6.2/6.5 Turbo CDR valve connection question

[Fenris]

Ok, so I was looking at the 6.2L banks turbo kit for GMC trucks, and I was looking at the 6.5L turbo for the HMMWV. I asked before about putting in a banks turbo in my 1986 M998 HMMWV and was told it would be better if I put in the 6.5L turbo system. But then I started looking at the systems really closely....

If you put in the 6.2L turbo kit in, the instructions say for you to cap off the fittings on the intake manifold where your CDR connects to, and move the CDR connection point to the air filter. But if I were to put in the 6.5L funny looking turbo which has been engineered specificly for the H1/HMMWV, the intake manifold for the 6.5L turbo has a spot when you plug in the CDR valve into.

My question is, what is the difference where you put the CDR valve?

[DmaxMaverick]

The CDR is the "Crankcase Depression Regulator". It's purpose is to maintain a slight vacuum in the crankcase, preventing excessive vacuum that may damage seals and pull dirty air (or whatever) past the seals. For this reason, on a charge-air engine, the CDR MUST be plumbed in a non-pressurized location. If you plumb it between the turbo compressor and intake, any boost will pressurize the crankcase.

I've seen this once. Banks systems were still new and very expensive, at the time. A friend installed a piecemeal turbo system on his 84 6.2L pickup and asked me to ride along during a test run. I didn't look under the hood first, just jumped in. There was nothing noticeable at idle or low power, but it was a good thing he didn't turn up the IP, yet. At 4 PSI boost (WOT uphill), we could hear most of the engine seals leaking air, then a loud boom as a CDR hose blew off. About a 3 second event. There was no real damage to the engine, just blown RTV and gasket seals. The mains survived (non-rope), but took a couple weeks to get it back together after a tear-down. Fun times, back in the day, before TDP.