Fox T-Bird/Cougar Forums

Technical => Engine Tech => Topic started by: sum_weirdo on January 14, 2007, 12:33:46 PM

Title: Benefit of exhaust cutouts?
Post by: sum_weirdo on January 14, 2007, 12:33:46 PM
I already knew about them but when I saw them on Musclecar today it got me thinking about my exhaust plans.  I'm planning a 387 stroker for my car and the software simulations show it'll make 300 horsepower and 400 ft/lbs of torque with my chosen cam and my current 570 cfm carb (the gain above 570 was negligable).  Should make for an awesome commute but 300 is a little on the low side for competition I feel so I'm wondering what sort of gain I might expect with some electrically actuated cutouts.  My most recent thoughts about the exhaust system included shorty swap headers, an H-pipe, 2 high-flow cats, maybe 2 cherry bombs, 2.25 or 2.5 piping.  If I placed the cutouts early on the H-pipe what could I expect?
Title: Benefit of exhaust cutouts?
Post by: Clayton on January 14, 2007, 01:07:49 PM
more upper hp.. less bottom end torque.

or an easy way to have side pipes and not run them all the time lol
Title: Benefit of exhaust cutouts?
Post by: sum_weirdo on January 14, 2007, 01:26:43 PM
:flame: Well I figured that.  Any idea how much horsepower it would gain?  Given that they're electric I could probably open them mid-race after the torque peak.
Title: Benefit of exhaust cutouts?
Post by: Tbird232ci on January 14, 2007, 02:07:19 PM
Generally, they arnt worth it unless you have a restrictive exhaust. You NEED backpressure for the car to make power. There is a point of too much, but you need pressure to create the scavaging effect, among other reasons. do a full 2.5" exhaust, and you wont need em.
Title: Benefit of exhaust cutouts?
Post by: vinnietbird on January 14, 2007, 05:12:01 PM
my Warlock lers have them built in.I've run the car with them closed and open,and there was no difference.I have 2 1/2 inch exhaust,no cats.For a 387,I hope you get a lot more than 300 HP.
Title: Benefit of exhaust cutouts?
Post by: sum_weirdo on January 14, 2007, 06:42:09 PM
Quote from: vinnietbird;123825
For a 387,I hope you get a lot more than 300 HP.

I'm just going by what Engine buttstuffyzer said.  Based on Edelbrock RPM heads and the cam I chose it makes 400 ft/lbs at 3000 rpm and 312 horsepower at 4500 rpm with open exhaust.  Ofcourse the program doesn't account for the design of the heads so it could be higher.
Title: Benefit of exhaust cutouts?
Post by: Ether947 on January 16, 2007, 07:46:49 AM
Quote from: vinnietbird;123825
my Warlock lers have them built in.I've run the car with them closed and open,and there was no difference.I have 2 1/2 inch exhaust,no cats.For a 387,I hope you get a lot more than 300 HP.

Really? I had those same lers and I could definitely tell the difference. I had NO low-end torque. lol. And it was loud as !
Title: Benefit of exhaust cutouts?
Post by: vinnietbird on January 16, 2007, 08:35:30 AM
I like those lers better when they're capped and not so loud.
Title: Benefit of exhaust cutouts?
Post by: jasontbird on January 25, 2007, 11:21:04 PM
I am planning on doing that but my reason was so that I can be quite when I want and be loud when I want to be loud.  I live amongst retired folks and don't want to start up a loud car every morning and risk waking up the neigbors.  I just need to find a good ler shop near me that knows how to listen and not catch my car on fire.  The elecronic was a litte pricey for me so I was thinking of doing the cable ones.  I did see the show too.  It is a cool concept.      Jason.