Wastegate noise?

raysturbov6

New Member
Joined
Mar 12, 2003
I have an 87 GN, all stock, and when i back off the gas, usually after a hard throttle punch, the wastegate seems to be making an excessive amount of noise (flapping sound). Any ideas as to what might cause this noise or what can be done? the car seems to perform OK otherwise.
 
thats compressor surge aka turbo flutter. its all the air in the intake coming back through the turbo and out the air filter. normal on a stock TR due to lack of BOV. a BOV will cure this problem. do a search on compressor surge, blowoff valve, BOV, or turbo flutter. this topic is very popular and highly debated.
 
The debate seems to be over whether it is bad or not. I plan to add a BOV when money permits. I don't like the idea of all the air backing up in the intercooler.
 
the problem isnt the air going back through the i/c its the air going back through the compressor housing against a blade spinning hundreds of thousands of RPM flowing 800 CFM or more. if you read Garrett's product catalog thy clearly state that compressor surge is bad and harmful to the turbo which is why they also sell bypass valves. you are right though, a bigger i/c and more piping holds more air and therefore puts more air back through ther compressor housing. i heard a GN once on a dyno video that had a big turbo and i/c and ran in the 9s or 8s i believe and when he let off it sounded like a friggin Cessna.
 
Its NOT compressor surge, compressor surge is what happens when you get a real turbo thats big and your motor can't take the airflow that its dishing out, usually at part throttle, when the throttle blades are only open partways. What you guys are talking about is simply air going out of the filter when the throttle is shut. It doesn't hurt the turbo, and the turbo manufactuers will tell you they don't see many failures due to this. Sure seems like theres an awful lot of 1xx,xxx mile TR's out there with no BOV's, and no turbo failures. Ever wonder why that guy with the 8 or 9 second car wasn't running one?

BOV's :rolleyes:
 
Maybe compressor slam won't destroy a turbo, but there's no downside to having a BOV that's set up right, other than the high cost:)
 
turbosam6-whatever you wanna call it. its bad. 6 sec stangs run BOV so.....riddle me this Joker. BTW, since you are such a turbo expert why dont you call Garrett and tell them to re-think their engineering b/c they are full of BS, since you are an expert. turbo builder i talked to recommended them. oh ya ive seen 8/9 second buicks with BOVs. theres also an awful lot of GNs not driven a lot and an awful lot of stock turbos that are too small to really do any damage to themselves by compressor surge. after you tell Garrett they are full of it, go tell it to every turbo car maker that has put them on stock turbo cars like saabs, VWs, etc.

Brian Mc- look at the Bailey diverter valve. $125 shipped, single flash of air, not "ricey", can be plumbed back to intake, tested to 60 psi. i got a link if you wanna hear it.
 
from the Garrett online catalog:

blow-off valve
performance products
50mm Compressor Blow Off Valve Assemblies: The Garrett (TiAl) Blow-Off valve design is the result of extensive development and
testing. The 50mm compressor bypass valve is a vital component of any turbocharged blow-through induction system. This custom TiAl manufactured blow-off valve will improve throttle (time to boost) response as well as help relieve the damaging effects of compressor “surge loading”.

maybe they need to consider updating their catalog as BOVs are not needed and a waste of money by todays standards:rolleyes:
 
LONG LIVE THE BOV!

The primary function of any blow-off or by-pass valve is to prevent compressor surge by relieving the compressed airflow that reverses direction as the throttle is closed.

Blowoff and bypass valves reroute the pressurized air, that is normally forced backwards into the turbo compressor, into the intake stream or by venting it to the atmosphere.

Subsequently, engine performance is then increased from quicker turbo spool up, as the compressor speed is not reduced by the backward airflow.

The longevity of the turbo is also increased, as its bearings will not suffer from the impact that is also produced by compressor surge.

Though many vehicles incorporate factory by-pass valves, they are often undersized and quickly are beyond their capable operating range as airflow levels are increased.

HTH :)
 
MUTANT PIGEONS

Anyone interested in even more info on BOVs should do a
SEARCH on Mutant Pigeons.
_____________________________________________

Just type in:

Mutant AND Pigeon <------just like that
_____________________________________________

Please join the Society for the Prevention of Cruelty to Mutant Pigeons. Your membership is free with the purchase & installation
of any quality BOV.

HTH :)
 
Never said I was an expert, just that you were not using the correct terminology for the discussion at hand. Why you feel the need to be a smart ass I don't know. Once again, I'm looking at the whole picture, because once again, we have someone new to these cars and here you are with the BOV crap, which will do absolutely nothing for him. If you and anybody else that has been around for awhile wants to use a BOV, thats your decision, but for all practical purposes, nobody with a stock TR really needs a BOV, especially not as bad as they need a scan tool and fuel pump, etc. You called it a "problem" in your first post, when its not a problem. Especially on a stock car. You go on to say that stock turbos aren't big enough to hurt themselves. Contradict yourself much?

