External Gate DP 38 versus 44

[viperman5]

I am moving to an external gate DP. I am debating between a 38mm versus a 44/46mm external gate.

What are the limits of the 38 versus 44/46?

My car currently is stock heads and cam with a 66mm turbo. I do have plans for heads and cam in 2011.

Thanks in advance.

 

[RUQWKNF]

It's kinda a toss up actually.
The 39mm gate we offer, will work well with your current combo and the 46mm will work well once you install heads and cam.
The general rule of thumb is, the lower the boost level you want to run, the more wastegate will be needed to properly control the boost levels. Especially on a more efficient motor combo vs all stock.

IE: Low boost levels on a car with a decently sized roller cam and heads, will require a larger valve / wastegate to by pass more exhaust away from the turbine wheel, vs what a stock motor needs.

To give another example, on my old grey car, it had a 276ci off center stage 2 with ported and polished GN-1 heads, matching stock intake, and a baby 224/224 flat tappet cam. Turbo was a PT74GTQ at the time. With a 3" downpipe, dual 3" exhaust and a single Tial 38mm wastegate. I opened up the wastegate hole in the turbine housing to match the wastegate feed pipe as this is very critical when running any external wastegate mounted on the downpipe. With a manual bleeder valve, I was able to run the boost down as low as 18psi and as high as 35psi. Given, the choice of cam and the small Poston headers I'm sure had alot to do with me being able to get away with such a small wastegate. Other combinations similar to mine that ran roller cams and ATR headers, ran larger external wastegates. Deltagate Racegates and Tial 44mm were common in the class. (TSE)

If you know that eventually you will step up to heads, cam and possibly a larger motor in the future, I'd say go with a 46mm wastegate and you'll have all the control you'll ever need.
Just my O2's worth.

Patrick

 

[87WE4BOOSTED]

Boost Control

Hey Patrick ,

One of the new PW46 gates has landed in my lap, along with a DP setup to run it. My question is on my new motor along w/the Billet 6265, how would I get my boost down to 18psi? Please tell me it's as simple as placing the blue 18psi spring in and done. I do know the wastegate hole on the turbo has been opened up a bit.

P.S. My motor has heads and cam.

Thanks,

 

[RUQWKNF]

The PW46 wastegate should already have the Red and Green springs installed out of the box. You should have the Blue, Yellow and Natural colored springs loose in the box. The Red and Green spring combo is rated at 15psi. Also, if you look at the instructions on page 7, you will see how to properly hook up a manual boost control valve. If you have the Red and Green springs installed and have a boost control valve installed, with the valve closed I would test and see where the boost goes too under WOT. If the boost holds at 15-16psi, then in order to raise the boost, simply open the boost control valve under WOT slowly until you reach your desired boost level.

It should be pretty easy. However if you boost level runs higher than 18psi during this test, you will need to install lighter spring / springs in your wastegate. 99% of the time, the spring rate will be + / - a couple of pounds during real world testing. Meaning, if you have a 10psi spring installed, you might actually see 11-12 psi during testing. The "swing" varies from application to application.
Hope this helps.

Patrick

 

[87WE4BOOSTED]

The PW46 wastegate should already have the Red and Green springs installed out of the box. You should have the Blue, Yellow and Natural colored springs loose in the box. The Red and Green spring combo is rated at 15psi. Also, if you look at the instructions on page 7, you will see how to properly hook up a manual boost control valve. If you have the Red and Green springs installed and have a boost control valve installed, with the valve closed I would test and see where the boost goes too under WOT. If the boost holds at 15-16psi, then in order to raise the boost, simply open the boost control valve under WOT slowly until you reach your desired boost level.

It should be pretty easy. However if you boost level runs higher than 18psi during this test, you will need to install lighter spring / springs in your wastegate. 99% of the time, the spring rate will be + / - a couple of pounds during real world testing. Meaning, if you have a 10psi spring installed, you might actually see 11-12 psi during testing. The "swing" varies from application to application.
Hope this helps.

Patrick

Thanks Patrick,

This is exactly what I needed to hear.