Wastegates

[RedGsxEclipse]

What is the difference in performance between internal and external wastegate? Advatages and so on? Thanks.

 

[blcknspo0ln]

all you had to do was search real quick.. but i'm sure you read the rules already.

internal - usually a 31mm [up to 38mm I've seen] valve that stays shut until a desired amount of boost is built up. problem with these [especially on 16G's] is the internal wastegate is too small and doesn't let exhaust gas escape fast enough and then the exhaust gas exits through the turbine instead. This is called boost creep.

External - 38mm valve up to 46mm [ maybe bigger now? ] and is usually mounted off runner 1 or the collector of the exhaust manifold or at the o2 housing. Same concept, except it does a whole lot better. Reason? I kinda know, but not really. I'd rather have someone else who knows for sure how an external works to explain it better for you

p.s., not hating on you, because I don't know you.. but how can you ask such a question when you have a built 6 bolt with a 57 trim? WTF

 

[slugsgomoo]

the real advantage of an external is that they hold a given amount of boost (that you can set) and they open & close VERY quickly.

if you run with no boost controller on a dsm with a 14b/16g you will notice that you run 7-9psi. At that point, the wastegate starts opening. If you were able to use an MBC you could hold more boost, but it would be more efficient if you could keep the gate closed all the way.

My external has a 1bar (14.7psi) spring, and that is the pressure it opens. With an electronic boost controller, you can hold it even further, and it literally snaps open and shut in fractions of a second, rather than easing open like an internal.

I will never have another car with anything bigger than a 14b and an internal gate. They are less expensive, but vastly inferior.

here's a picture of the external gate on my talon. It's an HKS 40mm w/ 3" SS o2 elim, re-merged wastegate dump (instead of going to atmosphere)- oh, and the super 1337 uber ported 14b.

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[Drift_SM]

^ " here's a picture of the external gate on my talon. It's an HKS 40mm w/ 3" SS o2 elim, re-merged wastegate dump (instead of going to atmosphere)- oh, and the super 1337 uber ported 14b. "

I dont know anything about wastegates...but to what i can see through reading some stuff is that wastegates are a lil similer to BOV...they both vent eccess boost pressure....either it be recurculated or to atmospher......But if you cant run a bov to atmospher without running ritch...how do you run a wastegate to atmopher without having the same problem

 

[-silencer-]

BOVs are for the intake pressure and wastegates are for the exhaust pressure. Since the exhaust (wastegate) doesn't factor into the equation with the air mass that the intake (BOV) does, you don't have to recirculate it.

 

[Drift_SM]

BOVs are for the intake pressure and wastegates are for the exhaust pressure. Since the exhaust (wastegate) doesn't factor into the equation with the air mass that the intake (BOV) does, you don't have to recirculate it.

oh alright i see. thanks man

 

[v01dy]

If you increase boost, do you have to replace the stock wastegate like you would have to replace the stock bov?

 

[liquordrunk]

p.s., not hating on you, because I don't know you.. but how can you ask such a question when you have a built 6 bolt with a 57 trim? WTF

You are so true!

 

[-silencer-]

The stock wastegate is internal - it's a part of the turbo. If you want to upgrade to a turbo with an external wastegate, you'll want to get one that will handle the maximum boost level you're aiming for. The wastegate releases excess exhaust gas before it gets to the turbo to prevent boost creep.

Think of it this way..
The blow off valve releases intake air when pressure is too great (like letting off the throttle at full boost) and the wastegate releases exhaust pressure when it is too great (to prevent the turbo from putting out more boost than it should).

 

[v8s_are_slow]

okay guys, you're leaving out the main major benefit of the external gate. internal gates can leak (robbing you of power). you can get a bigger flapper door for the internal gate to keep from getting boost creep if you're getting it, but it's still not gonna be as good as an external. also, if you look at the flapper door on an internal gate, it's just flat. so it just sits against the hole. whereas my tial gate is angled at the edges to help align it and center it when it closes and a much better fit. you can also order the minimum spring rate you want it to have. i have a 1 bar spring in mine so if i don't have a boost controller, i can route the vacuum line from the turbo to the wastegate and run 14 psi all day (but that's as low as i can go). a stock internal gate would usually run at about 8 or 9 psi.

with an internal gate, ALL the gas goes thru the exhaust (unless you get an O2 housing that dumps to atmosphere), making chances for boost creep greater and also gives you more back pressure on the turbo. and we want a free flowing exhaust to make that turbo happier. more exhaust in the pipe is what we don't want.

external gates dump to the atmosphere unless you buy a kit that routes it back into the exhaust (just to rid you of the noise) or you have it done up that way yourself. but usually, they're made to dump to the atmosphere and this means less back pressure on the turbo.

external gate advantages: holds boost better and longer. less back pressure (if routed to atmosphere), have control over the spring rate you want to buy (but have to preorder it this way. spoke to a guy at tial and he said you'd wanna have a press to hold it down when taking it apart otherwise you could be seriously injured), less chance of boost creep.
external gate disadvantages: takes up more room in the engine bay, problem of getting it mounted if not buying a custom manifold or O2 housing, noise factor if routed to atmosphere, cost of buying the gate or cost of getting it mounted, and won't pass emissions if dumping to atmosphere (if they pop the hood and realize what you're doing anyway).

internal gate advantages: cheaper than getting an external gate, no noise factor (unless you buy an external dump tube on an O2 housing), no added space to the engine bay, no problem of getting it mounted, will pass emissions if routed to flow thru the exhaust pipe.
internal gate disadvantages: more back pressure if not dumped to atmosphere, usually a weak spring and gate opens early or leaks boost. can't "usually" control the spring size. easier to boost creep unless you get a bigger flapper door.

hope this clears things up a bit.
scott

 

[Drift_SM]

^ that deffinatly helped give me a better idea about them. thanks bro.