New Variable Backpressure exhaust - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

gtfalcon351 · 08-19-2004, 19:00

After my mum complaining about the house windows vibrating and awakening the dead when i take off in the mornings due to my previous exhaust system in the first attatched pic i decided to make an exhaust that could be quiet when i leave the street in the mornings and a bit louder for later in the day

So armed with my verniers i went to pick-a-part in search of a 2.5 inch throttle body which i found on an old magna

Then i went and purchased a 15 inch hotdog muffler and a choke cable kit from bursons to control the throttle

then all that was needed to be done was fabricate a flange to join the flange on to the throttle body to the hot dog and get some sections of exhaust pipe flared so i could join the TB/Muffler asembly to the rest of the exhaust

then i had to run the choke cable from the dash through the floorpan and to the TB and make a bracket to hold the end on the cable, then retension the spring on the TB so the tension wasnt as fierce and adjust the idle speed throttle stop to 1/2 throttle

the difference between the TB being from half throttle to full throttle is amazing, goes from sounding like a standard exhaust to barely roadworthy at the pull of the cable

Dellboy999 · 08-19-2004, 19:11

Be interesting to see how well the butterfly handles all the heat and gas, but a very enterprising fix to the problem.

barry_v · 08-19-2004, 21:44

perhaps you could link this with your actual throttle body so you had more back pressure at low rpm/regular driving but more flow when at WOT.

davway · 08-19-2004, 21:52

pretty cluey solution to keeping the noise down when you want. just a word of advice though...DONT LET THE COPS LOOK UNDER THE CAR coz youll have one of those pretty yellow stickers on your windscreen

stockstandard · 08-20-2004, 01:23

Quote:

Originally Posted by barry_v

perhaps you could link this with your actual throttle body so you had more back pressure at low rpm/regular driving but more flow when at WOT.

I read an article about a guy who was producing such a system. He apparently made a prototype and got some sort of patent on it but gave up in the end because there was no engine or exhaust combination where such a system actually increased power/torque.

Rodderz · 08-20-2004, 01:41

Dont the VB Challenge BAXR8 utes have a similar setup done at herrods? I heard a while back they have a butterfly type setup where it can be opened for more noise

Timmeh · 08-20-2004, 04:38

A turbocharged XR8 we saw at the Summernats a couple years back also had a similar system, where it bypassed the cats and mufflers from inside the car on command....

Interesting work!

Tim

TIKFD6 · 08-20-2004, 04:40

Rod, i think they actually run a Y piece that lets the exaust run straight out after the headers, not all the way down the pipes.
Its a dumper.

Good to see youve put a bit of thougt into it, its gunna be very interesting how it affects things.

zbenga · 08-20-2004, 11:50

almost reminds me of a SuperTrap

gtfalcon351 · 08-21-2004, 20:42

Quote:

Originally Posted by barry_v

perhaps you could link this with your actual throttle body so you had more back pressure at low rpm/regular driving but more flow when at WOT.

yeah i was considering doing this using a unit that controls the broad band manifolds on later falcons but i read an article on autospeed i think it was that said what stockstandard was talking about where this didnt make any extra power on the dyno but ive found that when putting through the city at lower rpm's the car is a much easier to drive and requires less slipping of the clutch to take off when the TB is closed up, but when the car comes onto cam at about 5000rpm it feels faster when the TB is left wide open which would appear to suit the type of sytem you are talking about

ive had the system in the car for just over a week now and is working great except the only problem appears to be that when the exhaust gets nice and hot after a 30+ min drive, once the car has been stopped and the exhaust allowed to cool to ambient then the Choke cable becomes very hard to pull open and closed and i need to push and pull on it about ten times untill it returns to normal