Thinking Compound charging with dual quick spool valves

[Iknowthefuture]

I have a s13 and im installing a rb25. I have a holset hy60 that I was going to put on my ls1 trans am but I started thinking, what about trying compound charging i.e. little turbo and big turbo, along with each turbo having a quick spool valve . A supra site sells a compund system that flows enough for 800+hp and spools fully at 2800 IIRC. damn.... Would a hy60 fit under the hood of my car? because thats the main deciding factor on whether or not to go ahead with this.

Main reason for thinking about trying this is it'll be cheap (~$1000) and insanely tunable (im running megasquirt 3x which is a boost controller and has outputs so i can control quick spool valves etc.)

[Iknowthefuture]

is hks the only company that sells bottom mount mani?

[ItzGenX]

There will be a major space restriction if you try and go with compound twins. RB engines lean toward the exhaust bank giving it less room to play with. There's also the steering column making things extra tricky. I am not saying that it can't be done, but you will surely need a custom manifold to work such a system in a tight space.

[yotik]

This sounds familiar...pretty sure someone brought it up before.

[julio]

Im running an HX-40 and can't fit my finger in between the turbine housing->valve cover or turbine housing->strut tower. Also, the compressor housing almost rubs the hood. I would say go with a more compact turbo, Holset's housings are huge.

[Carl H]

it will be a cold day in hell when anything larger than a gt35r bolts to an hks low mount cast manifold.

[Iknowthefuture]

I was pretty much thinking of a small turbo like alittle bigger than a stock turbo and a 50mm wg so itll have the stock and 50mm wg to bypass exhaust and feed the hy60 which is up at the front like in the area opposite the battery box. people on the ls1tech forms put bigger turbos in the battery box location sideways, ill post a link to get an idea. then I could route the exhaust behind the rad and out under the intake mani possibly. p.s. the hy60 is reverse rotation turbo and should flow 800rwhp on an ls1 soo..

[Iknowthefuture]

p.s.2. theyll have quick spool valves so and twin scrolls so theyll both spool like they are have half the a/r on the turbine :)

[julio]

http://www.youtube.com/watch?v=y-Me6yWApzY

Check out the other videos too, pretty sweet/expensive setup.

[Iknowthefuture]

exactly

[RustspecS13]

A quick spool valve on 2 turbos in the same engine bay as an RB25, crammed under an s13 hood.

Pick one or the other, its going to be a piping and tuning nightmare to throw all that together. When do you switch the spool valve 1, and spool valve 2 on and off? part throttle? full throttle? cruise?

I would take off your exhaust manifold, have both turbos in hand and try to fit them in the engine bay where ever you can. Then add the piping, and all that and your space will disappear quickly. You'll most likely need a custom manifold and of course all the piping. You'll want a very efficient intercooler, a great radiator, fans. And for that 800whp you'll need lots of other stuff of course.

~Alex