Btothe3rdDegree

over a internal? can you make a turbo internally WG, external?

PIC Performance

I think an external wastegate is better at preventing boost creep. It depends on the actual size of the wastegate, but from what I hear most internal wastegates are only suitable for low amounts of boost, unless you are running a tiny turbo. Once you start increasing it, boost creep becomes a bigger problem. I believe there is something inherently wrong with the internal design itself, but I'm not sure what it is. Apparently, an internal design causes turbulence in the path of the exhaust flow, and that hurts the turbo itself.
As far as converting internal to external, I think its possible to disable the stock internal wastegate (bolt the flapper down or something who knows), and add on an external one. HTH.

DaX

iTrader: (1)

What he said. Boost creep can become a problem. A good external wastegate with good plumbing will respond better also. Plus the just look better.

MikeMAN

pretty darn good 1st post there but yea, just to elaborate on what he said, internal wastegates are genenarlly small diaphram which can't bleed off boost fast enough and you get slight creep, non-steady boost whatever you want to call it. The larger diaphram of the external wastegates (primarily Tials 38mm and 40mm units) bleed the boost off must better and hold boost steady as a rock.

mike

PIC Performance

Got directed here from CSI's Got Boost forum. Still trying to plan out my future boost setup, and word on the street is H-T's got the know-how to answer my q's

Btothe3rdDegree

how much boost can a internal WG hold? is there anyway to go external from internal

PIC Performance

The question isn't so much "how much boost can it hold?" but "to what boost level is the wastegate effective?". And that depends on the wastegate itself, its hard to say unless you can provide the actual model turbo. It should be fine for stock boost, because its assumed that the manufacturer included an adequate wastegate for the turbo its installed on. Once you start increasing boost past stock, you are *possibly* looking at boost creep. I say possibly cuz its hard to say when you'll start havin probs, just check your boost gauge for spikes. See spikes, turn it down. No spikes, you're OK. Thats the quick and dirty, but spikes also mean damage to the turbo. So play it safe, just upgrade to an external.
There is no way to go from external to internal that I know of, only because an internal wastegate is actually built into the turbine housing (exhaust side) itself. Unless you want to go through the hassle of fabbing an internal wastegate, but why?
Sure, you'll spend more for a quality external piece and the necessary piping, but with FI, just like any sort of engine building, you really don't want to skimp or cut corners. Do it right, and save yourself some headaches down the road.

Btothe3rdDegree

thanks man, sorry i meant internal to external, you said just bolt the flange shut? can you weld it shut? i am looking for 250 whp on a built d series, and have been looking at some t3 48 trim off another car, do you think it would be wise to go external because of the psi? i am sure it will be over 10 psi to get what i want

PIC Performance

To be honest, I'm not really sure how you would go about disabling it. The design is pretty simple, just a flapper door that opens and closes to allow excess exhaust to flow out. I suppose you could go ahead and remove the actuator that opens/closes the flapper, and weld the flapper door shut. If this is a good idea or not, I couldn't tell you. Though it certainly sounds possible. Hopefully someone with more exp with this can straighten you out.
Can't help you on the turbo. If you think you'll be needing more to hit your goals, why not step up to a slightly bigger turbo? Is .48 even offered with the T3? It looks like you got your choice of 40, 45, 50 and 60 though. Perhaps t3/t04e?
Here's a site to calcuate output, if you have the necessary specs:
http://www.turbofast.com.au/javacalc.html

Btothe3rdDegree

yeah sorry i was thinking 50 and writing 48, the reason i want that size is because it is going to be a daily driver and i want a fast spool time, i dont want to wait til 4 or 5 grand for the turbo to start kicking in, if you have a suggestion let me know

MikeMAN

the funny thing is, (un until a certain amount) ,the lower the boost the bigger the wastegate SHOULD be. Lets say your running 5psi on X turbo. Well MANY turbos are good upwards of 15psi. a smaller wastegate has a smaller diaphram to bleed off ALL additional boost past 5psi. Make sense? The less boost you are running, the more boost a wastegate is bleeding off.

hope that helps some understand too!

good luck!,
mike

spoolinlude

finally, someone else who realizes you don't need a 50mm WG to run 29lbs of boost......... a local RX7 runs 28lbs with a 20mm wastegate..... boost is DEAD on.... always

danl

You need the bigger gate to bleed air AROUND the turbine wheel. Hence the name wastegate, or wasted exhaust gasses. Ideally, internally gated turbos equal the pressure best between all the cylinders and provide a more even flow. However, my crappy mitsu turbo creeps past 20 psi when I have the cutout open. I can keep it at 9 psi with my stock exhaust intact however.

Btothe3rdDegree

so do most cars that have turbos are internal? ie if i want a external wastegate i need to get a aftermarket turbo? like i said i want to make 250 whp on a built d series, so let me know

danl

No, you don't need a different turbo. You can weld the wastegate flapper shut. You can also disconnect the wastegate signal line (allthough this won't seal perfectly). With either done, you use the external to control boost.