fender dump exhaust

[nolanator]

I am looking for answers from those who either have done this or have legitimate knowledge on the topic. I am wanting to do a fender dump exhaust. For those curious, it's basically just an open downpipe routed out the fender area. A lot of my turbo friends have done this on their LSX cars and foxbodies. Other than noise, or emissions, what are the downfalls of this? Do our cars require a specific amount of back pressure?

My car will be getting a moderately large (for a 6 cylinder) turbo in the near future as well as the potential for a small nitrous setup, and I want to route spent exhaust out of the system as quick as possible.

Any input?

 

[2QUICK2B6]

is it a street car ?

 

[2QUICK2B6]

I just ran open dump pipe .... if u put it out ther fender don't plan on getting races

 

[nolanator]

It is a street car in the sense that it will be driven on the street, but it is not a daily driven car, nor is my intent to make it appear that way. My mentality with this build is to add a slight intimidation factor to the car without overdoing the aesthetics and relying on the fact that its a 6 cylinder car to give others a sense of confidence. Where I live, I am immersed in a scene with very capable cars, so getting a run isn't too much of a concern, especially given the egos and colorful personas out here. Refusing a race is basically admitting defeat.

 

[2QUICK2B6]

ok ... I just wouldn't do it to my car

 

[nolanator]

ok ... I just wouldn't do it to my car

Don't worry. I won't either. Your car is safe.....for now

 

[Pronto]

Just run a downpipe with a cutout in the cat delete if you want to go open. Plenty of TBs have run 10s through the exhaust. I know a couple of ones that have run 9s too.

 

[NY Twin Turbo]

If you run an open dump you have the option of closing it from time to time. It will sound basically the same. A lot of turbo whistle! Very intimidating.

If I had to do it again, and if I had one turbo, I would run a stainless downpipe into a stainless cut-out pipe, and the rest of the exhaust would be a 3.5 inch aluminum single shot pipe out to the back with no muffler. Saves a lot of weight and looks bad ass.

Currently I have true dual full stainless exhaust with strait through mufflers and no cut-outs. I should have went all aluminum after the downpipes and strait to the back with no mufflers and over the axle. But that's just me.

 

[turbodave231]

I had an "Old School" turbo fender dump that I removed from my car when I bought it. Back in the day, guys would take the turbo elbow and bore a hole in it aimed straight out at the fender. A flange was welded to the elbow. It can either be capped or a short pipe attached to route exhaust out thru the fender. I laughed and promptly took it off. Unfortunately, the original owner also cut up the inner fender to accommodate the pipe.

There are much better ways of running open exhaust than this crude arrangement. I you want it, I'll go up in my loft and see it I still have it.

 

[Mr.Spool]

Do our cars require a specific amount of back pressure?

yes they do

 

[Pronto]

I remember another style called "Jersey dump pipe" that was a regular downpipe with a dump cap facing down right at the point the downpipe turns to follow the chassis. Haven't seen that in years. Dumping right out the fender does a good job of cooking the tire too.

 

[Mr.Spool]

My car will be getting a moderately large (for a 6 cylinder) turbo in the near future as well as the potential for a small nitrous setup, and I want to route spent exhaust out of the system as quick as possible.

most of the time its not needed even with the spray depending on the shot.believe it or not bigger isn't always better.

 

[m233roller]

Here's an old school fender dump.

 

[nolanator]

Here's an old school fender dump.

is that piece on the left an OEM turbine housing? would that dump pipe work with an aftermarket buick style turbo?

 

[Jerryl]

. . . Do our cars require a specific amount of back pressure? . . . .

The car does not but the turbo does need pressure to drive the turbine, aka drive pressure which will depend on the turbo. The total energy required to spin the turbo and convert it all into work (mass flow) will vary.

If we are talking "after turbine" the answer is no . . . In which case lower is better because the delta pressure will increase exh flow and assist with spool time reduction.

This is my understanding.

 

[nolanator]

The car does not but the turbo does need pressure to drive the turbine, aka drive pressure which will depend on the turbo. The total energy required to spin the turbo and convert it all into work (mass flow) will vary.

If we are talking "after turbine" the answer is no . . . In which case lower is better because the delta pressure will increase exh flow and assist with spool time reduction.

This is my understanding.

I really appreciate this information. This is what I was looking for. thanks

 

[Boostian]

If I had to do it again, and if I had one turbo, I would run a stainless downpipe into a stainless cut-out pipe, and the rest of the exhaust would be a 3.5 inch aluminum single shot pipe out to the back with no muffler. Saves a lot of weight and looks bad ass.

This is what I run. TH down pipe to a test pipe with cutout to a 3" stainless ATR single shot.

If only I could find an electric cutout that wasn't a piece of crap it'd be perfect

OP I can tell you that my car originally had a fender dump on it and the original owner said you could hear the turbo at idle. He also said it was quieter than my cutout at the bottom of the downpipe.

 

[NY Twin Turbo]

This is what I run. TH down pipe to a test pipe with cutout to a 3" stainless ATR single shot.

If only I could find an electric cutout that wasn't a piece of crap it'd be perfect

OP I can tell you that my car originally had a fender dump on it and the original owner said you could hear the turbo at idle. He also said it was quieter than my cutout at the bottom of the downpipe.

Yes. But with no muffler at all and made of aluminum. That's what I would do. Not for daily street use of course. Just for bad-ass effect.

 

[m233roller]

is that piece on the left an OEM turbine housing? would that dump pipe work with an aftermarket buick style turbo?

Yes it would.

 

[turbofabricator]

I use to have a pipe out the stock elbow with a cap. At the track, I would bolt on a pipe that went forward and through the inner fender where the stock battery sits, then down and out pointing out just in front of the passenger tire. At the track when people were standing by my right fender, they'd JUMP when I started the car. Funny.
Today, Dennis runs 9.93@136 on a 3" down pipe, and through 3 mufflers with 2.5" tubing. (Dual mufflers under rear seat and cross flow Ultra Flow behind the rear end.) Also using pump gas, methanol, stock ECM, std Translator and 3.5" MAF. These engines sound like a damn John Deere Tractor plowing a field. I don't want the intimidating factor when driving on the street. I prefere to just blow past someone un-heard. Cops don't hear you, there for it wasn't you. But then again, my street racing days are over. Don't want to go to jail, when I can take it to the track AND DO IT THE RIGHT WAY!!!!!!