3b twin scroll turbo

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I'm not convinced about porting wastegates. The whole purpose of a wastegate is to maintain a pressure drop across the turbine wheel. If you drop the drive pressure then the turbine isn't doing as much work. A wastegate only needs ported for more/better flow when it can't keep boost down at higher rpm.

But what I think is important and maybe what Gerg is getting at is merging the wastegate gas flow back into the main flow. If done wrong this can bump up your turbine exit pressure which also bumps up drive pressure.
 
gerg said:
So I ported the wastegate and removed casting that really encroached into the main wastegated gas flow. I have no pics of that, but nothing revolutionary. I do leave a generous 2-2.5mm of overlap for the flapper to seal over as I never want to leak and sacrifice spool. Really easy to get carried away with a die grinder. One problem with tools that do a lot of work quickly is....you can make mistakes quickly. I was happy to note that higher rpm boost vs drive pressure improved considerably after porting the gate which was what I was aiming for as its when the gate is flowing the most gas.

I shouldn't have said I ported the housing but rather removed casting and gasket matched it. Gasket matching is not as easy as one might think and I had to sandwich the mls gasket in between another flange and bolt it together tight or the grinder would have warped it and lead to leaks.

I also oversized the housing reciever ports to eliminate having a mismatched port which can easily happen from the slight play you get from the bolts when you put it into the manifold. You can always cheat fitment a few mm this way and that way. The problem is you have no clue what is and what isn't lining up when you bolt it together. By oversizing the housing ports you will get slightly less effecient flow but will avoid the disasterous flow you get when they are off and a step is created that encroaches into the gas stream. Ok so now a show of hands of all the folks who just said that's probably not happening to my turbo. Guess again. I've never had a turbo that mated perfectly.

The housing had some leftover casting that would decrease gas speed and waste energy. I had to resort to a dremel.....puke....cough.....slow as molasses....arg...I'm dying here...to do the work, but it can fit into small spaces which is a must. It also could vary speed which is nice inside the scroll to control the work. I used a a flex shaft and just bought a 90degree attachment. Tough to fit a tool inside that thing. Thanks mcreight for the tips on the casting. I don't know why, but I've never cleaned up inside a scroll before......maybe cus it sucks! Hah! It's worth it, but it is a painstakingly frustrating job. It's like trying to do a root canal throught the maxillary sinus floor. I mean common. Can't you just extruded hone the nerve out?

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Haha yeah they can be fun to clean up .
I use an electric porting tool from cc specialty tools, it's designed for doing 2stroke transfer ports . But the Dremel works and a bit more budget friendly.

Some housings really benefit from a better flowing waste gate .

Happy to help as your info has helped me too, Good to see it performing well.
 
Dougal said:
I'm not convinced about porting wastegates. The whole purpose of a wastegate is to maintain a pressure drop across the turbine wheel. If you drop the drive pressure then the turbine isn't doing as much work. A wastegate only needs ported for more/better flow when it can't keep boost down at higher rpm.

But what I think is important and maybe what Gerg is getting at is merging the wastegate gas flow back into the main flow. If done wrong this can bump up your turbine exit pressure which also bumps up drive pressure.
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I argree for the most part but some of the aftermarket mhi copies I've seen aren't copied well at all. Nozzle size , AR and waste gate size all close but not exact giving up valuable performance .

For the average bloke I wouldn't recommend porting wastegates. Without testing like @gerg had previously done your just taking a stab in the dark. Gerg had already developed a test plan, I just suggested some areas of improvement I've found with his Particular brand of turbine housing .
 
So I finished work today and ran over to the dyno shop a couple of towns over as they had a cancellation. I didn't unhook power steering belts or add fuel conditioner or do anything to change it from what I drive everyday. Had a bit of wastegate flutter up top. I was trying to butt tune for peak torque at 1800 rpm and I'm pretty close I think. Overall I'm pretty happy. Here is the result.

image.webp
 
gerg said:
So I finished work today and ran over to the dyno shop a couple of towns over as they had a cancellation. I didn't unhook power steering belts or add fuel conditioner or do anything to change it from what I drive everyday. Had a bit of wastegate flutter up top. I was trying to butt tune for peak torque at 1800 rpm and I'm pretty close I think. Overall I'm pretty happy. Here is the result.

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I like it..
I'll PM you
:)
 
Usually wheel slip does not show up as a jagged line like that. I have not run a mustang Dyno before but the Dynopack and Dyno Dynamics I have operated in the past did not show wheel slip in that way. Most dynos actually have use a small amount of smoothing in the software to minimize that.
 
gerg said:
So I finished work today and ran over to the dyno shop a couple of towns over as they had a cancellation. I didn't unhook power steering belts or add fuel conditioner or do anything to change it from what I drive everyday. Had a bit of wastegate flutter up top. I was trying to butt tune for peak torque at 1800 rpm and I'm pretty close I think. Overall I'm pretty happy. Here is the result.
Click to expand...

So green is boost on 1/10 the torque scale? Is the power scale corrected or as measured at the wheels? What rubber were you running (chunky vs A/T vs road)?
 
Haha! so clearly I have some questions to ask them. It was closing time and I felt sort of in a rush. They kind of fit me in last minute. Im running 33' all terrains. I was going to Jack the tire pressure up but forgot. 30lbs pressure only. That is wheel power. I still can't make sence of the boost curve. I think it's 1/10th. He did t into my boost line. I'm not sure how they did engine speed but from reading on the all misleading internet I've seen dynos with wavy lines like my pull that come from engine vibration interfering with the rpm pick up. Not sure if they did an injection line sensor or used the dyno rpm? For the gear changes it sounded like he pulled in3rd gear.
So I guess it raises more questions than answers. Sorry guys.
g
 
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Very nice gerg. I like that nice low 1750rpm torque peak. As the power is still rising beyond 3000rpm, my guess is it would have peaked around 100whp? That is a very strong 3B turbo. Based on this graph, what do you estimate your crank hp would be?

$100 for a dyno session is less than I thought it would be.
 
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I don't like HP. I find it offends my inner child. Corse my inner child hasn't had his morning coffee so that might have something to do with it. Given the turbo Design chokes less I could see it improving a bit more. My timing is retarded so that wouldn't help that far up the rev range mind you. I can tell you though that it pulls very strong from 2000-3000rpm. It doesn't taper off or anything. It's got quite a broad usable rev range. Taking the drivetrain losses into account I don't know what the crank.....um....energy is. The stock engine puts out 90hp but many dynos show like 45hp to the ground? That's some high losses. I'm more focused on the torque number and when it peaked. It's not breaking any records but its a joy to drive.
 
What's the stock torque output?

Give your inner child some red cordial and tell him to happy the fxxx up!
That number he's offended by is at least a 50% increase on stock output, (assuming 30% drive line losses) and you've got torque along with it.

Not too shabby
 
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