Internal and External Wastegate

[almc2242]

As you guys can see from this shoot, you can see the internal wastegate with the little nipple on it. What is the diffrence between this WG and a Ext WG? How it is activated? Should I change to an external WG, of so, How? Any other info or links to info will be apreciated.

[88 LE]

Originally posted by almc2242
As you guys can see from this shoot, you can see the internal wastegate with the little nipple on it. What is the diffrence between this WG and a Ext WG?

A external wastegate is not part of the turbo. Its mounted to the manifold and the discharge from it is either vented into the air or plumbed back into the downpipe.

They both do the same thing, which is to regulate the amount of boost.

However a external wastegate offers more adjustability (you can change out the spring and it has a adjustment screw) and better flow.

How it is activated? Should I change to an external WG, of so, How? Any other info or links to info will be apreciated.

A internal wastegate is activated by pressure (boost). Theres a hose that goes from the nipple on the compressor housing to the nipple on the wastegate.

A external wastegate is activated by pressure from the exhaust. The pressure from the exhaust pushes on a valve within the wastegate. It also has a vacuum/boost reference.


External wastegate setup:

[luisitol]

is that ur car?

[88 LE]

Originally posted by luisitol
is that ur car?

No.

I found the pic on the net while doing a search for external wastegates.

[bgrieger]

For an internal wastegate however, that is one of the best designs I have seen. Hell, even externals should ideally be plumbed like that. What turbo is that (don't recognize the make).

Bob

[wontonjohnny]

how do you adjust boost on a internal WG??

[Piddy]

I believe an internal wastegate has a minimum setting of boost.... for example... an MR2 cannot go below like 6 or 7psi due to the internal wastegate. You can change the maximum flow with a boost controller to gain more boost. Internal wastegates are not adjustable though.

An external wastegate will allow you to adjust boost at the wastegate without having any boost controller. If you wanted you could set it to 4psi or 20psi with no boost controller. You can still use a boost controller on an external wastegate if you want to do an on-the-fly boost switch type thing. But an MBC on a ExWastegate setup would be kinda pointless.

[88 LE]

Some internal wastegates are adjustable.

The rod from the wga (wastegate actuator) to the flapper valve is threaded, so you can adjust it.

However you can only increase the amount of boost. The wga has a spring inside of it thats preset to a certain amount of boost.

Other then that you would use a boost controller, either manual or electronic. But once again you can only increase the boost because of the preset spring in the wga.


Edit: You can also shim the wga with washers to increase the boost.

Unbolt the wga from the compressor housing and use 2 - 3 washers on each bolt hole in between the wga and compressor housing.

My buddy did this mod to a mk3 supra that he use to have. Increased the boost by 3 psi.


Heres a pic of the turbo (Garrett T3) that I use to have (Charlie (white90dx) has it now):




Notice how the rod from the wga is adjustable.

[MRQtwinturbo]

another advantage of going with an external WG is that it helps eliminate boost creep...i had serious creep issues with the stock ct-26 but once i did the t3/t4 swap with ext WG....zero creep...i'll post pics of my setup when i get home later......

i also love the sound of my WG when it dumps (to atmosphere)...i thought it was really loud at first but it grew on me....it really surprises ppls when i blast by them......but i'm always scanning the surrounding area for POPO because of the sound also....i've had some ppls tell me its too loud...but for normal driving...if u don't get into boost....u don't even hear it at all......just under WOT car screams get out of my way......

[victor]

what does it sound like when a wastegate dumps?

[MRQtwinturbo]

^it sounds like an open exhaust.......

heres a pic of my setup....

http://www.geocities.com/mrqturbo/turbo1.JPG

[Piddy]

Q.... why are there 3 clamps on your TB inlet to IC pipe?? Just curious. And it looks like your SSQV is on that same pipe? Crazy shit. Looks good... just out of the ordinary. Which is good.... im sick of looking at the same shit (most socal mr2's are boring ) when I go to meets.

[88 LE]

Originally posted by ishcoleobo
Q.... why are there 3 clamps on your TB inlet to IC pipe?? Just curious. And it looks like your SSQV is on that same pipe?

So the pipes don't blow off when he goes under boost.

To solve that problem you can have the ends of the pipe beaded or weld a bead onto them. And use T-bolt clamps.

And yes the ssqv is on the same pipe.

[Piddy]

He knows what I'm talking about...