Compound pics

[935racer]

Brett, I am impressed, you have done your homework! You are dead right about the k24/t3 wastegate being too small. You gotta remember that for stages turbos when you are pushing that much air through your high pressure turbo you gotta have a big enough wastegate to get rid of the extra air pressue or the high pressure turbine will stall out. And you will loose spool on your low pressure turbo.

[andy2]

They hy spools ok without the k24 wastegate opening,That sugests ok flow through the k24 turbine/wastegate.I did enlarge the wastegate port from 3/4" to 1" I believe.The T3's hole isn't able to be opened up that much.I don't think the k24's wastegate/turbine is the problem here,its the compressor side thats the main restriction,or perhaps rarther the slow moving k24 compressor is slowing down the flow from the hy.As Bruce "QuickTD" and I were discusing the k24's wheels are possibly turning too slow with the wastegate fully opened this is what probably cuts down flow too much through both ends of the k24,espically the compressor side!I wonder if a switchover valve on the hy's compressor outlet bypassing the k24's compressor would help any :idea:.Does't mercedes have some intake bypass on thier compounds?

[DVST8R]

They hy spools ok without the k24 wastegate opening,That sugests ok flow through the k24 turbine/wastegate.I did enlarge the wastegate port from 3/4" to 1" I believe.The T3's hole isn't able to be opened up that much.I don't think the k24's wastegate/turbine is the problem here,its the compressor side thats the main restriction,or perhaps rarther the slow moving k24 compressor is slowing down the flow from the hy.As Bruce "QuickTD" and I were discusing the k24's wheels are possibly turning too slow with the wastegate fully opened this is what probably cuts down flow too much through both ends of the k24,espically the compressor side!I wonder if a switchover valve on the hy's compressor outlet bypassing the k24's compressor would help any :idea:.Does't mercedes have some intake bypass on thier compounds?

I would say that your dead on about that it seems to me under closer inspection that the k24 is close to the right size of charger but the wrong design.

Let me expend on this thought a little, iirc the k24 on the cold side has about twice the number of blades as the T3 (just using for refernce) now the reason for using more blades is to push the surge left on a map or for those not literate in turbo speak to alow for more pressure at low air flow. The K24 has about the most blades I think I have ever seen...

Now for the hotside you have to balance spool and flow, and for the amount of power you are running I think that your hotside is still just too small, it should be like .44 - .48, turbine design comes into play as well but, optmum design is out of my range I am sure QuickTD or TdiMeiseter could probably shed some light there.

I belive its is BMW and Opel that use a bypass valve, but that is just symantics :wink:  , and it may work very well for your app. The reason that you don't see it in alot of "homebrew" designs is cost and complications. That and the compound setups out there (cummins, powerstroke, duramax ect..) seem to work without it, but we are comparing apples to oranges there.

I think that a bypass both hot and cold would be optimal. Using just an adjustable pressure swtich like a hobbs #83298, just off the top of my head . As I write this I think that it may react to quickly and you would loose pressure and flow on the sudden switch and would be better off with a wastegate style controller that as the pressure builds it starts to open allowing more and more pressure to pass to the big turbo until 20psi or so and then it would all go that way.  Lots of options, but I know you have some bright minds already helping you. Keep us updated.
 

[fspGTD]

Wow- andy2, seriously nice work... thanks for the updates and congrats on the nice dyno numbers!

Let me expend on this thought a little, iirc the k24 on the cold side has about twice the number of blades as the T3 (just using for refernce) now the reason for using more blades is to push the surge left on a map or for those not literate in turbo speak to alow for more pressure at low air flow. The K24 has about the most blades I think I have ever seen...

Actually, the 1.6lTD Garrett versus the 1.6lTD KKK K24 do indeed have the same number of compressor blades: 6 long ones (extending to the inducer bore) and 6 shorter ones (that are set back a little... not extending fully to the inducer bore inlet.)  The K24 has a slightly larger compressor blade inlet surface area than the Garrett.

1.6lTD Garrett compressor on the left, KKK on the right:

[DVST8R]

Thanks, for the correction.

I must have been comparing to malone's Gt-20 or somthing else of similar size, that I had seen.

[greggearhead]

Hmmm - again, a compound newbie, so be gentle.  

Would porting/slightly englarging the exhaust housing help, and/or clipping some of the turbine blades?

[andy2]

I did enlarge the k24's wastegate hole,If I put any bigger turbine housing on there then I may as well just go with the single turbo as the smaller one would'nt spool that great anyhow.

I've came up with an Idea about using an hx35 that spools quick and has good top end flow.Not really my invention,But it would make the hx35 spool better than the hy35.

Here's a link to see the MultiStageTurbo,  http://www.atsturbo.com/atswebsite/ProductsDodge/TurboSystems.asp

Kinda like VNT/VGT just old school :twisted:

[DVST8R]

It's been ahwile since I had an Hy in my hand's, does it not have a split turbine housing like the Hx? I know I saw a smaller 6cm housing that still had the split housing so I think in my mind I asumed that they all did.

[935racer]

IF you are running justa big single with a split turbine housing you need to make a pulsed manifold, so that the turbine is getting even exhaust pulses, it wont help spool up as much the multistage turbo, but it wont create the backpressure/exhaust turbulence that the multistage will. I love how simple and effective those multistage turbos are though, thats a great idea.b

[andy2]

The hy does'nt have the split housing and It spools ok with the 9cm housing.With a pulsed manifold and all exhaust being forced through one half of the 12cm housing(6cm) it should spool as well as the t3,k24 I'm pretty well convinced it will.Any more thoughts on the idea now?

[andy2]

I will build the diverter and sandwich it between the turbo and header.It will open up with boost and act as a wall between the two banks of cyls.I think that makes some sence :lol:

[935racer]

I would say its likely a lot more hassle than its worth. Why not just run the hy35 straight up? Worried about smoke down low? Than you gotta use turbo underneath...  But I guess that isnt working for you either. I sent you a pm.

[RAMMSTEIN]

What about using a supercharger and a turbo then?

20 psi constant and the big turbo for high revs.

Just an idea like that.

[RAMMSTEIN]

Something like this.

[lord_verminaard]

Something like this.

Interesting- a bypass on the intake air around the supercharger.  You think maybe when the turbo reaches full song, it bypasses air around the charger?  As in the supercharger is a restriction??   :shock:

Uh-oh, I'm getting dirty evil thoughts a brewin'.......   :twisted:

Brendan
84 Scirocco 8v
00 Camaro L36 M49