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No, not really, because the exhaust housing I am running from Schwitzer has a "two-flapper" wastegate actuator, where my Piers HX-40/16 had only one.
I have checked my drive pressures with both set-ups, and it is no worse now than it was with the HX-40/16. Also, the EGT's are not any worse, although I have gone from the Snow Water Injection System to a Scheid Diesel Water Injection System, taking the water nozzles from two to five and the water pump pressure from 200 PSI to 500 PSI.

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John_P

 

Well I have no water... yet!

 

I have been thinking of taking my secondary (HX40) off and either drilling into the other volute, straight across from the existing w/g port or removing part of the volute right at the flange. The reasoning is that Holset only gates one side and when it opens its only directly dumping 3 cylinders. If I connect them I am hoping that it will equal out the pressure and cure my shutter that happens when the w/g opens. Thoughts????? Do they make a single volute 16cm for the HX40??

 

That is an idea that HOHN has put forward and maybe has merit. I really don't know the correct answer to that one. Only really doing it and being able to measure a before and after will tell for sure. Playing devil's advocate, if you do that and lose additional pressure through the wastegate, will that affect the ability for the top turbo to spin the way it should?

 

I know the 1st gen 12v guys usually drill out the divider so all cylinders are wastegated. I don't see how it could really hurt. Seems worse for the motor to have different drive pressures on the front and back halves.

 

Off the top of my head I am inclined to agree with you, after all, the wastegate orifice is only going to allow so much through it.

 

What he said.

Having wildly different pressures in the same engine cant be good. I am going to hook up a drive pressure gauge but I am not sure how to measure it before and after. The manifold is segregated and so is the turbine housing so on one side I will see a pressure drop when the gate opens but not much on the other. Another problem when putting in the gauge is getting a good place to hook it up since the compressor housing on my 3B wont allow me to use the extra port on the manifold. I really dont want to run two, gauges and drill two holes in the ex. manifold.

I am probably going to remove part of the volute in the 40s turbine housing since that is probably the cheapest and easiest part to replace if this experiment goes wrong.

 

When you do this be sure to report on what you find and how much difference it makes.

 

I have a question... 94ttss is fabbing his twins and I noticed on his cold pipe from primary to secondary he uses a smaller diameter cold pipe and reducers from the turbo to connect. I am asking why? Or what is the purpose/benefit of doing so? On my setup, Piers uses a 5" coldpipe. It is large and makes it tough for space. I notice BD twins uses a smaller cold pipe as well. Any ideas??

 

I was wondering the same thing about mine. Are you talking about the cold pipe pictured here?


I think the smaller diameter doesn't hurt anything because the outlet on the big turbo is that same size. Since you're force feeding the top turbo (instead of it taking in uncompressed air) it no longer needs that larger diameter on the intake side. That's my hair-brained theory anyway.

Maybe Nathan, the resident twins expert, will chime in and explain why?

 

Smaller diameter keeps the air velocity up = less lag???

 

There have been talk back and forth that the larger coldpipes make for some lag but I havent seen any proof either way. I think the smaller coldpipes are used for ease of installation. I run a 4" coldpipe and it was tight, I dont know how soulezoo got his in there. Just my $0.02

 

jrussell,
What wastegate actuator is that on your top charger? Similar to the Turbomaster? How do you like it?

 

jrussell--

Yeah-- exactly like that pic you posted. Now on mine, all the in/out and cold pipe are same size 5". Yeah, more volume to fill would = a little lag I guess but there is a return too in less compression and heat-- I think? I dunno, that's why I am asking. And yes! That 5" pipe is tight!!

 

The new actuator for the stock turbo comes from Nathan @ MPI. It's a very simple design that works REALLY well. Very easy to adjust when tuning the setup.

You got a pic of yours?