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Message: [QUOTE="IdahoF350, post: 399633, member: 2989"] Ross: Do you understand how positive displacement superchargers work? You have a 6.0L engine. That means you're consuming roughly 6.0L of air in 2 full revolutions of the crankshaft assuming 100% volumetric efficiency with 0psi additional boost over available atmospheric pressure. Now, in stock form, the engine makes just shy of 30psi with its turbocharger. 30psi being a reference point, sea level is just under 15psi, and the 30psi is on top of that, so it's atmospheric pressure plus two atmospheres, or 3 bar. For each additional atmosphere, the engine will consume an additional 6.0L of air, so at 30psi your engine is consuming 18.0L of air (still just assuming 100% efficiency for arguments sake). A positive displacement supercharger displaces its measured volume in one revolution. So if the supercharger is a 4.0L compressor, it will move 8.0L of air at idle for a 1:1 drive ratio. Typical drive ratios for these units are between 1.75:1 and 3:1. So for our diesel, let's go 3:1, shall we! That's 24.0L of air on a 6.0L engine, so with a 4.0L Whipple using a 3:1 drive ratio, you should net about 45psi! What the F? Am I saying a 4.0L Whipple alone might be enough? Not only am I saying that, but because of the lower peak RPM of the diesel, call it 4000rpm, vs the '04 Cobra 3.4 Lysholm I tuned recently that turned 7500rpm, you can run an even more aggressive pulley ratio, maybe 4.0:1, at which point you would see about 60psi! That 3.4L Lysholm (Lysholm actually makes the Whipple) made 740ish rwhp at 25psi on a 4.6L DOHC engine with ported heads and big cams (both of which increase efficiency as inlet pressure rises and reduce the total restriction and measured boost) all while only driven at about 2.0:1. Instead of barking up the failure tree, why not figure out a way to effectively charge cool the 4.0 Lysholm and build some long tube headers for your engine so it can breath! You would have no need for the complications of a compound or sequential system of power adders, and you could most certainly make 700hp and low to mid teens for torque, all with a single power adder. [/QUOTE]