Friday, November 18, 2005 - 06:40 pm, by: Daniel Drury(Danski)
Hi I am getting an air blowing noise on and off like a choo choo train (lol) when car is at about -5 psi and speed of this noise increases until i get into 0 pressure and up. maybe the length and volume of the pipe work has something to do with this. have blowoff valve and this didn't change anything. the two waste gate lines T into each other and then attach to the cooler piping. have attached photos have a look and see if anything stands out.
Friday, November 18, 2005 - 07:39 pm, by: Lew Radbourn(Marlew)
Daniel roller bearing ? .80 ar compressor housings? surge is back pressure on compressor wheel May be an idea to go 3 " in and out of the intercooler mate. if the compressor pipes from the turbo to the intercooler is 2" then thay join into 1X 2 1/2" it could be a little restrictive just in that area and with big ar sizes on the compressor wheel side of the turbo it can get pretty bad that's what i recon any way mate Lew
Friday, November 18, 2005 - 08:05 pm, by: Daniel Drury(Danski)
That is interesting and sounds right, but i assumed that the less volume the less lag, without going crazy and putting really small pipes on that is. but would going bigger solve the strange pulsing of air.
Compressor surge: You can think or surge as the point at which the compressor blades begin to “slip” in the air, losing their pumping ability, much like an aircraft wing loses its lift when it stalls. In a turbo, this happens in a series of bursts, as the blades slip, then bite, slip then bite. This sets up a pulsing wave in the turbo piping and explains why the sound has that characteristic “flutter”.
The interesting thing about compressor surge is that it occurs much more readily at low turbo shaft speeds. At these low shaft speeds, on road cars this is generally between 2000 and 3000 RPM, compressor surge is not much of a problem, as the loads generated by the surge are miniscule compared to what the turbo encounters at high boost. However, if surge occurs at high RPM and boost, it is possible to reduce the turbo life and/or damage the compressor. http://www.gofastbits.com.au/index.php?parentid=tech_info&option=tech_info
Saturday, November 19, 2005 - 09:13 am, by: Daniel Drury(Danski)
yeah that sounds like what it is then, what do u think is the best possible fix for a thing like this, even though it sounds as though it is not damaging anything, but it is an embarrassing noise, hey look at me everyone my hardcore car sounds like a train.
Saturday, November 19, 2005 - 09:22 am, by: Cihan Aday(Cihan)
I think it has something to do with the unequal length piping from the compressor outlet of the turbo's. The pressurised air from the rear turbo could overwhelm the front turbo in that split second and cause surge, especially if the housing AR is high, as there is less restriction/protection against this happening. If the intercooler is causing a large pressure drop, i would suspect that the issue is being magnified.
Guys with 800hp 2JZ's have what looks to be 4" IC piping off the turbo, if you want to exploit the potential of twin GT28's on a 2.5L motor.. which is way over 350rwkw, there are some expensive considerations that need to be made, piping is one of them.
Whats the power situation currently? Have you had it on the dyno?
Saturday, November 19, 2005 - 10:35 am, by: Chris Davey(Chris_davey)
Muzzy: it is just a boost reference source. You can get it from compressor outlet, cooler pipes, inlet manifold etc. I have my boost reference for my external gate on the cooler pipes as the wastegate will react earlier than if it were on the inlet manifold. For T28's that are internally gated you should just be able to use the compressor housing just as ct12as do.
Saturday, November 19, 2005 - 10:45 am, by: Daniel Drury(Danski)
i have not had it dynoed yet, i still have to get ecu tuned, i am just taking it very easy atm, i rarely put +psi into it. am looking forward to boosting the hell out of it, it has been a long time. $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
Wednesday, July 12, 2006 - 04:46 pm, by: Christian Garcia(Garcia)
sorry to bring up old thread, but did you ever figure this out? my car does the same. sounds like a train, i can't stand it... and i can't be bothered wasting money on "maybes"
Tuesday, July 28, 2009 - 01:06 pm, by: Paul Ince(Incey)
Found this old thread which sort of describes the problem I've started having.
During steadily increasing acceleration at low boost I am getting this ch ch ch ch sound almost like something dragging against a wheel at low speed or a steam train starting off.
Under hard acceleration it doesn't appear at all til the throttle is let off, then its just one big ch
Are my turbo's making boost out of sync with what is required by the engine?
Tuesday, July 28, 2009 - 04:04 pm, by: James Harris(Haro)
Wow old thread, i remember this bad boy from years ago haha ! It was compressor surge he was getting, Cihan was on the money.
Paul please explain your problem better mate. From what i can gather you mean it makes that 'choo choo' noise when you back OFF the accelerator at low RPM...... if so - THAT IS FINE/NORMAL. Most people dont notice this noise until they do the BFI or add a pod filter. It will sound different after adding a bigger intercooler also.
BUT if it is making that noise when you are accelerating that is NOT NORMAL. *i dont see why that would be happening anyways after looking at your list of mods in your profile.
Tuesday, July 28, 2009 - 04:35 pm, by: Daniel Clarke(Dieseltrain)
Paul, have you gone to high flow turbo's ? If so then its comp surge and if the comp housings you have chosen are too large then the problem will always be there . Quite common on high flowed twins with BB garret internals .
I think it happens mainly on the 1jz's because the pipework is too small . if somehow you could get some larger pipework made for the intake side, it may help things.
Another way is using adjustable cam gears to help flow down low . this doesnt eliminate it, but can reduce it. Is the car manual or auto ?
Tuesday, July 28, 2009 - 09:37 pm, by: Paul Ince(Incey)
James, The choo choo sound is happening under light acceleration once boost has started, I was pretty sure it wasn't normal hence the post. I probably haven't got all the latest mods in my profile, thanks for the reminder. So far its top qual exhaust and fmic, emb, pod, high flow steelies, ebc, and running 14 psi. The last tune after the turbo install was a bit of a disaster as the tuner couldn't make any more than 190 rwkw even up to 18 psi. When I got the car home I found a big leak in the boost side and have fixed that. Today I started noticing this sound and I think its getting worse. The tuner guy reckons it won't be hurting anything but I'm not so sure. Its booked in for another tune on Friday.
Daniel, Yeah I got some high flow steel wheel ct12's off cihan. All the intercooler piping is 3" now and I don't reckon I could get much bigger pipes too fit. The car is an auto.
Also when I was at the mechanics today they reckon it will take minimum four hours to install a set of injectors...does this sound right? I was going to get the 440's i bought installed but that would make it a prohibitively expensive job.
Thursday, July 30, 2009 - 02:46 pm, by: Scott Gates(Scotty_001)
Paul,
I have the same thing happening on my car. Its common on high flow turbos. When i got my turbos rebuilt by Bill at ATS he said it is normal and does not affect anything. Just a noise.
You will notice it more when going up hills just as boost starts.