Recently, we added an Evo IX to the local test pool. So we decided to do a design study on how our 50mm Synchronic wastegate would work as a bolt-on in that application. Our main goal was to see if we could come up with a simple bolt-on application that would fix a couple of problems traditionally seen with the internal wastegate.

It would be nice if we could build some sort of stealth pipe that could tuck in and hide the obvious hardware under the exhaust manifold somewhere ???



We got pretty lucky here to be able to tuck a 50mm wastegate and still have great clearance for a thicker radiator if needed. It works great with an LICP. The V-Bands also make it nice, because the placement for the WG allowed us to be able to rotate it for a full atmospheric dump, or be able to route back in anywhere before the cat so that it can be within spec of Time Attack's new rules for Street class.

The prototype was welded up and setup to be tested.



The part turned out pretty good for a prototype that is going to be hacked up and probed eventually. There isn't a flex pipe there because we still needed to tool this up and that would be best done on a rigid proto. We'll be picking up one of Vibrant's flex pipes that are specially made for forced induction. BTW, when it comes to flex pipes most people don't know that there is a different type of flex just for the pressures & temperatures of forced induction. Vibrant is the only one that has these AFAIK.

There's welds now, but if this thing goes into production with enough demand, we'll get the whole thing programmed as a 1 piece tube. The guys hate me too cause I'm a real stickler for less radius and eliminating bends. We were actually able to completely eliminate 1 bend with some creative rotation.



That flange is in mild steel on the proto, but will be laser cut 304 if it ever goes into production.



The angle cut on the dump looks pretty sick on the car, especially since it runs parallel with the ground



Now, on to what it actually does . . . besides scare the hell out of open pipe Cobras.

We're running on just pure spring, no solenoid, no bleed, no MBC. It is spooling a little slower at first but when you get up to RPM it pops to 20 psi. BUT, no spiking, and best of all, absolutely no boost taper all the way to redline.

If we're able to eliminate the taper, then all that needs to be done is some WGDC % at the lower RPM to spool it quicker. We should be able to get around to testing an MBC also to see if that fixes spool time.

 

For those of you unfamiliar with the Synchronic wastegate, it has several ports on it, like our DV/BOV. What this means is that you can change the boost just by choosing a different port, or port combo. You may also change the overall response of the wastegate with the different ports.

On Port C we were making 17 psi to redline, no taper
On Port D we were making 21 psi to redline with no taper, and it spooled up a bit quicker.

 

Does this configuration create lag because the twin scrolls are not sealed off from each other, so when there is a pulse entering the turbo on one scroll, the pressure goes from that scroll and bleeds off into the other, because there is no flap sealing the scrolls apart during spool up when the flapper is closed.
If that makes sense.

 

How about some before/after dyno or boost plots please, since this is R&D work

 

This design seems to be popping up on the X. Interested to see if there are any power gains.

 

This is definitely, not peak efficiency in terms of twin scroll setups. However, either way, the exhaust gas is making it to the turbine, so the energy is going to the turbo no matter what.

What is the real contributor to the lag, is that we have the WG lightly sprung, so it starts cracking open at around 9 lbs. We still have some tinkering to do with various springs. The goal for us in this exercise is to come up with an Evo specific setup.

I was encouraged with eliminating the boost taper. Everyone's blaming the turbo for that effect, and clearly it isn't up to 23psi . . . so far.

 

i would be very interested to know what difference it made, whether there is greater reversion etc because of it
i am running this same setup on my car, and i'm wondering if it's contributing to my lag.

 

Bust that Dynapack out

 

There has already been a couple guys that showed that tossing a wastegate on there without keeping it divided caused slow spool.

FP has come out and said there is no reason to use an external gate. The stock actuator can force the shaft speed to the max speed that makes best power. Forcing it past that point will up boost, but the increased exhaust back pressure offsets those gains greatly.

Lastly, 1 piece downpipes/O2 housings suck. I've had them twice now and will never do it again. There needs to be a flange that allows you to take out the downpipe without unbolting it from the turbine housing. That down pipe gets in the way on a lot of part installs and not being able to take it off easily is a major PITA.

