I know there are tons of threads on here about 3800 exhaust, and I've read pretty much all of them, but I think mine is a little different and I could use some input from you guys. My trunk is already cut, so I pretty much have a clean slate to work with.
I recently purchased a Ferrari 355 muffler that I am intending to use on my 3800 swap. The Ferrari muffler has 3 inlets, one is designed for a vacuum opperated bypass, which I will probably just cap off. Currently my swap is running stock manifolds into a high flow cat, and down to a dual outlet flowmaster, but the way it was done, it takes up about half the trunk. I am trying to decide if I should upgrade to headers when I change the exhaust, and if so which kind would best suite my setup? The speed daddy style that all tie into one collector, or would the pacesetter style be better with the modular Y pipe, or possibly not even use the Y and run each side independently into the muffler, which is where my question about the true dual exhaust comes in. Also I live in a county that requires emission testing, so I will probably have to plan on having a cat or 2 if it's a dual setup.
Also I could use opinions on what would be the best way to mount the muffler. I am thinking if I put it horizontal and have the inlets towards the motor I would probably only lose the thickness of the muffler, then just clock the outlets accordingly although I have not measured if it will fit this way yet.
Running dual, you will need to have probably 2 O2 sensors on each side, one pre-cat, and one post-cat, for each cat. I'm not sure if the ECM you're using has support for that, or if any 3800 cars came with that, though. To do it, you'll eat up a lot of space in the trunk area, to have shorter exhaust like the Ferrari has, and run dual cats and with that huge Ferrari muffler. You could run longer exhaust with one cat in the front, and one in the trunk area, but I'm not sure how that would mess up the sound or the flow.
For headers, I would definitely go with custom headers, regardless of what the rest of the exhaust looks like. The problem with all the 3800 headers available on the market, is that they're designed for front engined cars like the Grand Prix, and not a Fiero.
Personally, I would scrap the Ferrari muffler plan. It sounds cool, and "I have a Ferrari muffler" is a good conversation piece, but it's a giant muffler, and using it in a Fiero if you want to retain the trunk, is going to be pretty difficult, especially with a transverse engine. With a longitudinal swap like an Audi V8 with the Audi trans, it would probably be a great option, as you could build an exhaust similar to the actual Ferrari setup, much more easily. But you still might need to lose the trunk in the case, due to the muffler size.
Also, what are your future plans for the swap? Are you planning to go turbo or anything? How big a turbo if so?
While some 3800 equipped GM vehicles came with two pre-cat O2 sensors (Camaro) none of the SC S2 3800s did. So no stock S2 SC programmed PCMs will support it. As far as I know, no one has came up with a tune that supports the SC S2 with dual pre cat O2 sensors.
Also, what are your future plans for the swap? Are you planning to go turbo or anything? How big a turbo if so?
I plan to keep it SC, I actually haven't even driven it yet, and I'm sure that will plenty of power, and if I'm itching for more I can always go intercooled.
Currently my exhaust setup only runs 1 precat o2 sensor. I thought I read a post somewhere in my searches where someone posted about true duals, and darth replied that 1 o2 would be sufficient, you just wouldn't be recieving any data from the one bank, which is fine if your motor is in good running order. I could be wrong. [URL=http://s100.photobucket.com/user/zdm cdonal/media/32444__zps9ad9wtix.jpg.html][/URL]
I was thinking if I ran headers like in the first picture but without the Y, with small cats and tighter bends like in the second pic. Or if I have to I could do without the cats and figure out a way to plate it in another County.
Just my 2cents Do the Ferrari exhaust as it may turn out awesome. The ONLY reason to stuff that big azz muffler back there is to make a great sound. The 3800 SC needs all the help it can muster in the sound department. Custom headers would be the best but anything can be MADE to work with enough time and skill.
Originally posted by zmcdonal: I plan to keep it SC, I actually haven't even driven it yet, and I'm sure that will plenty of power, and if I'm itching for more I can always go intercooled.
