So. As the saying goes, bolt on is never truly bolt on.
This post will detail the mission, rather exercise in frustration that is getting ITBs to fit with the Otaku RB20DET adapter plates. People who have used them have just said that they are tough to get to work correctly but dont offer any details in what the process actually was.
To start, I would like to add that they were quick to answer any questions I had over instagram and this isnt a stab at them or anything.
When I had mocked everything up on the stand there was a huge interference in between the coolant passage on the Rb26dett intake manifold and where the thermostat would like to live. Turns out that even with the proper parts it would be a game of Millimetres to get everything to play nice.
Otaku instructed to get an RB30 thermostat housing for more clearance and to modify the lower coolant passage.
I marked in black the areas I needed to further modify the thermostat housing.
Modified the coolant passage and machined down the lower screw boss to get it to clear the thermostat housing. Just clears as is but still no room for the lower rad hose.
Got the thermostat housing cut and angled down to free up some more space. Also you can see I had to countersink the top bolt hole as well. Everything finally clears. Time for "final" assembly.
I also drilled out the threads marked with the "X" this is to allow the fastener to go through both plates into the block. I was concerned that the small area around the front water port wouldn't seal correctly.
I made a gasket to go inbetween the two plates and used a light buttering of RTV to make sure everything is sealed correctly. I completed the assembly with an HKS RB26dett intake manifold gasket set.
Those are the main hurdles in getting the otaku ITB adapter kit to work on RB20det. I can see why people knock on the kit because its pretty fiddly and doesnt fit out of the box.
Now I dont know yet if it leaks or anything. This was just to make it all physically fit.
I just need to plumb my swirlpot in and figure out some vacuum lines we are ready for fluids.
Getting there
-Jordie