My 1990 300zx Twin Turbo build by megaDan

5 minute(s) of a 731 minute read

Wash done! I guess I baby this thing more than I thought. I don't think I'll nee to wax it for a while yet. It might not look mirror smooth, but water still beads off like it was waxed yesterday. I'll probably postpone the full exterior detail until midsummer. I hit the interior with VRP to get rid of all the dust that builds up and gave the carpets a good vacuum too. So satisfying. Also so dumb I didn't take any pictures. Sorry.

I met up with a buddy and we went for a joyride Sunday evening. The weather was beautiful and we were both going a little stir-crazy. Everything felt good; but my buddy mentioned a little more smoke than normal. I have seen occasional puffs, but it must be more noticeable behind me. Pretty sure turbos are going. Already planning on new CHRAs. I'd expect them to make it through the summer given the low number of miles I'll probably put on them this year. Stock boost is 10PSI; I've been running 17 on 93oct since installation, and 24psi since last year. They were used when I put them on 9 years ago so I'd say I got my monies worth. I briefly daydreamed about upgrading to small ball-bearing turbos which would be better suited to higher boost levels; but shot that down pretty quickly when I did the math. Replacement turbos would almost certainly require an upgrade to 5 bolt downpipes and a new tune. All said and done the cost of install would be about $4000 without surprises. I'm just about maxed with my fuel system; so I wouldn't really even see more power, just potential reliability. New CHRAs are $500/ea. Cost of install well under $1500. I'd probably get another 10-15 years out of these. This makes the most sense to me. Hopefully I don't have to document my first turbo rebuild until this winter We got a bout of warm weather yesterday; with temps reaching 75. I got into the garage as soon as I got home while air temps were still up to give charging the AC system a try. With the system already evacuated charging was pretty straightforward, even given that I had never done this before (from empty. I've added refrigerant before). Quick rundown for those that haven't done this before. Close hose end and manifold end ports; connect to high and low ports, connect to vacuum. Start the vacuum and let it draw down, then open the manifold gages so the lines are completely evacuated, then open the port side valves and let it draw down for a few minutes. Shut both the manifold gages and turn the pump off. Start the car, turn AC to max and temp to Min. Connect refrigerant fill valve to new refrigerant can, connect vacuum line from manifold gage to fill valve. 'Close' fill valve on can to pierce the top, then open it back up. Bleed the air from the port on the manifold gages. Slooooowly open the low side valve and allow refrigerant to fill the system; the low gage will rise first, with the high side slowly following. As I was doing this I caught myself holding my breath because I had no idea if the compressor would kick on or not. The state of the compressor and electrical system were almost complete unknowns. Once the low side pressure reached ~30 or so I heard the compressor kick on and I did a little dance. SUCCESS, but not out of the woods yet.

I drained the first 12oz can completely and prepped can #2. What I found online said it would take 24oz, so I planned on using 2 cans; but I was going to fill based on high side pressure. For an ambient temperature of 77, the high side pressure should be 162-199psi. The car was idling for quite a while, and the air temp was in the mid 80's at least. I elected to fill the system to 175psi and call it quits there; that puts me just below the mid-point of the acceptable pressure range.

Unfortunately I don't have a digital thermometer or anything other than a mercury thermometer for cooking; so I had to go by feel for checking to see what was coming out of the vents. I realized afterwards that I could have used one of my smart home temp sensors which I might do in the future to get confirmation of vent air temperature. Either way, it was pretty clear I was getting nice cool air. I'd guess somewhere between 40-50F at the vent. I took a quick test drive, which was probably the slowest I've taken. Coolant temps were great, and air temps were even better.

When I bought this car it had a non-functioning AC, and the heater core bypassed. It only took 12 years; but the whole HVAC system is up and running. Maybe my next update will be to show off the (what I consider) neat automatic climate control. Neat just because I can't think of many cars in 1990 that had this feature.