I need every bit of info. on an external wastegate

[JoeyJigglesGSX]

ok i need to purchase an external wastegate. I am not going to buy another part for my car until i have researched until it makes me sick, because everytime i think i know what im doing and i seem to miss something and it screws me over.

Now, i want to know every single bit of detail on what i need for an external wastegate and problems people have run into so i dont have to make the same mistakes

Here are some things i have been seeing:

-what runner should it be mounted on?
-what is the deal with these different springs (hp? what does that mean?)
-what type of spring should i get?
-what size wastegate? (38mm, 40mm....)
-where should it be plumbed back into? (i dont want it to atm.)

(please if there is anything i have missed mention it, if i get advice from someone and you dont like it, say it...i want every aspect on an external wastegate)

...real quick info. i have an evoIII 16g if that matters any

Thanks

 

[Lunch_Box]

-You can either mount off the number 1 runner, the collector, or on the O2 housing.
-If you chose a 15 Psi spring this is when you waste gate is going to open, you will not be able run boost lower than the spring, and I belive you can only run double the boost of the spring safely (ie: 15 Psi spring means you can run a max of 30 Psi)
-Spring size depends on what kind of boost you want to run, when you want the gate to open.
-38mm is fine for you
-Just run it back in where ever is easiest.

Why not look into getting an O2 housing already set up for an external gate?

 

[JoeyJigglesGSX]

cool thanks Lunch Box, now we are getting somewhere...

- i think if i have read right it is best to mount after the number 1 runner?
- and on the spring thing, thats cool i obviously never knew that. I am not trying to be a psycho with boost i mean, maybe when my car is done i would like to be driving around on like 20psi or something aroudn there. I dont think i would ever need to go 30psi. But that spring sounds about right, maybe a little less would be perfect.

--- here is another problem i just heard, is it true that you have to replace your fans because they get in the way?

 

[UMR98GSX]

You might run into a fitment issue with the fans if you mount it off of the collector but you should be fine on the #1 runner or the O2 housing. As for recirculating, it is easier to use a tubular O2 housing made for an external wastegate rather than off of the manifold since you do not want an atmospheric dump.

--Anson

 

[JoeyJigglesGSX]

correct me if im wrong, but how does eliminating boost creep work off of putting it on the o2 housing?

my o2 housing is ported as a mother! and i still have boost creep. The main problem is my turbine housing which i dont even want to talk about because i have had everything done to it and i still creep. I mean if i put it on my o2 housing the creep is before that, so it probably wont do much.

 

[oldman]

correct me if im wrong, but how does eliminating boost creep work off of putting it on the o2 housing?

my o2 housing is ported as a mother! and i still have boost creep. The main problem is my turbine housing which i dont even want to talk about because i have had everything done to it and i still creep. I mean if i put it on my o2 housing the creep is before that, so it probably wont do much.

And you're correct. An O2 mounted external is still limited to the restriction on the turbine inlet and wastegate path as we have discussed prior in your other threads. If you're going external, get one that is mounted on the manifold.

 

[JoeyJigglesGSX]

And you're correct. An O2 mounted external is still limited to the restriction on the turbine inlet and wastegate path as we have discussed prior in your other threads. If you're going external, get one that is mounted on the manifold.

great, thanks a lot oldman. That sums up a lot of basically what i need to know, and here is how i am so far...again correct me if im wrong:

- i need a 38mm wastegate for my set up
- it will be mounted on my 1st runner
- i will need a spring that will begin to open up at a minium of 14psi and strong enough to be able to handle about 25psi

-- so the only thing that i am unsure about is if my fans are going to get in the way...anyone who has def. done this know of any problems?

 

[99gst_racer]

And you're correct. An O2 mounted external is still limited to the restriction on the turbine inlet and wastegate path as we have discussed prior in your other threads. If you're going external, get one that is mounted on the manifold.

ding ding ding. We have a winner! Bruce - you took the words right outta my mouth.


JoeyJigglesGSX - If you want to run a minimum of 14 PSI, then you will need to purchase your 38mm Tial with a 1 bar spring (which is actually 14.48 psi). That spring will allow you to run a maximum of 29 PSI.

Under 450 HP, there is no difference from mounting the wastegate on the #1 runner or the collector. After 450 HP or so, you will want it on the collector. It is possible to weld the stainless flange on the stock cast manifold. Here's pics of where mine is flanged at.

With it flanged like this on the #1 runner, your biggest concern will be fabricating a dump tube that will clear the PS pump. It is a very tight squeeze. Here a thread on that subject.

As far as cooling fans. Your driver's side fan is the AC fan, so if you don't use your AC, you can just eliminate it anyway. But if you want to retain your AC, you will more than likely need to upgrade to a slim fan. The wastegate shouldn't hit the stock fan, but the dumptube probably would. The way you fabricate a dump tube , will make all the difference in how much room you have for fans.

I hope this all helps. If you have any other questions, just post 'em up.

 

[JoeyJigglesGSX]

thank you very much 99gst_racer. I am very nervous about doing all of this for some reason. I just have a bad feeling it is going to cost a a lot more money then i am expecting. Since you have yours custom onto your manifold, have you had any problems of cracking at all?

also, does anyone have any pics of what an external wastegate plumbed back in looks like?

