so an update.
Twin charge works. Tuning it the past 2 days and getting plenty of fuel. Dropped one plug cooler because of some spark knock at high boost. Took some timing out of it at the top and a little bit off the bottom.
Twin charging works great. Super smooth power delivery and very good throttle response.
Well those are the good news, here is the bad. After a 4th gear pull it was boosting about 18-22 psi from 2,500 to about 4,500 rpm uphill perfect. Then lots of smoke from exhaust.
Take off at the light and lots of smoke again. When idling, its a bit of white smoke, when off throttle its lots of white smoke, when driving or under boost, no smoke.
So I get it home, and check it out. The smoke is oil, not your typical white coolant smoke. Pull the plugs and do a compression test. Its all the same as it was before. 120, 150, 125, 120. Not perfect but for 80K, not bad either. So oil is not from a blown piston. I pull off the intake tubes between the turbo and the supercharger. No excessive oil from there. Pull the intake tube from the front mount to the throttle body. Again no excessive oil from there. So I didn't blow up the Lysholm (thank god)
So I figured oil seal at turbo blowing into the hot side and flashing off into vapor (thus white and not blue). Problem with that is why does it only do it on compression braking. Turbo oil leaks are worst under boost and higher rpm. My next thought is valve stem seals. It is a 1990 and original seals.
So I do some more thinking. The was the system is now, the turbo is feeding the supercharger. The turbo wastage is managed by the intake manifold pressure (total system pressure). Well at higher rpm and closed throttle (compression braking) the G60 throttle body is diverting the charged air back into the pre-turbo inlet. What I didn't think of is that the supercharger is still spinning very fast and is pulling air though the turbo. I'm sure this is causing the turbo spool via the intake side, opposite of what a normal turbo does. This force suction that the supercharger is doing is causing a vacuum on the exhaust side to pull air from anywhere it can. Looks like its pulling air/oil though the valve stem seals.
This and compound the fact that the exhaust seals now see more pressure that it never saw with a supercharger, I think the seals just gave out.
I am having a set of seals come in tomorrow along with some tools that I can swap the seals without pulling the head. Hope this fixes the problem or at least stops the oil blowing problem until I can find a way to reduce exhaust vacuum problem.
Hopefully I can get this problem situated before next thursday when we head out that way.
(broken or fixed, it will be at the show next sunday. We would love to make the cruise on friday though lol).