Veloster Turbo Forum banner
1 - 15 of 15 Posts

·
Registered
Joined
·
211 Posts
Discussion Starter · #1 · (Edited)
[SOLVED] My Exhaust is Haunted. HELP!

UPDATE: Took it back into the shop and got it up on the lift. After much searching, we found a small 2-3mm area where the weld hadn't completely sealed the pipes in the fabricated section of the exhaust. He cut off the whole section and put together a new one from scratch. Long story short, the chorus of the damned has been exorcised, and the car now has a pleasant "neighbor approved" rumble.

--

Since I'm hopefully getting tuned next weekend, I figured it was about time to finally finish up my custom exhaust system. Got it all bolted up and it's a mess. And of course, I need to get it solved before I head to the tuner Friday.

Stage one: Replaced the stock muffler with a custom axleback with a vibrant ultra quiet resonator, and resonated tips. As expected, with no muffler and catless, it was LOUD. Otherwise, test drove was okay, no problems, no haunted Veloster.

Stage two: Cut out the stock resonator, and welded in a Flowmaster HP2 longbody muffler. Started her up, and she sounded amazing. Volume is about stock at idle, but much deeper. Nice smooth rumble from idle up to about 3000 RPM. Not loud at all like the Magnaflow was with my catless DP. After 3k RPM, things get weird:

3k to 4k RPM: I can hear faint fluttery hooting and whistley noises.
4k to WOT: The sound climbs to a shrieking train whistle of the damned. There are multiple whistling harmonics that sound like a banshee in a movie.

Meanwhile, the car pulls strongly, with no hesitation.

  • It doesn't whistle while gunning it in park or neutral. It only does it in motion.
  • It doesn't whistle when drifting down a hill at highway speeds, so it's not a natural whistle cause by unfortunate piping.
First thought was boost leak? Maybe the exhaust guy knocked something loose...
Am I hearing the turbo spool?
Is my car haunted?

Halp! I need my tune!

 

·
Registered
Joined
·
211 Posts
Discussion Starter · #2 ·
I called Flowmaster to see if they'd ever seen anything like this, and unfortunately this was a new one on them. I asked if there was any back pressure using this muffler with a turbo engine, and he said that there shouldn't be any back pressure from that muffler at all. It's a performance muffler designed to flow the significantly the same as a straight pipe, and would expect significantly more restriction from the OEM muffler. He seems to think it's something on the car, rather than the exhaust, especially since it's only whistling at speed.

Interesting comment: The laminar flow tech they use was originally designed for the military for use in Apache attack helicopters. Apparently you need good flow for military choppers. Did not know that.
 

·
Registered
Joined
·
2,836 Posts
1402-super-hp2-mufflers-product-review.jpg

"They feature stainless steel construction with an internal, layered-laminar jet engine gas flow design that uses guided sound control with broadband sound cancellation for a mellow '50s tone...."

Smoking gun???

I came from the world of American Muscle years ago and people used this to augment their exhaust. It sounded cool on a v8 (NA). I'd love to hear what it sounds like on a turbo 4.
 

·
Registered
Joined
·
211 Posts
Discussion Starter · #4 ·
I'm kinda half wondering if the guy installed it backwards...
 

·
Registered
Joined
·
1,116 Posts
No leaks?

Sent from my SM-G920V using Tapatalk
 

·
Registered
Joined
·
897 Posts
It should make the sound when you gun it stationary. Since it doesn't would be odd to be the exhaust whistling. Is there a certain gear you are in or doesnt matter?
 

·
Registered
Joined
·
211 Posts
Discussion Starter · #8 ·
Regardless, it looks like plenty of restriction.
Which begs the questions:
1: Is it more restrictive than the stock muffler I took off? (which didn't whistle)
2: Can exhaust restriction cause boost leaks or whistling?

At least in regards to 2, I'd think it would just limit power, but that seems to be fine.
 

·
Registered
Joined
·
211 Posts
Discussion Starter · #9 ·
No leaks?

Sent from my SM-G920V using Tapatalk
I looked over the intake, throttle body, and ORCP, and everything seemed snug. I'll crawl under tomorrow and see if anything is loose down there.
 

·
Registered
Joined
·
211 Posts
Discussion Starter · #10 ·
It should make the sound when you gun it stationary. Since it doesn't would be odd to be the exhaust whistling. Is there a certain gear you are in or doesnt matter?
Yeah, that's what I would think. Not sure on gear, since it's auto.
 

·
Registered
Joined
·
1,116 Posts
I looked over the intake, throttle body, and ORCP, and everything seemed snug. I'll crawl under tomorrow and see if anything is loose down there.
On the exhaust you'll see little black marks at a seams or joints if there was a leak.

Sent from my SM-G920V using Tapatalk
 
  • Like
Reactions: rottgrub

·
Registered
Joined
·
2,836 Posts
Which begs the questions:
1: Is it more restrictive than the stock muffler I took off? (which didn't whistle)
2: Can exhaust restriction cause boost leaks or whistling?

At least in regards to 2, I'd think it would just limit power, but that seems to be fine.
I would think it's a little less restrictive than the stock muffler but by how much I can only guess. Certainly not as much as a straight through design like magnaflow.

It may hold ya back a little but shouldn't be a deal breaker.

That is a normal sound for that type of muffler. It's because of the design. When ya have air being forced through it it augments that noise.

It should make the sound when you gun it stationary. Since it doesn't would be odd to be the exhaust whistling. Is there a certain gear you are in or doesnt matter?
When you Rev it you are not getting the same velocity/cfm as you would under load.
 

·
Registered
Joined
·
211 Posts
Discussion Starter · #14 ·
UPDATE: Took it back into the shop and got it up on the lift. After much searching, we found a small 2-3mm area where the weld hadn't completely sealed the pipes in the fabricated section of the exhaust. He cut off the whole section and put together a new one from scratch. Long story short, the chorus of the damned has been exorcised, and the car now has a pleasant "neighbor approved" rumble.

I'll try to get an updated video for those who would like to hear the final result.
 
  • Like
Reactions: Bigbird

·
Registered
Joined
·
118 Posts
Literally the coolest sound consider the time of this reply is in the month of Halloween. Can you imagine hahahah
 
1 - 15 of 15 Posts
Top