Wastegates

[michaeli]

Hi Guys,

For the more technical users, has anyone ever kept the turbos but changed/ported the wastegates?

I've come across this you see....

What effect would this have if any?

Thanks,

Mike

[SGHOM]

At £918 + postage, it can have any effect it wants !! It ain't going on my car !!

[bradc]

Uc's car has 2 external 38mm wastegates, they are giving him problems at the moment, when he tries to run above 10psi, but his car does make 205kw ATW

[michaeli]

So it will have an affect on Power...


Any ideas on max power output possible by changing wastegates and not turbos??

Can changing the wastegates be changed without taking engine out??

UC - what are you experiencing and why did you go this route??

Thanks,

Mike

[michaeli]

Just found this which explains alot....


Let’s begin by describing what a turbo wastegate is. A wastegate is essentially a device that bypasses some exhaust flow around the turbine section of a turbocharger to control maximum boost. A wastegate is usually controlled by a pressure actuator that is connected to manifold pressure. The wastegate is normally closed, held shut by a spring inside the actuator canister. When preset pressure limits are exceeded, the actuator progressively opens the wastegate, allowing exhaust flow to bypass the turbine, thus regulating manifold boost pressure. On the surface, it sounds like a simple premise, and in fact, a wastegate is a simple device. The problem comes from the pressure in the exhaust system, called turbine inlet pressure that can bear against the valve, overpowering the spring in the actuator, and forcing the wastegate open at lower than intended boost levels.

Original equipment turbocharger wastegate actuators are selected or engineered for a specified boost level and turbine inlet pressure. To keep costs down, such actuators are usually just big enough to do the job at the stock boost levels. If the turbocharger boost is increased for additional airflow and performance, the stock wastegate actuator is frequently incapable of holding the wastegate fully closed until the higher boost level is reached. This happens because turbine inlet pressure also increases as boost pressure rises. The fix is to use a bigger spring in the wastegate actuator to hold it closed until the desired peak boost is achieved, however, that also requires a bigger actuator diaphragm to override the heavier spring when the desired boost level is reached. That’s why Banks created the Big Head actuator that’s used on many of its diesel power systems.

The net affect is that the turbocharger comes up to peak boost more quickly and then maintains that boost level throughout the engine’s RPM range for optimum mid-range torque and top end performance. It’s another example of the engineering expertise you get from Gale Banks Engineering. We do it right.



The above will explain why when people up the boost and it drops off at the top end...




So, is it possible to change wastegates without taking engine out?

[michaeli]

And this is very good too...


Inside the wastegate is a diaphragm which creates a seal, and a spring which holds the wastegate closed. Spring rates vary depending on the amount of boost you want to run, typically they are given in a "bar" value for example 1 bar would be 14.7psi. This would mean that in order to open the wastegate you would need to excerpt a greater pressure than the 14.7psi spring holding the wastegate closed. In order for the wastegate to work you must have the compressor reference port hooked up to the compressor side of the turbo, if you don't have this vacuum line attached than the boost pressure will not be limited to the set spring pressure; it will build unlimited boost pressure until your engine is destroyed.

Normally pressure from a spooling turbo pushes against the diaphragm (though the vacuum line attached to the compressor reference port) which in turn pushes against the wastegate spring. When the pressure from the spooling turbo exceeds the spring pressure the wastegate's plunger opens releasing the excess pressure through the dump tube into the exhaust after the turbo or to open atmosphere. Typically, if you use the wastegate to control your boost levels you will experience a decrease in power and spool times. Why? Although the spring fully opens at its set spring pressure it tends to begin opening before reaching the set spring pressure. This "pre-opening" leaks boost pressure through the dump tube before max boost pressure is reached resulting in a decrease in power mostly toward the top end. This can be corrected by using a boost controller.


Boost controllers serve two functions; increase boost levels beyond the set wastegate spring pressure and reduce the "pre-opening" of the wastegate-controlled boost pressure.




As your turbos get older, your wastegate spring will get weaker, causing boost leak, so you get a boost controller to counteract this, but it will still pre-open and cause boost leak, whihc leave 2 options:

1) replace the springs in the wastegate or upgrade it
2) replace the wastegate (and turbos)

[Kieran]

So, is it possible to change wastegates without taking engine out?

