Swapped TD04 for VF35 - now whistles on boost?
 

I've had a VF35 fitted to replace the TD04 on my 98 WRX wagon.

Even though I'd planned to run it at 8-9psi until I get it mapped (by taking out the restrictor in the boost control pipework) I wanted to check that the VF was actually capable of making proper high boost, so I put the restrictor back in. The characteristics are slightly different to the TD04 in that it starts making boost a little later, but then spools up a lot quicker. With a couple of seconds of almost full throttle it hits 15-17 psi no trouble at all, but from around 5 psi upwards it is really whistling/buzzing quite loudly. The note varies with the level of boost. Keeping a steady 3/4 throttle and watching the boost gauge I can see it hitting 15-16psi for a second or two, then dropping back to 10-11 psi with a corresponding change in note. I couldn't work out whether the noise was dependent on revs, as the boost that the VF makes is dependent on revs itself.

Is this a problem with the turbo or is it the sound of the factory 2-port solenoid working flat out trying to vent the excess boost? The sound is not a bog-standard unobtrusive whistle, it's more raspy/buzzy than that but it does follow the boost level precisely and comes in very clearly at around 5psi as far as I can tell. Kind of an asthmatic sort of noise like wind whistling through a drafty window or door.

Any ideas, things I can try out to test where the sound is coming from? I can't see any boost leaks anywhere at the moment. Anyone with a VF35 who can confirm that this sound is normal? Is it the sound of a wide open wastegate resonating or something?

Help!

BTW I'm running Tesco 99 with Milers octane booster, standard ECU, H&S exhaust with sports catted downpipe apart from OE headers still. The old TD04 only ever whistled very quietly which gradually came in as boost built. My old car ran a T28/T3 hybrid which also whistled fairly quietly in the same way. What I'm hearing from my VF35 is not a normal turbo whistle.

The VF's do have a whine to them.. if you in first pull away so the turbo spools and little and then press the clutch and lift off the throttle does the noise slow down / change pitch and go quiet? might also hear this blipping the throttle from idle.

If so then sounds like normal..

I assume you are Jason and I will be able to tell you for sure when i hear it tomorrow evening?

Simon :D

Did you replace the up-pipe gasket with a new one ? Sounds like it could be a blowing gasket before the Turbo, when they havent been replaced or just fail they make a raspy noise on any sort of boost and get louder the more pressure.

If you have used new gaskets give the studs on the up-pipe another tweak and see how it is.

My old modded MY01 had the same problem when the up-pipe was changed as the so called approved installer didnt use new gaskets.

Zippy

JGM - No I'm not Jason, but you do know me sort of. I'll email you!

Zippy - don't think the uppipe gasket was changed, no. I'll see if I can detect a slight blow down there then.

I've just been out for a drive. To take the boost solenoid out of the equation, I connected the compressor outlet directly to the actuator with no restrictor, just a plain piece of vacuum hose. This worked fine at limiting boost to 8 psi. I can STILL hear the rasping whistling noise clearly, but now it only comes in once it hits 7-8 psi. Basically it goes like this:
Cruising along
Floor it
Boost builds within a second or two
Just before hitting 8 psi it starts to rasp/whistle - briefly rising in pitch
Holds 8-10psi (depends on gear), then even though boost stays solid, noise very slightly lowers in pitch and then stays steady.

Does this shed any more light on it?

Sounds normal to me :thumb:

My VF28 does exactly the same :freak3:

No way...I don't know if I can stand it! It sounds like there's something harsh going on in there, like maybe the compressor blades are slowly milling out the housing every time I use full boost!

I took it out AGAIN and tried Simon's suggestion of flooring it in 1st then clutch in, but the throttle response is so sharp I can't make any sense of it. From what I can tell it makes the 'coming on boost' noise just like before ,except it's all done in what seems to be a fraction of a second. The instant I either dip the clutch or let off the accelerator the noise - and the boost - are gone, immediately. There's no run-on that I can detect in any gear.

I tried putting my hand down by the uppipe joint and revving it, but couldn't feel or smell a blow...