Like I said, if you and some others like BOV's, go crazy with it, its your car and nobody cares what you do with it. But to say that this guy has a problem that a BOV will cure makes it sound like the car is broke and needs fixed, which is total BS. He's coming here for advice, and will need so many things to keep his car running well, and to waste $$$ on a BOV is just stupid.
 
wtf, try reading the guys post! hes asking about the sound after he lets off the gas in boost aka compressor surge loading or whatever you want to call it. you know what im talking about so quit splitting hairs like a baby. nowhere in his post did i see any mention of a scantool or boost guage or any mention that he is new to TRs or has a problem with his car. in fact i see other wise with this quote, "the car seems to perform OK otherwise." ok so a BOV will cure his not-problem, since it isnt a problem. its not a top of the list priority but i was simply suggesting a cure for his not-problem. think, a smaller turbo will have less imapct on its parts then a bigger ("real") turbo. thats why i made the comment, not to contradict myself. use your head, guy. if he was running a big turbo i might have recommended a BOV more since IMO i would want to take whatever steps possible to insure the longevity of a pricey upgrade to my car. BTW are you 100% certain this guy is new to GNs or turbo cars in general? maybe he heard the sound and never paid much attention to it or maybe he had a car w/a BOV and never heard this sound before. maybe he is new to GNs. a BOV would do something for this guy if he doesnt like the compressor surge loading noise. every time i offer a BOV as a solution to someone wanting to know or get rid of the flutter noise, you jump in and call everyone that talks about BOVs a BS'er and such. its always the same 3 people, me and two lane vs you. too bad we cant all love compressor surge loading as much as you, expert.
 
Hmmm......lets see....Using a little deductive reasoning here. He has 4 posts, and an all stock GN, and is asking about a noise which anyone who has owned a TR knows about, so yeah, I would say he may be new to these cars. Of course, I could be wrong, but it seems logical.

YOU need to read my post, I said that YOU said "A BOV would fix the PROBLEM". Not that he thought he had a problem. The only time I jump into a post to say something about BOV's is when its newcomer to the board and probably the TR in general and you start this BOV crap, and I think it might cause some paranoia to someone who might not know better. You see what I'm saying?

If this guy had all the mods in the world and asked about BOV's, then I probably wouldn't say much except that I don't feel we need them, IMO. As far as splitting heirs, well, If you are going to give someone information, I usually try to use the correct terms, since "compressor surge" is a whole different problem. And one day when you get a big turbo, you might find out what it really is, and guess what? Your BOV will not help, pretty much nothing does. You can lessen the severity of it, but its just a bi product of using a big turbo. If you think the sound is annoying now, wait till its doing it while you're on the throttle.

Like I said, I'm not an expert, never claimed to be. Thats a phrase you came up with. I'm just passing along information from several experienced board members and Tr mechanics. And my personal experience. But since I obviously know far less than you, I'll shut up. Theres no point in arguing, it'll just whittle down into who's car is faster or something, and that wouldn't be fair, would it?
 
quote: "one day when you get a big turbo, you might find out what it really is"

gee Sam, i cant wait till i grow up and get a real turbo and stop messing around with this TA-49 crap. nice show of turbo superiority there, i congratulate you :rolleyes:

maybe from now on when people ask questions ill tell them they are S.O.L. instead of offering a suggestion that may help them.

i really cant understand why you always jump on me for answering a question with a response you dont agree with. i dont want to join your Facist regime so stop trying to control me, Mr. Government!!!

heres what it always looks like. poster posts about annoying/odd turbo flutter > i inform them what it is and offer a solution > turbosam6 comes in and tries to take over the thread calling everyone thats pro-BOV a BS'er > two lane agrees with me > thread goes to hell and original poster never comes back

quote: "since I obviously know far less than you, I'll shut up"

thank you:)

quote: " Theres no point in arguing, it'll just whittle down into who's car is faster or something, and that wouldn't be fair, would it?"

gee so kowledge is inversely realted to ET? and all this time i thought it was directly related to post count.:rolleyes:
 
Turbo superiority? Are you for real? I said when you get a big turbo. A ta 49 is not a big turbo. Not knocking it, just stating facts.

And to a degree, I feel knowledge is related to ET. You don't see a lot of 10 second cars owned by people who are unintelligent. It takes practice and a certain level of knowledge to accomplish fast ET's. Especially with TR's.
 
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