Leave it to Peckster to make fun of me waaah.

 

It's not hard considering you have some of the corniest Deutsch in your sig.

 

@theedge
Before you described some of the problems that I found too when looking at the supercharger + turbo set up. I would definetly not go for looping the supercharger into the alternator belt. It leaves too little contact angle on the circumference of the drive pulley to securely drive the charger. Additionaly it would put too high loads to the alternator bearing and the crank bearings too. The alternator has to move to the other side of the engine and needs to be driven with a separate belt. In this way the forces of the alternator belt and the supercharger belt cancle each other out to some extend and reduce load to the crank bearings. But it also means relocating the oil filter and pressure regulation valve which I like to do anyway (don´t like the stock arrangement very much...).
The air routing to the supercharger inlet is not ideal due to the proximity of the front axle but it can be solved. As you suggested I got a supercharger (M62) with short snout and it fits well. The air routing to the torbo is very convenient. It is just vertical up and into the turbo inlet in its strock position. And here the differences start.
The supercharged and turbocharged lay out I had in mind works slightly different compared to those used in the Lancia S4 for example. I thought of going to an set up where the air is first fed trough the charger and goind directly into the turbo inlet. At low rpm the turbo will not do anything but to start spinning. Than, when engine load increase the turbo starts to work. Until a certain point it gets all the air it needs through the charger. Exceeding this point, the charger can not deliver anymore all the air the turbo needs and there will be low pressure in the connection line between charger outlet and turbo inlet. This will opperate a flapper door that feed the turbo directly. At this time the charger does not see anymore any pressure difference and it is flywheeling and does not consume any more drive power besides for its mechanical losses. I assume the maximum power the compressor will consume to be 20kW which will go down to maybe 1kW. The compressor does not need to flow a lot but needs a high rpm limit. The smaller the compressor and the higher its rpm limit the better it will work to support the low end engine rpm band. This is due to the lower volumetric efficiency of "blowers" at low rpm.
I do not expect this set up to work as the stock engine, neither I expect it to be smooth throughout the hole rpm range or beeing relyable. I am expecting a lot of problems in areas which currently I don´t see and the amount of work necessary will be high. Anyway it will be fun to make it work. As mentioned I have all the components necessary but will not garantee that the project will finaly get real. It currently is third priority on my "car, to do" list.

 

"A 50mm valve can flow alot more air than a 30mm valve from a maximum standpoint. However when you take a limited flow volume, ie. 500mL of intake air, and push it through the two valves at a 2000 RPM cyclic rate the smaller valve will actually flow more than the large valve. This is a common principle of mass flow."

So would running dual 2 inch exhaust flow better or be less restrictive then a single 3 inch?

"You are talking about restriction, I am talking about flow optimization."

I think I was trying to say that by elminating restrictions you are in fact optimizing flow. I think they go hand and hand do they not?

And it's obvious you know more about flow rates and fluid dynamics than I do, so I'll have to take your word for it

 

Why does it seem that many truck turbo projects are mounted in the rear?

As your ideas about that not being the best seem right on.

I guess the only benefit of that 12' of IC pipe would be a much cooler charge air by the time it got to the intake.

 

I will let you all know how Bob Howards engine project turns out. He spent many dollars with Bob Norwood who could never get it to run right or hold together. He got so frustrated with Norwoods BS he was ready to sell it all. He finally sent it to John Millage and found out what the issues were. John put it back together and he now has it back. He told me last week that he is going to go ahead and keep it and put it back in the car and get it going. I will see him this weekend and find out more. The last I heard 22psi was suppose to get 600+. I'll keep you all informed as it comes along.

 

It will be interesting to see how that car turns out. The car was up for sale a couple of months ago 60.000 for engine- trans.-10.800$ body shell 30.000$ Hope it works out for him big money spent.

 

"A 50mm valve can flow alot more air than a 30mm valve from a maximum standpoint. However when you take a limited flow volume, ie. 500mL of intake air, and push it through the two valves at a 2000 RPM cyclic rate the smaller valve will actually flow more than the large valve. This is a common principle of mass flow.

It has to do with sonic fluid flow principles. When flowing the two valves the smaller valve will produce a faster flow velocity. If this velocity does not exceed the critical point, typically measured in Mach for valves, then it will be more efficient and create more mass flow than the larger valve. If the valve exceeds Mach 1 the flow then becomes supersonic and begins to develop turbulence which reduces mass flow. In this instance the valve is undersized, and deemed "restrictive".
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I can not realy follow your argumentation. I don not belive that supersonic flow is of any meaning in the intake of any piston engine. Considdering a 3L engine at 6500rpm with a good volumetic eff and 40mm valve you would reach an average flow speed of about 60m/sec this is well below the speed of sound. When reducing valve lift to maybe 1mm you would approch the speed of sound for keeping the same average flow rate as mentioned above. You should not forget that it needs a certain pressure difference to accelerate the flow to this velocity. I doubt that this ratio can be exceeded in the intake of a charged engine at boost levels we are normaly reffering to (<25psi).
Obviously the valve itself is the most restrictive part in the intake at low lifts (it can reduce the flow to zero if it is closed...Ha, Ha...). So the valve shape is very important at low lifts. Towards higher lift it gets less important and the port design will be increasingly important. I would like to keep the speed around the valve low to reduce losses. I think we need to divide between the speed in the ports and the speed at the valve.
The reason for higher speeds in the intake ports is more the momentum of the flow and its inertia. The speed can be influenced with the port size which than also affects the torque curve of the engine. Small ports=> high flow speeds at low rpms=> good low rpm torque but restrictive at high rpm. For big ports the optimum moves to higher rpms be penatising the low end. The same is true for the header design, which means race headers hit the bottom end but strenthen the top. It is uncommon that such headers incerase spool up as metioned by someone before.

 

Big engine, torque, more exhaust. Havent seen many 4 cylinder engine STS setups.

Moot point, I dont think you could even jam one in the back of our cars, unless it was where the muffler is, above one of the axles, or you ran a custom gas tank or something.

 

I think you forgot to read this:

The sizing disparity is to elaborate the point. Typically you are making increments in 1mm steps.

Meaning it wasn't based on an application, but more upon the theory behind it for someone who doesn't understand the theory.

I didn't spend the time to add up numbers, they are arbitrary for elaboration.

When I am discussing Mach number I am refering to the port velocity as it contacts the valve.

Port diameter also plays a roll in resonance tuning, so assuming a narrow port is restrictive for top end flow would typically have merit, but there are cases where the smaller port can outflow a larger one. It's a factor of port area and the pulse tuning effect.