How Much Hp Will 2.5" Td Support?
Thread Starter
On The Tree
Joined: Mar 2003
Posts: 104
Likes: 0
From: lewisburg tn
How Much Hp Will 2.5" Td Support? I Just Had My Local Shop Install True Duals Dumped At The Axle 2.5"pipe With Flowmaster Series 10 Race Mufflers They Are Straight Thru And I Am Wondering If They Will Support 450 Rwhp OR DID I JUST SCREW MYSELF Thanks Richie
TECH Enthusiast
Joined: Jul 2002
Posts: 618
Likes: 0
From: Pensacola, FL
Two 2.5" pipes flow way better than one 3".
They beat one 3.5" pipe by a hair.
The best way to use them IMO is to use 3" pipe as far as you have clearance for, then drop down to 2.5 when you need smaller pipe for clearance.
Exhaust gasses shrink as they cool, so smaller pipe further back in the flow would not be as restrictive as it would towards the front.
Dave
They beat one 3.5" pipe by a hair.
The best way to use them IMO is to use 3" pipe as far as you have clearance for, then drop down to 2.5 when you need smaller pipe for clearance.
Exhaust gasses shrink as they cool, so smaller pipe further back in the flow would not be as restrictive as it would towards the front.
Dave
Dont think of exhaust as only supporting up to some number and then hitting a brick wall. At worst, its will be a small percentage less efficient than dual 3" pipes. Personally, I havnt seen anyone choke a 3.5" single system, so it stands to reason that they wouldnt choke a dual 2.5. Furthermore, the added velocity of dual 2.5's over the 3" may actually add low end torque.
My opinion is that if youre running a car making enough power to require 3" true duals, you should probably be running open headers with stepped 2" primaries and 3.5" merge collectors and nothing else.
My opinion is that if youre running a car making enough power to require 3" true duals, you should probably be running open headers with stepped 2" primaries and 3.5" merge collectors and nothing else.
Trending Topics
TECH Enthusiast
Joined: Jul 2002
Posts: 618
Likes: 0
From: Pensacola, FL
Originally Posted by Ferocity02
I dont think flowmaster can screw up and make 2.5" pipe that doesnt flow well... 
They are refering to the entire system, not just pipe.
So it stands to reason they are expecting you to use a 2.5" muffler in the system.
It doesn't seem to take into account for different mufflers, or even stepping up the pipe size of the muffler and leaving the 2.5" pipe which would certainly help.
I am pretty sure they are also figuring 2.5" pipe from the collector back. If you use larger pipe up front as space allows, the pipes to the rear would be little restriction as the exhaust gas cools and shrinks.
Then you have a balance pipe option to relieve overlapping pressure to the other pipe.
It all comes down to the muffler being the prime loss of flow in any system IMO.
Dave
BTW: I wasn't taking your post to seriously, just using it to point out some options that they don't seem to take into account.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Originally Posted by ratio411
I don't quite read it that way...
They are refering to the entire system, not just pipe.
So it stands to reason they are expecting you to use a 2.5" muffler in the system.
It doesn't seem to take into account for different mufflers, or even stepping up the pipe size of the muffler and leaving the 2.5" pipe which would certainly help.
I am pretty sure they are also figuring 2.5" pipe from the collector back. If you use larger pipe up front as space allows, the pipes to the rear would be little restriction as the exhaust gas cools and shrinks.
Then you have a balance pipe option to relieve overlapping pressure to the other pipe.
It all comes down to the muffler being the prime loss of flow in any system IMO.
Dave
BTW: I wasn't taking your post to seriously, just using it to point out some options that they don't seem to take into account.
They are refering to the entire system, not just pipe.
So it stands to reason they are expecting you to use a 2.5" muffler in the system.
It doesn't seem to take into account for different mufflers, or even stepping up the pipe size of the muffler and leaving the 2.5" pipe which would certainly help.
I am pretty sure they are also figuring 2.5" pipe from the collector back. If you use larger pipe up front as space allows, the pipes to the rear would be little restriction as the exhaust gas cools and shrinks.
Then you have a balance pipe option to relieve overlapping pressure to the other pipe.
It all comes down to the muffler being the prime loss of flow in any system IMO.
Dave
BTW: I wasn't taking your post to seriously, just using it to point out some options that they don't seem to take into account.
Launching!
Joined: Nov 2003
Posts: 210
Likes: 0
Originally Posted by Ferocity02
Actually... The article that I saw it in was refering to a straight piece of pipe. No muffler, collector, flanges, bends... just a piece of pipe
Originally Posted by dannysbee
The F.A.S.T. racing cars are restricted to 2/12" exhaust...
just messin with ya 
from what ive read on this board, most people tend to agree that 2.5" duals should be plenty for up to ~500rwhp.
I'm just telling you want I read.....
Also, any car using N20 will make more power, no matter the exhaust size since N20 doesn't add any additional air into and out of the motor. Much different for blown cars.
Also, any car using N20 will make more power, no matter the exhaust size since N20 doesn't add any additional air into and out of the motor. Much different for blown cars.
Originally Posted by dannysbee
The F.A.S.T. racing cars are restricted to 2/12" exhaust and several of the cars make near 500 RWH. The fastest cars run 11.30's at 126+ mph on Reproduction bias belted tires and most of them weigh 4000# with the driver. Any of these cars would be well into the 10's on Mickey Thompsons, and all these cars must run an over the axle exhaust so I dont think you have hurt your self.
Launching!
Joined: Nov 2003
Posts: 210
Likes: 0
Originally Posted by Ferocity02
I'm just telling you want I read.....
Also, any car using N20 will make more power, no matter the exhaust size since N20 doesn't add any additional air into and out of the motor. Much different for blown cars.
Also, any car using N20 will make more power, no matter the exhaust size since N20 doesn't add any additional air into and out of the motor. Much different for blown cars.
