compound turbo "twins" with elbow mounted pac brake

[robertyoke]

my twin pictures with an elbow mounted brake.

I have a new respect for the guys that have built their own twins from scratch, that was a pain in the rear.
I wanted to use my brake, and not a remote mount brake, so I built my own set of twins. primary turbo is b2 and secondary is b1/03.
So far on some short test drives 50 ~55psi boost after a spike of 58 psi. this may change the actuator for the waste gate is damaged (dented in side and likes to stick) and I am waiting for a replacement.
egt's with tst box on 9/9 1250~1300 then drops to 1100 or so at 110 mph
here are some pictures.

http://community. webshots.com/album/273256516NxRijF

-robert

 

[Jeff_K]

That is awesome! I want to do the same thing. Keep us informed!!

 

[Glen Pratt]

That is awsome. I am amazed you got everything to fit. Turbo mounted Pac Brake with twins. Thumbs up on your determination to keep your exhaust brake and fabrication skills.

 

[LaserBob]

Robert,



You now fit the description for tuff. That is a lot of work, isn't it? Did you keep track of how many times you removed something that you just thought was finally right?



Looks like you won the war. CONGRATULATIONS!



LaserBob

 

[lklauder]

alternate configuration for twins ?

What would be the down side of trying to find a top turbo that would spin in the opposite direction (i. e. counterclockwise when viewed from front of truck) so that the discharge could be ducted fairly directly to the input of the lower turbo. In a given steady state operating condition all that would matter would be the power developed by each turbine so it should be possible to configure them for equivalent results at a selected condition such as full power at 2400 rpm. If this routing could be worked out it would save a lot of tubing and make things less crowded. I do not have any idea how spool up response or other transient behaviors would be affected or whether people find a benefit (such as cooling or reduction of turbulence) with the long conventional tube between the compressors. Just curious.



Lou Klauder

 

[Jeff_K]

... What would be the down side of trying to find a top turbo that would spin in the opposite direction (i. e. counterclockwise when viewed from front of truck) so that the discharge could be ducted fairly directly to the input of the lower turbo...

Lou Klauder

Its the discharge of the lower turbo that goes to the inlet of the top turbo. The direction of the top turbo would only affect the piping to the intercooler.

 

[robertyoke]

Robert,

You now fit the description for tuff. That is a lot of work, isn't it? Did you keep track of how many times you removed something that you just thought was finally right?

Looks like you won the war. CONGRATULATIONS!

LaserBob

I think I only took the top turbo out 5 times, now the bottom turbo had to be taken apart and put together in the truck and that is a big p. i. t. a. and after 10 times in and out it was perfect.


all I can say it was worth it, the truck just keeps getting faster and the egt are lower, like the b2 had to break in.

 

[lklauder]

Its the discharge of the lower turbo that goes to the inlet of the top turbo. The direction of the top turbo would only affect the piping to the intercooler.

Jeff, the installation pictures I have seen are all as you describe. What I am curious about is the possibility of running fresh air through the compressors in the opposite order. It would save a lot of piping. Is it not done because the dynamic behavior would be unfavorable or because there is no compressor housing available for the upper turbo that would allow a smooth direct connection down to the intake of the lower turbo. - Lou

 

[Hohn]

You can't route the small compressor's inlet into the big compressor's for one reason at least-- the large compressor needs more air than the small turbo can deliver.



How can an HX35 (which flows . 46KG/sec) supply a much larger turbo which may flow 1. 2KG/sec of more?



If you don't have the large charger feeding the small charger, there is no compounding-- You'd simply have laggy nightmare trying to spoolup up a large charger that will only give you the flow of the small one. It's like anti-twins; all cost, no benefit. It would perform much worse than stock.



Justin

 

[lklauder]

You can't route the small compressor's inlet into the big compressor's





Good point. So to think about my question, assume small turbine driving large compressor on top and large turbine driving small compressor below. Is there an obstacle that the available housings and wheels cannot be matched that way ? Or maybe with RPM limits set by the large wheels the small wheels could not be operated at the speeds where they are effective. Lou Klauder

 

[robertyoke]

well so far I like the twins!

I have reflashed the tst box with the new program and spool up is even better, but more importantly this program is way smoother.

back to the twins, the b2 must be broke in now, it spools much faster and boost pressure is up to past 60 psi on box level 9, just touches 60 psi on long pulls on level 8 and level 7 is 55~57 psi.
egt's, even on level 9 just enter into the low1300 deg. mark when loaded and only 1200's when empty.

back pressure is 2psi higher up to 22psi then boost is higher 'till 35 psi when they stay even 'till they peg 60 at about the same time.

I have not towed in the mountains as of yet.
-robert

 

[Jeff_K]

Cool! Great to hear they are working out for you. What do you have your B1 wastegate actuator set for? Mine is set to 42psi from TAD and I am wondering if it will need to be changed when I build my twins. I am still trying to decide if I should use an external wastegate or the internal one on the B1 with pop-off valves to limit boost. Which TST program do you have now?

 

[robertyoke]

that wastegate actuator will not work with the pac brake. If you look at the pictures you will see the bracket I used for a stock 03 actuator, and there is no boost elbow so it opens at 20~22 psi.

I may take the b1 off and see if I can make the wastegate hole bigger so it will flow more to drop the overall boost down, if I see +60 psi at 5000 ft it will be higher at sea level and it may be too much???? head gasket may go boom???will see I need more testing.

the tst box is the twins program.

 

[thejeepdude]

Robert, if I move to Colorado... will you be my friend?!?! I sure would like to be able to do something like this myself. I am impressed. . excellent job! Let us know how it works out in the long term. I'm just waiting for my warranty to be over.

 

[robertyoke]

Robert, if I move to Colorado... will you be my friend?!?! I sure would like to be able to do something like this myself. I am impressed. . excellent job! Let us know how it works out in the long term. I'm just waiting for my warranty to be over.

you would realy want to be my friend if you saw my shop/garage... . I am a framing contractor by trade.



repeat after me, I am my own warrantee station.
-robert

 

[LaserBob]

Robert,



Show him a pic of the sawdust that must be there.



I really like you last line.



LaserBob

 

[Jeff_K]

ttt... . for a non-member