Speedy

Updated 2/14/07
I've decided to go with a Magnaflow 18" and a single pipe straight out the back. See other questions below about my ideas on pipe sizing and tip choice.


I was looking to get dual exhaust pipes on my 2002 4Runner. I've searched around and can't find anyone that's done this. I found pics of it on a 97, but apparently there's more "stuff" above the rear axle on my 02 that doesn't leave room for the pipe to run to the left side of the vehicle. I Went to two exhaust shops today and both said it can't be done unless I get rid of the spare tire, which I'm not gonna do.

I've always loved the look of dual exhaust and most newer cars and SUVs have it from the factory. I'm sure there's not a lot of performance to be gained over a single exit, but both exhaust shops claimed a dual exhaust setup was superior

So, should I just give up on this altogether or run the dual 2" pipes straight out the back on the right side ala Euro style? I had already decided on a Magnaflow 2.25" in and dual 2" out in the 18" size.

midiwall

In fact, there's a lot of performance to be LOST if you do it wrong. But, it looks like you understand that.


Remember that the exhaust shops want to sell you something trick, and they may not understand this engine. I can speak from experience that too much pipe on THIS engine will KILL performance.

Before I knew better, I let a shop talk me into 2.5" pipe from the headers back, and then a 3" exit from the muffler. OMG that was HORRIBLE - and this was while I was still N/A. I had them put it back to 2.5" head to toe and things were MUCH better, but that's still a lot of pipe for this engine as N/A. Once I went to a SC, the 2.5" was just _fine_.

Now, if we're talking about a nice strong V8 with a bunch of torque waiting to be unleashed, then yeah... running dual 2.5" head to toe is awesome - but not on this engine.

Speedy

Yep, I agree. I've been fooling with the 3.4L since 1997 on my first Taco. I was thinking on this 4Runner a 2.25" in and dual 2" out should be a pretty good setup.

I'm gonna crawl under it and take a look myself tonight to see what I see. I may do a dual out on the same side straight out the back but was hoping to get it on each side.

I did the ISR and things felt pretty good. Then I did the deckplate and now it feels kinda funny at low RPMs. I was wondering if it's because it can't get the exhaust out fast enough to deal with the new air intake.

midiwall

Hmmm... Can you define "funny"? The deckplate's been dyno'd numerous times at +6hp on stock exhaust, you should be okay.

What kind of shape is your cat in? $56 could net you even more power:
http://search.ebay.com/Carsound-Magn...ytic-Converter

Air filter? Plugs? Fuel Filter? Cleaning the MAF? Cleaning the injectors?

We know this engine is starved and the deckplate will let more air in. The ECU should detect the additional airflow and summon up some more fuel. If the rest of the system is ready for it, you should get the power.

Speedy

It's kinda funny you bring up the Dyno. I was the first guy to dyno it on a 3.4L as far as I know back when I was the president of the TN Chapter of TTORA. I still have the dyno graphs as a matter of fact. That was on a 1999 TRD Tacoma 4x4 with a 5 speed.

My 4Runner just seems to feel a little sluggish when I first step on the go pedal. It lasts for just seconds and then seems to pick up. As I said I had this on my 99 Taco, but didn't have the ISR done. I know that shouldn't make a difference though.

I did pull the EFI fuse while I worked on the deck plate so it was out for at least an hour. It's been about 200 miles drive time since I did the mod, so maybe the ECU just needs to learn a little more. 1999 was a long time ago so I don't remember how long it took on the Taco.

I just recently did my 60K maintenance which included all drive train fluids changed over to Mobil1 Synthetic, Oil and filter change, new plugs (NGK Iridiums), new fuel filter, new Toyota air filter, and a drive shaft lube. I checked the MAF and it looked ok. I ran a bottle of BG44K through the truck as well. I did the ISR at the same time as the rest of this.

