• Sign Up! To view all forums and unlock additional cool features

    Welcome to the #1 Fiesta ST Forum and Fiesta ST community dedicated to Fiesta ST owners and enthusiasts. Register for an account, it's free and it's easy, so don't hesitate to join the Fiesta ST Forum today!


How much power can 2.25" exhaust support?

Based

Senior Member
Messages
805
Likes
84
Location
Nope
#1
I am about to order the Borla exhaust #140525. I'm just wondering if I wanted to go hybrid turbo in the future, how much power would the 2.25" exhaust be able to support? And when I order this exhaust (or any new exhaust), do I need to get any type of gasket(s)? For the downpipe?
 


OP
B

Based

Senior Member
Messages
805
Likes
84
Location
Nope
Thread Starter #5
Wow I guess you gain a lot of potential just by going from 2.25 to 2.5"... But the Borla sounds so good :/. I don't really like how the bigger exhausts sound on this car it sounds to burbly
 


Messages
293
Likes
69
Location
Tucson
#6
Wow I'm glad I went with 3 inch mbrp! But yes based it is so loud.


Sent from my iPhone using Tapatalk
 


kivnul

1000 Post Club
U.S. Army Veteran
Messages
1,193
Likes
711
Location
Deer Park, WA
#10
This doesn't seem accurate, unless I am reading it wrong. It seems like there are at least a few members making significantly more power than what the above specifies.
From what I understand, the Volumetric Efficiency suffers if you restrict the exhaust after the turbo.. thus the turbo has to work harder to get the same HP. So it would totally be possible to run an undersized exhaust and get good power numbers, but you could get better numbers with a bigger exhaust.
 


jmrtsus

1000 Post Club
Messages
1,521
Likes
1,155
Location
Ooltewah
#11
I find those number to be shaky, especially since we have a 2.17 system not even a 2.25........maybe the forced induction has something to do with it. The MP215's typically push close to 220 on the stock cat/exhaust. Many forum members far exceed these numbers.
 


Messages
192
Likes
42
Location
Suburbs
#12
From what I understand, the Volumetric Efficiency suffers if you restrict the exhaust after the turbo.. thus the turbo has to work harder to get the same HP. So it would totally be possible to run an undersized exhaust and get good power numbers, but you could get better numbers with a bigger exhaust.
That makes more sense... the graph is a little misleading as it states "Max HP"
 


Messages
137
Likes
34
Location
flagstaff
#13
From what I understand, the Volumetric Efficiency suffers if you restrict the exhaust after the turbo.. thus the turbo has to work harder to get the same HP. So it would totally be possible to run an undersized exhaust and get good power numbers, but you could get better numbers with a bigger exhaust.
I imagine I could get another 30-50 whp with a 3". If there was a sort of quiet cat back, I would get it. I had a CPE cb for a few hours and went back to stock cuz it was so loud. I have no cat though.
 


re-rx7

1000 Post Club
Messages
1,639
Likes
215
Location
Ardmore
#14
I imagine I could get another 30-50 whp with a 3". If there was a sort of quiet cat back, I would get it. I had a CPE cb for a few hours and went back to stock cuz it was so loud. I have no cat though.
Not likely. It's been tested over seas that a larger exhaust nets almost njothing in the hp dept. DI changes everything.
 


Messages
80
Likes
20
Location
Berkley
#15
For comparison I dynoed at 249/267 with C39 Hybrid on stock exhaust. During testing of DHM new 3" exhaust, which I am buying when it comes in, we Vdynoed 280/302. Mods in my sig. It was a noticeable difference we did not expect. Only thing I can think of is the hybrid likes the larger piping.
 


Messages
137
Likes
34
Location
flagstaff
#16
Not likely. It's been tested over seas that a larger exhaust nets almost njothing in the hp dept. DI changes everything.
So think the stock exhaust is not restricting my gen 2 gtx2860 dhm kit at 29 psi. Lol.
 


re-rx7

1000 Post Club
Messages
1,639
Likes
215
Location
Ardmore
#17
So think the stock exhaust is not restricting my gen 2 gtx2860 dhm kit at 29 psi. Lol.
Actually no. Not as much as you think. 5-10whp maybe. They tested a efr fist overseas with the large exhaust hardly anything. 30-50whp is funny though.
 


A7xogg

Active member
Messages
580
Likes
143
Location
Hampton roads
#18
It's more than piping size, exhaust design plays a part especially if the exhaust design create swirl then the exhaust gases get forced out naturally. If an aftermarket DP doesn't make more power than stock one on stock turbo then exhaust size won't. Also if you don't dyno comparison at the same dybo on the same day, a dyno comparison means nothing especially a vdnyo because a vdyno adds more variables. On bigger than stock turbos I could see bigger exhaust adding power but not as much as venders and ppl think
 


OP
B

Based

Senior Member
Messages
805
Likes
84
Location
Nope
Thread Starter #19
Well I decided to order the Borla. It sounds just too good for me not to get it


Sent from my iPhone using Tapatalk
 


M-Sport fan

9000 Post Club
Messages
14,000
Likes
6,700
Location
Princeton, N.J.
#20
IF there is one single area of the aftermarket where we have too many great choices for this car, it is catback exhaust systems. [wink]
 




Top