What goes first The Turbo or the Suppercharger

The only thing i don't buy about twincharging lowering charge temps is... now you have TWO things generating heat.

That generates more heat by definition.

Don't confuse intake charge heat with combustion chamber heat, which is affected by how much exhaust gases are left in there from the previous cycle.

Intake charge heat you solve by intercooling/aftercooling. Exhaust residuals and chamber cooling, you usually have to make compromises in order to keep things happy.

this thread is useless without pictures:

ive always understood twincharging to be easiest when a bypass type valve is used. in the picture you can see he control valve that allows the turbo to draw more air when it starts to outflow the supercharger. the hardest part is getting a good transition of the control valve at the right time to smoothly transfer from the supercharger to turbo.

i would think this would also help prevent the issue of high intake air temps since once the control valve opens there would be very little load on the supercharger after the control valve opens since its charge side will essentially become open and wont be building pressure, then your intercooler only has to deal with the heat from the turbo

as usual these are all just theories ive made up in my head that make sense to me i could be way off

I wonder if you sized everything right, and ran the supercharger after the turbo, if the turbo would actually spin the engine through the supercharger at high boost. Like a pneumatically coupled version of this.

http://en.wikipedia.org/wiki/Turbo-compound_engine

I have a spare BP 1.8, 16G with a billet 20G wheel swap and MP90 that I've always been tempted to setup like this.

No one has commented on my Frankin Suppercharger. That is an M62 Not an M45 by the way. I took two M62's and disassembled them. Then took the bits I wanted from each unit (front housing, snout and rotors from one) and the back housing from another and came up with this very compact medium snout stand alone unit.

I also have an M90 on the shelf as well that I got from a GRM member about 6 years back.

Knurled wrote: Intake charge heat you solve by intercooling/aftercooling.

Or Nitrous. Or alcohol. Just sayin....

did you miss the post about heat? basically, to make your theoretical 600HP with a standard turbo setup, you would need the heat and pressure from the exhaust to generate ALL the extra airflow. with a twin charger setup, only roughly half the heat is necessary, cause only about half of the 600HP comes from the turbo. the exhaust side of the turbo is usually MUCH larger in this case, sized to match the turbo you would use for 600HP by itself, think 1.01 AR, as opposed to a .63 or .82, but the cold side is sized for only a fraction of that, say 60 trim, or even a 50 trim if the VE is right. the exhaust pressure is greatly lowered, as is the temperature of both the manifold and the valves/combustion chamber. this drop in heat retention almost always results in LESS detonation ('virtualy eliminating it' is a stretch). DO it! and post pics! -J0N

Houston, we have a problem. Or several.
Very little heat in the intake charge of a turbocharged engine comes directly from the heat in the exhaust gases. The majority of the difference between ambient temp and the temp of the intake charge comes from compression. This is called adiabatic heating. http://en.wikipedia.org/wiki/Adiabatic_process#Adiabatic_heating_and_cooling
No matter what type/mix of compressors you use, to get a certain amount of airflow through a certain restriction (which in this case is a spinning engine) requires a certain pressure ratio, so you have to end up with air that is compressed by the same amount no matter how you choose to get there. Different types of compressors have different adiabatic efficiency. This is what a compressor map for a turbo is actually plotting. Turbos tend to be more adiabatically efficient then superchargers. What that means is that if you take a 'big single' turbo build and replace it with a compound super+turbo setup, you will probably be LESS adiabatically efficient and add more heat to the charge air.

In a super+turbo compound setup you would typically use the turbo as the larger blower and blow through the supercharger. This is because the supercharger allows you to spool a larger (and less restrictive) turbo, but a giant supercharger doesnt need any help from a tiny turbo to get spinning. So, there is basically only one way to implement a super+turbo compound setup, and that means having a big turbo blowing through a 'smaller' supercharger. In this layout you can actually get away with a larger/less restrictive turbine section than with a 'big single turbo' setup, but that does not impact charge temp. It reduces pumping losses on the exhaust side, but not by more than the drive losses from adding a supercharger.

So basically, there is no way you end up with substantially less heat in the intake charge by going to a compound setup. The only real purpose of a compound setup is to create a wider powerband on a small motor that would otherwise need a very laggy large turbo to hit your power goal. So the smaller the engine and the higher the power goal, the more useful it becomes, and the bigger the engine and the lower the power goal, the less useful it becomes. There are good reasons why you dont see compound setups very much! They have a very specific use and not many people need them.