Catalytic Convertors… How Do They Work?

MVS Volvo Forum Contributor rmmagow lays it out on catalytic converters (abbreviated often as simply “cat“): The CAT is a pretty simple device, no moving parts. The front O2 sensor is before the CAT and is the important part in the mileage equation. The rear O2 sensor (in most cars) does little but watch the stream […]

Aftermarket Headers – Significant Quality Differences

Part quality has never been a stranger to MVS Forums. In fact, I’d put it up against any other subject in terms of the levels of emotion and sheer number of posts it generates.

This fine example of aftermarket parts inequality caught my eye last night because it’s so stark. I’m no metalsmith to see the difference in weld and material quality between the DNA Motoring exhaust manifold and one that was made in Estonia.

Replacing Exhaust Manifold – DIY Basics

The one time I’ve actually removed an exhaust manifold from an 850 n/a I remember the two lower bolts of the heat collector. That was a donor car that I was stripping so there was no need for finessing. I think I finally just ripped it out. Memory of details is vague as that was 5 years ago.

What Does The Rear O2 Sensor Do?

Is the critical unit is the upstream O2 sensor for emissions inspection? And what are the clear indications (based on scanner data) of a bad catalytic convertor, and by extension a failing rear O2 sensor?

Catalytic Brand, Install Tips & Answers

Replacement Volvo Catalytic Convertor

Welding tips and Catalytic converter buying advice So here are the questions (I have searched up and down the forum!): Catalytic Convertor Brand “Davico” is out (not a good brand). “Bosal” seems OK, long history of quality. “Magnaflow“: $80 for the cat alone vs $300-400 for the direct-bolt in. “DEC” (aka “Diversified Environmental Catalysts”): I have […]

OBX Exhausts Good? Opinons Found Here.

“I had the OBX DP on my S60R and it worked very well. It is still on the car after a year and a half and there are no issues with it at all.” — Volvo forum user FCPGroton “I bought an OBX header for my son’s ’96 N/A. The quality was outstanding but he has EGR […]

XC90 – Replacing Oxygen Sensors DIY Tutorial

Replacing heated oxygen sensors is a low-medium level DIY project you can do to save money on car repairs, and if your sensors are old, can increase your fuel economy. Really straight foward to swap out. They should be done on a COLD XC90, i move it all of 10feet and running for 3 minutes […]

Volvo V70 Straight Pipe Exhaust Mod

What a straight pipe exhaust modification looks like (plus the owner’s description of the sound and power increase). In addition to that, there are a few give-and-takes about general aftermarket exhaust noise and about aftermarket exhaust quality. I have a 1998 V70 with a B5254S 168hp engine and 140K miles. Recently replaced the muffler, catalytic converter and all pipe […]

Performance Exhausts for Volvos

Performance Exhausts for Volvos: Theory and Practice If you care about getting good performance, mandrel bending is important. Mandrel bending is bending the pipe such that the cross sectional area remains a perfect circle, as opposed to be distorted to an ellipse, which has a smaller cross sectional area, which also has poorer flow characteristics. […]