 

[99gst_racer]

thank you very much 99gst_racer. I am very nervous about doing all of this for some reason. I just have a bad feeling it is going to cost a a lot more money then i am expecting.

With the WG itself, both flanges, porting, welding labor, and shipping both ways, I paid like $397. It's expensive, but well worth every penny IMO.

Since you have yours custom onto your manifold, have you had any problems of cracking at all?

I've had absolutely no problems whatsoever with cracking (and I do inspect it regularly). SBR's stainless-to-cast welds truely are the best I've seen.

 

[JoeyJigglesGSX]

it def. is worth it 99gst_racer and that is an incredible price i think, but i need it plumbed back into my downpipe. That is the only thing that sucks, and like we talked about before, the room for it, who knows what problems i will fall into.

 

[RavenX]

this is how i got my tial 38mm wastegate welded. I already had a evoIII manifold(ported) and it only cost me $100 to get the external welded on there. As for the fitment i have to reposition my slim a/c fan lower but the wastegate doesn't touch the radiator although its a very tight clearance theres maybe less than an inch between the end of the external and the radiator.

 

[Eclipse96Ryder]

wow good picture bro. and on my 1g talon I had my WG mounted to my 02 housing and it was great..

 

[talontsi97]

I have a question about the spring. If i have a 9psi spring does that mean right when i hit 9 pounds of boost the wastegate is going to open?
The 9psi spring makes it so the lowest i can turn the boost down to is 9psi, right?
I just wanna make sure for myself to.
Thanks alot
Good luck with it JoeyJigglesGSX

 

[oldman]

I have a question about the spring. If i have a 9psi spring does that mean right when i hit 9 pounds of boost the wastegate is going to open?

This only true if you don't have a boost controller and the pressure source is hooked up directly to the wastegate.

The 9psi spring makes it so the lowest i can turn the boost down to is 9psi, right?

Correct.

 

[talontsi97]

Thanks oldman for the quick response.
Im still wondering about it. If i am running 15psi on my boost controller and i have a 9psi spring then i would still be running 15psi rite?
Just wanna be positive and fully understand it.
Thanks

 

[oldman]

Im still wondering about it. If i am running 15psi on my boost controller and i have a 9psi spring then i would still be running 15psi rite?
Just wanna be positive and fully understand it.

The answer is yes. The function of a mbc is to block or bleed (ball/spring vs bleeder) off pressure creating a delay of the actual pressure source from reaching the actuator, the wastegate then opens later than it should resulting in a higher boost level.

 

[99gst_racer]

Thanks oldman for the quick response.
Im still wondering about it. If i am running 15psi on my boost controller and i have a 9psi spring then i would still be running 15psi rite?
Just wanna be positive and fully understand it.
Does anyone have a chart of the colors and all that stuff for the tial springs?
Thanks

Whatever spring you get, that will be the minimum amount of boost you can run with that spring; no matter what. Adding a boost controller will allow you to run anywhere from the set spring rate to double that rate. For example:

If you get the .9 bar spring (13 psi), you will not be able to run less than 13 psi. If you install a boost controller, you will be able to run anywhere between 13 psi and 26 psi.

 

[oldman]

Adding a boost controller will allow you to run anywhere from the set spring rate to double that rate. For example:

Why so Paul? I would think maximum boost should depend on the design of the mbc, the spring tension of the mbc and the maximum capability of the turbo itself. No?

 

[Black95TSIawd]

Why so Paul? I would think maximum boost should depend on the design of the mbc, the spring tension of the mbc and the maximum capability of the turbo itself. No?

you are absolutely right, old man. But, dont forget that many mbc shops sell higher strength springs to interchange within the mbc. If you are running external, you are NOT going any less then what the spring in the gate is rated at.

 

[oldman]

If you are running external, you are NOT going any less then what the spring in the gate is rated at.

No argument there, I was questioning the "max boost = double the spring rate" part.

 

[DSMJim]

No argument there, I was questioning the "max boost = double the spring rate" part.

I have a Tial 38mm off the runner (Turbonetics Manifold) with a 9psi spring. I have run 26psi on my car no problem

When using a boost controller is bleeds pressure away from the bottom of the diaphram and if you constantly bleed enough away it will take a lot of boost to make enough manifold pressure to open the wastegate on it's own.

If you get a electronic boost controller it will also apply pressure to the top of the gate thus allowing pressure to keep the gate closed harder longer. Most electronic boost controllers also allow you to control when the boost comes off the top of the gate. On my EVC i set it so that the gate opens as late as possible, but this can only be done on an electronic boost controller that runs in a push pull configuration (used top and bottom fittins on the wategate). With a manual boost controller you really loose a lot of flexability over control on an external wastegate that you could otherwise have with a good electronic unit.

 

[99gst_racer]

No argument there, I was questioning the "max boost = double the spring rate" part.

I originally got my info from this post, but after doing a little more research on the subject, I discovered it was more of the functioning ability of the boost controller itself. Many controllers just aren't designed to exceed double the value of many common size springs. I guess it's just a coincidence.