Exhaust - is bigger better?
 

Question for the masses....for a car that's gonna be running close to or just over 500hp (N2O or blower + some other goodies in near-distant future http://www.mustangworks.com/msgboard/biggrin.gif) - would you recommend short tube or long tube headers? 1 1/5" or 1 3/4"? 2 1/2" of 3" exhaust? Is it true that longtubes will take away some low end torque? Should I stick w/ my BBK 1 5/8" equal lengths shorties and just work back? Sorry for all the ?'s http://www.mustangworks.com/msgboard/biggrin.gif

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'90 LX 5.0;12K original miles (no sh*&);3.55 gears; March pulleys;Edelbrock Performer Heads;BBK 1 5/8" equal length shorties;MSD 6AL ignition w/ blaster 2 coil;FMS E303 cam;Pro-M 75mm MAF;BBK 70mm TB; Eibach drag-launch spring kit;Southside welded subs;9" K&N cone filter charger;Hurst shifter;Cervini's 3" turbo hood;A/C delete; gutted cats;2 chamber Flomasters;Corbeau racing seats;FMS 30# injectors;JMS chip; Holley 190lb fp;TFS track heat Intake (12.299 @ 113 - 1.78 60')

I am not sure what others will say but I would recommend the long tube headers and 3" exhaust but I am bias because that is what I now run and it sounds awesome.

347 with long tubes w/3" x-pipe and 3" 1 chamber flowmasters with turndowns. http://www.mustangworks.com/msgboard/biggrin.gif

As for size I would say go with the 1 3/4" and you should make up the loss in low-end torque with high-end horsepower, that’s even if you loose any torque.


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James Cox
nochevy@hotmail.com
1991 Mustang LX
12.565 @109.38mph 1.764 60ft

I'm not making quite 500 hp but I did find that installing 3" x 2 1/2" reducers on my headers may have increased hp just a little. Take a look at my numbers from two weeks apart. The weather as about the same. Hot!

With 2 1/2 reducers

60' = 1.446
1/8 = 6.650
1/8 mph = 102.43
1/4 = 10.516
1/4 mph = 126.27

w/3" turndown

60' = 1.472
1/8 = 6.649
1/8 mph = 102.59
1/4 = 10.523
1/4 mph = 125.99

Notice that even though I had a better 60' with the 3 x 2 1/2 reducers, my 1/8 mile time was not as good. But I pulled more hp on the top end and passed that time up.

My 3 x 2 1/2 reducters have a 2.375 ID. I wonder what a 2.500 ID would do.

You can veiw my web page and see all my mods.




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88 347, Twisted wedge heads,Comp Cams 224/230 cam, 1/4=10.516 @ 126.27, 60' = 1.446 http://xs-fx.com/raughammer/larrysample.htm

As you can see with 8850's results even with a 347 3" may be a tad too large. Even many big block Chevys run 2.5 - 3" systems for street use. Racers tend to go with 4" mufflers with big blocks. For a street driven 302 car, stick with 2.5" system with 1 5/8" headers either long tube or shorty.

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Frank W
90 5.0 LX coupe Daily driver. Silencer removed, K&N filter. Flexalite fan, 3 core radiator. FMS flywheel and Clutch, FMS blue wires Energy Suspension end links
88 Notch 2.3L 5 speed Parts/beater car My two Notchbacks

74 Chevy Laguna Type S-3 305 Finally fixed getting a 454 to put in garage
<A HREF="http://www.chevellepages.com/folingo" TARGET=_blank>www.chevellepages.

Thanks for your input!

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'90 LX 5.0;12K original miles (no sh*&);3.55 gears; March pulleys;Edelbrock Performer Heads;BBK 1 5/8" equal length shorties;MSD 6AL ignition w/ blaster 2 coil;FMS E303 cam;Pro-M 75mm MAF;BBK 70mm TB; Eibach drag-launch spring kit;Southside welded subs;9" K&N cone filter charger;Hurst shifter;Cervini's 3" turbo hood;A/C delete; gutted cats;2 chamber Flomasters;Corbeau racing seats;FMS 30# injectors;JMS chip; Holley 190lb fp;TFS track heat Intake (12.299 @ 113 - 1.78 60')

Actually, in my book of dyno runs, it shows long tube headers make more power throughout the whole power band from idle to redline. So their is no trade off in putting in the long tubes vs. shorty's.

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1993 Mustang GT - March Ram Air & Pullies, K&N, C&L 73mm MAF, 3.73 Gears, Super Competition Hooker Headers, 2 1/2 in. High Flow H-Pipe & Cat Back, Pro 5.0 Shifter, 16* Timing Advance, 8.5mm MSD Super Cunductor Plug Wires, Romoved front Sway Bar, Pro-Shift Lite, LX lights

Thanks guys! Your help is much appreciated to help me make up my fragile little mind http://www.mustangworks.com/msgboard/biggrin.gif!

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'90 LX 5.0;12K original miles (no sh*&);3.55 gears; March pulleys;Edelbrock Performer Heads;BBK 1 5/8" equal length shorties;MSD 6AL ignition w/ blaster 2 coil;FMS E303 cam;Pro-M 75mm MAF;BBK 70mm TB; Eibach drag-launch spring kit;Southside welded subs;9" K&N cone filter charger;Hurst shifter;Cervini's 3" turbo hood;A/C delete; gutted cats;2 chamber Flomasters;Corbeau racing seats;FMS 30# injectors;JMS chip; Holley 190lb fp;TFS track heat Intake (12.299 @ 113 - 1.78 60')

5.0 Mustang and Super Fords had a dyno comparison on their web site where the shorties made MORE peake power but the long tubes made more average power over the entire powerband. That's great for first gear, but once you're on to second, the band where you shift is pretty narrow and it is better to have more power in just the specific working range.

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351W 89 Mustang GT Convertible