While out on the highway yesterday, I opened it up to see how it would run as I haven't had many chances since the install. It was going like mad until I hit about 5,000 or so RPM, then it seemed to lose power a bit. I got off the highway, and then noticed this raspy sound (brap-brap-brap is the only way I can describe it) whenever I get up to about 3,000 RPM, just before shift revs. Has something happened to my supercharger? Engine sounds fine below 3,000 but then sounds like an exhaust leak over that.
[This message has been edited by NetCam (edited 06-08-2014).]
I'll try to do a video tomorrow. It's never sounded like this before, started immediately after I went WOT on the highway. Strange part was the loss of power as it hit the upper RPM band almost like the SC had cut out.
Are you running it through the stock muffler? I've had one to deteriorate to the point that it sounded like an airplane. The inner and outer layers were apparently banging against one another. Or something. "BRRRAAAP" describes the sound perfectly. Was a real WTF moment when it happened.
If it's making a whole lot of noise, your knock sensor might be picking it up as "knock", and pulling out a bunch of advance.
I'm running a Magnaflow muffler, and it's less than a year old, but you're right, it does sound like a shot muffler, but I can't really see that being the case this early on. I will see if I can get under to have a look just in case, but my jack doesn't do a very good job since I lowered the car. Canadian Tire has a sale starting tomorrow on low profile jacks so I'm hoping to get out there first thing in the morning and grab one.
I had a problem like that. It sounded like gravel in the heads around 3,000 rpm when I would tromp on it. Mine turned out to be a loose vacuum hose on the boost line to the fuel pressure regulator. It is actually acting like a rev limiter as it gets starved for fuel.
Checked all the vacuum hoses and can't seem to find anything loose. Scope won't do me any good, because I can't seem to get it to make any noise in the driveway, even if I rev it up to 3K. Seems it will only do it under load.
The sound is now getting worse and worse, to the point I can hear it at idle. I got it up on a hoist and put a scope on it, and it is definitely something internal. Seems to be coming from the number one cylinder, and could be a spun main bearing or connecting rod related. I guess I'm in the market for a new engine......