I was thinking if I ran headers like in the first picture but without the Y, with small cats and tighter bends like in the second pic. Or if I have to I could do without the cats and figure out a way to plate it in another County.
If you really want to stick with the 355 muffler, first thing I would figure out is how you're going to mount it in the Fiero, and get the outlets tweaked to fit how you're going to mount the muffler and fit the Fiero exhaust tip pockets in the bumper. It won't mount into the Fiero at the same angle as in the Ferrari, without cutting the trunk, and you'll still need modification to the outlets on the muffler I think.
Then with the muffler and drive train mounted in the car, figure out a reasonable exhaust routing.
What you can do with the exhaust depends on how much space you have. You'll want to at least use an X-pipe if you do want to run dual exhaust. But you will be very limited on space with a transverse engine, so will take some creative work to use that muffler.
+1 on running just a single O2 sensor. Not the optimum way to do it but it will work fine.
If I was going to run dual exhaust on a PCM that only supported one, I'd make a circuit to use two, and average the signal so it looks like one, but both banks impact the reading in a similar way to having one O2 just after the Y before the cat in the factory setup.
the mustang header i am using, came with a place to mount a second o2 sensor. I bought a gauge to monitor it from the dash. As for the muffler, I am going to be running the same 355 muffler. My trunk is cut already, so i am hoping i can make it work without a whole lot of trouble. I would like to use the third port also, with a vacuum operated butterfly mounted in a similar fashion to the ferrari setup. troy
The single upstream (of the cat) o2 sensor the 3800 PCMs use only really needs to see one bank of (3) cylidners. Is it better if it can monitor both banks (ie: all 6 cylinders)? Sure. But it will work fine only monitoring 3, and I certainly wouldn't try to combine two separate o2 sensor signals to feed a single o2 sensor input to the PCM. Doing that would be asking for trouble.
That having been said, I'm not sure if running true dual exhaust on a 3800 is going to make it sound any better. However, I can't say that I've ever heard one so the jury is still out on that. But you should be aware that keeping the two exhaust banks completely separate with no balance pipe or merge will probably cost you some power, at least under the curve (usually more prevalent in the mid RPM range).
-ryan
------------------ OVERKILL IS UNDERRATED Custom GM OBD1 & OBD2 Tuning | Engine Conversions & more | www.gmtuners.com
[This message has been edited by Darth Fiero (edited 09-12-2014).]
the mustang header i am using, came with a place to mount a second o2 sensor. I bought a gauge to monitor it from the dash. As for the muffler, I am going to be running the same 355 muffler. My trunk is cut already, so i am hoping i can make it work without a whole lot of trouble. I would like to use the third port also, with a vacuum operated butterfly mounted in a similar fashion to the ferrari setup. troy
You guys realize it won't sound anything like a Ferrari by just copying what the Ferrari exhaust setup is like, with a 3800, right?
I think the best option would probably be a Y-pipe exhaust with a single cat, and after the cat, a custom collector is made to balance the output between the 3 ports. A standard Y for the two lower muffler inputs for normal exhaust flow, and a third port with an electronic (or vacuum if you really want) controlled butterfly valve, that goes straight up to the third input on the muffler. That should give the best balance between the 3800 and what the muffler was designed for, and should allow for a reasonable exhaust system in the somewhat confined space of the Fiero.
I would first understand how the 3 pipes flow through the muffler.
From their location, I would assume the center top inlet goes through the muffler portion (lots of room between inlet and outlets). The two lower inlets in the corners are right by the outlet pipes and likely just dump right to the tail pipe cavity, which would be the same as running w/o a muffler. If those are the only two you hook up, you might find the exhaust to be super loud. This also makes sense for a high flow exhaust with valves - you need a small amount of flow to be highly muffled (center inlet) so it will be quiet at idle and cruise. At WOT you need a large amount of flow with very little muffling/restriction (dual corner inlets) for maximum power.