The truck ran REALLY good with all that done and I drove it for about a week before doing the deck plate mod. After that it just felt not quite as peppy at low RPMs (like 2000 - 3000).

Maybe the truck just needs a little more time to adjust.

X-AWDriver

Also consider you'll be adding 20+lbs of extra weight so it's a lot to consider the performance drops for the sake of looks.

midiwall

ahh... n/m then.


VERY weird - the ISR should increase throttle response. That lag is a LOT like th silencer tube/boxes needing to "fill" before the air gets to the TB.


You're right on the threshold... My truck will trim up around 100 miles, but I "help" it along. Other folks see something closer to where you are.


Hmm... dang dude.

Go for a 100 mile spin and see how life is.

Finger's crossed!


(oh, and sorry about hijacking the thread)

Speedy

Update.....

I may have had bad gas or the truck needed a little more time to adjust to the deck plate but now it's running much better.

Back to the dual exhaust question.....the local performance shop claims they can get dual exhaust pipes on this thing and have them exit on each side. The guy said he'll run them over the rear cross member like the stock exhaust, and then run the left side around the spare tire. However it looks like there's a brace bar on the axle at that point which I believe moves with the axle and it'll hit the second pipe. I'll have to do some checking on this.

The more I look at it the more I think running both pipes side by side straight out the back on the right side of the hitch is the best way to go. I know the performance difference over the two pipes vs. 1 is probably nill, but if I modify something I like it to be custom all the way around and just welding a new muffler up to the stock pipe just doesn't do it for me.

Now, my concern is that I've been searching the board and found this thread:

https://www.yotatech.com/forums/show...light=ISR+Pipe

And several have noted they felt like they lost low end torque just changing the muffler. Can that be so? Nearly every car I've messed with, and even more so on the sport bikes I've built, changing the exhaust has always resulted in gains in power and torque.

On my latest sport bike project, a Honda CBR1000RR, I gained 6HP from just putting a new slip on exhaust on it. I didn't even change the headers on the bike. I then gained another 5-6HP by having it tuned on a dyno using a PowerCommander (small controller for A/F ratios that can be mapped). I have dyno sheets that show exactly what was gained and where as well. Just hit my site in the link below if interested.

In a nutshell, by adding performance filters, a new muffler, and having the bike's A/F mapped I gained nearly 15HP and over 7Ft/lbs of torque. That's on a 998cc motor and a bike that weighs around 400 lbs wet so it's VERY noticeable. About 5 - 6 HP of that is just from the mapping. The stock base line dyno run showed 142 RWHP. The final dyno run after all the mods and mapping was 157 RWHP. Funny that this 400 lbs bike is probably putting out the same power as my 4Runner.

So taking the mapping out of the equation, it's about an 8% increase in performance on just the air filter and exhaust mods alone. I've done similar intake mods to the 4Runner, now if I get an upgraded exhaust would this result be even more prevalent since the 3.4L motor is larger?

3.4L motor = 207 cubic inches = 3400 cubic centimeters
Honda CBR1000RR = 998 cubic centimeters

Went out to Magnaflow's site and looked up the Tacoma's Dyno sheet. Other than them showing over 200HP on the stock run, they show a gain with the cat back system, which I presume is 2.5".

http://www.magnaflow.com/02product/dynos/tacoma.jpg

Here's the system:

http://www.magnaflow.com/02product/s...mainall&id=175

They don't say what size the pipe is, but the dyno sheet and picture match that of the one for the SRunner:

http://www.magnaflow.com/02product/s...mainall&id=174

My guess is that it's the same system and they just show the dyno sheet for the SRunner since it has a higher base HP number.

HELP!

Hoopster

I don't know a thing about engines , but it seems that if performance is your main goal as opposed to looks, you would be better off with maybe a slightly larger dia. pipe, performance muffler and high flow cat. The 3.4 is obviously not a high revving horsepower maker. In a heavy vehicle like the 4runner, torque is king and a dual exhaust would loose torque imho.