Thanks Pete. I don't get out to club events/meets/shows like I used to, hopefully that will change once this Fiero get road-worthy again. I still have a lot of work to do. The priority right now is getting it back on the road taking care of mechanicals and the basic cosmetic aspects first. After that phase is sorted I'll make it pretty again.
Mock up is currently 6" wider than stock, may be wider when done. Quarter panels are ready for some massaging to allow for the extra width, clean fitment and to still retain a stock-like appearance. Rear bumper and diffuser treatment coming as well. F40 6-speed transmission swap is a high probability. Planning a 2-into-1 exhaust merge after the 180 header collectors into a Spintech muffler, center exit under the rear bumper and/or diffuser. More details to come...
Here's a sneak peek at the new muffler of choice for this project, Flowmaster's laminar flow Pro Series muffler. Early on, I had planned on using Spintech muffler, but after a lot of listening to 180 headers with different muffler types, I became convinced that a chambered-style muffler design would not produce the sound I was looking for. Due to packaging restrictions with exhaust routing after the collectors, the Pro Series muffler looks to be a beautiful choice. It's overall small size is a huge bonus. It also has a bass-heavy sound quality and is well known for not producing annoying drone. All things I am looking for in a muffler.
Today I ordered Flowmaster part #13516100, which is a 3.5" in/3.5" out straight-through muffler with a 16" case length. The plan is to run it after a 3" to 3.5" y-pipe connecting the two 3" header collectors. This Flowmaster Pro Series 3.5" in/out muffler size is now discontinued by the way, I had to snatch one up off of Amazon from an external source. It was not cheap, but it is a very good sounding, fully welded stainless steel muffler with a lifetime warranty. It will still be a tight fit to make it work, but well worth it. More details coming soon...
[This message has been edited by ITALGT (edited 03-19-2020).]
So I recieved the new 3.5" Pro Series muffler and after sizing it out behind the engine, the 16" case length may be a little too long for where it needs to be routed. I do have a plan B ready using a slightly different setup.
Exhaust system after the headers, plan B. My first idea of using a single 3.5" system after the collectors has changed due to many reasons. It's not a loss or setback though, as the more plan B has taken shape, the more I realize it should have been plan A to begin with. Rather than dive into the many reasons why, I'll get to the new setup and the planned components that are involved.
I'm switching from a 3.5" to a 3" diameter system after the 180 header collectors. I'll be using a shortened Howe Racing 3" to 3.5" y-pipe #H2023 after the 3" header collectors followed immediately by a Flowmaster Pro Series Outlaw race muffler #13509130 with a 3.5" inlet and 3" outlet. This racing muffler will not only provide an excellent merge point after the y-pipe, it will also give a nice 3.5" to 3" pipe transition that I'm looking for without having to use a reducer cone. And since the muffler is standard steel, I can easily weld the shortened y-pipe section directly to the muffler's case after cutting the inlet pipe off. Here is a quick Photoshop I did which shows what the shortened y-pipe and Outlaw muffler combination would look like if used:
I'm still going to use a Flowmaster Pro Series laminar flow muffler further down the single 3" system, but it will be the "Shorty" version #13012100 with a 3" inlet/outlet and a 12" case length. It will be used as the main muffler of the system, while the Outlaw race muffler will act more as a system resonator and also help the rather small laminar flow muffler do its job. Should be a sweet sounding combination.
More pictures and details coming soon...
[This message has been edited by ITALGT (edited 03-26-2020).]
Howe Racing 3" to 3.5" y-pipe. I have to say it's a very nicely built piece. I messed up and ordered the outcoated version... not a big deal, just need to media-blast the coating off before welding and final finishing. Both Flowmaster mufflers are on their way. 3" 90 degree mandrel bends will be ordered for the header collectors next...
[This message has been edited by ITALGT (edited 03-10-2020).]
Hey there Will... I did actually consider using an X-pipe early on mainly just for the sound, but there really wasn't enough room after the collectors to effectively use one. I decided to run a Y-pipe for a few reasons, limited space was a big one. Dumping both exhaust collectors into one pipe looked like the best option for how I wanted to route the exhaust as a single center-exit system through the back.
Another reason I'm using a Y-pipe instead of an X is sound. The 180 degree header Y-pipe combo will have a slightly smoother and higher-pitched tone compared to what an X-pipe design would produce. The Y-pipe sound can often be heard when around modified asphalt and dirt track race cars using 180 headers. It's a very unique and noticable sound... very aggressive and exotic.
The Y-pipe after the collectors also reduces the overall length and weight of the entire system, since it reduces things down to one length of exhaust tubing instead of two. Routing two seperate exhaust pipes could definitely be done if a person wanted to, but there would be a good chunk of time and fabrication involved to do it correctly. Not to mention plenty of extra weight involved.
When all is said and done, a 2-into-1 Y-pipe system after the 180 headers should, by design, be very effective at making smooth power across a broad RPM range for a short-stroke SBC V8. The very short overall system length after the Y-piped collectors should produce massive amounts of scavenging and maintain a very high exhaust flow velocity... and it should end up being very light weight.
Once I get the Flowmaster mufflers and 3" 90 degree mandrel bends for the collectors, I'll post some more pics of the system as it takes shape.
[This message has been edited by ITALGT (edited 03-19-2020).]
Slow progress right now as there was a delay getting the mufflers. There may already be a slight change of plans with the Y-pipe/Outlaw muffler combo. I may end up using the Y-pipe directly off the collectors instead of using two 90 degree mandrel bends. A single 90 degree mandrel bend routed towards the passenger side would follow after the Y going to the Outlaw muffler. This would simplify, shorten and lighten the system even more, not to mention be much easier to route overall.