Cold Air Intake, Headers, and Exhaust

[micondie]

Originally Posted by ncs

And the practical application of this information is? A warm air intake will pay for itself on some vehicles. Are there any exhaust mods that will actually recover their cost over the life of the vehicle?

The cost/benefit ratio is subject to many variables:[LIST]
How inefficient is your stock exhaust? (What can you gain?)
How expensive are parts for your car?
How much of the work can you do yourself?

The WAI on most cars is a DIY project with minimal expense.

If you are at the point of needing exhaust work then that would be the ideal time to look at improving efficiency.
A low restriction muffler, the easy mod that is the most likely to have a benefit will probably cost less than an OEM muffler (although it will not last as long) but will take some work to install.

[Christ]

Thrush Turbo Muffler... they're like $30, and come in sizes comparable to most OEM setups.

[HighDesert]

Marty, I have the same year and engine but a tacoma 4x4 PU with manual transmission. After reading a variety 4x4 forums, it appears the header-exhaust provides minimal mpg gains given the cost of investment. The stock header, as you might have read, has a tendency to crack. Mine has not, but that might be the time to swap to an alternative. Personally, so this is anecdotal, I have found the greatest gains simply by better shifting, keeping highway speed down, and using much less aggressive tires. Regarding the CAI, a simple mod is to open the airbox and grab some of the cool air coming in from around the headlamp. An opening is cut into the airbox below the filter. This opening can be "framed" using PVC and a screw on cap or by using a "boat deck" plate. This allows you to reseal the airbox should the need arise. Some have also removed the metal spacer from below the headlamp to facilitate the cool air intake. Finally, if you have auto locking hubs, you could consider adapting to the manually turned hubs as this will allow the front axle to completely freewheel reducing parasitic drag.

[Marty]

Tons of information guys, thanks. Installed a Borla cat back exhaust, and have not noticed any power gains (except when I let the sound convince me I'm in a V8). It does idle at lower rpm's in addition to cruising at lower rpm's. I've yet to compare freeway mileage to the stock exhaust, which while driving 55-60 an costing in parts, garnered 31 mpgs. I'm interested to see what this baby can do. Thanks for the tips HighDesert, on the air box, that seems like an easy mod, even though some people say warm air-intake and others CAI. Most driving is 2000 rpms and below. Thanks again.

[IsaacCarlson]

crappy and weak at low rpm??? I have seen a few turbos and they sound bad while accelerating and cruising.

[Christ]

Originally Posted by Marty

Tons of information guys, thanks. Installed a Borla cat back exhaust, and have not noticed any power gains (except when I let the sound convince me I'm in a V8). It does idle at lower rpm's in addition to cruising at lower rpm's. I've yet to compare freeway mileage to the stock exhaust, which while driving 55-60 an costing in parts, garnered 31 mpgs. I'm interested to see what this baby can do. Thanks for the tips HighDesert, on the air box, that seems like an easy mod, even though some people say warm air-intake and others CAI. Most driving is 2000 rpms and below. Thanks again.

Not unless you changed your transmission, tires, or something in that line while changing your exhaust. Cruise RPM is dependent on gearing and vehicle speed, not exhaust work.

Idle RPM can change with exhaust/intake work, as the PCM won't compensate for small differences.

[Christ]

Originally Posted by IsaacCarlson

Christ, is there another inexpensive option for mufflers that doesn't sound crappy and weak at low rpm??? I have seen a few turbos and they sound bad while accelerating and cruising.

Nope, most of them aren't designed to sound OK at low RPM. If you get one that does sound good at low RPM, it's probably because you've tuned the exhaust specifically to low RPM operation, but that will choke out your high RPM (not that you get there often) power.

I haven't personally heard of anything that doesn't have some kind of unwanted noise at low RPM, or just doesn't make any noise. Changing your intake will change your exhaust note, as well.

[IsaacCarlson]

there was a plastic plate that sat against the filter and only had a 2.5" hole in it!!!! Before the delete, i would change the filter only to find a very dark spot on it about 2.5" in diameter, the rest of the filter was clean!!!!! and this filter is like 10x12!!!! lower tone now....maybe it would sound okay then???

[Christ]

It might.

I was getting up to 28 MPG on a full tank reading (several of them) with Granny before I gave her to my Father. We had an open element stainless mesh filter from APC, using a 45* generic aluminum intake pipe. the IAT was plugged in via a hole drilled in the intake pipe with a grommet in it, and the PCV line was just stuffed into a hole in the rubber coupler.

Even though your throttle body is probably an oval, there is an intake pipe adapter that fits perfectly. I think it's 3" against the TB. This gives great induction noise, but I can't say whether it will actually help or hurt FE. I assume it does nothing but make the car sound cool.

FWIW, 60* V6's have an annoying resonant tone in the exhaust. Get rid of that, and you're golden.

[99LeCouch]

Ahh, you gutted your airbox? That's a nice, easy mod to do. I've done mine. There's not a big difference in FE. If anything it slows down the air coming into the engine if you took out the back piece. I'm thinking I want to put in a few pieces of Coroplast to redirect air towards the throttle body so the airbox is nice and wide-open in the front, then it tapers down in the back so air isn't stagnating in the corners of the box. I wonder if that would do anything.

The 3800 is a 90* V6, not a 60* like the 3100 and 3400. Changing the exhaust on an H-body like mine and Isaac's doesn't do anything but change the sound. It's mandrel-bent 2.5" stainless the whole way back with big, gentle bends in it. Even guys with the supercharged cars putting out decent power stick with the stock exhaust since the guys who spent $$$ on "freer-flowing" exhausts got zero power increase.