Compound turbo or Bi-turbo set ups

[Smokey Eddy]

heh thanks guys. If i were to block half of it off i'd make one i think out of  waste gate parts

[TurboJ]

Yeah, DIY is the way to go if you do a valve flap!

Smokey Eddy, do you have measurements of the exhaust side of your Holset?
The compressor side seems quite large at 55 mm. If the turbine is much over 60 mm you will definately need a smaller turbo or a supercharger to spool it up, even a valve won't be enough.
On a 1.6 with extensive head work and custom manifolds, a 60mm turbine would give full boost just before 4000 rpm, WITH a valve... On a compound setup this could work well if you can set it up right.

[Smokey Eddy]

Yeah, DIY is the way to go if you do a valve flap!

Smokey Eddy, do you have measurements of the exhaust side of your Holset?
The compressor side seems quite large at 55 mm. If the turbine is much over 60 mm you will definately need a smaller turbo or a supercharger to spool it up, even a valve won't be enough.
On a 1.6 with extensive head work and custom manifolds, a 60mm turbine would give full boost just before 4000 rpm, WITH a valve... On a compound setup this could work well if you can set it up right.

My build is a 1.6 TD MF bottom with a ported 1.9 AAZ head and a ALH intake manifold. I have a FMIC and a big 2.5 inch exhaust from turbo to under the back seats where it Y's to two 2.5 inch pipes that exit infront of the rear tires.

There are two weakspots with my build, the stock exhaust manifold and here is something askew with my IP's fueling (possibly three weakspots seeing as the TDI intake is really quite small.) As it is now i have the pump just cranked for max fueling possible and it barely smokes - certainly not a plume of black. builds boost relatively slowly compared to other's videos i've seen. Never EVER see EGT's over 1,200 and thats with me trying to get them up there doing huge pulls up big hills from 60-100kmh in 4th with my foot to the floor.

Unfortunately I've just been too exhausted after work this week but I don't work tomorrow so i'll have time this evening or at the very latest tomorrow morning. Sorry for the hold up, i really appreciate the input from you guys - i've just been exhausted from 13 hour work days this week.

So my synopsis so far is:
 - more fuel (maybe a bigger pump head and definately a lift pump)
 - a DIY valve to block half the run out of the turbo
 - port my head and intake manifold more, especially the exhaust (I'll really bore it out)
 - My Garrett T3 will give the same boost it is now (likely faster with the added porting) and should be able to spool the holset at WOT
 - I'll leave the T3's waste gate set to bleed at 20psi and set the holset to limitless... i'll weld the wastegate closed on it.

[rabbitman]

Hey Ed be sure you get a video of the head flying through the air when it comes off!!!!!!

Hope it works for you

[Smokey Eddy]

i doubt that will happen. I'm not going too crazy.

[Smokey Eddy]

OK! So i confirmed that the exhaust turbine is indeed 60mm and the compressor wheel was about 75-80mm in diameter.
in the midst of taking the compressor wheel off to give it a good clean.

Edit: I actually managed to get it back on exactly where it was when it came off.

[Rabbit on Roids]

OK! So i confirmed that the exhaust turbine is indeed 60mm and the compressor wheel was about 75-80mm in diameter.
in the midst of taking the compressor wheel off to give it a good clean.

Edit: I actually managed to get it back on exactly where it was when it came off.

that was my next question. cause theres definitely some big balance marks on that compressor. and it needs to be where it was. else the turbo is gonna go *BOOM*

[Smokey Eddy]

I have a query however,

When I first tried to undo it i forgot that turbos are reverse threaded... so i pushed a bit... not hard, nothing happened.
I thought, "that's odd?"
Sprayed some WD-40 and waited about 10 minutes
Tried again... and something turned... but it didn't feel like threads on threads... but the ratchets definately turned...
What moved?
I later kicked my self for not remembering, DOH reverse threads... and did it right and it came undone very easily.
I guess i'll have to get it balanced anyways but what turned exactly?

[Rabbit on Roids]

who knows. maybe the shaft is about broken.

[Smokey Eddy]

who knows. maybe the shaft is about broken.

what do you mean about broken?
It spun smoothly and at least 90 degrees... It didn't feel like i was bending anything. It felt like ... if you rolled up two peices of paper intop of each other and rotated the one on the inside... except smooth as glass.

[Smokey Eddy]

My t3 will still give the same drivability as it does now even though it's going through the holset would it not?
ie. I'd still see the same boost as i do now, just perhaps slightly more lag due to the added volume of the 2nd turbo and plumbing from the T3 to the HX35

But since its just pressurizing the inlet of the holset and in turn giving the holset a false pressure inside, i'd still get 20 pounds out of the outlet of the holset at full boost on the T3.

Also, the compressor wheel of the holset would be rotating too as it gets fed from the same exhaust that's feeding the t3, so it wouldn't be an impedement of the flow, it may actually slightly improove it, if not build boost of its own ontop of the 20psi.

This brings another item to my attention.
EGT's. Should i get a second EGT set up and measure 1st at the manifold PRE-Holset (the way it is now for my T3) and a second probe & gauge reading PRE-T3/POST-Holset.

Date TBD: Auto CAD drawings of T3/HX35 set up on AAZ head in an MKII engine bay.

[RabbitJockey]

i thought that the hx35 would act as the inlet for fresh air, and then the pressure side of the hx35 feeds into the garret, then the garret goes to an intercooler and then the intake. and on the exhaust side the engine feeds the garret which then dumps into the holset which then dumps into the rest of your exhaust.

[Smokey Eddy]

i thought that the hx35 would act as the inlet for fresh air, and then the pressure side of the hx35 feeds into the garret, then the garret goes to an intercooler and then the intake. and on the exhaust side the engine feeds the garret which then dumps into the holset which then dumps into the rest of your exhaust.

If you had the HX35 "cold pressure side" going into the Garrett it would over spool the Garrett tremendously. You want the small turbo to feed the big one. The small one needs to help the big one.

[Smokey Eddy]

I just went up to the Drafting floor at work and asked my buddy if he had any autoCAD hand books and i asked him what he thought of my idea.
His response was as follows...
"...
wait what?"
I re-explained, drew some pictures on paint 
"Oh my god. That's the craziest thing i've ever heard... "

 
I'm going to draw up the 2 turbos, the back of the engine with the engine mount & bracket and the rest of the engine bay and down pipe.
Just roughly, no real detail - basic dimensions. And i'll figure out on AutoCAD how everything will fit together.

Then I'll take a few screen shots & post the pics. 

[truckinwagen]

compound setups traditionally go like this:

exhaust manifold to high pressure turbo to low pressure turbo to downpipe

air filter to low pressure turbo to high pressure turbo to intake

high pressure turbo being the smaller of the two.

this way the exhaust has less volume to spool the small turbo quickly, and the intake volume after the high pressure compressor is reduced keeping volume induced lag to a minimum.

once the high pressure turbo has spooled and the motor is making enough exhaust gasses to spool the large turbo, the high pressure wastegate opens and the high pressure turbo effectively freewheels.

apparently the risk of overspeeding is low as long as a suitably large wastegate is used to bypass the exhaust past it to the low pressure turbo.