TBob

Hi all
I've read tons on this forum about the different types, sounds, prices ect...
but with all 3.4L owners that have change their stock mufflers have you noticed any increased performance or mileage from doing it?
Has anyone do a before and after dyno?


Thanks - TBob
03 taco

rimpainter.com

No increased MPG (and I track it religiously).

Slight seat of the pants gain in HP. Not much, but it felt like it was a tad quicker.

I think a full system would yield better and more noticeable gains.

TBob

Anybody else?

RTdawgs

i definitely lost low-end torque due to loss of back pressure.

mike_d

it's not because of the lack of back pressure. back pressure is always bad (unless you have so little that you start screwing with the valves - but we'll ignore that for now). the reason that you lose torque with a bigger pipe is that the exhaust gasses expand quickly to fill the big pipe. the expansion causes the gas to cool. cool gas doesn't flow as well and abruptly slows down, which creates more back pressure.

the best thing to do is tune the size of the pipe to have the fastest flowing gas (or more precicely lowest back pressure) for the rpm range you normally drive - it can't be optimal for all rpms.

TBob

so by the sounds of things the only real reason to put a different muffler on is sound? - correct?

RTdawgs

i didnt get a bigger pipe, i just replaced the muffler.

midiwall

When I went with a freeflow muffler, I screwed up and used 3" pipe. That killed my low-end power. I got it back - and gained some up around 3200+ when I went down to 2 1/2" pipe. When I added headers, the low-end really came on.


Moving to a freeflow allows the engine to exhale better. If the rest of the engine is bone stock ('specially in terms of getting more air INTO the engine) then you probably won't notice a thing.

If you've done work to get the engine to take deeper breaths (deckplate mod, freeflow air fitler, ISR mod, S/C) then getting the most out of those mods will require you to get the engine to exhale better (freeflow muffler, SLIGHTLY larger pipe, headers).


Oh! And a nice side effect here is that you get a better tone out of your rig.

Maddog

just changing the muffler only ,will only change the sound,performance increase will be minimal,depending on the state of the old muffler.

But changing out the pipe at the same time will add sound & perfomance depending on the system or pipe used.(as midiwall describes above)

TBob

So with my deckplate mod & an Amsiol filter allready in place what would be the correct set-up? and with those mods would I see an increase in performance or mileage?

Thanks,
Bob

midiwall

Yes you will see an increase in performance, but don't expect 100hp - probably 7ish. Your powerband will tend to shift up in the RPM range as well, mine went up about 1000rpm before the headers.

You may get a slight mileage increase, but it'd be within the normal variances of mileage and you probably won't see it.

Setup wise, I think your stock exhaust pipe is 2 1/4" now. If you're thinking that you'll ever put headers or a supercharger on, then go up to 2 1/2", but nothing bigger. If you think you want to try the dual tailpipe thing, then each tail should be 2 1/4", maybe even 2".

Past that... there are a lot of mufflers out there. Magnaflow, Dynomax, Jardine, Flowmaster. I run a no-name "Allied Meanstreak" and people have commented in nice ways on the tone. I really like the sound of "the classic" Flowmaster 40, and the Jardine system sounds really nice as well.

When shopping a muffler, know that a longer muffler will be quieter than a shorter one. An 18" Magnaflow is _loud_, a 24" is quieter than stock. You'll want to check for how much space is under your turck, you may be restricted in how long of a muffler you can run.

Corey (one of the admins here) has an exhaust comparison page up that may help a bit:

http://pnw4runners.com/exhaust/exhaust.htm


Have fun!

superduper

I have a 98 4runner with a S/C, Deckplate mod(closed) w/ Amsoil Filter, TRD exhaust, and other non-performance mods. The tone I get from the muffler is great but I definitely lost some power after adding the exhaust. I SC with the stock exhaust gave me very little increase, if any at all, and after adding the TRD exhaust, I lost even more. I do not have any fuel mods because it's too complicated for me to find someone that will install it. Does anybody out there have the same problem? Would TRD headers or Downey Headers fix some problem? Please advise a hill struggling 4runner with performance mods.

TBob

sounds to me like you just need more fuel - have you checked out this set-up?

http://www.urdusa.com/Merchant2/merc...Store_Code=URD

midiwall

I know that other people will have a differing opinion, but I think adding a S/C to a stock airbox is kinda' harsh. People say that you're supposed to keep the deckplate closed with an S/C (I think in order to help the pinging and lean-out issue), but that means that the only way for air to get into the engine is through the elbow, which is really restrictive.

An engine that's starved for air isn't going to produce any more horsepower.


Wait... you added the supercharger and didn't notice ANY increase in power? Is the drive belt hooked up?

If that's true, then there's some other problem going on here... Headers will help, but there's something else wrong.

bktaco

thanks in advance to midiwall and corey for the knowledge base.

doug thorley is coming out with headers for the 2.7L later this year. thorley is teamed with jardine cat backs (for marketing purposes at least). i have a feeling that the 2.7L specific hardware will $$$, but I just might save up my lunch money for them.

the jardine will have mandrel bends, and i'm sure the pipe size will be determined by thorough engineering. but if i dont go $$$ cat back (ie, get the no-name muffler), what size pipe do you all recommend I have the shop use - the stock 2 1/4, or move up to 2 1/2?

i will post some pics and beta when i get the job done.

superjoe83

my taco had 2" stock (3rz) and the jardine cat back was 2.25"

fish

My theory is that you will always see lower MPG on a vehicle with loud exhaust. Why? Because it sounds good, and you want to hear it more, so you give it more gas and boom...there goes your mileage.

Corollary: First the exhaust, then the intake. Gotta inhale if you wanna exhale. Of course more air requires more fuel (stoichiometry requires the engine's computer to insert more fuel when it senses more air). It may be a little faster, but at the expense of your gas mileage.

So...not only are you going to get worse (in some cases, much worse) gas mileage, but you are going to pay a pretty penny in non-recurring costs to do it (exhaust + intake systems).

Just drive it.

I may be wrong, but I don't think so.

superjoe83

tell me about it, the taco sees at least 4500 daily, not nessasary for the exhaust tone, but because it pulls the hardest between 3500-5000

maverick14213

i had a catback flowmaster installed on my truck and at first there was no difference cause ofcourse i wanted to hear it alot so i was playing with it. Now that ive calmed down with it and have done my normal driving habits, im getting about 7 more mpg per tank on the street, and 10mpg per tank on the freeway. I know its not alot but every little bit helps. Mine is a 3.4 on a 2003 Tacoma Doublecab PreRunner.

RTdawgs

Wow, that is a huge difference. 10 more MPG? that would be a 60% increase for me, thats huge.

anything special you did? what was your before and after mileage?