[quote="eogbaker"][quote="323F Rock"][quote="eogbaker"]
It is an old trick I was taught by my old boss who used to race a RX2 back in the day. basically if you take any form of radiator or intercooler and you put both the inlet and outlet on the same side in the same tank then put a division between them it will then force what ever is being cooled to pass through the length of the radiator or intercooler twice. once from the inlet to the other end and then back through again to the exit. If that makes any sense.[/quote]
Ahh yeah in the heat exchanger industry that is called a twin-pass unit as the media to be cooled will pass through the core twice. It's a good way of increasing your flow per tube value but increases your pressure drop through the core
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Is that not because the density of the air is becoming thicker due to it being cooled more? Also surely if the bypass valve runs off the pressure in the manifold (and if he works out correct pulley sizes) even with a pressure drop through the cooler he can still make sure it has his 6 or 8PSI that he wants making it into the engine[/quote]
Not exactly no, it’s because of the cross sectional open area is now half of what it was, hence the flow per tube speeds up but so does the pressure drop. Every charge air cooler will have a pressure drop.
For example 14 tubes, 500mm length, twin pass core can be estimated to be the same as a 7 tubes, 1000mm length, single pass core.
The bypass valve needs to open at 6-8psi (or whatever pressure Lerch has the balls to go to!
) the valve will read the pressure at the manifold as this is what we’re interested in. Say the charge cooler has a pressure drop of 3psi then the super charger will have to produce 3psi more pressure to meet the desired pressure at the manifold, this isn’t taking in consideration the pressure drop through the pipe work!
Without knowing what pressure the supercharger is capable of now with that pulley (or what the original pulley belt run and diameters were) it is near impossible to calculate a new pulley size straight away.
I still think a bypass valve which is actuated by the manifold pressure (similar to a waste gate on a turbo system) and stick with standard pulley as a base mark is the best way to go, and if we need to create boost faster then fit a smaller pulley or if the bypass valve is always open a larger pulley to control the pressure build up.
In the capillary tube from the manifold to the bypass valve we can fit a boost controller if the bypass valve is opening before the desired pressure in the manifold is reached.
Just need to find a decent bypass valve now and pipe it in
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1.5 SC, super interesting 
