351c Exhaust?
6th Gear Member
Joined: Apr 2007
Posts: 10,468
From: California
If you run a 2.5" exhaust the run Hooker Maxflow mufflers, since they offer essentially no resistance(Borla I think also offers an almost 0 restriction muffler). If you run 2.5" with Flowmaster mufflers, it will be like running a 2.25" straight pipe or smaller. It will strangle your engine. If you want to run a Flowmaster or other restrictive muffler(yes, Flowmasters suck ***** for airflow) then you probably want a 3" setup.
5th Gear Member
Joined: Dec 2008
Posts: 4,462
From: Texas
When I bought my car it was straight pipes (no crossover whatsoever) off of exhaust manifolds and I thought it was loud and obnoxious as hell. After I intalled Hooker long tubes I had a 2.5 inch exhaust with custom x-pipe and dynomax mufflers put on and I liked the sound quite a bit. It was unique with a nice rumble (more or less quiet in the car) with a nice bark when you let off of the throttle. It was not to loud but loud enough.
Dynomax Ultraflo and Race Bullets are straight through low restriction design as well.
If you run a 2.5" exhaust the run Hooker Maxflow mufflers, since they offer essentially no resistance(Borla I think also offers an almost 0 restriction muffler). If you run 2.5" with Flowmaster mufflers, it will be like running a 2.25" straight pipe or smaller. It will strangle your engine. If you want to run a Flowmaster or other restrictive muffler(yes, Flowmasters suck ***** for airflow) then you probably want a 3" setup.
I agree that Flowmaster sucks for more than one reason, but I don't see how running larger diameter pipe will help any. The muffler itself is the same case and same internals. It just has a larger inlet/outlet.
Dynomax Ultraflo and Race Bullets, as well as Magnaflow are straight through low restriction mufflers.
Last edited by tx65coupe; Jun 21, 2010 at 08:14 PM.
6th Gear Member
Joined: Feb 2007
Posts: 7,635
From: state of confusion
I'm getting closer to choose my exhaust set up for the Mach 1. I am thinking of going with 2.25 or 2.5 exhaust with a custom X pipe and 2 Super 44's. Has anyone run this or a similar set up with a 351C? Just curious to hear the good and bad reviews and maybe even a sound clip if possible. Thanks in advance for help/opinions.
-Tim
-Tim
You definitely want 2.5" pipe with that much power, and I'll toss in another vote for the Hooker MaxFlo's. The EFI-355-powered Malibu in one of my albums has this arrangement with long tubes and uses a single huge cat (4" in/out) to effectively function as an X. Gut feel - an X should make a little more power once the mufflers start offering more than just a little resistance due to better exhaust mass flow sharing between the two downstream pipes.
As you go from completely separate duals to duals with an "H" crossover to an "X", the sound quality goes from rough to smooth (with the H being somewhere in between) and the sound level at idle drops some. An H makes more of a rumble, an X more of a snarl (especially as you hit 3500 rpm or so).
I don't have any sound clips, and no way to make them available even if I did, but maybe you can get something out of the graphs. Top one is for true duals/no crossover, bottom is for an X. The big widely spaced spikes (widely spaced = low frequency) in the top chart is the rumble that dominates the V8 dual exhaust sound. With an X, the spikes are much smaller and closer together (higher frequency).
FWIW, I happen to like both sounds. I wouldn't change out the rumble in the '08 Mustang, but if I was building a project with a typical V8 I'd pick the X every single time.
Norm
Last edited by Norm Peterson; Jun 18, 2010 at 07:04 AM.
6th Gear Member
Joined: Apr 2007
Posts: 10,468
From: California
While a muffler will still remain restrictive, the larger inlet and outlets on a muffler help with flow coefficients into and out of the muffler. It can also help with gas particle pathways as the exhaust enters the muffler's internals, keeping the velocity higher. Also the big thing is the pipe leading up to the muffler, if the muffler is already a cork, having a small pipe before it results in even more resistance that backs up into the headers and reduces tuning efficiency.
