Hey guys,

One thing that's been troubling me that I haven't figured out on my new fd is why the turbos sound so damn loud with a stock engine, zero modifications (even stock brand air filter). When I enter boost, I have an extremely loud whistle noise that sounds like my previous fd with apexi intakes. I've already removed all of the intake tubes to the air box and checked the hard piping as well. I've been over all of the couplers and even replaced some with new silicone and t bolts. My boost pattern is 8 10 8 iaw normal sequential operation. Only "issue" is the crossover tube cracked off its mounting bracket but I don't see any penetration points within the tube (I have an efini y pipe I'm installing when I get time). It doesn't sound like your typical boost leak ie pshhhhh or air blowing noise, it sounds exactly like an open intake would.

What could this problem be caused by? I love hearing me some 747 jet engine take off noises but bothered that I can't find the issue. Thanks everyone!

Joe

 

Joe,
Check the rubber connections on the stock setup. They tend to heat crack, sometimes very small cracks, and can cause a high pitched whine.
Mike

 

Sometimes deathwine will sound like that too.
Could be worth having a look at the turbos. See if there's any excessive shaft play.

But I agree, boost leaks can make the sounds also. Do you have a pressure tester? Pressurize your piping and see if you can detect leaks.

 

No pressure tester, I'll look more into the death whine issue. Should be able to access the front turbo pretty easily, it's damn near impossible to remove the rear hard intake with the stock downpipe. I'm waiting to get a downpipe before I try to get that off.

Edit: listened to 4 or 5 death whine turbo videos on YouTube, if our car sounds like that then absolutely not. My sound is no different than a louder version of normal induction noise.

 

rear turbo feels good, minimal shaft play in the side to side direction, none in the in-and-out direction, spins nicely.

 

Ok just installed the efini y pipe. Check every single intake hose, had off most of the parts for the intake to the turbocharging system, no obvious cracks, rips, tears, etc even under bending tension stresses. To be honest, the hoses look pretty damn good for 25 years old, I was surprised. Took the car out, same noises again, boost was a nice 10-8-10, holding strong at .705 kg/cm^2. I have no idea what could be causing this, but I've basically ruled out the entire intake system prior to the turbos, and now the y-pipe/crossover pipe combo since the efini is now installed.

I will say that boost is much more rapid now, feels like a newer car in terms of boost response. It's almost hard to keep it from entering boost, lol.

Am I just being stupid? I haven't been in a stock FD for a while, are these cars just louder than the new age cars that are essentially quiet?

Joe

 

youre probably not used to hearing anything over a quiet stock exhaust...

 

Haha, possibly. My focus rs is quiet as hell, last older turbo car I had was a 93 mr2.

 

A bone stock FD has sort of a "vacuum cleaner" noise at full throttle from the intake. With most any exhaust that's quickly drowned out.

It only takes a small leak to make a noise, you may have one small enough that it isn't leaking much if any boost.

Dale

 

Dale I think you're right. Probably a tiny hole that is going to be difficult to find or a coupler that looks good.but isn't. I'll keep pushing

 

Carefully examine the hoses off the car, squeezing them all around and up and down their length. I had one that looked perfectly fine just looking at it, but when you squeezed it in just the right spot a small crack would appear.

 

Also you may want to free-rev the car in the driveway, I found a boost leak on a buddy's car that way. You may also be able to isolate where the noise is coming from.

Dale

 

Just throwing it out there ..... you don't by chance have the bottom of the airbox cut out right? AKA cheap bastard intake mod ....

 

Amp did bring that up as well, I actually haven't checked that yet. The filter is OEM, but it is possible that the airbox was modified. Seeing how everything else on the car was left alone, I doubt the owner removed the bottom lid and drilled holes in it though.

 

he just might enjoy this....

 

It wouldn't be forced induction noise then...

 

One easy way to check those plastic hoses is to use a little water with some dishwash or carwash soap on them. Get some soapy water on the surface of the pipes, then start the car up. If they're off the car, dip em then blow into one end.

Sometimes those plastic intake hoses will get a hairline crack that's nearly invisible unless the hose is pressurized. The soapy water will bubble up if air escapes.