I would snake a light through the tail pipe section and look if you can see the light from those corner inlets. If you can, then those two corner inlets will likely do very little to quiet the exhaust down.
That having been said, I'm not sure if running true dual exhaust on a 3800 is going to make it sound any better. However, I can't say that I've ever heard one so the jury is still out on that. But you should be aware that keeping the two exhaust banks completely separate with no balance pipe or merge will probably cost you some power, at least under the curve (usually more prevalent in the mid RPM range).
-ryan
My idea behind having a true dual setup was more for ease of install and potentially take up less space. I didn't see a point in having it all sent into one collector only to split it up again for the dual inlets in to the muffler.
quote
Originally posted by dobey:
You guys realize it won't sound anything like a Ferrari by just copying what the Ferrari exhaust setup is like, with a 3800, right? .
I am not necessarily going for the Ferrari sound, but my brother and I figured that exotics have the same issue that the Fiero has, muffling a lot of exhaust in a short area. So I thought it should do a pretty good job toning it down, and if it ends up sounding sort of exotic at the same time, that would be a plus too.
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Originally posted by fieroguru:
I would first understand how the 3 pipes flow through the muffler.
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Surprisingly the top center hole of the muffler was the one that vacuum operated on the Ferrari. I was considering putting electric cut outs in there as well that would divert to the top hole if I wanted to make more noise
Here is a diagram of how it's setup on a 355
[This message has been edited by zmcdonal (edited 09-12-2014).]
Originally posted by fieroguru: I would first understand how the 3 pipes flow through the muffler.
From their location, I would assume the center top inlet goes through the muffler portion (lots of room between inlet and outlets). The two lower inlets in the corners are right by the outlet pipes and likely just dump right to the tail pipe cavity, which would be the same as running w/o a muffler. If those are the only two you hook up, you might find the exhaust to be super loud. This also makes sense for a high flow exhaust with valves - you need a small amount of flow to be highly muffled (center inlet) so it will be quiet at idle and cruise. At WOT you need a large amount of flow with very little muffling/restriction (dual corner inlets) for maximum power.
I would snake a light through the tail pipe section and look if you can see the light from those corner inlets. If you can, then those two corner inlets will likely do very little to quiet the exhaust down.
All of the inputs have some muffling. The two lower inputs are 1-in and 1-out ports. The third upper input is a single in, dual-out, system. On the Ferrari, The two lower inputs on the muffler are from exhaust flow going through cats. The upper cat gets a Y from both headers, that bypasses the cats, and it splits into a Y internally in the muffler, to the additional tip on each side. I think the two lower inputs result in a pipe which goes upward into the muflfer, makes a 180, comes back down, and then goes out the tip. The F355 is not that loud at idle, really. You can hear it get louder when the butterfly opens though, and it only opens after about 3000 RPM.
Originally posted by zmcdonal: My idea behind having a true dual setup was more for ease of install and potentially take up less space. I didn't see a point in having it all sent into one collector only to split it up again for the dual inlets in to the muffler.
I am not necessarily going for the Ferrari sound, but my brother and I figured that exotics have the same issue that the Fiero has, muffling a lot of exhaust in a short area. So I thought it should do a pretty good job toning it down, and if it ends up sounding sort of exotic at the same time, that would be a plus too.
A true dual setup won't save space with a transverse engine (or in generally, really). Two 3" pipes that are 36" long is twice as much space as one takes. Then if you need to put dual cats in, those take up more space, as they are larger than 3" diameter. True dual in a Fiero will take up lots of space. This is why I mentioned it would be much better for a car with an Audi V8/Audi trans swap, for example, because that's longitudinal, so you can get away with a short true dual exhaust much easier there.
