Name : Codith Age : 32 Location : Villa Park, IL Joined : 2007-02-08Post Count : 3646 Merit : 135
Subject: Equal-length exhaust secondaries Sat Sep 28, 2019 9:32 pm
I think this warrants its own thread. I'm not the first to do this on a 3800 but I am in the middle of an experimental exhaust project so I'll keep adding into this thread as I get things accomplished but today was a good day for my ears. Most of us on rivperformance, these days, aren't doing performance builds on our beloved rivs like 5-15 years ago but I wish I knew about this much sooner. So it's pretty well-agreed upon that the FWD 3800 is pretty unsoundly when uncorked. That's why I did up a whole mess of different exhaust systems and eventually went back to quiet as possible as of recent. You watch a bunch of these youtube videos of RWD cars - especially australian vehicles with the same motor and they sound pretty cool loud - like a really aggressive high performance 6 cylinder purr. Why the difference? It's 100% exhaust piping length. The cylinder banks have about the same length of piping before they join together. Our transverse layout means the front bank has significantly more pipe length before it can meet up with the rear bank (something to the tune of 3 feet). This affects exhaust pulse phasing and with our unequal length secondary piping, we get paired-up pulses that sounds kinda cool at idle but goes way sour with rpm. By the way, keeping the two exhaust banks totally separated for the whole exhaust system sounds just as bad as the stock unequal configuration. I guess it's a matter of effectively two 3-cylinder motors not sounding very nice either. But if you get the lengths right and merge them together, it sounds cool. I bet you could go more fancy and do a kind-of bundle of snakes and tune each primary on a individual basis and get it even better but that's outside my ability so I'm just looking to get the bank to bank lengths evened out.
First thing to do is just buy a set of Pacesetter style headers. The copies are a lot easier to get than the O.G pacesetters these days but doesn't matter either way. You can get them in 304 stainless for about $500 or mild steel for about $150. They are w-body headers but the main point is unlike any other header design I've seen, those keep the two exhaust banks separate at the upper downpipe region of the exhaust system. The kit includes a 2-1 junction that you slip on and the the rest of the actual downpipe connects to that. The trick is the move that 2-1 junction much farther back in the exhaust system and add piping to the short exhaust secondary bank however you can within the packaging constraints of the car to make the two banks pretty equal.
This is about where I'm at. I installed the headers on an otherwise totally stock 99 riv. I also got a whole DIY exhaust builder 16 piece piping kit for about $120. There's a number of things I need to work out later such as the oxygen sensor placement & the trans dipstick tube interfering with the header crossover pipe but for now, my mission is tuning the pipe lengths and packaging.
first setup that gave me a result I was after (really just literally throwing pipes together out of the box) The muffler sorta merges the two not quite like an x-pipe (there's an open space in the middle of the muffler) but I wanted to see if I could make it work for neatness.
All exhaust leaks and stuff aside, this is dangerously close to sounding awesome
Name : Rick Location : Lancaster, MA Joined : 2008-09-13Post Count : 6222 Merit : 112
Subject: Re: Equal-length exhaust secondaries Sun Sep 29, 2019 2:55 am
EXCEPT FOR THE DAMN DOG RUINING THE AUDIO.
Don't get me wrong, I love dogs but if your trying to make a sound video, put him/her in the house.
BTW, I'm surprised at what those Stainless Headers cost now. All this info just further pisses me off that I let the car go.
I got this together to a driveable point. With the one muffler pictured its really tame at idle but wow it picks up big time with some throttle. When I go forward with it, I'm probably gonna add another removable straight-through muffler at the back. It sounds really good if you drive with some aggression and get the engine to sweep through the range a bit rather than like the stock tune wants - upshifting early and lugging the car. This would be right at home on the green riv. I'm wanting more rev's and not getting them haha. On the white one, it sounds so much faster than it goes.. Blipping the throttle sounds awwwesome
I have pics and some little video clips but I'm leaving for a vacation in a few hours so I'll have to do it later. I'm doing too much lately