PheonixLS1

iTrader: (4)

I have a TD setup with 2 1/4" piping. I don't race, so would it really be worth my time and money to have the shop go back and re-do it with 3" pipe?? Would it really be that much difference in HP.

thunderstruck507

iTrader: (18)

Depends on your mods.

My car picked up between 15-20hp (based on ET/MPH) going from 2.25" to 3" and the sound alone was worth the change...much deeper and throatier now.

PheonixLS1

iTrader: (4)

Mods are
LT's
SLP Lid
Ported TB
Hi-flow cats
TD w/ X-pipe
LM1 resonators
Quad 4" outlet resonated tips

Did it make it louder???

omarrakeen

iTrader: (2)

it would make it louder, maybe a lil bit but it will for sure. if your going with future mods like a cam id say get it done now to 3 or at least 2.5 inch. good luck

PheonixLS1

iTrader: (4)

I have thrown around the idea of a cam just because I love the way a cam sound. But I don't have the money or the time ( have 2 kids ) to buy the parts or do the install. So I probably will not be doing a cam.

thunderstruck507

iTrader: (18)

Without a cam you might not need it, 2.25" duals should still be better than a y pipe. It would be louder with the larger pipe.

Likely better ways to spend money unless you can get it done cheap.

PheonixLS1

iTrader: (4)

Probably cost me $200 to have it redone

Fb0dy0nly

iTrader: (10)

from the stickies my friends...
A 2.75” (stock) single system is good for a 310hp engine with zero loss…
A 3” Single system is good for a 370hp engine with zero loss…
A 3.5” Single system is good for a 503hp engine with zero loss…
A 4” Single system is good for a 657hp engine with zero loss…
A 2.25” dual system is good for a 457hp engine with zero loss…
A 2.5” dual system is good for a 513hp engine with zero loss…
A 3” dual system is good for a 812hp engine with zero loss…

PheonixLS1

iTrader: (4)

Is this RWHP or Crank HP??

TImmy_Jones

iTrader: (4)

Doesn't matter, a bolt on car is no where near 457 even at the crank.

If you're curious read the whole exhaust FAQ.

Darkman

iTrader: (2)

The data in the stickie is wrong.

The underlying information is taken from a 2005 magazine article. The magazine article assumes, counterfactually, that there is a linear relationship between pipe sizes and volumetric flow gas flow based on relative cross sectional area. The actual relationship between pipe sizes is far more complicated and is usually calculated using complex engineering formulas. Those complex calculations however, can be reduced for estimating purposes to an exponential relationship.

In the attachment below I have substituted the actual exponential relationships and recalulated the relative horsepower levels assuming that the lowest horsepower shown in the magazine article (310 horsepower) is measured.

In most case the corrected data will not lead to a different conclusion regarding which exhaust systems are appropriate. There are however, a couple instances where the miscalulations in the magazine article suggest more horsepower from an exhaust configuration that actually has a lower flow capacity.

PheonixLS1

iTrader: (4)

So, with this being said, I SHOULD go to 3" or am I still fine at 2 1/4"???

PheonixLS1

iTrader: (4)

I read most of it, but didn't really understand or find the exact "smack me in the face obvious" answer I was looking for.

AlamoTA

iTrader: (10)

After looking at both sets of data and your current mods. I say stick with what you have. In the future, maybe go with the 2.5" TDs, but no sense in throwing another $200 if your current system is good. You wont get much if any gains, with the exception of sound. Maybe a different sound is worth it to you. To each his own!

senicalj4579

iTrader: (41)

I go by engine hp. I say change it to bigger pipe so you can have it all set to work better with other mods in the future.

Darkman

iTrader: (2)

It depends on cost. If you can convert your existing 2 1/4-inch dual system to a 3-inch dual system for $200.00, I would do it. I suspect, but cannot prove, that you would gain some horsepower immediately, and you would be essentially done with the exhaust system if you add mods later since the dual-3 inch system would have more than twice the flow capacity of your existing system.

thunderstruck507

iTrader: (18)

You aren't going to gain enough to feel, so if you don't race, it's not worth it unless you want the louder deeper sound.

And I don't really care what that info from the stickies said, I had 2 1/4" with dual cutouts, with them closed I lost ET/MPH and gained with them open (they are less than a foot behind the collectors). Now that I have 3" I do not gain anything by opening them.

Full-Force

iTrader: (11)

It will make a little more power for sure. If it only gained 1HP then we can trash these charts saying zero power loss. All this theoretical power vs. pipe size is rubbish IMO.

I say if it makes more power at all then go for it. I would rather have the comfort of knowing Im not leaving anything on the table with my exhaust.

just my 2 cents