 

I wish dude, I only have a 2 WD right now, on the hunt for 2 more pods We might go up and use someone else's Dynapacks.


I'm actually experimenting with this setup specifically to solve the issues of some of these upgraded turbos. The matching that I've witnessed are producing some serious on-load compressor surge. I can better linearize the lift rate of the valve in our wastegate vs the diaphragm gate. I actually want to create a slight opening of the wastegate at low RPM without dropping spool or boost. Pretty much to fix the on-load compressor surge. We have to measure exhaust back pressure to see what the change is in backpressure.

It might be a good idea to put a v-band in there and make it modular for some other options. It is a PITA to have to take those 02 housing bolts off.

 

What are you running for wastegate now? Is it VTA or routed back? More importantly, what boost do you hear it cracking open? What RPM do you hear it cracking open?

Some of the main things I want to get out of this little experiment are:

1) Can we eliminate on-load surge with upgraded turbos
2) The effect on backpressure
3) Eliminating boost taper

 

i'm running a Tial 44mm wastegate off the internal ports like your test setup is.
It's being plumbed back into the exhaust for comforts sake.
it's running a 15psi spring, but i'm running ECU controlled boost control. It's being held closed for as long as possible.
I'm reaching max boost in 5th gear at about 4000rpm, but 2nd gear is about 5000rpm.
When i installed my new ECU (got rid of the MAF) and my 3" exhaust, the turbo started to compressor surge(onload surge) at about 4000-5000rpm in the higher gears (4th/5th). It never surged with the 2.5" exhaust and the stock ECU. Whether it's because there is less backpressure now so the turbo is spinning faster quicker, or something else i'm not sure.
I'm running a custom exhaust gasket so that there is no leakage from the wastegate section to the turbine exhaust section of the exhaust.
Next time it's on the dyno, i'm going to install a standard wastegate onto it, to see if i can get better spool with the wastegate ports fully closed.
My tuner was surprised how little boost it made when load was held at 3000rpm. It was making about 3psi. His HKS3037 makes 20psi at the same RPM (diff car though).
My boost plot is a steady 23psi.
Hope that helps.

Cheers, Mike

 

Damn good info Mike! Are you still on stock turbo?

We run a 3" no cat exhaust and no surge on the stock turbo. But then again, our WG is vent to atmosphere. We're not spooling that late, totally different engine, though.

 

Interesting idea, sounds highly sensitive to setup though?

 

I'm running a FP Red 64mm. The rest of the setup is rather plain. Just intake/intercooler mods, and 3" exhaust with 1x straight through muffler and another cross flow/chambered muffler in the rear, No cat. (i hate loud cars).
If the stock turbo was spooling that late i wouldn't be very happy lol.
I'm building a stroker (2.3) motor in a few months, and i've got a Mivec head on the way from the USA. I'm seriously looking to keep standard cams for increased response at the moment, but i'm thinking they will really strangle the motor.
We've just tuned the Motor on a new Link G4 Extreme ECU. it's running 23psi on 98 Pump gas (in NZ, maybe it's the same as 93 in USA?). It made 270kwatw (~360whp). So it's nothing crazy. But it's good for mid 11's in my little mirage.
We stopped at 270kwatw because it's an old evo6 motor, with probably 60,000+ miles on it.
My aim is 350kwatw on 30psi with the new setup, but we'll have to see how it goes.
(sorry if that was a little OT lol).

But when i do some testing with the internal wastegate put on, i'll definitely share the results with you. I'm very interested in doing it, i might actually call my tuner and organise it lol.

Just to clarify the Surge on Load issue too, this is created when the Compressor is flowing more air than the engine can consume right? And it reverts the airflow back out the compressor cover, rather than turning the extra air into boost pressure. Maybe it's just started Surging because we turned the boost up, it wasn't surging on 20psi. The stroker will fix that problem me thinks

Cheers, Mike