Got the longtubes...now do I need 3" exhaust?

Stang_ROTY · 06-24-2003, 10:07 AM

My longtubes should be here today and the 1 3/4" primaries collect at a 3" collector. Looking for opinions as to whether or not I should go 3" all the way back, only a 3" H/Xpipe, or just stay with the 2 1/2" Hpipe?

whatcha think?

what type of thought goes into exhaust size? I had heard that anything over 450HP needs 3", is this true (Cause I'm not making that much......yet)

If I just put the longtubes on and reduce them to 2 1/2", will I still get the power gains.

BilLster · 06-24-2003, 10:27 AM

you should see some gains but if you dont have the money dont sweat it to much right now.

if you had a power adder i would say go 3 inch but unless your exhaust need replacing or you have the money it will work fine for now.

I have a 2.5 h pipe that im going to replace it , It work's fine on the street with low boost 8lbs but at the track i unbolt it I've been told its to small but i dont have the money to change parts that arent broken.

I will be getting a 3" x pipe with 3" muff's that exit before the rear wheel's when I have the money or need to replace the exhaust. the hard part will be the turbo outlet which is 2.5"

Stang_ROTY · 06-24-2003, 11:31 AM

That's a good point that I didn't articulate. I really don't want to "fix what ain't broke". I would much rather connect the longtubes to my 2.5" H-pipe and mod the h-pipe to accept the 3" collector (or vice versa) than to throw more cash that I don't have around. I'm just looking to help her breathe a bit more using the longtube setup and maybe gain some MPH while at it.

Generally speaking, how do you know when it's time to go 3"? I always thought the ol big block had 3" exhausts, and anything around 450-500 HP needed it. But with a 393 ci small block making appx. 400 HP, do I really need to fix what ain't broke? I guess you're telling me to save the bucks.....which sound great to me.

Dark_5.0 · 06-24-2003, 12:27 PM

I wouldnt sweat it yet. You probably would make a few more ponies with 3 inch exhaust but not enough to justify the cash that would go into it.

My 2 cents,

Mach 1 · 06-24-2003, 07:04 PM

why are you only running 12.68 @ 105 mph with a 393? Are you still tuning? Your car should be faster than that.

06-24-2003, 10:07 AM	#1
Stang_ROTY Registered Member Join Date: Feb 2001 Location: Berkshire County - Massachusetts Posts: 735	Got the longtubes...now do I need 3" exhaust? My longtubes should be here today and the 1 3/4" primaries collect at a 3" collector. Looking for opinions as to whether or not I should go 3" all the way back, only a 3" H/Xpipe, or just stay with the 2 1/2" Hpipe? whatcha think? what type of thought goes into exhaust size? I had heard that anything over 450HP needs 3", is this true (Cause I'm not making that much......yet) If I just put the longtubes on and reduce them to 2 1/2", will I still get the power gains. __________________ Red 1993 GT Street Machine Best E.T. - 12.41/Best MPH = 108 Engine is a 1969 351 block w/393 stroker kit. Dynamic Roller Myte C4, 8 pt cage. Edlebrock Performer heads and Victor Jr. EFI, FRPP 30lb injectors & Cartech fuel system. MSD ignition. Sothside Machine bars & Sub-frames, adj. upper's, 3.73's, Koni rear shocks, much more

06-24-2003, 10:27 AM	#2
BilLster Registered Member Join Date: Oct 2000 Location: Ontario canada Posts: 446	you should see some gains but if you dont have the money dont sweat it to much right now. if you had a power adder i would say go 3 inch but unless your exhaust need replacing or you have the money it will work fine for now. I have a 2.5 h pipe that im going to replace it , It work's fine on the street with low boost 8lbs but at the track i unbolt it I've been told its to small but i dont have the money to change parts that arent broken. I will be getting a 3" x pipe with 3" muff's that exit before the rear wheel's when I have the money or need to replace the exhaust. the hard part will be the turbo outlet which is 2.5" __________________ 89 with 331 t3'/t4 hybrids. upr Suspention worked out finnaly . 9.89 144 mph .

06-24-2003, 11:31 AM	#3
Stang_ROTY Registered Member Join Date: Feb 2001 Location: Berkshire County - Massachusetts Posts: 735	That's a good point that I didn't articulate. I really don't want to "fix what ain't broke". I would much rather connect the longtubes to my 2.5" H-pipe and mod the h-pipe to accept the 3" collector (or vice versa) than to throw more cash that I don't have around. I'm just looking to help her breathe a bit more using the longtube setup and maybe gain some MPH while at it. Generally speaking, how do you know when it's time to go 3"? I always thought the ol big block had 3" exhausts, and anything around 450-500 HP needed it. But with a 393 ci small block making appx. 400 HP, do I really need to fix what ain't broke? I guess you're telling me to save the bucks.....which sound great to me. __________________ Red 1993 GT Street Machine Best E.T. - 12.41/Best MPH = 108 Engine is a 1969 351 block w/393 stroker kit. Dynamic Roller Myte C4, 8 pt cage. Edlebrock Performer heads and Victor Jr. EFI, FRPP 30lb injectors & Cartech fuel system. MSD ignition. Sothside Machine bars & Sub-frames, adj. upper's, 3.73's, Koni rear shocks, much more

06-24-2003, 12:27 PM	#4
Dark_5.0 Registered Member Join Date: Apr 2001 Location: Staging lane Posts: 4,337	I wouldnt sweat it yet. You probably would make a few more ponies with 3 inch exhaust but not enough to justify the cash that would go into it. My 2 cents, __________________ 92' LX-Big brakes, Lots and lots of suspension, GT40X heads, Ported cobra intake, stock cam, Vortech SC trim. 00' Lightning-Stock 88'CRX-13 second ego killer

06-24-2003, 07:04 PM	#5
Mach 1 Registered Member Join Date: May 1999 Location: Georgia Posts: 3,866	why are you only running 12.68 @ 105 mph with a 393? Are you still tuning? Your car should be faster than that. __________________ 2002 GT 1993 GT (SOLD) '93 Mustang GT RHC member #142

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