Errr. Not sure as I've never looked but I imagine doing all that fiddling with it in situ would be hugely awkard - In fact I bet it's nigh-on impossible on the rear turbo.

[michaeli]

You see, please share your wisdom....

[bradc]

He is coming into my work today, I'll hit him over the head, and tell him to reply to this topic

I think his engine was out when it was all being installed. The main reason he went with them was the noise from the screamer pipes, the extra boost control is just a side effect

[mitzylongboy]

michaeli..... mate!! if you want new BOV's find something cheaper. you got that baby coming..remember? you're looking at £2,000 + fitting!!
maybe you should start getting your nappy supplies. lol
in all seriousness i have seen a couple of pikkies with aftermarket BOV's and it appears the back one is VERY close to the ground. the owner did actually state it's close to to scrapping the ground!

[mitzylongboy]

looks close don't it?

[Kieran]

He's not on about BOVs though! He's on about ninja-spec wastegates!

[Rossco Type-S]

michaeli..... mate!! if you want new BOV's find something cheaper. you got that baby coming..remember? you're looking at £2,000 + fitting!!
maybe you should start getting your nappy supplies. lol
in all seriousness i have seen a couple of pikkies with aftermarket BOV's and it appears the back one is VERY close to the ground. the owner did actually state it's close to to scrapping the ground!

BOVs are not wastegates!

[michaeli]

Don't worry, they wouldn't be the ones in the link... that was just the spark for the idea really....

I was thinking along the lines that if I don't need to take the engine out then I could uprate the wastegates fairly easily and for less money/time than changing turbos...

It entirely depends on the turbo flow... what was the CFM of our turbos again? Valmes??

If I changed the wastegates, this wouldn't change the CFM though... would it??

[Nick Mann]

It entirely depends on the turbo flow... what was the CFM of our turbos again? Valmes??

If I changed the wastegates, this wouldn't change the CFM though... would it??

Not enough.

No.

Sorry to p!$$ on your bonfire.

[michaeli]

How much more BHP could we get with a better wastegates??

[Nick Mann]

Assuming your wastegates are functioning properly, not a lot. AFAIK the wastegates are shut to hold pressure. The pressure drop at high revs is a flow problem, not a wastegate problem. The simple fact is that to get high 300's (without the use of laughing gas!) we need to flow more air. Our little turbos can't do it. I'm sure better wastegate control would help, but at anywhere near the costs you have posted up there the better option would be turbos with more flow. In my humble opinion!

[You See]

UC - what are you experiencing and why did you go this route??

Do it, but those HKS ones are way too much for the standard turbos, it's best to stick with the smallest possible as in my case the wastegates dump it all out too quick and therefore the turbos aren't able to hold peak boost (boosts up to 14 then drops back to 10psi)
I was recommended to re-route the piping from where the wastegates flange are on each manifold and joining them to one.....thus only using 1 wastegate and allowing both turbos to spool and hold boost.
I went this route mainly for the noise....sounds awesome!

You see, please share your wisdom....

It was only 8am when you guys were posting, on a Saturday I'm allowed to sleep in....aren't I?..lol

[michaeli]

You're probably right Nick....

At least we got to a conclusion... Kind of...

I'd still like to know what UC has experienced...


Nick
Is the above wastegate info I posted worth making a sticky??

[michaeli]

Ooops... posted at the same time...

Do it, but those HKS ones are way too much for the standard turbos, it's best to stick with the smallest possible as in my case the wastegates dump it all out too quick and therefore the turbos aren't able to hold peak boost (boosts up to 14 then drops back to 10psi)
I was recommended to re-route the piping from where the wastegates flange are on each manifold and joining them to one.....thus only using 1 wastegate and allowing both turbos to spool and hold boost.
I went this route mainly for the noise....sounds awesome!

Ooohhh... post the sound... sound is always good... or at least describe it!!!

It was only 8am when you guys were posting, on a Saturday I'm allowed to sleep in....aren't I?..lol

Yes, whever I'm not asking you a question.... (Only joking)



What BHP increase did you get?
What problems are you experiencing that Bradc mentioned?
WHAT DOES IT SOUND LIKE??
Would I have to remove the engine?