Waste Gate mounting options - Whats your experience?

[bgreen776]

I don't want to cut into my manifold to mount my 50mm external gate for two reasons, the biggest is that it wouldn't provide anything near an ideal exhaust flow path into the gate, the other is because I will soon be flipping my manifold and building a 63/480 compound setup. (currently running a single box S363 with a .91 twin scroll turbine housing) I would like to install this gate before I make the conversion as I currently have no waste gate and I'd like to spray it this summer. Using a 1" plate with a 1/8" wall 2" tube butt welded onto the side of it, I would get approximately the same flow at any given pressure as I would with a 38mm gate.

Given the poor flow path of a 90* mounted gate, and the reduced area due to the pinched down tube, do you think I will get enough flow to support a single 63/68 .91 and a solid shot of N20? (I know, I know, lots of variables!)

I see lots of people recommend a steed speed with the integral waste gate flange, but that method results in a 90* flow path as well. The real question becomes; what is good enough? Are gate plates and their inherent reduced area good enough for all but the most competitive racers, or are they just a sales gimmick? When does providing a smooth laminar waste gate flow path become important? (HP, Money, Consistency...?)

I hope to run low 12's this spring just the 363. I hope to run high tens with a 63/480 and N20 this fall. The truck is an 03 SRW crew cab. Thanks in advance for any kind of input. :Cheer:

 

[bgreen776]

The other option I have been thinking about is cutting into the turbine housing itself. I don't know how common that is, but it looks like the best way to package a mount and still have a good flow path?

 

[chris lang]

Waste gate or blow off valve is only relieving pressure, don't think it matters too much on fluid dynamics

 

[Smokem]

 

[Hurley]

^ha, nice info.

I don't want to cut into my manifold to mount my 50mm external gate for two reasons, the biggest is that it wouldn't provide anything near an ideal exhaust flow path into the gate, the other is because I will soon be flipping my manifold and building a 63/480 compound setup. (currently running a single box S363 with a .91 twin scroll turbine housing) I would like to install this gate before I make the conversion as I currently have no waste gate and I'd like to spray it this summer. Using a 1" plate with a 1/8" wall 2" tube butt welded onto the side of it, I would get approximately the same flow at any given pressure as I would with a 38mm gate.

Given the poor flow path of a 90* mounted gate, and the reduced area due to the pinched down tube, do you think I will get enough flow to support a single 63/68 .91 and a solid shot of N20? (I know, I know, lots of variables!)

I see lots of people recommend a steed speed with the integral waste gate flange, but that method results in a 90* flow path as well. The real question becomes; what is good enough? Are gate plates and their inherent reduced area good enough for all but the most competitive racers, or are they just a sales gimmick? When does providing a smooth laminar waste gate flow path become important? (HP, Money, Consistency...?)

The pinched pipe and elbow are minor losses IMHO, I would focus on the gate area versus the vented flow required.

 

[bgreen776]

Waste gate or blow off valve is only relieving pressure, don't think it matters too much on fluid dynamics

^ha, nice info.







The pinched pipe and elbow are minor losses IMHO, I would focus on the gate area versus the vented flow required.

In order for it to efficiently relieve pressure, it has to flow efficiently. The lower the flow the slower it will relieve pressure. Smashing the tube to half it's original cross-sectional area acts like an oriface, reducing the gates efficiency and decreasing the rate at which the valve can reduce drive pressure. I haven't done a flow calc yet, but that would tell us what percentage a 1.7 square inch opening will flow compared to a full 2.8 square inch opening.

 

[JD Dearden]

I had a set of triples a few years ago and ran 2 50 mm gates off the manifold between 5&6 and 1&2 off the bottom and recycled into the primaries with another 50 at the end to control overall. It worked perfectly.

 

[Signature600]

In order for it to efficiently relieve pressure, it has to flow efficiently. The lower the flow the slower it will relieve pressure. Smashing the tube to half it's original cross-sectional area acts like an oriface, reducing the gates efficiency and decreasing the rate at which the valve can reduce drive pressure. I haven't done a flow calc yet, but that would tell us what percentage a 1.7 square inch opening will flow compared to a full 2.8 square inch opening.

