(02-18-2017, 05:37 AM)barrote hy,
I have been testing this system too, i use a GT23V and a HX35W #12 twin scroll turbine. and in a 605 engine.
I can´t say it rock´s but i´m still dealing with the controls of the thing, but compared to the HX alone is a huge difference. or the Garret alone.
Engine behaves well in low idle by 1500 rpm .5 bar and by 2000 it hits 1.3/1.5 depending which gear and keep going to 2 bar consistently from 2.5 k untill 6k.
As i said i opted to have twin operation instead of one at a time style, but controling them is been quite demanding, to say the least.
my problema is with the unloading of the HP to match the wake of the LP. i still haven´t found the right springs and actuators. Can you explain this bit again?

another issue to adress "is the no turbo at all" until engine reaches 1.5k, due to excessive EGP, from my trials engine exibit more tq in N/A condition than with some boost. This shouldn't be too bad with my planned 7.5mm pump?

in time all this problems will be solved. i belive
which type of bypass valve are u intending to use?
I'm not intending on using one on the intake side to bypass the HP turbo... but wondering about one on the exhaust side to have less restriction around the exhaust side of the HP turbo.

(02-18-2017, 06:14 AM)ross

(02-18-2017, 05:37 AM)barrote but controling them is been quite demanding, to say the least.
my problema is with the unloading of the HP to match the wake of the LP. i still haven´t found the right springs and actuators. Can you explain this bit again?


another issue to adress "is the no turbo at all" until engine reaches 1.5k, due to excessive EGP, from my trials engine exibit more tq in N/A condition than with some boost. This shouldn't be too bad with my planned 7.5mm pump?

in time all this problems will be solved. i belive
which type of bypass valve are u intending to use?
I'm not intending on using one on the intake side to bypass the HP turbo... but wondering about one on the exhaust side to have less restriction around the exhaust side of the HP turbo.

(02-19-2017, 11:34 AM)barrote That is what some people use, others use flap valves, as far as i have seen here and there. The hell is the control detail...
Imagine one wants the LP compressor to benefit from the HP flow, (series with each other) how would u limit the max boost? expecially if one uses a VNT type as HP?

(02-20-2017, 05:43 AM)atypicalguy

(02-19-2017, 11:34 AM)barrote That is what some people use, others use flap valves, as far as i have seen here and there. The hell is the control detail...
Imagine one wants the LP compressor to benefit from the HP flow, (series with each other) how would u limit the max boost? expecially if one uses a VNT type as HP?

The max boost should be limited by the LP turbo wastegate.

Fajita an hx30 will work ok, but I think you want really quick spool in a street car. It is pretty easy to figure out from maps when a given turbo will spool on a given motor, although the housing size complicates things. It is a lot harder to figure out how the hp turbo behaves as it is fed air at varying densities by the large turbo at different rpms.

I actually found that an he451 (non vgt) which is a bigger compressor (67/93) than an hx40 super but similar turbine, is a bit small for an LP turbo at my target fuel of 150cc. This is because it will only flow enough air (80 lb) at a PR of 3.5. The system would be better and easier to control if I had a bigger lp turbo that would allow the small turbo to stay on its map a bit more.

Doing this sequential setup means my little turbo is really only making any pressure ratio at lower rpms. So the small turbo can be truly tiny. In my case, it would only need to flow 26 lbmin, which an he200 will do. I think an he221 will spool faster than an hx30, which is why I suggested it to you. Blacksmoke had a 221 paired with an hx50 and a comoressor bypass for awhile, but I think no one really ever gets compressor bypasses to work well, and it was replaced.

Lots of different stuff will work, but I think you really want a bigger LP turbo than you would normally use, to keep the hp turbo pulling a bit all the way up. 

You may find this useful:

https://www.google.com/url?sa=t&source=web&rct=j&url=http://www.w124performance.com/images/OM603_exhaust/Turbo_Calculator/CompoundCalculator_OM603.xlsx&ved=0ahUKEwjXqaHizNnRAhVM92MKHRHPC0AQFggiMAM&usg=AFQjCNFKPTCnv03Rh0jWUvrqg0Lyg45KLQ&sig2=gq9d14FJpnXB6dLBUJl3Sw

(02-20-2017, 08:17 AM)barrote sory , sory , something is missing to me.
thats something i dont get here, after all learning everyday, why  such a huge LP machine, as far as i found in my system the HX35 as LP only wake decently by 3k , untill there only the HP is doing the trick, and it feels it needs fuel , i already have 150cc (605). (at wot 450º EGT , 2,5 EGP /2,5 boost . not so much overheating and nothing melted yet)
could u explain a bit about the use of such a huge machine, and such a diff for the HP, 220 is about the size of a stock 605 turbo, good for nothing , i know the compressor and turbine has some 20 years dif , but doesn´t soud good to me. it would be of good help if u share your points...

