ZW 944

Hey guys,

my 951 has been doing this for a while now, since I put a new turbo on as of this summer, where the turbo spool is extremely loud (woosh) on even light acceleration (anything other than babying the car, even when manifold pressure is still >1bar), and is accompanied by an equally loud fluttering sound on heavy acceleration.

Boost leak test at 15psi via air compressor & pvc cap on J boot showed a number of leaks, which I have been able to fix all of them but 1 from under the intake manifold. I highly recommend everybody doing this to their car. Its become noticeably faster since. There were leaks on either side of the throttle body, the idle control screw, one of the intercooler hoses, the thermo-vacuum valve (on the rear water neck- I didn't have a replacement so I just eliminated it) and both ports on the intake manifold where the port connects to the manifold itself. I am still somewhat suspicious of the intercooler hose that connects to the turbo - it is the lindsey silicone one, but it didn't seem to fit very tightly compared to the other silicone hoses. boost test says its okay though.

The turbo is a newly rebuilt k26/6 cheater turbo from Charilie at Evergreen running 13psi confirmed with innovate guages. AFRs are spot on, and the thing runs like hell. I was expecting a lot of shaft play when I finally was able to tear it down, but its as tight as new both laterally and front to back.

please help me get my car sounding normal again!!!

eman930

Can you make a recording of the sound? Also are you running a MAF setup? And how did the blades on the turbin look?

numbskull

Does 13psi hold? Sounds like a leak or bov issue. I just replaced a k26/6 with a much larger turbo and it now sounds like a helicopter, still finding leaks but much better now.

ZW 944

It will hold 13 psi but its extremely loud and I don't want to hurt anything, so I usually back off. I suppose it is possible that if I find and fix the last leak under the manifold that it would help, but the fact that it makes this noise when the pressure is still low (less than atmospheric) leads me to believe that the noise isn't related to air escaping from the intake... I am questioning of the BOV though its the forge unit from LR.

My setup is still with an AFM, A tune, and the blades look just like they did when new. I will try to get a video recording if I can find somebody to take the video while I drive and some way to upload it. maybe over the next few days.

User 52121

Hole in the exhaust?

bordin34

If your downpipe is very loose or cracked it can make a similar sound.

Dougs951S

You mentioned it was a cheater turbo, so the cold side was bored out for a larger compressor then, possibly also a larger turbine in the hotside? do you know the exact specs of the new turbo? I went from a k26/6 to a k27/8 running 18 psi, and after the swap the car sounds like a jet taking off. Every turbo has a unique sound signature associated with it, you may just not be used to it yet.

ZW 944

Pardon me if I'm wrong, but if there were an exhaust leak post-turbo wouldn't it still make a deep bass sound at idle? or does the turbo muffle that out? I would believe it if it were an exhaust problem due to how the sound seems related to turbo speed, but at the same time comes on before positive manifold pressure is obtained.

The turbo housing I believe uses the regular turbine wheel, but clipped. the build sheet is pretty vague, but it also mentions a lightened compressor wheel.

User 52121

If you have an exhaust leak close to (but after) the turbo (or really, anywhere before the muffler) you will definitely hear it spinning up and down.

ZW 944

I'll have to check my downpipe connections then because it definitely seems to be coming from the front of the car.

azbanks

are you still running the factory air filter or did you switch to a cone filter?

ChrisJ951

Check the clamp on the intercooler pipe to the throttle body where it connects to the TB. I had my clamp too low towards the bottom on the hose and it made the turbo very loud. I but a clamp up by where the hose connects to the TB and it solved it.

shortyboy

i would also check hoses and clamps on the J-boot.

Black51

J-boot to turbo connection tight? It's hard to get the bottom side get on fully with the alternator in.

ZW 944

Well, none of these fittings leak air with the air compressor hooked up, so I'd have to say that the noise probably isn't originating from there. I do run the stock air box too.