Wastegate help

TrboVan · 03-08-2005

I have the following turbo:

Precision SC6152S
Compressor:
Garrett GT40 56 trim (aka GT35R) wheel in a TO4S 0.70 A/R ported shroud housing.
Turbine:
Garrett T350 (aka T3 Stage 5) wheel in a Precision T3 0.63 A/R housing.

I need to know my options for wastegate/boost control.

Thanks
-Bryan

**JET** · 03-08-2005

I would do an external gate off the O2 housing. TiAL 38mm may work, but I would go bigger. My turbo is basically identical to yours, but with a mitsu turbine housing and I run a TiAL 40mm.

TrboVan · 03-08-2005

Quote:

Originally Posted by JET

I would do an external gate off the O2 housing. TiAL 38mm may work, but I would go bigger. My turbo is basically identical to yours, but with a mitsu turbine housing and I run a TiAL 40mm.

I have heard that controlling boost is a problem with the external gates.

Tell me more, it is all new to me.

Is 38mm not as good as 40mm?

Will I be able to run 30-40 psi with an external gate?

**JET** · 03-08-2005

You can change springs in the TiAL's if they don't hold enough boost. Nash's held 40 psi out of a nearly identical turbo to yours. His is also a TiAL 40mm. They have some higher quality components compared to the 38mm. I think TiAL came out with a 42mm to replace it now, but I am not sure. Depending on the quality of the unit and signal strength, you can get a little boost spike. The TiAL's are pretty damn good though.

MustGoFaster · 03-08-2005

38 and 40 mm just refer to size. For the boost your looking to run a 38mm should be fine. If you want low boost you need a bigger gate. (bypass more exhaust gasses) It can also depend on motor size. Chrysler 2.2l turbo?

You have dealt with turbo’s and Waste gates before, just not external WG’s right? They all do the same thing. Open a flow path around/away from, the turbine wheel to regulate the speed of the turbo, and in turn boost produced.

I should note that I don't use external waste gates so JET is probably more knowledgeable on them than I.

TrboVan · 03-08-2005

Yes, 2.2 Chrysler.
I have worked with the internal wastegate for a few years now.
Just not sure on the external thing.

Does someone sell a flange for the turbo?

**JET** · 03-08-2005

If you have the 5 bolt housing, check here:

http://www.diamondstarmotorsport.com/diyparts.shtml

TrboVan · 03-08-2005

Thanks Jet!

Yes, here is the turbo.

TrboVan · 03-09-2005

Please remember I know nothing about external gates.

Does it matter where the external gate is installed?
Can I install it in the intercooler plumbing, or does it need to be near the exhaust header?

TrboVan · 03-09-2005

I am guess you need to "waste" the exhaust, so my question is pretty damn stupid.

john · 03-09-2005

Quote:

Originally Posted by TrboVan

I am guess you need to "waste" the exhaust, so my question is pretty damn stupid.

Yes it is. The wastegate can be installed on the exhaust manifold or it can be installed on the O2 housing. I ran mine off the O2 hosuing but have also ran one off the #1 runner. Both worked fine for me. As far as wastegates are concerned, I ran a tail 38 in my car and a HK$ wastegate in my brothers. They both worked fine. Ryan is right.

The size is the difference. You choose the spring to set the boost you want to run (ofcourse you would change it with a mbc). You will have to think about what boost you are going to run before buying a wastegate. You want to select a spring that is not too strong or too weak. If you get one too strong, it will never open when you want it. If you get one too weak, you run the risk of it opening too early if you choose to run a boost level well above it. If you wanted to run a minimum of 15psi, get one in that range (~1 bar).

**JET** · 03-09-2005

On the TiAL's there is also a material difference between the 38mm and 40mm. The 38mm is their basic, price leader model. The 40mm works better with race gas, which turbovan runs, so I would go with a 40mm.

john · 03-09-2005

From what I remember when I was purchassing one, there is an option for a different valve which is supposedly better on race gas (atleast on the 38mms). I remember talking to CVD at school about it one time. I did not get it. I bought the cheaper one. I do not have time to search now though. The obvious difference between them is the size and the flanges are different.

**Goat Blower** · 03-11-2005

I don't know what race gas would have to do with a wastegate except to match the spring to the boost level you're running, the EGT on the wastegate valve is going to be about the same.

**JET** · 03-11-2005

The diaphram in there used to be made out of a different material. I see the diaphrams are now the same on all the models, but the valve is not made out of the same stuff on the 38mm.

john · 03-11-2005

I am pretty sure it is/was an option. Not worth arguing about though. I did not see it as a problem as why I went with the standard one.