Dual exhaust on SO

Topic: Dual exhaust on SO (Read 1615 times) previous topic - next topic

Dual exhaust on SO

April 08, 2017, 08:56:22 AM

I'm thinking of installing headers,H-pipe & duals as I gather parts for ho conversion . Any tips or advice? Its on my 87 Bird with AOD floor shift... headers are BBK shorties and H-pipe is a stock unit from a 93 stang. Thanks for any help.

Dual exhaust on SO

Reply #1 – April 09, 2017, 01:06:27 AM

h pipe is gonna have to be modified and i would get lx tail pipes and have an exhaust shop mod them to fit also

Dual exhaust on SO

Reply #2 – April 09, 2017, 06:17:20 AM

Quote from: Moonmount;460249

h pipe is gonna have to be modified and i would get lx tail pipes and have an exhaust shop mod them to fit also

What part of H-pipe will need modified? I have Tbird specific tail pipes from Stinger, so that part is covered(I hope)

Dual exhaust on SO

Reply #3 – April 09, 2017, 07:53:49 AM

The only modification that MAY be necessary is to nip off one of the hanger rods. Got a hacksaw? Aside from that, those are great headers, I run them myself and that h-pipe will otherwise fit like a glove. You can run stinger tails, but you'll have to add a little pipe to the pipes between the H and the lers. Don't forget that your HEGO's will be relocated 8 inches or so down on the h-pipe, so you'll need to either find extensions, or replace them with Mustang or Mark VII HEGO's (which have longer leads). What WILL require modification is the mounting of the shift linkage. You'll have to adjust the position of the pivot mound that attaches to the k-member about an inch.

Dual exhaust on SO

Reply #4 – April 09, 2017, 08:05:04 AM

Thanks for info guys... 1 last question....What size pipe is ideal for my exhaust shop to install? I will be adding a few ponies later but nothing extreme.

Dual exhaust on SO

Reply #5 – April 09, 2017, 09:22:42 AM

The '87 will have the fuel filter hanging on passenger side frame rail near where it angles upward over axle... I dunno how close exhaust comes to this area... '87/'88 Turbo Coupes & '88 V8 cars have filter ahead of ler in area near passenger door...

I have a 2.5" Hooker full system with H pipe and BBK 1515 shorties... No major issues, even extention pipes between H-pipe & lers needed shortened, mainly a little hanger fabrication as already mentioned... Some H/X pipes do interfere with factory floor shifter, I tried to use a X that ran directly into shifter cable bracket, wasn't going to happen...

Here's my H compared to LSC H(fit without issue) and a unknown X that didn't fit... Notice how the driver side pipe is more inward than the H & X, the X set directly on the bracket that mounted the shifter linkage... The H is close and I trimmed bracket a little but never gave any issues...

Dual exhaust on SO

Reply #6 – April 09, 2017, 08:19:25 PM

Quote from: ISTLCRUZ;460254

Thanks for info guys... 1 last question....What size pipe is ideal for my exhaust shop to install? I will be adding a few ponies later but nothing extreme.

If you won't be making more than stock HO (225hp) power than 2.25" pipes are fine. With iron GT40 heads or better 2.5" pipes are a must.

Dual exhaust on SO

Reply #7 – April 09, 2017, 09:08:28 PM

Overkill is a thing when it comes to exhaust, so know where you plan to go and map out your project. Thing about too small exhaust is you know by driving it that you're choking out, with a too big exhaust, you don't really feel what you're not getting. Commonly, you don't end up with the kind of low end punch you would have with a right sized system. It should punch hard at the bottom, and pull strong to the top of the cam. If it doesn't punch, you're too big, if it doesn't pull, you're too small. 2 1/4 should suit you well to around 300 (crank) 2 inch will be ok with 205 to 225 stock HO's, but over 300 you need 2 1/2. If you have to get bigger injectors, you should probably be looking at bigger exhaust.

Dual exhaust on SO

Reply #8 – April 10, 2017, 03:29:20 PM

I would tend to say that an 11% gain in area (2.5" vs. 2.25") is not the only thing that a person should take into consideration when building or spec'ing a performance exhaust. I would also be looking into the design of the header (unequal length shorty, equal length shorty, full length header) which would consist of the primary tube to head (one piece and how thick), primary diameter, and collector diameter. I would also get myself educated on ler design as well as the type of crossovers (H vs. X vs. none) as they play a part in exhaust flow as well. IF you can you will want all mandrel bends and not crimp bends on the tubing. Watch the exhaust shop install a system or two before they do yours. Being able to fit pipe plays into how well it is welded as I have seen some shiznitty welds due to bad fitment which caused large deposits of the weld bead in the ID of the exhaust.

One thing you can do it so watch where the primary tubes are welded to the header as the manufacturers typically glob up the weld there. You can get a carbide bit to cut the excess weld out of the primary ID which will greatly help. The other issue with the premade headers is the fire cone diameter. Mine were 2-1/8" openings on a 2-1/2" system so I opened those up as well with the carbide bit. I showed some of the work I did on mine in this thread starting on the second post down on page 3:

http://www.foxtbirdcougarforums.com/showthread.php?34313-Porting-the-Edelbrocks-Heads-and-Lower-Intake/page3

Dual exhaust on SO

Reply #9 – April 11, 2017, 07:24:02 PM

I'd do at least 2.5" if it were me. If it's worth doing right, you might as well be happy with it. Depending on which ler you get, it could choke it up or open it up more then the difference between the two sizes of pipes. Tons of lers neck down to 2" regardless of the input or output sizes, especially cheap ones.