Turbo chat. Educate me (About wastegates)

[shrike]

16 hours ago, Muncie said:

So it's single scroll, 2.5" v band mount, was curious if it would be better to run dual gates or not eg one for each bank of the v6.

One massive gate would make plumbing far easier. 

Aiming to start at 14-15 psi with any luck that'll be pretty peppy the block will take that no problem. 

Typically single scroll you just run one and as close to the turbo as possible, twin scroll you generally want to run one per scroll. (with twin scroll you can get away with one per pipe if youve merged pipes before hand)

Assuming your going to do a 3-1 for each bank and then merge two pipes into the vband flange? (if so youll need to do the gate so it has gas from both pipes able to flow into it.

There is a balance between flow and velocity ideally you want more gas velocity to help spool the turbo and then good flow out of the turbo, but you don't want it too restrictive as that can cause back pressure etc

Alternatively I am still a fan of putting the gate on the turbine housing but it can be a pain for packaging (and welding cast isn't fun) 

Main thing with any wastegate is you want the exhaust to be able to easily flow through it when its open and divert away from the turbo, can have the biggest gate in the world but if doesn't have a good flow of gas going to it then its not that effective.

The chinese wastegates can be ok if you dissemble them and do QC/ reassemble them correctly, know a few people who have replaced diaphragms etc with genuine options as well.

Obviously if your happy to spend the coin genuine is the way to go

Cool so 1bar spring in the gate it is then :p

Hope that makes sense, and I am no expert but just things ive picked up over time

[Muncie]

On 11/01/2022 at 13:28, shrike said:

Typically single scroll you just run one and as close to the turbo as possible, twin scroll you generally want to run one per scroll. (with twin scroll you can get away with one per pipe if youve merged pipes before hand)

Assuming your going to do a 3-1 for each bank and then merge two pipes into the vband flange? (if so youll need to do the gate so it has gas from both pipes able to flow into it.

There is a balance between flow and velocity ideally you want more gas velocity to help spool the turbo and then good flow out of the turbo, but you don't want it too restrictive as that can cause back pressure etc

Alternatively I am still a fan of putting the gate on the turbine housing but it can be a pain for packaging (and welding cast isn't fun) 

Main thing with any wastegate is you want the exhaust to be able to easily flow through it when its open and divert away from the turbo, can have the biggest gate in the world but if doesn't have a good flow of gas going to it then its not that effective.

The chinese wastegates can be ok if you dissemble them and do QC/ reassemble them correctly, know a few people who have replaced diaphragms etc with genuine options as well.

Obviously if your happy to spend the coin genuine is the way to go

Cool so 1bar spring in the gate it is then :p

Hope that makes sense, and I am no expert but just things ive picked up over time

Went with the 60mm wastegate in end turbo arrived and is pretty damned nice so ordered same brand. 

Will be using the old flipped manifold method as after flipping the passengers side over it sits right where I need it, Will be room to give the wastegate priority flow at the merge of 2 exhaust banks as well

Plenty of room to fit a 3.5" downpipe between chassis and engine.

 

[drftnmaz]

Nice, the bigger the dump pipe the better for spool/transient response, this helps with pressure drop across the turbine, it can step down to smaller down the line with next to no losses (ie 4" dump to 3" system, it's cheaper, easier to get, clears ground better etc)
And don't go too big on the exhaust crossover pipes, you need to keep velocity high pre-turbine, so close to factory ID and a nice merge where they meet.

Being a V motor I'd also consider using a slip join or maybe flexi between the two sides to help with expansion etc (i've never played with flexi's on high temp/pressure side so unsure which one you'd use)

[Muncie]

8 hours ago, drftnmaz said:

Nice, the bigger the dump pipe the better for spool/transient response, this helps with pressure drop across the turbine, it can step down to smaller down the line with next to no losses (ie 4" dump to 3" system, it's cheaper, easier to get, clears ground better etc)
And don't go too big on the exhaust crossover pipes, you need to keep velocity high pre-turbine, so close to factory ID and a nice merge where they meet.

Being a V motor I'd also consider using a slip join or maybe flexi between the two sides to help with expansion etc (i've never played with flexi's on high temp/pressure side so unsure which one you'd use)

I've planned on going 3.5" exhaust front to back as I've got the room underneath car is 15-20mm higher than stock on the VF wheels (which I like) and will help later on not be a cop magnet.

Sinco do these sweet bellows was going to to the crossover pipe in 2" with one in middle and heat wrap the shit out of it can imagine she'll grow a few mm on song. Will also put one on the wastegate between the outlet and where it plumbs back in.

[Muncie]

Despite some of the above advice I ended up buying the bigger turbo the GTX3584RS GEN2 I did have 0.83 exhaust housing fitted so that should help it spool up over the 1.01 a bit better.

I don't mind some lag so I can still get  good economy and be able to keep it from arcing up at highway cruising speeds once I change the diff gears for some 3.4's or 3.7's, I should then be able chop it down a cog and land right into the power zone.

 

[ThePog]

It's time to fity turbo bleed valve, is it better to have it close to the turbo or doesn't it matter? I imagine a certain lag in the response time if it's too far away ....?

[mjrstar]

Any difference will be negligible, put it wherever is convenient to access. 

 

Maybe even mount it in the cab do you can adjust it on the fly, then install it permanently once it's set up. 

[ThePog]

6 minutes ago, mjrstar said:

Any difference will be negligible, put it wherever is convenient to access. 

 

Maybe even mount it in the cab do you can adjust it on the fly, then install it permanently once it's set up. 

Chur, it's only temporary until I decide on the level I'll go to, I have a kinugawa actuator on the way that I can swap springs to suit.....

[Muncie]

Its Just a controlled leak if you have a maf sensor make sure you plumb the bled air back in behind the maf. I had a leak on my vw at this point and it would go into limp mode/check engine light till I sorted it.