Straight Pipes & Mufflers...Why Not?

[Cheesehead]

This is my first V-6 car with twin turbos. Actually, first car with turbos. I have had Mustangs with both pushrod motors and the 4.6. On all those cars I got rid of the cats, put on an H-Pipe and got some decent mufflers. Pretty good gains on each car.

I have read on this forum that turbos do not need back pressure, so I am like cool! I will take it to my exhaust guy and have him replace everything from the turbos to the tailpipes.

From reading all of your posts this is a bad idea and a waste of money. The sound is terrible and there are no gains to be had for all the time and money invested.

Is this accurate? It seems counter intuitive to me, but what do I know. Just wanted to hear some more discussion on this because it just seems like it would work.

 

[yaycandy]

Its weight saving also. Stock exhaust with cats from turbos back is really heavy. Catless downpipes from lms were alot lighter then what i pulled off and the cat back system, obx that i have on is very light. I have no cats, just pipe, x pipe and mufflers on the ends. You would have to read alot about x pipe vs h pipe. Turbos dont want anypipes but x or h pipe should be better than true straight pipes on turbos, if full length exhaust has to be in the equation.

 

[Jordan_R]

So I think the big turn off is sound because frankly every exhaust system other than stock sounds raspy and like booty. As far as flow goes though before upgraded turbos the biggest downfall is the exhaust housings themselves which are extremely restrictive then the downpipes afterwards which the piping diameter is <2" all the way to the exhaust which is 2.25" stock to the rear. So technically there isn't a restriction per say after the downpipes until the most restrictive aspects have already been addressed.

 

[rubydist]

Crossover pipes (X or H) are not needed on even firing engines, and serve no purpose. The reason they help on nearly all v8 engines is that nearly all v8 engines have dual plane cranks, so they are not even firing. By providing a crossover path, the exhaust flows better on the dual plane v8 engines. Every 6 cylinder engine I have ever seen is even firing, so it has no need for any type of crossover - the straight duals are just fine.

The raspy sound from straight pipes has to do with the shape of the pulse coming out when the exhaust valve opens. This is one of the primary reasons for a muffler - to muffle the obnoxious noise. In my experience, a large glasspack as a resonator under the floor pan makes a pretty significant reduction in the raspy sound without reducing sound levels and without introducing back pressure. That idea might be worth a try on the EcoBoost.

 

[skyshadow07]

^ some serious knowledge dropped!