So if you already know so much, why did you ask?


Is maximum wastegate flow really that important? A 38mm wastegate is way bigger than any factory turbine housing wastegate, and is more than adequate for most street setups. You're installing a 50mm....

Chris

 

[Mooner1]

Not gonna debate the mounting vs flow thing cause I am not a big fan of the 90 degree mount either. However, after looking at one of Steed's comp manifolds with the built in w/gate first hand I have to say it looks about as good as a 90 mount could get IMO. I'd throw some pics out there if i had it handy. At some point packaging vs performance has to come into play to me. Maybe not in Dodge engine bays as much, but in a Dmax or stroke..good lawd.

 

[Bponci]

I did this a long time ago. Very simple yet compact and yielded good results.

 

[Bponci]

Here is a couple more pics of it. Hope this help with your project.

 

[CREED1]

Mine is welded to turbine housing in close proximity to what brad has his mounted..

Actually had it crack awhile back think the weld was faulty. We preheated and rewelded this time tappered the carbon weld down farther down pipe.. Haven't had an issue since.

 

[Signature600]

Forgot to put these in here earlier. Here's how I did my first one.

Chris

 

[Mooner1]

:clap: and :Cheer:

 

[bgreen776]

So if you already know so much, why did you ask?


Is maximum wastegate flow really that important? A 38mm wastegate is way bigger than any factory turbine housing wastegate, and is more than adequate for most street setups. You're installing a 50mm....

Chris

The real question becomes; what is good enough? Are gate plates and their inherent reduced area good enough for all but the most competitive racers, or are they just a sales gimmick? When does providing a smooth laminar waste gate flow path become important? (HP, Money, Consistency...?)

Thank you for the pics, I think that method is a pretty good compromise considering my application, just so long as it leaves room for a hot pipe and an S400 in the future? I've got some measuring to do!

Most street setups never come close to the power required to put a crew cab in the tens, much less the 12's. Also, a factory turbine housing waste gate was designed to flow enough to manage a system with roughly the same amount of exhaust flow as its standard compressors put out (ignoring the effect the engines compression and the combustion process), but it seems to make sense that when you throw that little turbo in front of a much larger turbo, the total output far exceeds the flow that the wastegate on the little turbo was ever designed to manage. Hence the much larger external waste gate. (someone please correct me if I am wrong)

While I believe I understand the physics (or at least most of it) on paper, I don't have the practical experience to tell me what is actually necessary in the real world. This is why I ask. I'm a mechanic, not an engineer. I care about practical field application more than what some book told me. And since I don't know it all, hopefully there is someone out there willing to share their knowledge.

The "book" tells me if I want maximum efficiency I would use a full 50MM diameter port installed in a manner to provide a smooth, laminar flow path. Not a 38mm port mounted 90 degrees from the normal flow path, but as you said, in the real world a 38 is probably good enough. That is exactly the kind input I am looking for. As we can all spout off theory and parrot other peoples experiences, I'd like to hear it from people who have actually put their money where their mouth is. That is why I posted on this forum.

 

[bgreen776]

I had a set of triples a few years ago and ran 2 50 mm gates off the manifold between 5&6 and 1&2 off the bottom and recycled into the primaries with another 50 at the end to control overall. It worked perfectly.

Good Lawd! :clap:

Here is a couple more pics of it. Hope this help with your project.

I hadn't considered a bolt on mount. :doh: You just blew my mind! :woohoo:

Mine is welded to turbine housing in close proximity to what brad has his mounted..

Actually had it crack awhile back think the weld was faulty. We preheated and rewelded this time tappered the carbon weld down farther down pipe.. Haven't had an issue since.

This attachment point seems like the best place for me, but I am concerned about cracking as well. Do you remember what rod you used? My first inclination was to just TIG something on there with about 400*F preheat and some 309L filler, then burry it in a bucket of sand. But some Jupiter B or some other high nickel SMAW rod might be better. I had one of the inspectors shoot the housing with his XRF Gun today, and verified that it is cast Iron, so I am pretty leery.

