Yes. I have a buddy with a hx/s475 that runs 70psi.

 

The max usable PSI for the little guy does not go up, it's still the same PSI, it's just pushing that air into the big guy and the big guy is making more boost

 

Exactly ...

Sent from my C771

 

I thought the larger turbo (low pressure, bottom) fed the smaller turbo (high pressure, top) and the pressure was then compounded into the intercooler. In this case, wouldn't the top (high pressure) turbo be the stock turbo...or am I wrong about how the compound setup works?

 

Yes. The high pressure turbo is compounding the boost from the low pressure turbo. The high pressure does not "create" more boost.

 

But is it the compounding of the pressure that gets the higher psi? Is the larger turbo's low pressure feed into the smaller one causing the smaller one to compound it to the higher boost level?

 

Yes! You got it but I think you're over thinking it. Lol!

 

Btw, sorry for all the questions about this...for some reason this seems to be the only thing about these trucks that I can't get my head wrapped around...yet. I really want to know though!!!

 

I think you might be right. I have seen the pictures of how other peoples' setups are built. Whenever I get around to building a set, I will just make them look like the pictures. Lol

 

There's a good thread that's been going on on compD discussing compounds that might shed a little more light on it for you..think the title is tuning twins but won't swear on that. Hope this helps you

 

Ok, that makes sense. I would love to get something I could put under my stocker for a nice set of compounds. I need a few more things first though: guages, tranny upgrades, more fuel, better box. Haha, I have a long expensive way to go...hopefully someday I will get there.

 

Haha, now u feel like the other 90% of the other members on here

 

Agreed wish i wasn't poor so I could stuff a 480 under my setup. Reason im poor is all the stuff you just mentioned

 

I'm always poor, cuz I'm always buying parts for my truck, cuz I'm never satisfied

 

I'm always poor from fixing the crap I break on it! Lol!

 

Well yeah, cuz everything that breaks ya gotta replace with aftermarket, that's at least what I tell my wife

 

Lol, I think the way you do. I will tell my fiance it's worth paying double or triple the price because if you don't then you will just have the same problem no too far down the road, which in reality is true. Kinda puts a fun twist to having stuff break.

 

Haha, he'll yeah it does man,

 

Thats exactly why I can finally have an excuse to upgrade. My KDP fell out. So I'm using that as an excuse to go tull tilt; colt cam, ported head, studs, 60lb springs, 4k gsk, 5x.011 injectors, and maybe a compound setup.

But one question about compounds, what the largest I can go on a bottom turbo without it being too laggy with my stock turbo?

I've read ideal is 71-75, but is 80 way to big?

 

I would say an 80 is too big for a vp44, but p-pump could handle it with proper fueling.