor in, I had to give up the H-pipe.I sure noticed the hole in the torque at idle to 2400ish. Deeper starter gear took care of that tho.

 

[DrCharles]

thats what i would do 3" into X to mufflers, then 2.5" out to bumper

I'm thinking about this on my '72 Dart with a 451/4-spd. (So far I have 3" back to the Summit X-pipe kit using mandrel bend pieces). The car now has a fuel cell in the trunk so all that room taken up by the gas tank is available for mufflers or piping.

2.5" would be a lot easier to get up and over the rear axle, but ground clearance would probably be better with the mufflers under the trunk floor (which would need 3" over the axle). Thoughts? :scratch:

 

[1Fast340]

I'm thinking about this on my '72 Dart with a 451/4-spd. (So far I have 3" back to the Summit X-pipe kit using mandrel bend pieces). The car now has a fuel cell in the trunk so all that room taken up by the gas tank is available for mufflers or piping.

2.5" would be a lot easier to get up and over the rear axle, but ground clearance would probably be better with the mufflers under the trunk floor (which would need 3" over the axle). Thoughts? :scratch:

Weightdistibution gets better aswell with mufflers under the trunkfloor.

 

[tekslk]

You might want to look at TTI exshaust systems.