How much power with exhaust?

[MY 85 GT]

I have an 85 GT with bone stock exhaust...I want to go with Mac full length 1 5/8 headers Mac off road h-pipe no cats...and the full cat back system....1st how will it sound...will it be loud...right now its so quiet....and how much HP will the system give me...My plan after that will to bolt on an B&M 144 blower making 6 psi....im hoping to get into the low 13's high 12's i hope what do you think?

 

[Flavadave4]

Louder yes, how loud is a subjective thing.
More power, alittle but not a ton. It will make it more fun to drive though!

 

[MY 85 GT]

Really only a little more HP i was told like 40 more HP with a complete exhaust swap long tube headers, not ctas and a good cat back...remember on my car it has a y-pipe going into one pipe back out to a Y pipe again into 2 mufflers and its all 2 1/4 size so i would think it would make a little more power no? and for sound im sure your right it will be more fun to drive....

 

[HTownFiveoh]

HP is all pretty subjective from an exhaust to what other mods you have done. Manufacturers often tell you that you are going to make "40 HP" but you arent going to get that power to the wheels. At the end of the day exhaust may give you 10-15HP to the wheels. But its going to sounds pretty incredible, nothing sounds like a 5.0 IMHO.

 

[MY 85 GT]

I agree with you on that nothing sounds better then a 5.0,,,,I forget to mention im bolting a B&M 144 supercharger with 6 psi on the car plus the full exhuast im guessing that will help with flow issues a good exhaust ...Im hoping for an honest 350 hp....im hoping anyways....I would like to get the car to run low 13's high 12's and still have a pretty decent driver....

 

[HTownFiveoh]

Dont be discouraged if the exhaust doesn make the HP that you are looking for think of it as a foundation for the future mods to be able to perform because you already are allowing the car to breathe. It the rest of the car stock as well? There may be some other alternative ways you want to approach the build other then an exhaust and a blower.

 

[MY 85 GT]

Yes this car is bone stock with only 69,700 miles on it im the second owner of it....i wanted to find a all stock carb 5.0 mustang to play with..lol so i think this is a good starting point for mods....

 

[HTownFiveoh]

Take your time whats the rush! I would do your basic bolt ons first. Pulleys, full exhaust, intake etc. Then you might want to start going with a cam, heads, intake manifold etc. I would map out a build for a blower before just slapping it on there. In my opinion it will save you money down the road.

 

[Sicarius428]

Exhaust will probably net you the worse power per dollar on a car... A full exhaust will run you about 1k... 1K goes a lot further elseware in the motor. Long tubes will help you with the low end torque compared to shorties... As said before It will be a good foundation but don't expect a huge jump in power. Getting rid of the stock H alone will probably help a lot.
Kevin

 

[MY 85 GT]

Thanks for the info...I donr even have an H pipe....a Y going inot a single cat back to a Y pipe....so im sure i should gain something going from a really bad stock set-up to a pretty decent exhaust im hoping anyways....I know it should sound good tho....I hope...lol

 

[SVT32VDOHC]

Here is a video of my 4.6L 2V engine with stock headers, but O/R mid pipe, and MAC tru fit catback with tail pipes. (If the car had long tubes, it would be quieter) Sorry I don't have a 5.0L clip for you....


It's loud!!
View attachment 327314

 

[Jmood]

don't forget the double-hump cross-member!! you'll need one.....ebay

 

[MY 85 GT]

Here is a video of my 4.6L 2V engine with stock headers, but O/R mid pipe, and MAC tru fit catback with tail pipes. (If the car had long tubes, it would be quieter) Sorry I don't have a 5.0L clip for you....


It's loud!!
View attachment 327278

WOW that sounds awesome.....nice really nice

 

[wythors]

On a bone stock 85 I would expect that you would actually lose power because you're lowering the backpressure so much. It is going to kill your torque. You need a minimum of heads, cam, intake and carb before you start putting that kind of exhaust on to get any kind of realistic gain. If you're set on doing exhaust first, I'd invest the cash in shorty headers, a good X-pipe and cat-back. The blower you say you're planning on is going to be severely restricted by the heads on your car. Your next step (or first step in my opinion) should be heads and then build up from there. The blower should be last.

 

[Turkey Sammich]

On a bone stock 85 I would expect that you would actually lose power because you're lowering the backpressure so much. It is going to kill your torque. You need a minimum of heads, cam, intake and carb before you start putting that kind of exhaust on to get any kind of realistic gain. If you're set on doing exhaust first, I'd invest the cash in shorty headers, a good X-pipe and cat-back. The blower you say you're planning on is going to be severely restricted by the heads on your car. Your next step (or first step in my opinion) should be heads and then build up from there. The blower should be last.

+1

Do the H/C/I first, if you don't and do the blower first and later on down the road want more power, and want to do the H/C/I, the blower will end up having to come out. Might as well do the H/C/I and save yourself the hassle and possibility of shop time if you're going to have a shop do it.