Forgot to put these in here earlier. Here's how I did my first one.

Chris

Thank you for the pictures!

 

[bgreen776]

Maybe one of you math wizards can correct me if I am wrong, but if we use a few generalized numbers, we can calculate how much the actual difference in flow is between a smashed flat tube and a fully round tube.

I took a piece of 2"x.125 wall tubing and mashed it to fit on the side of a 1" plate. This provided an opening on the inside of the tube that is .75" tall, and 2.5" long, giving me a cross-sectional flow area of 1.846"

A piece of 2"x.125 wall (1.75" ID) tubing in its most round form would have a cross-sectional flow area of 2.405"

Now... Lets say we are flowing 1500 CFM through that big 2" diameter tube (2.405 square inches = the cross-sectional flow area of a 2" .125 wall tube) for the sake of argument. Would the flow through a 1.533" tube (1.846 square inches) not be reduced to roughly 42% of the full 1.75" ID round tube?

 

[kjpcummins]

Why not do something like this.

 

[Hurley]

Maybe one of you math wizards can correct me if I am wrong, but if we use a few generalized numbers, we can calculate how much the actual difference in flow is between a smashed flat tube and a fully round tube.

I took a piece of 2"x.125 wall tubing and mashed it to fit on the side of a 1" plate. This provided an opening on the inside of the tube that is .75" tall, and 2.5" long, giving me a cross-sectional flow area of 1.846"

A piece of 2"x.125 wall (1.75" ID) tubing in its most round form would have a cross-sectional flow area of 2.405"

Now... Lets say we are flowing 1500 CFM through that big 2" diameter tube (2.405 square inches = the cross-sectional flow area of a 2" .125 wall tube) for the sake of argument. Would the flow through a 1.533" tube (1.846 square inches) not be reduced to roughly 42% of the full 1.75" ID round tube?

For the sake if discussion, estimating your 'vented' flow rate is the key for sizing the wastegate and associated plumbing - I agree that you can compare cross sectional area to a percentage decrease, but.... does that really matter if you don't know whether you're venting 20 lb/min or 50 lb/min. (CFM are out the window when you compare drive pressure differences of a setup - i.e. dumping a 50mm gate at 30psi drive is different than dumping a 44mm gate at 100psi)

to me it goes back to packaging; you make a compromise to fit the situation, and optimize from there.

 

[adamsmarshall]

For the sake if discussion, estimating your 'vented' flow rate is the key for sizing the wastegate and associated plumbing - I agree that you can compare cross sectional area to a percentage decrease, but.... does that really matter if you don't know whether you're venting 20 lb/min or 50 lb/min. (CFM are out the window when you compare drive pressure differences of a setup - i.e. dumping a 50mm gate at 30psi drive is different than dumping a 44mm gate at 100psi)

to me it goes back to packaging; you make a compromise to fit the situation, and optimize from there.

Not directed at your post in particular Hurley but just due to you mentioning the 50mm dumping 30psi and a 44mm dumping 100psi and so forth it reminded me of a question I searched for the other day and never brought up.

Does anyone actually know the flow of these wastegates? I searched through here, YB and several of the name brand WG manufacturers websites to no avail and couldn't find any numbers of what size X wastegate might flow at X amount of CFM/lb/min.

Just wondering as it would make sizing "smaller" turbine housings easier when running much larger primarys that require much more flow than even the larger secondary housings allow. So in order to run a housing that's small enough for street use the general consensus seems to be to just run the biggest gate you can find and just run it rather than running a smaller (physical and orifice size) wastegate and tuning to needs.

Basically the same thing that it seems a lot of people tend to want to do in running the biggest atmosphere charger they can find and expect it to push X amount of air through a 62mm turbo with a T3 housing. While it works, the efficiency just isn't there.

So after rambling on. Does anyone actually have any real numbers of what these wastegates flow? General 38, 40, 44 and 50 mm sizes would suffice, or a general formula would probably work even better (in my mind anyways).