[Dr J]

Ok. Took a while but finally got back to this and managed to find the problem so I am posting to show the resolution.

The root cause of the high IATs was the blowoff/bypass valve plumbing. In my configuration with EFI in speed-density configuration I did not need to recirculate the air so I used the valve in a blow-off configuration. In a turbo setup the blowoff valve operates when there is hard vacuum such as when you get off of the throttle. However, in a supercharger setup, the blowoff valve should be operating during idle and part throttle. It should only shut down on hard acceleration.

When I plumbed the blow off valve I plumbed it off the bottom port in the front of the throttle body. In that configuration the blow off valve would shut down as soon as you go off idle. Because the twin screw supercharger compresses the air whenever it is spinning, the air to the intake would heat up even though the engine was still operating in vacuum.

The solution was to plumb the blow off valve from the back of the throttle body, where the old decel valve used to be. Now it gets good vacuum signal all the time that the manifold is at vacuum so air intake temps increase only slightly during idle and cruise. Of course, the IATs should increase on boost but that is expected. Moreover, once off high load, the IATs will quickly cool back down. Now I can finally drive the car with the supercharger on.

Another suggestion I followed is moving the bypass air out of the engine compartment. I used the empty hole in the engine tin that was used to recirculate air to the exhaust. Now the air comes out of the engine bay. The hole was the right side when using 1in silicone tubing. Another plus was toning down the “noise” inside the cockpit.

Now that that issue is solved I can continue mapping the VE table on boost. With the Infinity ECU I can set engine protect at whatever boost level I want so that I can safely map that region of the VE table.

Thanks to all for your suggestions. I think I will keep the water methanol setup and not use the intercooler. For my setup the only reasonable intercooler I could fit was an air/water unit.