That said, the Fiero doesn't really have a problem muffling the exhaust. The stock exhaust routing provides plenty of exhaust length to get all the needed emissions equipment in, and muffle the sound. It's actually about the same length as the exhaust in a Firebird. The problem with swapped engines like the 3800, LS4, etc… is that nobody makes exhaust designed to fit the Fiero and those engines. The Ferrari V8 is a 5 valve DOHC engine, and makes peak HP at 8250 RPM. That's much higher than you're going to be running any stock or even mildly modified 3800 SC2 at. The F355 engine needs to be able to flow a LOT more air at that RPM.
I think the best way to get an exotic-ish sound out of that muffler with a 3800 in a Fiero, is to run a Y-piped exhaust that splits before the muffler. This really isn't any different than have a muffler with a single inlet, and dual outlets, like the stock Fiero 2.8 muffler. You're just choosing to use a dual inlet muffler.
So it looks like the tail pipes pass completely through the chamber where the corner inlet dumps, so it does look like the two corner ports do more muffling than the center dump one. That is opposite of what I had previously assumed.
[This message has been edited by fieroguru (edited 09-12-2014).]
I was just thinking it would get pretty messy having it all come into one collector and then have a cat somewhere and then split back off and go into both ends of the muffler. I don't know, it's hard to tell how much space I would really have to work with without actually having headers in hand and be able to see where the collector ends up and how the muffler looks mocked up into location. But I don't know which headers would be best, or if I should just set it up with the stock manifolds for now and forget the headers.
The actual muffler dimensions are 28" long 6" thick and 15" tall.
Originally posted by zmcdonal: I was thinking something like this:
I was just thinking it would get pretty messy having it all come into one collector and then have a cat somewhere and then split back off and go into both ends of the muffler. I don't know, it's hard to tell how much space I would really have to work with without actually having headers in hand and be able to see where the collector ends up and how the muffler looks mocked up into location. But I don't know which headers would be best, or if I should just set it up with the stock manifolds for now and forget the headers.
The actual muffler dimensions are 28" long 6" thick and 15" tall.
The big problems you have are the size of the muffler itself, and the headers you are talking about using. Those headers are designed for the Grand Prix, not the Fiero. On the Fiero, the rear header is going to interfere with that huge muffler. If you don't want to lose at least the bottom half of the trunk, the top side of the muffler will have to lean forward, and the outlets for the tips will be have to ground or cut off, and new outlet pipes welded on at the right angles and width to fit the Fiero. It's going to be very tight with those headers.
This is why I said you need to get the muffler mounted so you can see how much room you actually have. And I think the best solution for headers will be to have custom ones made (if you can't make them yourself).
Well I'm definitely not going to have custom headers made, that would be way too expensive. The only reason I am even considering headers is because there are affordable options.
That's another thing that makes this difficult, I don't know how to weld, so I have to have somewhat of a plan in mind before I take it to my exhaust guy.
[This message has been edited by zmcdonal (edited 09-12-2014).]
The big problems you have are the size of the muffler itself, and the headers you are talking about using. Those headers are designed for the Grand Prix, not the Fiero. On the Fiero, the rear header is going to interfere with that huge muffler. If you don't want to lose at least the bottom half of the trunk, the top side of the muffler will have to lean forward, and the outlets for the tips will be have to ground or cut off, and new outlet pipes welded on at the right angles and width to fit the Fiero. It's going to be very tight with those headers.
The tips are narrower than the openings in the GT bumper so they need to be reworked anyway, that's why I was thinking to just lay the muffler flat and have the inlets facing up.
I guess I will need to remove my current exhaust so I can mock up the muffler and get an idea of the kind of room that I have to work with.
This is the current exhaust setup that's on the car. As you can see it takes up a lot of the trunk area.
[This message has been edited by zmcdonal (edited 09-12-2014).]
Originally posted by zmcdonal: My idea behind having a true dual setup was more for ease of install and potentially take up less space. I didn't see a point in having it all sent into one collector only to split it up again for the dual inlets in to the muffler.
