Help with S/C noise on ACE kit!
 

Hi everyone –

I finally was able to get a pro speed shop to install the ACE kit and fuel upgrades, with the work completed last weekend. We ran into a major noise issue with the PT50 BOV that was sent with the kit. It squeaked and chattered even at idle, and the shop owner said that it sounded like Tweety Bird. He wasn’t happy with it, and knew I wouldn’t be, so he opened up his race car and pulled out his Tial Q50 to install instead. There wasn’t enough clearance for the Q50 between the intercooler and a/c compressor, so he moved the intercooler ¼” with spacers. That got rid of the high-pitched squealing at idle, and moved the “chatter” from the supercharger into a higher RPM. Now, it does it at cruising speed, 2500-3000 RPMs, when there is no load on the engine. Just a constant chattering, from the driver’s side of the engine compartment. It's quite loud, and simply intolerable!

It’s the shop owner’s belief that it occurs because the supercharger is creating more pressure than the engine requires when cruising, and the pressure is cavitating out the compressor fan blades out the opening of the intake. He’s calling it a type of “compressor surge.” I’ve got the “hair net” filter on over the opening, and he said that if you could rig up a GoPro camera to look at the filter, you’d see it vibrating in and out when cruising. He feels that the solution would be to put a pancake H&N-type filter on the intake, so that the supercharger is always pulling against a slight vacuum. Or, if there might be an S-curved charge pipe that could fit a larger filter behind the bumper. Just something to create a small amount of vacuum on the intake.

I asked TopGunz about this, and he said that the solution is on the BOV side. He said to put the Tial QRJ on, with the Vibrant crankcase filter, and that will fix the problem. Unfortunately, the QRJ won’t fit in the space available, unless there might be a fitting available to turn it at a 90-degree angle…but then you’re messing with the free-flow operation of the valve. (Another option might be to have a 90-degree pipe and mount the QRJ remotely somewhere.) The shop owner is unconvinced that any modification to the BOV will fix the problem. He has installed dozens of s/c kits on Mustangs, and he said every one of those kits has a charge pipe with a pleated filter on it, and he’s never had an issue with this noise.

There are apparently different configurations available for some Tial BOVs, but none for the Q50. There simply isn't a way to connect any kind of pipe to it, to run to a crankcase filter...even if that would fix the problem.

What are the rest of you doing? Any suggestions? Thanks!

Just to clarify something. You do know that the qrj had to be mounted horizontal. The inlet is on the side, not the end.

Does it sound like this?

https://youtu.be/71iNsASAbBE

The QRJ fits. The shop owner does not know that the QRJ can run both vertically or horizontally. I literally just installed one last night on the Rotrex kit using the same intercooler and brackets.

By installing that and the 1.5" exhaust port you can place a 1.5" filter on there and it will be much quieter. However it will still be there. I do have a fix that should completely muffle it but I am waiting to get the car up and running to prove it out. I could send one to you if you would like but you would be the first to run it.

Aaron,

According to Tial tech support, the qrj must be installed with the charge pipe connected to the side port to work correctly. Here's their reply to me:

"The QRJ may provide a more linear response characteristic than the QR, though, but just be sure to install it correctly, with the 'side' port attached to the charge tube"

Yes...that's the sound...except it only occurs now between 2500-3000 RPMs at zero engine load cruising. Before, the PT50 even did it at idle, and up and down RPMs like yours. The PT50 was higher-pitched as well, and sounded horrendous.

The shop owner put in the green spring into the Q50, which helped immensely. But even now that it's "improved," it's still a deal-breaker. If you didn't know better, you'd think the engine was coming apart.

I had the shop owner coordinate a remote-tune through Sebastian, who he knows personally. Sebastian sent two separate tunes, one a conservative tune for ambient temps above 80F, and a "beast mode" tune. I've been running the beast mode tune, and don't know if there's a change in the sound for the conservative tune. Haven't had time yet for testing.

Thanks for the offer, Aaron, but I'll wait until you've run some tests. This install went double over my budget, and I want to be sure before I have the shop pull the front of the car off again.

What about the intake filter you ran on the 1.0 kits, with the short charge tube? Were those quiet?

This is the first I've heard of it occuring at idle. It usually occurs when the vacuum is at 0. Not sure how that's possible when you're idle is at -17hg or so.

Some guys like the sound, others don't.
Yes the kn filter on the SC will quiet it down.

Btw. That video that was posted was on a soho kit. Correct? Hence it occurs on any vortech v3 without a filter. Lots of those on the road.

I tried the Q, QR, QRJ and every spring available from Tial. I was working with Tial tech support for about a month trying to figure it out. I also sought help from every sc expert in the US and no one could come up with a solution. A couple suggested I run 2 bov's but I never had a chance to try that before I blew my motor. By the way, I wasn't running Aaron's Ace kit so the issue isn't limited to the Ace kit.

Yep, soho kit with the V2. I never had the issue when it was making a lower psi which is weird. Also, mine would start making the noise as soon as it would start making boost and go away at 3 psi

I think this is the mistake...assuming it's entirely due to the BOV. Yes, the BOV can alter the sound, change the RPMs, etc., but I don't think you can address the entire problem from one end. The shop owner who installed my kit races, has lots of experience with superchargers, and, as I mentioned, installs many centrifugal kits on Mustangs. (He has a Viper GTS that makes 3500hp, among his cars.) He believes the issue is mostly with the intake side.

He explained it this way: Picture your s/c compressing 15 cubic feet of air into your manifold, but the engine is cruising, only drawing 5 cubic feet. That extra 10 cubic feet is going to squeeze out the front of the supercharger, and will be modulated by the spinning of the compressor. If you're always drawing against a slight vacuum, you'll moderate that "overpressure," and muffle the sound through a filter.

I hope we can nail down a good fix in this thread.

There's a muffler you can put on the QRJ and it will be gone. Redondoaveb has already done this. I have made a different version. They are free to anyone who bought an ACE kit.

Here's what you quoted above from the owner of the shop that built your car:

"It’s the shop owner’s belief that it occurs because the supercharger is creating more pressure than the engine requires when cruising, and the pressure is cavitating out the compressor fan blades out the opening of the intake. He’s calling it a type of “compressor surge.” I’ve got the “hair net” filter on over the opening, and he said that if you could rig up a GoPro camera to look at the filter, you’d see it vibrating in and out when cruising. He feels that the solution would be to put a pancake H&N-type filter on the intake, so that the supercharger is always pulling against a slight vacuum. Or, if there might be an S-curved charge pipe that could fit a larger filter behind the bumper. Just something to create a small amount of vacuum on the intake."

The owner of the shop that built my car told me the exact same thing and suggested exactly what your shop owner suggested. I'll never know now since I blew my motor before we got to that point. And as much fun as I had experimenting with superchargers, I accomplished pretty much what I wanted with my build(s), I'm going with tt's now.

Sorry to hear about your sad experience!

I admit I don't know a lot about all this, but from what I understand, it sounds like the PT50 has too strong of a spring in it (for starters), and doesn't open under light load or at cruising speed...forcing the extra air out the compressor side.

Unfortunately, mine still did it with the silencer. The video I posted was with the qrj and the silencer.