When one tests mufflers, can you be sure that the flow with hot, pulsing exhaust gas will be the same as a cool, steady flow of air? Or at least comparable from one muffler to another? ;) Ken Quoting Tom Jennings <tomj@xxxxxxx>: > On Tue, 17 May 2005, Bruce Hevner wrote: > > > Ahhh, mufflers. > > Ever wonder which "flows" best?? Which "is louder/quieter than the others? > > So have I!! > > NO SH*T!!! I didn't even bother to ask casually on the list about > that stuff I guess because mufflers (and street-type exhausts in > general) are one of those areas with a knowledge and info vacuum. > It's been like that for so long I gave up trying. I suppose if I > was in your shoes I'd be more upset by it like you are :-) > > Summit lists CFM for a few higher-end racing mufflers, but that's > it. The $29 muffler looks no different in the catalog than the $200 > job. Besides hype, there's got to be some difference, but what that is > is a mystery. > > Using hocus-pocus and the brains in my ass I decided (not > determined) that the better brands around $50 in Summit are > probably the best choice for me. That's the basis for me asking. > > What a way to choose. > > I'll go with dynomax (or closest spelling thereof :-) > > > I know that the physics of flow in pipe is well known, and there's > good rules of thumb for determining losses (diameter, bends, > length, etc) and a lot of it is obvious, but mufflers need to be > tested. > > It would make a good article for one of the 'rod mags. Just bench > flow 'em cold, at least hit the barn door with data. > > And noise, that can't be that hard to test either. Standard pipe > setup on probably a chevy 350 at two, three RPMs would also hit > the barn door. > > Bandsaw 'em open, hit the parts with a rubber mallet, guess whose > will fall apart first. > > > > > > > > Read an article in one of the car rags a while back comparing a few of the > > leading brands. They made an interesting statement. Their comparison > showed > > that matching a mufflers "flow" to your engines size and HP output is > > important. And that although a mufflers internal design affects sound, > > matching a mufflers "FLOW" is the important part. So WHY aren't mufflers > > rated in FLOW so we know which one to choose?? Turns out the exhaust > system > > industry as a whole IS fighting publishing flow ratings for mufflers. > There > > IS a formula for choosing the approximate flow rating for your muffler. If > I > > can find out what I did with it I'll post it. > > And WHY isn't there some kind of standard "Noise" rating for mufflers? As > > it is now unless you have actual experience with a muffler you have NO > idea > > how quiet they will be. I DO realize that the installation affects the way > > they sound. > > I have tried finding a source that has compared mufflers that does not > > actually SELL them. The only place I've found so far wants $65 for their > > book. > > > > In my opinion mufflers should AT LEAST be rated in FLOW! That way we could > > at least get some kind of idea of which one to use for the performance we > > are looking for. > > > > But HEY,,, that's just me. > > Bruce Hevner > > > > > > > > >