(02-20-2017, 01:48 PM)atypicalguy

(02-20-2017, 08:17 AM)barrote sory , sory , something is missing to me.
thats something i dont get here, after all learning everyday, why  such a huge LP machine, as far as i found in my system the HX35 as LP only wake decently by 3k , untill there only the HP is doing the trick, and it feels it needs fuel , i already have 150cc (605). (at wot 450º EGT , 2,5 EGP /2,5 boost . not so much overheating and nothing melted yet)
could u explain a bit about the use of such a huge machine, and such a diff for the HP, 220 is about the size of a stock 605 turbo, good for nothing , i know the compressor and turbine has some 20 years dif , but doesn´t soud good to me. it would be of good help if u share your points...

If you want sequential turbo, first little, then big turbo takes over. For this, the small turbo is bypassed at high rpm. Wastegate bypasses the turbine, and you hope the smal turbo is spinning fast enough for a PR 1.0 to move all the required air through the small compressor. This is like most street setups, small turbo early, big turbo late in rpm range. If you have a smaller Large turbo, you can light it up with a smaller hp turbo, but it will require a lot of boost from the large turbo to get enough air kg into the motor at high rpm. When large turbo is at high boost, small turbo cannot add much without too much total boost. So small turbo needs to spin, but not too fast. Tricky.

In true compound, both turbos operate at low pressure all the time. The pressure ratios multiply to give a high total boost all rpm. The large turbo should flow max required air kg at pr 2, not pr 3.5 or 4. So small turbo can still add some boost, and will not block compressor path. So large turbo needs to be quite large to do pr 2 at 80 lb/min, in my case with 606. An he451 does 80 lb/min at pr 3.5 for instance, and it is far larger than hx40. Still not big enough for true compound setup.

I will build mine sequential, because manifold is done. But if I did it again I would pick hx52 I think, with 70mm turbine, or larger, eg hx60, for 606 with 150cc/1000 injections per cylinder.

(02-18-2017, 05:37 AM)barrote hy,
I have been testing this system too, i use a GT23V and a HX35W #12 twin scroll turbine. and in a 605 engine.
I can´t say it rock´s but i´m still dealing with the controls of the thing, but compared to the HX alone is a huge difference. or the Garret alone.
Engine behaves well in low idle by 1500 rpm .5 bar and by 2000 it hits 1.3/1.5 depending which gear and keep going to 2 bar consistently from 2.5 k untill 6k.
As i said i opted to have twin operation instead of one at a time style, but controling them is been quite demanding, to say the least.
my problema is with the unloading of the HP to match the wake of the LP. i still haven´t found the right springs and actuators.
another issue to adress "is the no turbo at all" until engine reaches 1.5k, due to excessive EGP, from my trials engine exibit more tq in N/A condition than with some boost.
in time all this problems will be solved. i belive
which type of bypass valve are u intending to use?

(02-18-2017, 05:10 PM)MFSuper90 As long as you have a big enough wastegste to flow around the HP charger, there should be no loss at upper rpms.

A compound system will not make the peak hp a single turbo will (of relative sizes), but the usable power range is so much greater it really outweighs the small hp loss. Unless it's in a competition engine where every last hp counts

(02-18-2017, 05:37 AM)barrote hy,
I have been testing this system too, i use a GT23V and a HX35W #12 twin scroll turbine. and in a 605 engine.
I can´t say it rock´s but i´m still dealing with the controls of the thing, but compared to the HX alone is a huge difference. or the Garret alone.
Engine behaves well in low idle by 1500 rpm .5 bar and by 2000 it hits 1.3/1.5 depending which gear and keep going to 2 bar consistently from 2.5 k untill 6k.
As i said i opted to have twin operation instead of one at a time style, but controling them is been quite demanding, to say the least.
my problema is with the unloading of the HP to match the wake of the LP. i still haven´t found the right springs and actuators.
another issue to adress "is the no turbo at all" until engine reaches 1.5k, due to excessive EGP, from my trials engine exibit more tq in N/A condition than with some boost.
in time all this problems will be solved. i belive
which type of bypass valve are u intending to use?

(02-19-2017, 03:16 AM)Sultzi Here is some good info and links when calculating turbos
http://www.superturbodiesel.com/std/showthread.php?tid=7536

I myself used not2fast calculator and one excel calculator when I picked up my turbos (master power r545 and master power 6568). These seem to work pretty nicely together.

(05-24-2017, 09:54 PM)atypicalguy

(02-19-2017, 03:16 AM)Sultzi Here is some good info and links when calculating turbos
http://www.superturbodiesel.com/std/showthread.php?tid=7536

I myself used not2fast calculator and one excel calculator when I picked up my turbos (master power r545 and master power 6568). These seem to work pretty nicely together.

Sultzi what AR is the turbine housing on your little turbo again? They list many options. Thanks.

My hx30 super with 46mminducer is a bit smaller than your 545, but my 6cm turbine housing is tiny. I should have gone for the 60mm wastegate also; I am at 42mm but could use the internal gate on the hx30 also if needed.

Your large turbo is very similar to my large turbo.