With a restrictive muffler you need large pipes to compensate for the restriction....it's not ideal, but it helps. Especially in a 500hp engine, as 500hp is pretty much the max for 2 x 2.5" STRAIGHT pipes....add in a muffler with a ton of restriction and then your exhaust starts to have a huge impact on performance. It may not matter much on a 400hp engine or less where you're not maxing the pipes out, but when you're maxing out the pipe size WITHOUT restriction....adding any more restriction becomes a major performance killer.
With a restrictive muffler you need large pipes to compensate for the restriction....it's not ideal, but it helps. Especially in a 500hp engine, as 500hp is pretty much the max for 2 x 2.5" STRAIGHT pipes....add in a muffler with a ton of restriction and then your exhaust starts to have a huge impact on performance. It may not matter much on a 400hp engine or less where you're not maxing the pipes out, but when you're maxing out the pipe size WITHOUT restriction....adding any more restriction becomes a major performance killer.
2nd Gear Member
Joined: Oct 2007
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From:
Sorry, and don't take this the wrong way, I'm really old school and while I can post pics I don't have any way to post a video. Yep, that's how old my phone is.
2nd Gear Member
Joined: Oct 2007
Posts: 241
From:
Good choice on the Dynomax mufflers. Which ones did you get, Ultraflo or Super Turbo?
To the comment about Flowmaster not flowing well, thats true, but I don't see how running larger diameter exhaust will help since the muffler itself is the same but just has different inlet/outlet diameters.
Dynomax Ultraflo and Race Bullets are straight through low restriction design as well.
I agree that Flowmaster sucks for more than one reason, but I don't see how running larger diameter pipe will help any. The muffler itself is the same case and same internals. It just has a larger inlet/outlet.
Dynomax Ultraflo and Race Bullets, as well as Magnaflow are straight through low restriction mufflers.
To the comment about Flowmaster not flowing well, thats true, but I don't see how running larger diameter exhaust will help since the muffler itself is the same but just has different inlet/outlet diameters.
Dynomax Ultraflo and Race Bullets are straight through low restriction design as well.
I agree that Flowmaster sucks for more than one reason, but I don't see how running larger diameter pipe will help any. The muffler itself is the same case and same internals. It just has a larger inlet/outlet.
Dynomax Ultraflo and Race Bullets, as well as Magnaflow are straight through low restriction mufflers.
5th Gear Member
Joined: Dec 2008
Posts: 4,462
From: Texas
While a muffler will still remain restrictive, the larger inlet and outlets on a muffler help with flow coefficients into and out of the muffler. It can also help with gas particle pathways as the exhaust enters the muffler's internals, keeping the velocity higher. Also the big thing is the pipe leading up to the muffler, if the muffler is already a cork, having a small pipe before it results in even more resistance that backs up into the headers and reduces tuning efficiency.
With a restrictive muffler you need large pipes to compensate for the restriction....it's not ideal, but it helps. Especially in a 500hp engine, as 500hp is pretty much the max for 2 x 2.5" STRAIGHT pipes....add in a muffler with a ton of restriction and then your exhaust starts to have a huge impact on performance. It may not matter much on a 400hp engine or less where you're not maxing the pipes out, but when you're maxing out the pipe size WITHOUT restriction....adding any more restriction becomes a major performance killer.
With a restrictive muffler you need large pipes to compensate for the restriction....it's not ideal, but it helps. Especially in a 500hp engine, as 500hp is pretty much the max for 2 x 2.5" STRAIGHT pipes....add in a muffler with a ton of restriction and then your exhaust starts to have a huge impact on performance. It may not matter much on a 400hp engine or less where you're not maxing the pipes out, but when you're maxing out the pipe size WITHOUT restriction....adding any more restriction becomes a major performance killer.
6th Gear Member
Joined: Apr 2007
Posts: 10,468
From: California
The irony is that many of the lousy flowing mufflers are also the loudest.