Lets speak on what tuners want vs What Manifold designers build. Lets keep it civil and work together like big boys and girls
i resesrve the right to close this at anytime..lol

 

I would rather use twin 38's....slightly smaller volume than a 60 and about the same price, with more versatility.

 

My twin 38's are awesome, thanks to Morgan for setting me on that route. It looks and will work so much better for me

For a twin scroll design I can't see wanting to use a twin 44 setup ever again.

 

I say weld it shut and use a CO2 to control it.

 

I love the new 38's... I would love to see some more of these twin 38 setups and see how theyre working for people on different setups.... I have been contemplating going to a twin 38 setup next year...

 

this is amazing, i was just about to post a waste gate question.

right now i am running a twin scroll turbo with a single 38mm but we are redoing the manifold to a top mount twin scroll.

so two 38mm turbosmart wastegates are fine?

ohh yah im running a gt3776 turbo

 

we got twin 46mm but results will be for later car is almost done.

 

twin mvs's is my favorite

 

Whatever it takes to stop boost creep. All setups are different. If it creeps more than a couple psi at low boost then it needs more gate as far as I'm concerned, especially for a street car.

 

My single 44 works great for me but my manifold design is good and my exhaust housing is less than ideal.

 

what size is your exhuast eric

 

im also going with twin 38mm mvs...on a t4 twinscroll...from what i understand wastegate size depends on exhaust efficiency...the more efficient your exhaust is the harder it is for a small wastegate to control boost..but 2 38mms is 76mm..so thats enough for any set up..

 

I have a 44mm with a SLS protype manifold and 3 inch piping

 

Really, it's going to come down to exhaust flow's bias towards the wastegate. Wastegate feed quality is extremely important for street cars that wish to run oversized compressors at low efficiency ranges.

A properly designed manifold should favor the wastegate no less than 40% or so, especially when used with a super-flowing engine combination, and a larger exhaust-side on the turbocharger.

Let's take a quick look at what happens when you design a manifold with a 90-degree sharp turn welded onto a collector.



*Photos courtesy of Geoff @ Full-Race

As you can see, exhaust gases have the tendency to blow right by the wastegate entry, rather than bypass the turbine.

Now, as long as there is a larger amount of restriction in the exhaust housing, exhaust gas will "back up", so to speak, and be more inclined to evacuate through the path of least resistance, which in that case would be the wastegate.

If you'd like an example of proper wastegate entry design, take this:


There is a flowing turn into the wastegate entry from the base of the collector.

Another good example of good wastegate system design comes from HyTech Exhaust. If you happen to stumble upon a picture of their B-Series side-mount manifold, there is a near 50/50 split of exhaust flow between the turbocharger and the wastegate.

What I love, personally, is this image provided by Precision Turbo and Engine that is included with purchase of their 46mm wastegate.


I'm pretty sure Precision knows a thing or two about turbocharging systems.

I think boost control in terms of wastegate flow is something that has been severely over-looked in our portion of the racing industry.

- Derek

 

I think ideal wastegate position is pretty clear to most people, but often real world fitment requirements results in less than ideal placement. In these situations, a bigger gate is necessary to make up for bad placement. It's usually easier to fit a big gate than it is a small gate in an ideal place. On most the crap we work on at least. lol

This is a setup we just finished. Everybody knows an S2K will creep with a single 44, even with the teardrop inlet like FR does. This was with a 6262, T3 .82, full 3" exhaust. A TiAl 60mm gate in about the worst possible position, 90 deg off the collector and opposite of flow. Holds 5psi all the way to redline, not a hint of creep.

 

Can you have too much? (I know it overkill but for arguments sake), if your setup requires a 38 gate, n u slap a 60 on it, what gains or losses would you see?

 

I've yet to see a negative affect from too much gate.

 

IMO you would actually help drop back pressure closer to a 1:1 ratio if not a 1:1 considering the size of the hole, without going to a bigger A/R on the turbine side. The bigger a/r would increase spool, which is a downer on a street car, usually.

 

The 'flow' out of the wastegate is what's going to dictate boost. If you put a bigger gate on it and open it enough to drop backpressure, boost is going to drop as well. Unless you're at a point where the compressor is maxed out and a bigger gate will allow more flow without dropping boost, you won't see a change in backpressure with a change in gate size.

 

Gotcha, so it has to be at that point before back pressure drops, Otherwise it's just Keeping up with Exhuast gases that would usually fly right by the wastegate and into the turbine wheels thus creating more boost. I think i see now.

 

I drew up the same exact picture, this is the main issue with manifolds with small collectors where the middle dips down. The back runners just flow right down and past the wastegate port.

 

i'm running an LPS divided top mount on mine with the twin mvs's and they work awsome. We're using S300 w/pwm and boost holds pretty solid. I street drive the car on pump at 1bar without issues and pretty much at the track, boost does exactly what we tell it to do. Other then the earlier fitment issues with the MVS's, they've worked out great.

Also, those who are or have been running your MVS's, be sure to regularly take them apart and check the bolts inside the housing that holds them together as we've seen them come loose and leak.

 

Some great info in here guys thank you. Im still doing a lot of learning on these crazy setups so to hear suggestions from some of the best is awesome

 

My favorite wastegate setup at the moment is the dual MVS gates. They make it easier to fit dual gates into tighter spots, which is helpful for most of the cars this community is going to build.

I am looking into adding dual MVS 38s to my current manifold to help control my boost a little better at lower pressures. I have a T3/T67 .82 on an RLD manifold with a single 44. With 2.5" exhaust I get minimal creep ~ 2psi right off the 5psi wastegate spring. As soon as I go open downpipe, it is near impossible to keep the boost under control.

 

are the MVS used on twin volute setups or open volutes?