External wastegate - use it as a boost controller?

[filthyrich]

Hi guys

I\'m just wondering if this is:

A) Doable

B) A good idea

I have an external wastegate fitted on my car. I think that using the springs inside I can achieve the boost level that I want, and remove the factory boost solenoid completely.

Is this true?

The only downside I can see is that it will always be set at that level, instead of the ecu limiting the boost at lower rpms and loads.

Just kind of thinking out loud.

Thanks

[Guest]

If you unplug the solenoid it will throw cel. When it hits boost cut it will still cut coz map sensor. But yes putting a spring in will be algoods I have no idea how you would run solenoid and external in the same sentence. I dont know but dont think that there is heaps of boost limits. Maybe when its cold and you try giving it a hiding it would. My G4 has to have the car up to temp before it lets you have any boosties.

A DECENT EBC is a good way to control external so it doesnt start creeping open at half your desired pressure.

[funkytown]

You could set it at a given wastegate pressure and use it as a boost controller.

It wont come on boost as hard.

Make sure the gate is big enough so you dont get boost creep in high rpms

[filthyrich]

My ECU has the boost cut removed, and I have a later model MAP sensor which is good for more boost than I want to run. I guess I can tuck the factory solenoid somewhere.

I was wondering about the creep though.

I guess an aftermarket EBC still needs the factory solenoid to be plugged in to avoid the CEL?

[filthyrich]

Just out of interest, why wont it come on boost as hard?

[boon]

The boost control bleeds a percentage of the pressure feed from the compressor cover to atmo (or back into your intake in most cases) meaning that the spring sees much less pressure until it is time for it to open, when the solenoid goes fully closed.

Even if you put in a "14psi" spring it will start to creep open with only a few PSI of boost, meaning you\'re not getting full flow to the turbine so boost won\'t build as fast. This is part of the reason some people run those pressure relief valve dealies, which don\'t allow any boost to reach the wastegate until a certain point and then let it all through.

Also, ideally with an external you put boost on the other side of the diaphragm while building boost to hold the wastegate completely shut. Which you can\'t do if you\'re just running a spring.

[Pappu1]

u can run internal gate and external gate and then have them switchable and have one as low and the other as high

[Guest]

Nature of the beast. I had a 12psi and it started opening at 7ish. I had a SCREAMER pipe so I know it was opening.

Yea unless you run ecu boost control you will need to have the solenoid plugged in. You could possibly run a resistor.

Out of interest how did you tune the computer to make it run safe with more boost?

[filthyrich]

Ahhhhh that makes sense.

So I\'m on the hunt for an EBC.

I cant run both because its twisted and welded shut hahaha

I\'ve been tuning ECUs for many many many years

[Pappu1]

even with ebc u will be limited to the spring pressure as they will only allow u to go higher

the racecar finally getting ready ay bro!

[Guest]

 filthyrich said:

Ahhhhh that makes sense.

So I\'m on the hunt for an EBC.

I cant run both because its twisted and welded shut hahaha

I\'ve been tuning ECUs for many many many years

A good ebc not an electronic tap.

How do you tune ecus and what versions?

[madmike]

I have a nice gizzmo IBC here..

I used it to run my tdo5 at 15psi on my RS.

Comes with all wiring and solinoid.

$350 and it\'s yours

[Marky]

me i would say take the relief valve route for boost control unless you need it to do something crafty... or if you just have deeper pockets than me

factory wastegate suffers the exact same situation with creeping as well for what its worth

[Rosssub]

If you want to disguard the factory boost solenoid without throwing a cel could you just plug the return to inlet/vent hose with a ballbearing, then solenoid can open and close all it wants but it wont bleed any pressure out.

Then \'T\' your EBC or bleed valve hose in pre factory solenoid.

[lachlan]

unplug sensors/solenoids you dont want any more

measure resistance across the pins

buy 5 watt resisters from jaycar for $3 the matching resistance

jam the leads in the plug .

tape it up

tuck it out of the way

hey presto no more useless s*** on the inner guard .

have done the above to the map sensor the waste gate solenoid and the map sensor bypass solenoid thing on my car about a year ago .

still idles good . still has good afrs everywhere

also the short answer of why a 12 psi gate will crack open at 7 psi is bacause it has to be half way open at 12 psi

to move 10 mm to be half way open it will open 1 mm at 7psi

pneumatic things do this being being compressible

a relief valve will negate 99% of this .

a servo or pwm oil pressure controlled waste gate gate will negate 100% of it

[filthyrich]

So just chuck a pooey boost tap in and call it a day?

[Marky]

i would

for all the ranting about how they spike and cause the car to ignite and your kids to all be ginga and other terrible things, they do tend to work just fine - especially the newer turbosmart gated ones (they work kinda like a grainger valve or relief valve, holding boost back till about 75% of target pressure and going a long way towards stopping boost creep) or similar

not perfect but you get what you pay for, if you end up with a decent ecu it can then control the boost for you but in the meantime the cost if an ebc can go a long way towards other stuff.

i know its not the common opinion but hey

ebc has its place - dont get me wrong - but if the thing spools up fast, and holds pressure, and doesnt spike, then why blow more cash on something which wont do anything different or make a minute difference

but its not my money

[lachlan]

manual boost controllers only have a bad reputation because of the $30 pos on trade me that have a ball bearing as round as a river stone , a spring from a cheap pen that doesn\'t fit and the taper on the needle is about as fine as the end of a fence post , and made from a similar material

coupled with engrish enstrukshin and lil jonny wants his cef to hit it with no idea on the principals of boost control = fail

http://www.gfb.com.au/technical/dyno-proof

that is a good explanation of waste gate creep and what only runnign spring pressure does .

[filthyrich]

Makes sense now.

Thanks guys

[Pappu1]

depends what u use them for the 30$ TM ones do work to a point

just based on what u need them to do

just saying....

[filthyrich]

I have a turbosmart one kicking around somewhere. I\'ll dig it out.

Will work at least to get it going and then I\'ll worry about an EBC later.