2 inch pipe vs 2 1/4 inch pipe

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pjc360

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I'm trying to determine wich size pipe will give me the best performance. The engine is a 360 magnum on the dyno its putting out 319 horse power and 424 ft lbs of torque. The engine is in a 91 dodge power ram four wheel drive truck, so i want the size thats going to give me the best torque of course. I have been told 2 inch exhaust pipe is ideal on a four wheel drive for torque, but i also been told 2 1/4 is better. Also need to find out what header tube size to run, i am considering 1 5/8 tube diameter or 1.625 tube diamiter, wich would be the best? would it be best to run 1.625 inch header tube dimiter with 2 inch exhaust pipe or 1 5/8 header tube diamiter and 2 1/4 inch exhaust pipe? keep in mind i'm wanting to go with the pipe and header thats going to give me the best torque and best throttle response.
 
i agree with the above post, at least 2 1/4" for your setup! 1 5/8" should be just fine, you might actually loose power with a bigger primary because you're engine isn't too radical. Sounds like a sweet truck don't see too many around! :mrgreen:
 
Thats what i thought \, i always run 2 1/4 inch exhaust pipe but i bought this truck without an engine, but the exhuast on the truck was brand new its dualed exhaust with heeder collectors its 2 inch exhaust and has an h pipe welded into the exhaust right before the mufflers wich are 24 inch glss packs. So is it worth paying 300 bucks to get all the 2 inch exhaust taken out and replaced with 2 1/4 inch exhaust? It just makes me sick to think i have to shell out another 300 bucks just for pipe thats a quarter inch bigger... would it relly make that much of a difference? cause if it will then i shall get it replaced with 2 1/4, i was just told that 2 inch exhaust is plenty for a 360 specially a 360 in a four wheel drive truck. I been told the 2 inch would have a slight edge over the 2 1/4 in the low end torque compartment. this truck will never see anything over 6000 rpm and it will rarely go over 4700 rpm.i was hoping to hear the 2 inch exhaust pipe would be just fine and luck out for once
 
what would be the advantages and dis advantages to running 2 inch exhaust pipe vs 2 1/4 inch exhaust pipe? does one provide better torque and better throttle response over the other?
 
This is nonsense. Automotive engines DO NOT gain torque when the exhaust is sized down.

IF YOU are working with OPEN tuned headers, you can tune the collectors for more/ less torque and HP, but once you add the restriction of a "full" exhaust system, you pretty much are better off to make it as large as possible.

I doubt very much that any full -- to -- the -- bumper systems are "tuned" to promote much scavaging, and once somebody changes the mufflers, that's all changed.
 
I went with 2 1/2 on my magnum build. This may help relax some of the comments.


exhaust-size-chart.jpg



2 1/4 is just too small man.
 
so if 2 1/4 is too small then 2 inch is deffanatly to small correct?
 
You don't need sewer pipes on a truck. Headers suck on 4 wheel drives bad enough. Quality is evrything.
 
I say if you already have a 2" exhaust stick with it. I don't think It is going to make a huge difference going bigger.
 
The way i see it is, exhaust is all about getting burnt gasoline and air from your engine to the atmosphere right? And the bigger the pipe the more cfm it can handle. Now, since this is a stump puller, and not a goddamn datona 500 10k rpm thunder car, you aren't going to be taking advantage of that full cfm shown in my previous post's chart. After milling it around in my head, 2-2 1/4 will be fine. Its kind of a standard size anyway, and summit carries kits.
 
i judt read something on exhaust and exhaust pipe size and it said you want to decide on the diameter of the exhaust pipe size based on what rpm your max torque output is at and engine size. it had a chart with small block and big block dodge engines. I went to the 360 on there chart and it said 2 inch exhaust pipe is ideal for a 360 with its max torque output being at 4750 rpm. My engine puts out its max torque at 4500 rpm. So that is darn near perfecr according to there chart. If you guys would like i could post a link so you guys can see it as well, it was from hotrodders.com. After seeing that i am not stressed about it anymore and will keep it. I'm going to go to my local exhaust shop just to double check its 2 inch exhaust pipe but i am 90 percent sure it is. sure looks like 2 inch exhaust pipe to me.
 
There are so many theories and opinions on this subject that you'll go crazy making a decision if you ask everybody. Just pick a size and run with it.
 
