I am posting this for my friend who is about to do a big turbo setup on his 1.8t. He asked me which is better. I said I like external wastegates better b/c I have heard of internal gates failing and not being as reliable as an external gate.

What are you thoughts and why?

 

From what I've picked up, (and I'm in no way an expert) there are a few advantages of running an external gate..

First of all, they open up differently, an internal gate opens like a flapper so even when it's all the way open it's only open at an angle.

Internal wastegates also have a tendancy to open up a little before the desired boost is reached because of the way it opens...

Internal gates direct the extra gas right back into the main stream and cause turbulance which doesn't help performance...

External wastegates pop open and the whole piston opens up, releasing more gas more efficiently...

There are some other points that I can't think of right now, I'm sure other people will be able to give better info than me...

But that's my $.02

 

At low boost levels the internal wastegate doesn't open enough and may cause boost creep

At higher boost levels the internal wastegate opens too soon and is not as efficient as external

The only advantage I see in an internal is that it's not as loud and can pass visual emmisions because the gas is routed back into the exhaust system

 

thanks you guys for some information. Who else has some input?

 

as a shop owner working on only turbo cars I can say right off the bat I would go external. internal gates are a cop-out for their cheap production cost in castings. they are sufficient only if the gate and turbine housing are matched well with the displacement and boost pressure you may run. no wastegates "pop open". they run on a spring and diaphram, so if you have a 7lb spring, the gate is going to START openeing around 3-4psi and be wide open at 7psi. other ways of doing it are with a nice boost controller that has a gate control function. then if you have lets say a 7lb spring in the gate, the boost controller will not release input pressure to the gate until it sees whatever pressure you want. so if you have a 7lb spring and gate pressure set top 7psi, the gate will STAY CLOSED completely until the controller sees 7psi, then and only then it will "pop open" in full.

boost creep is a real bitch and deadly to a stock motor and some driving that is not paying attention. if the boost comes up, it creates more exhaust, and if the exhaust flow overcomes the wastegate port size you have a problem.

hope that helped.

 

external is COOOLER CAUSE ITS LOWD AS HELL

 

any more ideas.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by agileauto.com &raquo;</TD></TR><TR><TD CLASS="quote">as a shop owner working on only turbo cars I can say right off the bat I would go external. internal gates are a cop-out for their cheap production cost in castings. they are sufficient only if the gate and turbine housing are matched well with the displacement and boost pressure you may run. no wastegates "pop open". they run on a spring and diaphram, so if you have a 7lb spring, the gate is going to START openeing around 3-4psi and be wide open at 7psi. other ways of doing it are with a nice boost controller that has a gate control function. then if you have lets say a 7lb spring in the gate, the boost controller will not release input pressure to the gate until it sees whatever pressure you want. so if you have a 7lb spring and gate pressure set top 7psi, the gate will STAY CLOSED completely until the controller sees 7psi, then and only then it will "pop open" in full.

boost creep is a real bitch and deadly to a stock motor and some driving that is not paying attention. if the boost comes up, it creates more exhaust, and if the exhaust flow overcomes the wastegate port size you have a problem.

hope that helped.</TD></TR></TABLE>

So you are saying Internal wastegate is only good when you have a good boost controller? When the gate start opening around 3-4psi, wouldn't you lose some boost and will not hit 7psi, maybe around 6psi? Or when it start opening around 3-4psi, it will take more pressure to open up the gate fully which means that it might take 8-9 psi just to open the gate up fully at 7psi?

 

i think with external you can control boost alot easier and consistant

 

when i first installed my turbo i thought that i wouldnt be able to get a filter to fit either, it was too close to the block, but i rotated the housing 180 degrees and now i can sqeeze one in between the block and radiator

 

If the option is available, go with the external.
That being said, internal wastegates are very good at regulating large amounts of boost &gt;~17ish PSI. They are less effective at regulating smaller amounts of boost, ~7-13PSI, typical of most Honda applications. You stated you friend is running a 1.8T which brings to mind 2 things:

1: There is NOT alot of room between the firewall and the engine for an external wastegate, which would require a special manifold also, correct?

2: VAG motors must run more boost to achieve the same power levels as a Honda. At these levels, an internal gate is usually more than enough.

You also said your friend is doing a "big turbo" upgrade. You need to find out some more information, like what turbo, what PSI, and what manifold is neccesary. The manifold may REQUIRE an external gate. Anyway, I hope that helped, if you need any more help feel free to PM me, I have alot of VW friends, and 2 aftermarket turbocharged.

 

tell your friend that his internal gate will be fine . Many people with APR Stage 3 kits run 24psi with 0 problems

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by oxSLEEPERxo &raquo;</TD></TR><TR><TD CLASS="quote">

So you are saying Internal wastegate is only good when you have a good boost controller? When the gate start opening around 3-4psi, wouldn't you lose some boost and will not hit 7psi, maybe around 6psi? Or when it start opening around 3-4psi, it will take more pressure to open up the gate fully which means that it might take 8-9 psi just to open the gate up fully at 7psi?</TD></TR></TABLE>

the gate will begin to open around 3-4psi. this only means it is beginning to open so that it can keep up with the pressure. you will continue to build boost until it is wide open. the reason you still hit 7 psi is because the turbo is still in the process of spinning up to speed.

you don't lose "boost" when it begins to open. you lose exhaust gas that would otherwise power the turbine. this means your boost rise is more sluggish. in other words, you will build boost slower if you have no way of keeping the gate completely shut until desired pressure is achieved.


as far as internal gates being better for big boost it's a two way street. yeah, the gate needs to vent alot of exhaust to maintain low boost, but when you are running high boost ~17psi or so for example, you have increased the amount of air and fuel you are injecting in the combustion chamber and this in and of itself will increase the amount of exhaust output you have dramatically. so, it's almost the same. this is why wastegate manufacturers recommend their 40-50mm gates for over 5-600 horsepower instead of the 35-38mm gates. if you're making that type of power, you must be building alot of boost pressure and consequently creating a boatload more exhaust gas for the wastegate to deal with.

hope I cleared up any mysteries.

 

External wastegate will be better if it dumped outside the exhaust stream. If it is plumped back into the exhaust system then it is no better than the internal wastegate. FYI, GN and turbo Buick Regal have ran into the 9's with internal wastegate turbo.