as for the pipes, if anyone has the time and money, build a set with 2inch primary pipes 40inches long into a pair of 3into1 merge collectors
with 2 1/4 inch secondaries 12inches long into a single 3inch system.

as for the pipes, if anyone has the time and money, build a set with 2inch primary pipes 40inches long into a pair of 3into1 merge collectors
with 2 1/4 inch secondaries 12inches long into a single 3inch system.

interesting idea, one hurdle being legality on emisions, as we all know the further you move the cat down the line, the less effect they have cleaning up the emisions. long series headers like 4480's and JMM race series are borderline on emisions.

sweet looking pipes though, have you ever tried a straight through muffler, like a hooker instead of an offset? Im thinking of using a hotdog too, but up front, want to keep as much flow speed as possible meaning one straight thru muffler just before the diff bend.

IT WONT WORK!... sorry couldn't help it What's the most you have managed to increase torque/hp on engine analyzer just from exhaust?

just remember that a 3 inch cat might only have the flow of a piece of 2.25 inch straight pipe.

Pacemaker 4480
Primary Pipe:
1 ⅝"
(41mm)
Secondary Pipe:
1 ¾"
(44mm)
Outlet (flanged):
2 ½"
(63mm)

Pacies do not have a 3 inch flange if you team them up with a 3 inch cat you need to cut them back a few inches and weld on a new flange at the 3 inch diameter mark.

the idea is to keep flow rates up. a fast flowing cat, and straight through single chamber mufflers would be a better port of call than increasing the size of your pipe that far. Its not a v8, its only 4 litres, and only revs to ~5500 rpm. the ricers only use 3 inch pipe to get better spool up, due to a hi pressure on one side of the vanes, and low pressure on the other. having 3 inch pipe after a 3 inch cat would see low rpm air speed drop after the cat, as it is restricted and slowed, and then fed into a low pressure chamber.

just to put it into context about mass and velocity, a 6 litre V8 revving to 6500 rpm will need the exhaust capacity to move 39,000 litres of air a minute (on paper, reality differs slightly with gass expansion, sacavenging, and residual deposits). a 4 litre 6 revving to 5500rpm needs to move 22,000 litres of air a minute. which is almost half!

Im not saying 3 inch is bad, just size the pipe for where you want it to be most efficient, and thus make its power. size it to your mods. Biggest is not always best.

I garauntee you, get a stock falcon on a dyno, then put on a 3 inch and dyno it again. there will be a small hole in the torque on the graph early on.

It was a few years ago know, but there was about 10hp peak over 'traditional' headers. with no loss under 3000rpm compared to the same headers

do you the specs of a stock cam? or is that why you used a wade cam?
Also what engine did you start with?

I have only been playing with a 302 able to flow 400cfm through the exhaust and managed to get 10-12hp out of it through exhaust

the idea is to keep flow rates up. a fast flowing cat, and straight through single chamber mufflers would be a better port of call than increasing the size of your pipe that far. Its not a v8, its only 4 litres, and only revs to ~5500 rpm. the ricers only use 3 inch pipe to get better spool up, due to a hi pressure on one side of the vanes, and low pressure on the other. having 3 inch pipe after a 3 inch cat would see low rpm air speed drop after the cat, as it is restricted and slowed, and then fed into a low pressure chamber.

just to put it into context about mass and velocity, a 6 litre V8 revving to 6500 rpm will need the exhaust capacity to move 39,000 litres of air a minute (on paper, reality differs slightly with gass expansion, sacavenging, and residual deposits). a 4 litre 6 revving to 5500rpm needs to move 22,000 litres of air a minute. which is almost half!

Im not saying 3 inch is bad, just size the pipe for where you want it to be most efficient, and thus make its power. size it to your mods. Biggest is not always best.

I garauntee you, get a stock falcon on a dyno, then put on a 3 inch and dyno it again. there will be a small hole in the torque on the graph early on.

I wonder if the hole is because of too much scavenging drawing the mixture out of the exhaust ports before full combustion has taken place?

Or is it the other way around, is the excess scavenging drawing a small amount of unburnt intake fuel through and out the exhaust before the exhaust valve is closing (prior to compression stroke)?

I know i've read something, sometime, about this.

My impression is a bigger muffler is better than a smaller muffler in terms of reducing noise without increasing drag. But they are usually heavier. It would be interesting to compare the noise and drag of one of them versus two or even three hotdogs or similar.