Missed last week? Monster Bolt-On Turbo Kit. Take the Fast Friday Poll.
Some Notes First
Meet Joe, Dad, 2004 S60 turbo owner
This is a make-believe exhaust purchasing excersize. It's a Tune My Ride from someone who doesn't exist, essentially. (It's actually not too far off me and what I need to buy. Maybe I'm living vicariously through a fictional composite character on my own weekly Volvo performance column Whoo boy.)
Joe must consider these factors
- Exhaust Diameter
- Exhaust Shape
- Exhaust Material
- Exhaust Ease of installation
- Exhaust Warranty
- Exhaust Sound
- Exhaust Cats/Legal
Let's also say the exhaust is to be paired with an ARD Green Tune, because that is an excellent midpoint between sheer power and daily driverness. Oh and loads of people think it's simply outstanding. This duo will deliver nice manners, and a good shove in the back when you need it. Joe wants to get his tune after his exhaust, so ARD's Lucky can make the tune's programming curves allow for the exhaust. Tunes and exhausts are symbiotic, and Joe is wise.
Joe is Not a Raging Felon
If you're getting the impression that Joe is an upstanding citizen who does not smoke blunts, drink Chevas Regal, and blast crunk music at 2am, you are correct. Joe's a dad, so his exhaust can't drone in town or on the highway, it can't wake the neighbors when he backs out of his driveway, and it will be used with a catalytic converter. Joe is in no mood to swap components every year when he gets an emission check, so the factory catalytic convertor will stay put, making this a "Cat-back" exhaust.
Ok, on with the Fast Friday discussion...
Exhausts - The Seven Things to Know
As suggested by the man himself (Matt) this week let’s cover the various aspects of exhaust systems specifically looking at Cat-back systems available in the market today! Per Matt’s suggestion we’ll be considering this topic against a 2004 S60 turbo. ['04 S60 turbo being a good composite example of the MVS reader]
Let’s start by breaking down the aspect of exhaust choices based on diameter, shape, materials, installation, warranty, sound, and legality with regard to catalytic convertors.
For the most part 2.5" ID exhaust will be more than enough for most folks sub 400 bhp. For those above that level 3" becomes a necessary option although some of that will be determined by the nature of the muffler and resonators used. Obviously the less restrictive the muffler/resonator the smaller the exhaust can be in terms of diameter. For the Downpipe portion of the exhaust, 3" is preferred since the exhaust gasses are still quite hot and taking up considerable room as opposed to post catalyst gasses that have cooled considerably and take up less space, hence the reduction in pipe diameter for the cat back section.
Round or oval the most important part is total area of flow. Whether larger round pipe is used or smaller oval/elliptical pipe is used the total area is what you should be comparing. Elliptical pipe is however desirable for models like the S60 in question, where ground clearance can be an issue. Round pipe at 3" could become the lowest point of the car especially if lowered and potentially create interference problems. Twin tube can be a good option as well so do your math and compare flow area to get a sense of which system you’re considering has the best fit for your setup. [added 2013-2-18] MVS reader John S. notes this article failed to recommend mandrel bending, which means the curves are bent smoothly.
Most quality exhaust systems will be made from stainless steel in either 304 or 409 grade. 304 has higher nickel content and polishes out nicer but 409 is tougher even though it can develop a boundary layer of corrosion which can be less attractive. Both are ultimately fine choices but for my money 409 is my favorite, unless you’re in an area with salted roads and corrosion issues... in that case 304 would be a better choice.
For the P2 line of cars, installation is pretty straight forward, no driveline or axles to drop to gain access and a system can typically be installed on a lift in under 30 minutes. On the ground with jack stands figure about an hour without any broken studs or bolts. For earlier 850/70 series models the install can be a bit tougher since you have to weave the exhaust in and around the rear delta links and control arms so give yourself a bit more time if you’re installing to one of these models. As far as construction look for high quality V band joints as opposed to the standard flanged joints with gasket. V bands are easier to both install and adjust when fitting exhaust systems.
Warranties vary quite widely from manufacturer to manufacturer but expect to get at least a 1 year warranty on the system. For those systems that include a downpipe and catalyst be sure to ask as some catalyst equipped downpipe manufacturers offer no warranty at all. Buyer beware and ask!
This is likely the hardest part of deciding on an exhaust system: video and sound clips rarely provide a good glimpse of what the system will actually sound like once on the car and driving. Drone is the major concern during light throttle cruising since this is where most drivers spend the majority of the time when driving. Systems prone to bad drone will tend to be constructed more cheaply, keep an eye out for the following to select a system with the least amount of drone.
Muffler & Drone
You’re looking for a muffler that is of reasonable size and multi chambered or baffled to help exhaust pulses collide and reduce sound without so much collision that it restricts flow. This can be a bit tricky to determine since you may not have information as to the internal design. However some dead reckoning will help you get a sense of how much pipe length occurs inside the muffler and the more the better!
Resonators & Drone
Most resonators will be straight through perforated and surrounded by muffler packing to help reduce resonation in the exhaust. The longer the better with these, and look for oval resonators vs. round for best sound reduction.
Mounting and clamping. V bands add mass to the connection points of the exhaust which help dampen resonance caused by vibration. Proper mounting with consideration to exhaust hangers is crucial as well so keep an eye on how the system is connected to the factory rubber hangers or if they are replaced with new units.
Resonated Exhaust Tips & Drone
Resonated exhaust tips give more of a smaller impact but still notable and worth consideration for a system you're looking at.
V band clamp
Depending on your area the system you choose may or may not be legal. Technically if it is changed from stock and not EPA or CARB approved it is likely in violation of Federal emissions laws. Check with the manufacturer as they should know better than anyone if there system has been approved for road use and is 50 state legal.
Great video here by the way of some work Ferrita did building the exhaust system of the C30 Polestart concept. If you haven’t seen it yet be sure to check it out!
Robert Lucky Arnold