Remember that the IC isn't just a 'dead' aluminum plate. You'll be using 2 fiber gaskets instead of the normal one. This helps provide more thermal isolation, as the IC doesn't actually touch the SC or the lower intake manifold.

You guys are correct, that spacer doesn't provide coolant passages. I'd be interested in the flow difference between the Series 1 and Series 2 LIM'*, to see if it'* even possible to block off coolant flow without disrupting something else? Is it parallel or Series flow? Also, how do they seal off the coolant passages? Just with the stock o-rings (for the phenolic spacer).

I blocked mine with a pair of 1/2"-13 plugs and a tap. I flow-tested my spare LIM first of course.... I find I can't tell when the thermo has opened up anymore, heatsoak seems to be invisible.

After you plugged yous, flow from the front to the rear head was uninterrupted to all passages? So this is a parallel branch we're talking about? Where does the coolant come from and go to before you plugged these? Are you positive that after blocking it, the coolant still flows through the rest of that path?

(I'm asking because I don't know, although I do have my suspicions).

I sat my spare on a pair of jackstands, And put a water hose to all the holes, When I hit the coolant port that got the most flow out of the TB ports (right bank, flywheel end), I plugged the ports with my fingers, Flow increased on the branches. From looking inside the LIM, that area of the coolant passage is like a cave with the TB holes drilled into the top, and a little ramp on the floor to shoot flow up.

maybe a two piece spacer that would allow you to run the lines through. That way you dont have to worry about drilling holes in the LIM, holes you have to plug somehow when you sell the car.

Why do you want to block coolant holes? Isnt the point to keep it as cool as possible?

You don't really have to drill, I just happened to have a 1/2" tap and not a 3/8" one.

The idea is to block the hot coolant from touching the IC and TB, that way you're keeping the heat away and getting cooler air in. On my L27 I figured it would be worth stealing the idea from the L67 guys That and I had a coolant leak farther down those lines that this nicely eliminated.

I'm concerned about this. What exactly did you observe? I would be concerned if you saw much indicated change on the temp gauge from simply blocking that passage to the TB.

Well, I used to be able to feel when the thermo opened under WOT, I could tell if it was open or closed at idle, Now I can't. The engine still gets just as hot, It just doesn't affect performance even half as much. Once it warms up, the performance doesn't get any worse because of heat soak.I'm still running in the same neighborhood of temps, 220 in 110 plus stop and go, 180 on 60 rural highway. I think this can be done on S1 L67'* to help out the intercooler...

Im not really concerned with the added heat of the coolant going into the SC, my coolant temps hardly ever get over 180-190 and ive heard the SC temps are usually running better than 270 degrees, I cant see a big advantage to blocking the coolant passages, when the SC turning itself is what is causing the heat. I plan on either doing a heat exchanger in the LIM air intake passage or a plate design....right now my biggest challenge is sourcing a heat exhanger in either 4 1/2" x 4 3/4" x 1 1/2" or in 3 8/10" x 4 1/4" x 1" I have only had the chance to check a few places and still havent recieved word from the shop in Indy that does custom IC work.....Doing a little more reasearch I may want to stick with the plate design, as it sounds like it will liekly work better...it will also likely cause less intake restriction, and will allow for the use of a thicker heat exchanger core, all good for allowing small azz pulleys, which is what this is really all about.

Might try:
http://www.bellintercoolers.com/Pages/contact.asp
and
allen@allenengine.com
and
http://www.motdyn.com/html/machine_services.html
and
http://www.turboneticsinc.com/intercoolers.html

If you haven't already.