The smallest possible exhaust system that takes up the least space is one like pictured below that hooks to the stock 3800 exhaust manifolds (yes, it is a single system that only splits in the muffler to dual outlets). You aren't going to get any simpler or more compact in size than this.
Granted the Magnaflow muffler in the above picture does require trunk wall massaging to get it to fit; but there are other brands of single in/dual out mufflers that will fit in a stock Fiero without any modifications being needed.
The smallest possible exhaust system that takes up the least space is one like pictured below that hooks to the stock 3800 exhaust manifolds (yes, it is a single system that only splits in the muffler to dual outlets). You aren't going to get any simpler or more compact in size than this.
Let me clarify, I know that true duals will take up more space typically and will not be the most compact. However with the muffler I am going to use I'm not sure how I would route things and use less space with a single collector a cat and then split to reach both inlets. Seems like it would have to snake back and forth a lot.
I've only ever heard one 3800sc that I've liked the sound of. And that's the 3800sc that's in John Carlo's car (which is currently in transition). Blair up here in BC put this engine in and custom built the exhaust and it sounds beautiful. I have an autocross video here shot back in 2010. It was the first time that John had ever been on a track. He was nervous and was just taking it easy... but listen to his car!
The first Fiero (with no suspension ) in the video has a stock 2.8 in it, and then John goes for a cruise. You won't believe this is a 3800sc.
Click to view the video - HERE. (It should open in it's own window.)
I've only ever heard one 3800sc that I've liked the sound of. And that's the 3800sc that's in John Carlo's car (which is currently in transition). Blair up here in BC put this engine in and custom built the exhaust and it sounds beautiful. I have an autocross video here shot back in 2010. It was the first time that John had ever been on a track. He was nervous and was just taking it easy... but listen to his car!
The first Fiero (with no suspension ) in the video has a stock 2.8 in it, and then John goes for a cruise. You won't believe this is a 3800sc.
Click to view the video - HERE. (It should open in it's own window.)
That thing does sound sweet! After searching around I found a pic of his setup, he says it's a spintec muffler that's all he's knows about it.
Originally posted by zmcdonal: Well I'm definitely not going to have custom headers made, that would be way too expensive. The only reason I am even considering headers is because there are affordable options.
That's another thing that makes this difficult, I don't know how to weld, so I have to have somewhat of a plan in mind before I take it to my exhaust guy.
Too expensive? You realize you're trying to use a Ferrari muffler in a Fiero with a 3800 right? No matter what you do, you're going to have to get custom exhaust made. Headers are not that expensive. They can be, but they don't have to be, either.
Have you even gotten a quote for what it would cost to make the exhaust? If you can't weld and can't pay a shop to do it, I'd suggest finding a local who can help for cheap then; or learning to weld. No time like the present.
The true-dual exhaust system on my Fiero with L32 (3800SC series III with 4T65e HD), Haltech Nexus ECM/TCM, a drive-by-wire system. L32 is an even fire engine, so does not need crossovers. Flanges are West Coast Fiero, headers are based on my design, fabricated to my spec, and mufflers are custom SpinTech. Trunk is not cut. Yes, have dual O2 sensors with Haltech gauge.
If two head pipes diverge at the muffler is this really true dual exhaust? I believe that a true race dual exhaust system is totally separate containing two head pipes, two mufflers and two tail pipes. Whether a true dual exhaust system would provide any more horsepower on a 3800SC swap is an unanswered question. IMO, since the 3800 is not a high revving engine I would say that gains, if any, would be minimal.
------------------ " THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, P-log Manifold, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, Champion Radiator, S10 Brake Booster, HP Tuners VCM Suite. "THE COLUSSUS" 87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H " ON THE LOOSE WITHOUT THE JUICE "
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) in the video has a stock 2.8 in it, and then John goes for a cruise. You won't believe this is a 3800sc.
