Thread: Internal Wastegate That Can Hold 22psi

I need recommendations from people on an internal wastegate that can hold 22psi no problems to redline. Any personal experiences? Must be 2 bolt design and be compatible with the ATP bracket.

-G

There are a host of internal wastegate actuators out there that have swappable springs that should be able to get you there no problem. There are also ones with dual ports to make it easier to hold higher boost and control them like a typical external gate even if the spring is not strong.

Here's a thread with links to a few types: http://www.sr20-forum.com/wanted/52688-wanted-gtir-t28-wastegate-actuator.html

I personally went with Forge Motorsport for mine, but Turbosmart has options and you could go with a cheaper unit from Summit/Jegs too.


These are the typical spring options for the Forge Motorsports units. You could go with the blue spring and use a typical manual boost controller on top of that... Or just go with the red spring... Lots of options.
https://sphotos-b.xx.fbcdn.net/hphotos-snc7/416015_10151088573070100_1551935292_o.jpg

Pics from my build thread: http://www.sr20-forum.com/members-rides/554-benfenner-s-1994-black-se-r-30.html#post889511

Do you have an EBC Ben? If so, how much pressure were you able to hold w/the green spring? I bought a wastegate that was supposed to run 9psi..come to find out it only does 7psi or so and can't hold more than 13-14 psi at redline no matter what I do w/my EBC.

-G

I have a boost control solenoid that needs to go in, and I'll control boost with the AEM EMS. But none of that is hooked up yet.
I hold 4 psi for a while until things creep to 9 psi with this green spring.

If you can make over 14 psi of boost elsewhere but can't hold it at redline that's usually a sign the turbo is over it's limit. I don't think any boost control or springs can help. But who knows...

So you have an EBC hooked up to an internal wastegate with only one port right? That is a single port actuator right? Other than adding some preload, or cutting open that actuator and putting in a stronger spring, there's no way to really solve the situation. I would however get a cheap MBC (Vadim has a thread with links to great, cheap, eBay ones that I love) and test with that to make sure it is not an issue with the EBC.


There is probably some cheap wastegate actuator out there that can be had with a much stronger spring to suit your purposes. But I would rule out the EBC and the turbo running out of steam as failure modes first.

Hey Ben,

What do you base this off? I'm just wanting to know your thoughts behind your statement. I can get up to 19 psi before 5500 rpm for a very brief time but it seems right at around 5500rpm that the boost will start to fall quite rapidly and by redline I'm at 13-14psi. I was guessing that when the S4 cams kick in and the car start pumping a lot more exhaust gases that the wastegate spring just can't keep the flapper closed and is releasing too much exhaust which is causing the boost to fall off. I've set the EBC to almost max, which should be simulating something close to no pressure to the wastegate line(like you take the vacuum/pressure hose off it)

I theorize this because the last wastegate I had had the opposite effect where as the RPM went up I was gaining *more* boost. Come to find out, this was most likely caused by a threaded wastegate arm and the extreme angle I had the arm at, the threaded arm was getting 'caught' on the diaphragm housing(rubbing against it, causing it to catch). Anyways, with that wastegate I was hitting 17psi+ at redline but starting off at 12psi or so. It was annoying because I had a low amount of boost until I was getting close to redline.

I've had nothing but wastegate issues w/this damn car and I've literally taken the turbo off over 4 times just to change or fix a wastegate issue. I want this to be the last time!

-G

p.s. you've risen! I thought you were dead..

It would take a dyno sheet to really know what is going on, but it is possible that you're making around 375-420 WHP at 19 psi early in the rev range, and that is all the flow your turbo has to give. (Remember with a properly divorced wastegate you're going to make almost 40 WHP more at the same boost, which means most others are probably having to run 23 psi or so to make the same power you do at 19 psi. And that turbo is possibly happier at higher pressures, AKA a smaller or less flowing engine) So as the S4 cams really start to come on, your turbo is already maxed out for flow and the engine gobbles up that pressure a lot better than it did before and all it does is cause your intake pressure to drop, but you could be maintaining that 375-420 WHP all the way to redline.

Now, your theory of there just being tons of exhaust flow and thus exhaust pressure causing the flapper valve to creep open could also be what is happening. It really depends on how much power you're making throughout the rev range, or how much air that turbo is flowing. That's why a dyno chart would be really helpful to know what is really going on.
Or really knowing what is going on with that wastegate flapper.

One thing you could do is to disconnect the actuator arm from the flapper valve, and wire-tie the flapper valve shut with some thin bailing wire or safety wire or something. Or just disconnect the vacuum line from the actuator and wire shut the flapper valve. You should be able to do this without taking the turbo off the car. It may require removing a charge pipe or two, and the exhaust manifold from the head. But usually that is way easier and faster than removing the whole turbo. If you do this just make sure to keep an eye on boost levels and if you spike over 19 psi early or hold 19 psi for longer than normal then shut things down early because you know you've found the issue.

Making sure that you test with the flapper valve absolutely shut all the way, all the time, will be a great test to help narrow down if this is an issue with the turbo maxing out, or the spring in the actuator being too weak, or the EBC not doing its job properly, etc.
This test should be a lot less painful and cheaper than swapping actuators around to test stuff.

Now that I re-read your post I see that you had 17 psi at redline on a different actuator setup (that was snagging). Well, that sort of solves the problem for us I guess? Somehow that flapper is opening, whether it be the EBC or the vacuum line setup or the weak spring.