I myself would run the 2-1/2 since your not running at wide open throttle a lot. While the 2-1/2 pipe on the Flow Master chart has merit and the differences small, at this level, it is something not to go crazy over.
 
All this is nonsense. This would have SOME merit IF you had a straight through system, no mufflers.

But airflow is STILL affected by

the bends in the pipe, IE the number of bends, the angles, and how restrictive they are

the length of the overall system

You stick a pair of mufflers in there and the whole theory goes right out the window. I'd bet money that 2" is too small on any good running 360, and 3" is not too big

And what are you gonna do "if you discover" that to be effective at scavaging, your system needs to be longer or shorter? You gonna stick the tailpipes out 2' behind? You gonna cut them off underneath and gas yourself?

The lesson here is "always run open headers." The fuel mileage you gain will EASILY pay all the noise tickets you get "NOT"

Stroker's right. We could all donate a LOT of money to research on this, and every time somebody changed mufflers, you'd have to "retune" your exhaust for that last bit.
 
ya know, after reading all the comments dude its gonna cost you $300 that can go towards something else that will really increase power if thats what you're worried about....it's not a race truck pick some high flow mufflers and put them on the current pipes and just enjoy it! Think of the application....not a dyno champion, not a 1/4mile queen but a badass off road truck, a few hp isn't gonna make or break you in that application and you can spend your $ more wisely in my opinion, best of luck:mrgreen:
 
ya i guess i can put that 300 bucks in the engine or drive train, with 375 bucks i can get a bad A$$ built valve body for my transmission from crt. I'm not a whole lot worried just saying i always run 2 1/4 inch pipe on all my small block mopar's and 2 1/2 on big blocks, i have no expierence with running 2 inch exhaust pipe on anything from what i have read it works good for small blocks and on trucks for the torque nd some people say its too small but since its already on there and brand new i wont worry about it, unless i come into some money and can easily afford to get it changed to 2 1/4.
 
pjc360 said:
Anyways here is the exhaust pipe size chart that i looked at that says a 360 engine putting out max torque at 4750 is fine with 2 inch diameter exhaust pipe.



http://victorylibrary.com/mopar/header-tech-c.htm
Click to expand...

Two things. That guy is always a point of contention with inaccurate information. A lot of the stuff on his early Hemi pages is just wrong as all hell. Second, as stated above, that chart is not exhaust pipe diameter, it is header primary ppe diameter. You need to start listening to those here. You asked HERE. You have gotten good answers. Use them instead of arguing.
 
I love how guys like to argue what they don't know/ask advice on after there shown the answer via exhaust company web site suggested pipe size charts, been there done that guys and dyno tested items.

They'll find one little item, obscured text somewhere and shove it in your face as if you and everybody else is wrong/ do not know what there talking about/the dyno is busted, your gas gauge is busted, you short filled the tank of gas on your MPG test. etc......
 
I wasnt trying to argue with anybody just pointing out that this is a subject with alot of different opinions as to what size of exhaust pipe to run, and i must not have read the title correctly i thought it was refering to exhaust pipe size not header tube diameter, thats my bad there. I dont want people to think i am arguing. I would rather have 2 1/4 inch exhaust pipe over the 2 inch exhaust pipe, i was just hoping the 2 inch would work ok because its brand new exhaust and i was hoping to avoid a 300 dollar exhaust pipe bill to get it changed.
 
pjc360 said:
I wasnt trying to argue with anybody just pointing out that this is a subject with alot of different opinions as to what size of exhaust pipe to run, and i must not have read the title correctly i thought it was refering to exhaust pipe size not header tube diameter, thats my bad there. I dont want people to think i am arguing. I would rather have 2 1/4 inch exhaust pipe over the 2 inch exhaust pipe, i was just hoping the 2 inch would work ok because its brand new exhaust and i was hoping to avoid a 300 dollar exhaust pipe bill to get it changed.
Click to expand...


If you have 2" that is brand new and already on the truck, that is what I would run.

Going bigger would give you a little more but (hell... If all you do is fart knock around and drive the thing you probably wouldn't even notice going up in size), it's a truck. Just drive it around until your new exhaust needs to be replaced then go bigger.
 
I'm with Sir Dan. Run what you have till it wears out. There is no sense of throwing away your money on new pipes if you already have them. I'll bet you won't feel any difference in power with your *** dyno.
 
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