I've given some thought to using compound twin turbos but have found relatively little information on turbo sizing. I've been able to do some basic math on the subject, but it leaves me with some unanswered questions. Does anyone know of a book that has the correct equations for turbo sizing in this setup?
All of the single turbos I've looked at that can produce the kind of boost I'm looking for (30-50 psi) are way past their surge limit. "Twins" are probably the only way this is going to happen. I've considered using a supercharger inline with a turbo as well, but twin turbos would be easier. With all of this comes the thought of making a kit so that others might give this route a try as I have the means and capabilities to put something like that together...granted there is much time needed for testing before anything could become of it. Packaging is the least of my concerns - I just want to make sure it works properly and efficiently.
I would suggest the soft cover book "Turbocharging" by Hugh MacInnes published by HP Books out of Tucson would be a good place to start. As I recall, there is a new edition every few years. Don't know if the current editions have anything, but in the 1976 edition, Chapter 15 'Tractor Pulling' the author walks you through sizing the turbos for 2 stage turbocharging.
Back in '76, he reported some of the tractor pullers with 2 stage turbos were running charge pressure of 105 psig!!!!
Piper106
I would suggest the soft cover book "Turbocharging" by Hugh MacInnes published by HP Books out of Tucson would be a good place to start. As I recall, there is a new edition every few years. Don't know if the current editions have anything, but in the 1976 edition, Chapter 15 'Tractor Pulling' the author walks you through sizing the turbos for 2 stage turbocharging.
Back in '76, he reported some of the tractor pullers with 2 stage turbos were running charge pressure of 105 psig!!!!
Piper106
They're definitely running more pressure than that these days. I've heard around 200 psi, but they're farely tight lipped about these things.
I,ve got my compound setup sized pretty good I feel,I'm running the k24 with a k14 compressor on it also I ported the k24's wastegate hole out from 1" to 1 1/16" the k14 housing was too restrictive and could not be modded enough to bypass the needed flow to the Hx30W.With the k14 I was getting 60psi backpressure and now with the modded k24 housing the backpressure is around 40psi thats with 32 psi boost also factoring a 2-3 psi pressure drop throughout the plumbing and IC.I believe that If I increase boost to around 35 psi that the backpressure will not rise very much at all.BTW this is on an AAZ 1.9TD engine,and It would be equally effective on the 1.6TD.The lag is very minimal IMO and The transition of the two turbos is undetectable all in all Its worked out great.
I've got most of the numbers worked out and it looks like I can make over 60 psi efficiently using turbos I already have....but will need other parts to make it work. I think I'm going to keep my mouth shut on this for a while
