I'm in the process of having Abe fab a manifold and DP for me. Instead of trying to mate it with my existing exhaust, I'm considering having him run a straight pipe from the DP (w/ flex) back as far as the diff, and then having it dump to the ground at that point.

I don't run any sort of muffler, so why run it all the way to the back of the car? Any downside to terminating the exhaust at the diff? Is anyone else doing this?

Any feedback would be appreciated. Thanks!

 

Id terminate it directly after the 2nd exhaust hanger just in front of the diff based on building quite a few exhausts for these, however if someone has tried it and had a fume issue speak up.

Dann

 

are you going for the loudest most annoying miata out there?

 

My recollection here is a tad hazy, but it seems to me that the last person who tried this melted both the bumper cover and the taillights.

 

Melted a bumper of mine because the exhaust terminated right before edge of the bumper.

 

Already running straight to the back of the car, and I'm nowhere near the loudest car at the track.

I'm also going with a straight dump off of the wastegate if you think that'll help :-)

 

Will ensure things are aimed down. Thanks for the warning.

 

I've always said that a turbo is the best sounding muffler you can buy.

 

I melted a bumper cover and the inner, plastic bumper support with an exhaust which stopped at the driver's side half shaft. Even with a turn down, it will melt the bumper if you drive it on the interstate or at interstate+ speeds for an extended period (i.e. 45mins+). Never had a problem around town, but then one drive on a normal summer day and the bumper was ruined.

If you try it, make sure the exhaust is really directed at the ground...

 

No problem with heating the fuel tank?

 

Assume this is a track car?

I'd take a page from the pros. Get it away from the body of the car somehow -- out the rear, to the side, whatever. You WILL shoot fireballs. Fire is bad. You have gasoline, plastic, wiring and rubber parts back there.

 

That's usually the test I apply. If neither the OEMs nor competitive race teams are doing a certain thing, then it's probably not a thing that's good to do.

Merely angling the pipe downwards ain't gonna hep. Airflow down there be all whirley-like when the car be movin'.

 

Ryan has this on his car.
If you want to go deaf, and choke on fumes, by all means do this.

Running it all the way back will still be quieter than terminating at the diff and turning down. His did just that, it was a nightmare. I would take headache pills before tuning his car.

 

Looks like the nays vastly outweigh the yeas. Thanks for steering me in the proper direction.

 

You guys are sissies, the fumes are not that bad unless you like to sit and idle for hours at a time like some sort of maniac. Its not even that loud either. Harleys are way louder than a turbo car with an open downpipe.

This is a real mans downpipe:


Ignore the fact that its running on 3 cylinders. Even down a cylinder its still a 1.7L

 

Dumping right before the diff is pretty standard for auto-x miatas, it needs to have a turn down though so you dont melt the gas tank.

Mine exits out the drivers side of the rear bumper.

 

Accord? F23 Motor?


I ran open downpipe on my turbo single cam Honda for an entire summer and I don't remember it actually being that bad. An NA car with an obnoxious muffler is louder. I was younger back then though.

 

I got the muffler shop to put it out past the rear on the XP car. Straight 2.5" from the turbo. Well sort of, 14" resonator section but it is basically just a section of heavier 2.5" pipe :P

 

F22a swapped into a 97 civic hx.
It will get 3" straight pipe all the way out to the back bumper eventually. But for now it will run like this and it will be fastest like this.
Open downpipe is a gift from the gods. Everybody raves about how awesome 3" is compared to 2.5", but 3" open downpipe is like a fast spooling, horsepower making, mind ****.

 

So if I run the exhaust all the way to the back of the car, what are the pros/cons of running it to driver's side versus the passenger's side? The only con I can think of is not routing through the cutout, but I hardly care about that.