wastegate sizing?

[brett_celicacoupe]

is there a rule a thumb for the horsepower a wategate will flow safely? are the horsepower figures associated with wastegates for the respective flow of the wastegate on its own??

im estimating about 450 engine hp from 10-14 turbo psi.

im guessing nearly half the exhaust gas will go through the wastegate at full noise


help/links appreciated

cheers

[Bored?]

I've never seen any information on it, but here is my rationale:

In the steady state:
* Too small: Boost rises uncontrollably due to excess exhaust forced through turbo.
* Too big: Wastegate doesn't open fully, which doesn't matter particularly.

The other thing that will change is the response time of the wastegate. If you buy a good boost controller that shouldn't matter, as it should be tunable to wastegate response time.

So the short of it is buy one a little bit too big, and buy a good boost controller.

Sorry for not answering your question

[brett_celicacoupe]

yeh im looking for numbers dude

[Bored?]

You won't get numbers. It's not that easy - it will depend on how much exhaust gas your car is producing, and how much pressure differential and flow your turbo needed to produce the corresponding amount of intake flow and pressure.

And that depends on the capacity of your engine, both the turbine and compressor specifications of your turbo, the fuel, the AFR, etc. etc.

This is even harder than answering the question of what size turbo housing or A/R ratio you need.

[JustenGT8]

There's no rule of thumb that i'm aware of Brett but from personal experience 32mm would probably do, 35mm would be fine for sure and 45mm would most likely be too big.

The more efficient your WG pipework the smaller you'll get away with.

If you go too big compared to your turbine size you'll get a horrible surging setup

[The Real Roadrunner]

engine size?

turbo specs?

more info and i should be able to tell you whats needed.

you should actually try to keep waste gasses to a minimum as they aren't producing useful drive of the turbine/comp wheels.

if your using a small rear housing it will choke the combo anyway so a big wastegate wont help much.

cheers
linden

[brett_celicacoupe]

thanks,

im just expecting to need one a little bigger then usual as the turbo will be flowing a lot of air for relatively low boost.

[brett_celicacoupe]

engine size?

turbo specs?

more info and i should be able to tell you whats needed.

you should actually try to keep waste gasses to a minimum as they aren't producing useful drive of the turbine/comp wheels.

if your using a small rear housing it will choke the combo anyway so a big wastegate wont help much.

cheers
linden

3rzfe 2.7L
GT3540 ford spec garret thing,
eaton M90 blower after the turbo

the turbo is probably going to make 10-12psi and the M90 i will ratio to try make about 5psi. total boost will be just over 20 i suspect.

[slydin-cressy-style]

Turbosmart website has some info. It goes a little something like this (straight from the Turbosmart website) :

The more powerful the engine, the bigger the wastegate you need. This is one of the more popular misconceptions. Use this simple guide before setting out to find the biggest wastegate you can afford.
Big Turbo/Low Boost = Bigger Wastegate
Big Turbo/High Boost = Smaller Wastegate
Small Turbo/High Boost = Smaller Wastegate
Small Turbo/Low Boost = Bigger Wastegate


Wastegates don't really need to cope with high temperatures. Contrary to the popular belief, external wastegates are usually mounted at the hottest part of the exhaust. Its the place where all the exhaust gases meet, creating extra heat. This combined with the late combustion of unburnt fuel significantly raises the exhaust temperature. Check the temperature rating of the wastegate to make sure it's suitable for your application.

The larger the wastegate valve diameter, the bigger the flow. While the valve diameter is, without a doubt, an important part of the flow rate, equally important, but often misunderstood, is the importance of the valve travel. When comparing wastegates, dont be guided only by the valve size, check the amount of valve lift. In most cases it's more beneficial to have a wastegate with a smaller valve and long valve travel as this will give you a better control of your turbo resulting in a smoother boost curve.

Hope this helps bud

[wilbo666]

Big Turbo/Low Boost = Bigger Wastegate
Big Turbo/High Boost = Smaller Wastegate
Small Turbo/High Boost = Smaller Wastegate
Small Turbo/Low Boost = Bigger Wastegate

I was also going to mention this,

It doesn't give you 'numbers' as such, and guess with the twin charge doesn't really offer a lot of help initially...

Cheers
Wilbo

[The Real Roadrunner]

3rzfe 2.7L
GT3540 ford spec garret thing,
eaton M90 blower after the turbo

the turbo is probably going to make 10-12psi and the M90 i will ratio to try make about 5psi. total boost will be just over 20 i suspect.

id personally throw a 38mm tial on there, would have the required amount of flow especially when your running the 1.06 rear housing that is std on the ford version of a GT3582r.

chris eastons rb30 with a 25 head runs the same turbo/wastegate combo with excellent boost control and makes 280+rwkw @ 16psi on a paris hilton tune.

cheers
linden

ps, if your wondering why such little power from that engine/turbo combo, its a wrecker r31 rb30e short that was purchased for $100 with 178K kms and its still running 2yrs later.

[twentyEight]

Big Turbo/Low Boost = Bigger Wastegate
Big Turbo/High Boost = Smaller Wastegate
Small Turbo/High Boost = Smaller Wastegate
Small Turbo/Low Boost = Bigger Wastegate

So it can actually be written as:

Low Boost = Bigger Wastgate
High Boost = Smaller Wastgate

[brett_celicacoupe]

i was going to run the internal gate out for a while but im sure it will play up sooner or later?

ive heard they arent to stable

[The Real Roadrunner]

well it depends on what you call stable? it will control boost fairly well to a point but they start to overboost fairly easily as the hole is only small in them.

diegrind the hole out and fit a bigger flap on it to start with, if that still aint big enough then upgrade to an external gate.

cheers
linden

[fixeruperer]

im got my internal gate machined out to 32mm becuase it kept overboosting its been fine for years, but when this new turbo comes ill have to get external.