percussionist
New member
Have a 1981 244 DL B21F engine, naturally aspirated (US 49 state version). I've done an exhaust mod that has started a running argument with another Volvo geek. I went to a shop and cut the header pipes just at the point they entered the collector pipe. Increased the pipe size from 44.5 mm to 50.1 mm, then ran them directly into a high-flow cat. From there, into 57 mm pipe, then to a straight through muffler at 63.5 mm.
This represents a "4-1" exhaust system, with the cat becoming a collector. The result has been noticeable improvement on the low end, with more power starting at 2K-2.5K rpm, and much better response 3K-4K. This is about 500 rpm earlier than before the mod. My next mod was to be a somewhat hotter cam. My friend says that a hotter cam will "suffer" because the Volvo B21 has to have a 4-2-1 exhaust system to scavenge the most power, and to take the most advantage of a higher performance cam, I need to re-do the entire exhaust system.
Any thoughts?
BTW, interesting forum. Glad to be here.
This represents a "4-1" exhaust system, with the cat becoming a collector. The result has been noticeable improvement on the low end, with more power starting at 2K-2.5K rpm, and much better response 3K-4K. This is about 500 rpm earlier than before the mod. My next mod was to be a somewhat hotter cam. My friend says that a hotter cam will "suffer" because the Volvo B21 has to have a 4-2-1 exhaust system to scavenge the most power, and to take the most advantage of a higher performance cam, I need to re-do the entire exhaust system.
Any thoughts?
BTW, interesting forum. Glad to be here.