screamer pipe at 1bar TD04
- Thread starter craigant
- Start date
Fatman
Member +
It really does depend on personal taste as to whether you like the sound of a screamer.
Is there benefit? Definitely... is it noticeable? Probably not. I personally have my external wastegate plumbed back into the downpipe just before the firewall flange on a shallow angle, this way it has negligible detriment to the efficiency of the exhaust and I can hit boost without everybody around immediately knowing about it
HutchGlanzaV
Member +
An external gate will hold boost better than an internal one, if I understand correctly they pretty much eliminate boost creep. I'm open to correction on this though!
Dane_Bristol
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Fatman
Member +
External wastegates offer a much greater potential to bypass exhaust gases than your average internal wastegate. Boost creep is caused by the inability to bypass enough, on a CT9 this is primarily caused by the small internal gate and pressure differences caused by a larger diameter exhaust.
An external wastegate left to its own devices will very accurately self regulate to the rating of the spring installed. You can use conventional manual bleed, ball and spring or electronic solenoid based systems to then raise this boost level by manipulating the pressure seen by the wastegate.
To limit a turbo to 10 psi, you're going to end up bypassing a significant portion of the exhaust energy that could be used to drive it, in an external/screamer scenario this exhaust is dumped unmuffled and is fairly loud. At high boost, you are bypassing less of the exhaust energy, putting more through the turbo. The counter-intuitive thing is that the higher the boost, the less noise you're going to get from your screamer.
People often go to a bigger wastegate when they're running bigger power, this is actually pointless.. the situation that really calls for larger wastegates is when you're trying to run low boost.
An external wastegate left to its own devices will very accurately self regulate to the rating of the spring installed. You can use conventional manual bleed, ball and spring or electronic solenoid based systems to then raise this boost level by manipulating the pressure seen by the wastegate.
To limit a turbo to 10 psi, you're going to end up bypassing a significant portion of the exhaust energy that could be used to drive it, in an external/screamer scenario this exhaust is dumped unmuffled and is fairly loud. At high boost, you are bypassing less of the exhaust energy, putting more through the turbo. The counter-intuitive thing is that the higher the boost, the less noise you're going to get from your screamer.
People often go to a bigger wastegate when they're running bigger power, this is actually pointless.. the situation that really calls for larger wastegates is when you're trying to run low boost.
flyingorphan
Member +
But would a external wastegate be needed for a CT9 hybrid running over a bar???
Shorty
Member +
well i run an external wastegate on my ct9 hybrid, with front exit exhuast, front mounted air filter, fmic ect and never had any creep with it apart from when my ebc fucked up but that was the ebc not the external gate. its spoton for a ct9 as thier internal gates are tiny and usless for expelling the air hence cracking and creep issues.
Fatman
Member +
Required? No. Helpful? Definitely. The CT9 internal wastegate is pretty pants once you start to improve intake and exhaust flow. A TD04 should be able to cope just fine, in its original form it's designed to cope with the exhaust energy from a 2 litre motor and as such is well specced for dealing with the worst our little 4e's can throw at them. The CT9 on the other hand starts to struggle severely with just a large exhaust and a decat.
The higher the boost, the less of an issue it's going to be.. however if you're attempting to limit boost due to fueling/concern over damage to engine internals or just practical reasons like wheelspin or fuel consumption you might have some difficulty regulating it to a lower level stably. You could try porting the wastegate port, there is a little to be gained without compromising the flap seat, however the more material you remove, the more likely the housing is to crack, ruining your expensive hybrid.
An external wastegate will definitely solve your problem, however for the expense required of a manifold to suit and actually BUYING the wastegate (and this is something you should NEVER EVER skimp on!) you could have just about gone for a basic td04 manifold and a used turbo, be pushing more power, putting less stress on your engine and just generally having a whole heap more fun
The higher the boost, the less of an issue it's going to be.. however if you're attempting to limit boost due to fueling/concern over damage to engine internals or just practical reasons like wheelspin or fuel consumption you might have some difficulty regulating it to a lower level stably. You could try porting the wastegate port, there is a little to be gained without compromising the flap seat, however the more material you remove, the more likely the housing is to crack, ruining your expensive hybrid.
An external wastegate will definitely solve your problem, however for the expense required of a manifold to suit and actually BUYING the wastegate (and this is something you should NEVER EVER skimp on!) you could have just about gone for a basic td04 manifold and a used turbo, be pushing more power, putting less stress on your engine and just generally having a whole heap more fun
This is a ridiculous statement! Get a grip of yourself man. You made a lot of sense up to the point where you said this.
MentaLEP91
Member +
external wastegates are NOT needed to any settup as long as u are sure that the internal WG can withstand the gas pressure an not creep.
Fatman
Member +
Is it? Explain why..
If you were to run the absolute MOST power your turbo could possibly provide, you wouldn't be bypassing ANYTHING past it. E.g you would have no wastegate at all... following that logically, if you wanted to run a little bit less power, you'd need to bypass a little bit, requiring a small wastegate. Extend that line of thought. Why would you need a giant wastegate (or even two) when there's no need for anything to go through them?
There are people all over the planet who use them and for good reason. Silly of you to say that putting one on a car with high power is pointless, when if their setup requires one, then thats just that.
People don't buy them for nothing, most know exactly what they buy them for and do so with good results.
People don't buy them for nothing, most know exactly what they buy them for and do so with good results.
fastglanza
Member +
Nope he's correct...seen a 4g63 running 40psi on gt42 running a wee 38mm wastegate no boost issues
