


Exhaust Pipe Size...
Now I have been talking with a buddy of mine who is well respected car enthusiast in my area who also runs many well Horse Powered f-bodies...And he is saying that I am...What he calls "Constipating" my engine by running 2.5" TD with a blower. Which I am currently running 10.5 psi out of a D1SC Procharger
He is telling me by going up to 3" or even 3.5" TD I could see as much as 30 to 80 "At the Engine" HP
Now I have been running the 2.5" for clearance reasons thus far...but now that the car is not my daily driver anymore (more of a weekend warrior)...I have been looking into some of the 3 or 3.5" oval piping that some exhaust companies offer now. To keep as much clearance as possible, but gain power.
So my question/questions to all your Blower FI guys is what size of exhaust piping are you running on your "STREET" cars? My car isn't much of a strip car, so I'm wanting street car opinions ultimately...
Do you believe the numbers he has given are possible by making the exhaust pipe size change? (now granted i understand get the air in, get the air out it makes sense that power will increase, but by how much?)
The reason for the questions is I know to get either one of those setups done in True Dual/X-Pipe like my current setup which will go out the rear into my CME dual/dual tips will cost a pretty penny...Will it be worth it?
And finally I just want to cure my curiosity of what he has told me, and confirm a round-about number in you guys opinionated HP gain, per $ spent on this project...
Obviously if these gains are possible it would be more than worth it. I'm just wanting to get some opinions before I spend the money on this kind of project...Sooo with all that being said...POST AWAY!
Lastly I am including a POLL to include votes/opinions on what I should do!
Last edited by HILL_SS; Mar 31, 2009 at 08:58 PM.
Two ea 2-1/2" in two ea 2-1/2" out MagnaFlo W/X pipe (true duals) with 2 DMH 2-1/2" wide oval cut outs at end of long tube headers = no recordable difference in torque or HP with cut outs open or closed on dino pulls. 5.3L, 112 MagnaCharger, 9.5lbs+ boost, 460lbs T & 490 HP. Prior to this setup Y pipe into 3" single then into 2 2-1/2" in 2 2-1/2" out Flomaster @ rear of car = about 20 HP gain with same cut outs open.
I hope the explanation makes sense.
F1C here on a 364 from stock dual 2.5 to dual 3inch i picked up a lot but it was a stock 2.5 on before. with a dual 3 inch im still seeing a little back pressure
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Also if you guys have some sound clips...I really like the tone of the X-Pipe (Eliminates all the rasp and drone from the y-pipe) but I also haven't heard a 4".
Also here is my only battle with doing 4" is I have the CME on my SS... may be very difficult to incorporate that and make it look right...My car is a street/strip/show car...must keep a clean look along with make gobs of power...
Here is a quick shot of the rear and what I am working with...
Last edited by HILL_SS; Mar 31, 2009 at 08:53 PM.
Also Single 4in has been the most suggested way to go by the post....but 3in TD through the POLLS...
I will let the thread cook a little longer and see if the posts/POLL stay the same...
My numbers by the way at the rear through a 3400 Stall are 521RWHP with the 2.5" TD's...
Last edited by HILL_SS; Mar 31, 2009 at 09:11 PM.
Here is a little vid of my car from last may. This is 4" mufflex with spintek muffler. It's best if you click on the hq button and watch it that way.
http://www.youtube.com/watch?v=C1C2CY9qpIs&feature=user
Here is a little vid of my car from last may. This is 4" mufflex with spintek muffler. It's best if you click on the hq button and watch it that way.
http://www.youtube.com/watch?v=C1C2CY9qpIs&feature=user
So are you 4in off the header back? If so are you using oval piping under the front driver side floor pan? Seems like clearance would be an issue...
And speaking of "surface area" I saw this in another thread that may apply to this...
Quoted from: jmilz28
For comparison, let me give you rough cross sectional area, which indicates maximum flow:
single 3" - 7 square inches
single 3.5" - 9.62 sq in
dual 2.5" - 9.8 sq in
single 4" - 12.5 sq in
dual 3" - 14.1 sq in










