Quickdraw

Two days ago I got a whole new exhaust system: new cat, pipes, muffler, and tip. I went with the 14" magnaflow and just a regular replacement cat.

I have done the deckplate and ISR removal mods and added a K&N Air Filter.
I thought that a new exhaust would free up some more power since my stock stuff was all blocked up and needed replaced.

However , when I picked my 4runner up from the shop it seemed that i lost some of the power i had just with the intake mods. At first i thought it might just be psychological, since it is louder than I'm use to and just think I should be going faster for how loud it is. But I've had two days to let it set in and I still think I might've lost power. CAN ANYONE HELP ME?

midiwall

How big is the new piping? If you went larger than 2.25" on an NA engine, you're losing power; if you went larger than 2.5" on a S/C engine, you lost power.

04 Rocko Taco

Exactly.
How do you like that 14"? Pretty loud?!?

Elton

your muffler is going to get alot louder in a few weeks when i got my 18'' magnaflow installed i thought great just going to be queit but now a few weeks later its way louder

Quickdraw

My piping is 2.5" which is what my stock piping was. The 14" is really, really loud. And if elton is right and it does get louder, it'll be a quick trip to the muffler shop and get that bad boy cut out.

midiwall

Ummm, not to push this but, it may have been "what was on there before", but it's not "stock". Stock really really is 2.25" for the 3.4L. There's a similar thread running over here:

https://www.yotatech.com/forums/f2/24-magnaflow-muffler-installed-98-a-91447/

This is part of what I posted up over there:
That chart is in CI, so 3.4L = 207 cubic inches:
http://www.google.com/search?hl=en&q...=Google+Search

Quickdraw

According to that chart the recommended pipe diameter was 2.25 to 2.5. It also said going bigger would just be losing power unless you had more air coming in with like a supercharger. So would going with the 2.5" pipe really cause power loss, even with the deckplate and isr mod

midiwall

At 207ci, we are on the way lower end of the 2.25-2.5" recommendation.


Actually, I said that... not the Magnaflow site.


Yes. I've been there, done that, and even got the T-shirt in the form of having to pay for my exhaust system to be redone TWICE.

I went through a bunch of exhaust stuff starting about 3 years ago. I let a shop talk me into 3" pipe and a free-flow muffler. It was HORRIBLE.

A week later I was in there with the math showing them that they didn't know what they were talking about. I went down to 2.5" pipe 'cause I was planning on installing a S/C in the next couple of months. The difference movingh from 3" to 2.5" pipe was like night & day, but it was still sloogier than the stock pipe.

So, to add insult to injury, soon after the exhaust I installed Downey headers, 'cause... "I was planning on installing a S/C in the next couple of months". big mistake.

I didn't put the S/C on for almost a year. So for that year I dealt with a very weird powerband, slugy torque, no pull up top and basically a lot of wasted money hanging off of my engine. Yes, I had done the deckplate and ISR mods.

side note: The deck plate fixes an issue inherent in the design of the 3rd Gen air box. Air normally comes into the box through a tube that has a nasty elbow in it. This is starving the engine for air, hence the deckplate mod showing a constant 5-6hp gain on a dyno. While this is in effect more air, it's still normal induction - the engine will only suck in as much as it can by way of vacuum. When compared to forcing air in through a S/C or turbo - it's barely anything at all.


Anyway.. eventually, the S/C went on, and the power was INSANE, more than other S/C'd 4Runners without exhaust work & headers. I then moved to a free-flow cat, more power. I then had a REAL performance shop redo the hack job from the first shop. I stuck with 2.5" piping but when things got cleaned up my powerband smoothed out.

Spanky

when i threw on my 2.25" pipes, magnaflow cat, and flowmaster muffler in march... i was kinda disappointed in the power gains (none) even with the airbox mod, K&N.
I was not expecting miracles by any means, but anything woulda been nice.
If a increase is there i sure havent noticed it. just a little on the sound side, and that wasnt even that much more.

midiwall

This was on the 2.2 in your sig, right? 2.25" pipe is too big... I think the stock is 1.75 (1.375?), people have been okay going to 2", but that's it.

2.2L is 134ci, and that's even below the chart on Magnaflow's site which goes down to 2" pipe.


Engines in our class need backpressure in order to induce exhaust scavenging. If the pipe gets too big, the backpressure is reduced to nil, and the exhaust can't fully get out of the cylinder. That's where the power reduction comes from. There's still exhaust in the cylinder on the intake and power stroke, which reduces the power of the blast.

These aren't big block V8s or diesels where you can run a 4" exhaust system.

Elton

the 14'' is loud and they drone alot and are way to loud my 18'' is pretty loud i can just see how loud the 14'' is

Spanky

yeah its the one on my sig. 2.4L actually. Anyways, I was asking around and everyone was kinda suggesting that 2.25" pipes were the way i should go, but definately not any bigger.
i understand the concept of backpressure. I just put on my system on going by what i found on here and by calling around a few shops.
oh well, i am not putting new pipes on it again.

Elton

^ i had all that on my 22re in your sig and when i put a header on wow it had some power buying a header was the best money i spent on my 22re

Spanky

thats what i hear!! i am for sure doing that. its just a matter of when.

midiwall

Yeah... the 3.0 and the 2.2(4) respond really well to headers when they're NA. THEN you can use the 2.25" pipe.

(ain't this fun? )

Spanky

well i better get on that header soon then!! i am kinda trying to save for a big lift and wheels, and new meats... then new gears. so eventually, hopefully

Elton

nice... i looked at a few lift kits for my pickup and found it cheaper to buy a truck with a lift already installed