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Turbo boost problem on 951 track car - Altitude?


Vehicle Information: Year: 1986; Engine (type, size, modifications): 2.5L Turbo; Total Mileage: 3000 miles on engine - 42,000 on car;

I bought this track car with a fresh engine. After breakin, discovered very low boost - maybe peaking at 7 lbs. Replaced wastegate with a Huntley racing delta gate and MBC. Boost increased to about 14 lbs at altitude (5200 feet in ABQ, NM), maximum of maybe 20 lbs at lower 2000 ft. in Phoenix. OK, but not enough for a successful track car, so installed a new Garrett ball bearing turbo (approximately a stage II Huntley, i.e. intermediate compressor, re-vaned k-26-8 hot box, etc.), with a stage IV MAF and assorted fuel controls, etc. Actually lost boost - producing maybe 12 lbs now. Have completely blocked off wastegate, flow and tank tested intercooler, rechecked all plumbing, including blow off valve, etc,, and no luck. Nothing obviously wrong, but this thing just doesn't seem to be spinning up enough. No meaningful exhaust leaks...basically a complete puzzle!!!The KLR is out of the picture (with the MBC), and the Auto Autority stage II chips are basically being fine tuned by the fuel controller. Independent checks with the shop O2 sensor confirm the mixture's reported from the new O2 sensor we installed, and the readings from the mixture meter.EGT is pushing about 1450 degrees two or three inches off the number four head, and well, there's just no good reason that I can think of.Any thoughts before I sink this boat?

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