I have a 1994 3.0 4x4 Pickup and I am going to put a high flow cat and flowmaster delta 40 on it. My question is what size exhaust 2-1/2 or 2-1/4. The truck is all stock but i might put on A K&N intake some day.

 

if you're gonna replace all the stock pipe, go with the 2.5-inch...and also check into some aftermarket headers, as that'll open things up a bit...

 

Thanks for the imput. I would LOVE to have headers but this is my first viehicle and headers aren't quite in the budget. But I think the 2.5 is sounding pretty good.

 

I would personally stick with a 2.25" The 3.0 doesnt flow enough to justify a 2.5" pipe size.

 

is our stock pipe 2.25 or just 2?

 

I would go with 2.25.....I just did mine to a magnaflow and stuck with 2.25 all the way through

 

Did the 3.4 swap and had custom exhaust built from the manifolds back. Muffler shop said that 2.25" is fine for the V6 and that anything bigger wasn't really worth the investment.

 

Stock size is 2 1/8th very odd size.

the only v6 that would need 2.5 is the 3.4, even then only if you have some goodies under the hood.

 

I concur with the majority 2 1/4 is the way to go.

 

2 1/8" is the stock size, the bends on the stock pipe are about 1 7/8" due to the crush bending. So 2 1/4" will have more volume, and have bends that are around 2" from crush bending which will improve flow coupled with a 2 1/4" free-er flowing muffler.

The best exhaust size for the 3vze would be mandrel bent 2 1/8" but good luck finding an exhaust shop with a mandrel bender (theres one in my province I believe, mind you it's right near my house) and to make matters worse you would have had some divine intervention if you managed to find an exhaust shop with not just a mandrel bender, but also the 2 1/8" dies to mandrel bend pipe coupled with stocking 2 1/8" exhaust tube (which can be found, but it's slightly more expensive because it's an exotic size).

I have a Borla catback and it is 2" mandrel bent and I'd say if you want a bit more torque it's a sweet set up.

 

I've got 2.5" on my 3.0, and I love it. I guess what ever one is the better deal between the 2.25" and the 2.5". 2.5" isn't gonna kill yer rig. Hell, someone I used to know used to have a 3.0" exhaust from the headers back on the 3.0. Now that was a little much.

 

So I guess majority rules and my yota will be getting a 2.25 exhaust! I can't wait as soon as i'm done painting it the exhaust is going on. Thanks for all the help.

 

Just so I can establish the mentality on this site, I've got a question for everyone.

How many people believe that, cut and dry, smaller pipe=more backpressure=more torque, larger pipe=less backpressure=lower torque?

How many people believe that backpressure is what creates torque?

How many of you, say "in order to have torque, you have to have backpressure"?

 

I believe nothing of the sort, at least relating to the explanation you put forth. Back pressure is one of the most commonly mis-used terms on auto discussion forums.

I believe that your engines exhaust size relative to your RPM's and desired performance is determined by volume. For exhaust pulses to flow properly, they need to stay hot. To keep exhaust pulses hot you have to have the right size exhaust. If your exhaust pipes are too large, your exhaust pulses cool which slows the flow of exhaust and causes the engine to have to work harder to push against that cooled exhaust soaking up power. This is one reason why guys who run pipes on the larger size of the spectrum for a particular engine will notice lost torque down low, because there aren't as many revolutions of the crank shaft which means less exhaust pulses, which means cooled exhaust, but when they rev the piss out of it, there are much more exhaust pulses which heats up the pipes and you get High RPM performance. There may not be one perfect exhaust size to cover your entire power band of your engine to have good power and torque at all RPM's, but I do believe there is one size that will satisfy most.

Another thing that influences performance is turbulence. An exhaust pulse is exactly that, a pulse of exhaust. In behind every exhaust pulse is an area of negative pressure, sort of like a vacuum. This vacuum pulls on the exhaust pulse behind it. This phenomenon is called scavenging. At a certain RPM's, your engines scavenging effect is so great that (read, efficiency!) that exhaust pulses passing by exhaust valves help pull other exhaust pulses out of the more downstream cylinder. When you start crush bending pipe so that you have bends that are smaller than the diameter of the straight pipe, you create turbulence of these exhaust pulses as opposed to mandrel bending which has consistent size in both the bends and straight sections.

Generally speaking I think you're going to find that smaller pipes will offer you better low end torque, and larger pipes will offer you higher RPM horsepower.

 

heres a good read - http://www.geocities.com/MotorCity/7...usttheory.html

 

Hey-

I've got a 2.25" magnaflow cat and a 2.25" flowmaster super 40 with a 3" turndown right after the muffler. My 2.25" tubing starts about 1 foot before the cat.

If you want a loud deep rumble, then i'd go with a similar setup. Every time i drive through a parking structure i set off car alarms. Even driving through the neighborhoods here i set off alarms. I love it!

just my 2¢

 

i'm gonna call bs on that one...i mean, really, a 3VZE setting off car alarms b/c of it's "rumble"...

 

100 percent no lie! (why would i lie about it?)

the flowmaster super 40 muffler has great sound and with the 3" donkey d*ck right afterwards it sounds so deep, healthy, and clean.

 

well, if you say so...i just said that b/c i'm running the same exhaust with a 3.5 inch tip and it's deeper than stock, but i've never set off alarms when revving it out in packed parking lots...and back when i had my 3 12s hitting over 160db, it was not that common to set off alarms with it...

 

I've set off car alarms before with my 3VZE......of course that was on the way to the muffler shop running nothing but the headers......

O, yeah, I also removed my stock muffler bearings and replaced them with TRD ones. That shut er up pretty nice, too.