travisnd

This is on a full race car with coilovers so no leaf spring to blow hot exhaust on. Anyone do this? Was thinking about taking some old stock mufflers and cutting the flanges off and making turn-down pipes just ahead of the rear cradle. I assume the air flow at speed will pull the hot exhaust out from under the car? Or, should I just leave it be with tail pipes out the back?

zigspeed10

I know some have done this successfully. I plan to do this over the winter and wonder if it's necessary to still utilize the exhaust hanger or if the headers alone can hold the weight.

hungryhippo

That's how i had my mustang, but without turndowns. No issues besides black soot on the axle housings.

5280Racer

it will be very loud!!!! I tried it on mine last summer sounded like a tractor!

RX-Ben

I would put a couple hangars in, that weight and the leverage could be bit much for the header bolts. No need to risk it.

JerryTX

My exhaust dumps straight down but after the diff (no mufflers or cats). There is a LOT of heat and I'm working to add mufflers and exit straight out the rear bumper just below the steel cross beam. All of this serves a few goals:
1. Quiet the car
2. Don't overheat the diff/trans (my current setup does not btw).
3. Do not exacerbate lift by blowing hot air under the car where it has time to cause lift
4. Make room for a future diffuser when funds allow.

On # 3 while my current exhaust blows straight down, the fact that it is aft of the diff leads me to believe any lift is negated by the airflow that far back that would pull the exhaust out. But again, any downforce I can gain I need to take so that is why the future plans are for out the rear.

froggy47

I don't know any "big show" cars (F1, drag, alms, etc) that would allow a design that just dumps extremely hot exhaust gasses in the general path/area where a fuel or oil leak will migrate.

Not to be a worry wart, but I would not do on my car.

articwhitec6

I built a rr Mustang a few years ago and did dumps. I am not a picky guy and love stuff loud. With that said let me say that the exhaust fumes will find their way in your car especially if you like driving with the windows down. The heat is excessive too. Remember all that gas is hard to get out from under the car with dumps. Their loud but who cares right? I also believe there could be some safety concerns.

spazegun2213

I ran 3" dumps for a few years on my ARH setup. With some hangars right before the tranny I never had a problem. I was running coilovers and the car was VERY loud. I had to wear earplugs whenever I drove the car.

I've recently put mufflers back on the car and am now having to put a tranny cooler on because of the heat the pipes create (over the tranny/diff).

RX-Ben

With the OEM configuration, the pipes are pretty ideally situated to start a fire in the event of a fuel leak at the filter/FPR. From personal experience, they will also pick up trans fluid coming out the trans vent and convert it to smoke.

I think the dumps will lessen the chance of a fuel fire and you will be in the same position (or slightly better, with the use of a deflect/heat shield above the pipes) regarding trans fluid.

rmackintosh

This, I do it for simplicity on the race car. Dumped right at the rear bell housing. I put a aluminum shield to protect the bell/trans/diff. But it is DAMN LOUD in the car. And people tell me my car is one of the quietest from the pits!

travisnd

Did you have any mufflers on the car?

There's already the OEM hangars off of the rear of the torque tube that support the mid-pipe. A few inches of pipe off the end shouldn't require adding more support. The headers aren't supporting anything back there.

Every car I've seen with a diffuser has side exhaust through the frame rail or dumps just ahead of the cradle. You can't go out the back unless you cut up the tub and go out the license plate area (which I've seen on one car).

Thanks, but take a look under your car. You have the catback over axle pipes already in very close proximity to the fuel lines. I don't see any increased risk from dumps.... actually it'd probably decrease it.

This is a race car with no side windows at all, doors gutted. Won't be driving around in traffic or anything. When you say the heat is excessive can you elaborate? Excessive even when moving on track?

Any mufflers at all or dumped straight pipes?

I looked up the pictures of your exhaust on your build again... I see what you mean. You've got yours dumping straight down right at the end of the torque tube. I wonder if dumping them a little farther back by the cradle and angled at 45 degrees would make any difference.

Paul Schmidt

If at anytime I see something that I can use in a future build or if I see something super sick I will save it. This set up is just that!





Forget the dumps and do this!

travisnd

Yep... that's the car I was referring to. Neat way to get the exhaust out the back while allowing for a diffuser.

Hi Volts Z06

If the concern is making room for the diffuser you can simply just put a 90 degree bend on them and exit to the side just behind the wheel. I did this a few years ago with that intention. The above picture does look bad *** BUT that's where my oil cooler is so not an option.

spazegun2213

no mufflers... loud was an understatement. I heard some people put some circular mufflers in before dumps, but I never did.

rmackintosh

It probably would be quieter. But I like the simplicity of the system. I can get in there and work around the trans easy. I have all kinds of tranny/diff cooler lines running in there and occasionally I need to check fluid levels and get to them. Custom Molded Earbuds solve the noise for me!

I would LOVE to go out the frame rails like a REAL race car, but with our local sound issues, I fear pointing the noise out one side or the other would be a problem....all tracks sound meters are on different sides!

5280Racer

To your question about mufflers.. no mine was pfadt headers uncapped x pipe and nutting else!

redtopz

Randy are you making sound at T-hill and Sonoma like that with no mufflers?

drivinhard

I don't think it's NASA legal though