newbie exhaust question

[indycecil]

Well this may sound kinda dumb to the ole timers on here but here goes. I was thinking about putting a 4" exhaust on my truck but was told with the 3.73 gears I might loose power. Is this true? thought I would ask the experts before I spent the money and didn't like the result.

 

[Tx_Atty]

I doubt that but Im no expert. I have 3.55 gears and had no power loss with my 4" turbo back from Tymar. fwiw.

 

[DaveBen]

Well this may sound kinda dumb to the ole timers on here but here goes. I was thinking about putting a 4" exhaust on my truck but was told with the 3.73 gears I might loose power. Is this true? thought I would ask the experts before I spent the money and didn't like the result.

No way you will loose power. It is not a gasser, which might loose some power down low with a bigger exhaust system. These guys don't know what they are talking about.

Dave

 

[powerboatr]

there was some scandouls talk a few years ago that the free flow exhaust would move the tq curve up a few hundred rpm off idle
I never really noticed on my 02 any loss of low end grunt.
the engines backpressure really doesnt change, all the needed backpressure is in the exhuast manifold ,its required to have pressure and volumous flow, to spin thh turbo that pumps up the intake pressures, which inturn builds more power,
its a required evil , however the HP gains far outweigh any back pressure issues.
now after the turbo in the exit path, its good to have no restrictions, so there is only one hold back on the turbo not two, which allows it to spin faster and keeps temps lower due to increased air flow all around,
so when we lower temps, then we can add more fuel, build more boost and make more power, its a never ending cycle

 

[Tail_Gunner]

Just to kind of piggy-back what Robert said, the general concensis around is that 4" is all you'll need unless you get extremely horsepower crazy. Most of the discussions I have read have centered around size of the down-pipe, some say 3 1/2" is enough, others say 4" is the way to go. Many say the 3 1/2" down-pipe while give you a torque peak at lower rpm and a 4" will give you a torque peak at a few hundred rpm's higher. Hope this makes this clear as mud.

 

[powerboatr]

oh yeah i forgot to add
if your running the stock turbo, the outlet is 3.5 inches, so if you clamp on a 4" downpipe, make sure its mandrel expaned not just a 4" pipe welded to a 3.5 inch bung ring, or it will create much UNWANTED exhaust turbulence leaving the turbo.

 

[Car_nut57]

4" is just fine and the amount of low end you might loose using the 4" DP is not enough that you would ever miss it. The benefit of the 4" pipe out weighs any loose in low end.

 

[Mark Craig]

indycecil,

You'll be fine! Call us if you have any questions, we stock the AFE and MBRP systems and can help you on most anything. The AFE systems even have a short piece of 3.5 inch down pipe (approx 15 inches) to make sure you don't lose any bottom end HP on a stock or lightly modded truck.

Mark @ DPPI