Having listened some more to the noise, I'm beginning to think now it's more like a squeal, almost like a slipping fanbelt on an old banger or a referee's whistle (not a kettle whistle). Surely it CAN'T be a normal noise?

Another factor to throw in - I've no longer got the old heatshield over it like I had on the TD04. Could this be part of the problem?

have replied to PM.. ring me during the day tomorrow and I listen to see if it is normal.

Simon

Try the lower up-pipe joint onto the exhaust manifold - I had a good squeal from a leak as the boost ramped up to its max. After that, the noise would vanish.

Nick

If loud enough, check for a borken compressor blade. Otherwise an air leak somewhere will do it too (pre or post turbo - you're moving a lot of air!). Exhaust leaks aren't normally whistly, but is another area to check.

Richard

I'll just throw a leaky dump valve into the pot :)

My '35 does exactly the same . No leaks on the headers or uppipe or dump valve. Bob R mapped it on Saturday and never mentioned it either ....

Cheers

Steve

Just how good is it then Steve :norty:

Me next with the VF35 :thumb:

:D :thumb:

Thanks for all the replies so far. So is there an easy way to tell if an exhaust's blowing apart from the obvious - a load of exhaust fumes blowing out every time I rev the engine?

Just thought of something else. Surely if it's boost related - which it definitely does seem to be - it can't be coming from BEFORE the turbo? Or can it? Surely the faster the turbo spins, the LESS pressure there can be in the uppipe and headers, so you'd expect leaks to close up and noises to quieten down?

Weird request but there's no-one on here with a VF35 (or any other VF) who's recorded the sound of full throttle acceleration is there?

Any idea about whether the removal of the heatshield would have made 'normal' noises sound much more prominent?

VF's do tend to do this. My VF28 sounds like an old whistling kettle coming on to boil as the bosst build upto and beyon 1 bar. PE didn't comment on it when the mapped the TEK, and it as since been fitted with an Apexi Power FC.

A mates VF34 also does the same, as noticed it whilst passengering round brands on a track day.
This was a spanking new Turbo, fitted and mapped by Bob Rawle.

I PM'd bob and he said it was quite normal, especially noticable at higher boost and a decat.

I even took it off and used new gaskets before being told it was normal.

I know what you mean though, it can get annoying. Just crack the window down or turn the stereo up a bit. The noise soon disappears.

It's not so much that I mind the noise. I used to run a 3" side exit exhaust on my old car. It's the not knowing whether it's normal or whether it is the precursor to an expensive repair bill!

i love the sound of my VF

seamed to make a hell of a lot MORE noise when the zerosports uppipe/ported headers was fitted for some reason :D

Looks like you're going to have to change your username to Whistling Running :D

LOL exactly. Or 'Kettle Boiling' or 'Banshee Wailing'.

I've done a few videos on my phone while doing some straight acceleration runs in 2nd, 2nd and 3rd, etc. Surprisingly enough, these genuinely ARE on a private off road testing facility. Only place I could get a long uninterrupted straight with no other traffic.

Does anyone know how I can upload these or link to them so you can all have a listen? 4 files up to around 300k each, they play fine in my Quick Time program on the PC. 3gpp files or something like that.

i started my car up today after fitting a vf35 and a bigger intercooler and some more supporting mods,ive taken the car out for a run and the turbo does whissle a lot more than the td04 did, i wasnt goin to boost it to much untill its mapped but i couldnt resist it so i floored it once to see if everything was working ok, it takes a bit longer to boost than the td04 but then it went strait up to over 20psi but it didnt seem to pull very good. is this just because it needs to be remapped do you think?

Does the whistle come in loud at a particular boost level or does it just gradually increase the more the boost builds?

yep, mine was both laggy and sluggish before the map. A set of ported headers fitted at the same time probably didn't help :)

Your td04 map will be quite thin in places with the higher flowing turbo

Much , Much better after a session with Mr Rawle :D

Louder on the way up .... from <> .5 bar upwards , then quietens down once it's spooled up to full chat ...

it just gradually builds up but it is a lot more noisy than the td04

cheerz mate i'll get it booked in for the remap asap