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-Is that too much cam for the stock EFI from a '75, and would it flow enough to work anyway? I was always under the impression that the EFI flowed pretty well, and that might be easier and cheaper even than the intake, carb and porting work. Perhaps with a Megasquirt or Haltech on the stock manifold?
Wayyyy too much cam for the stock FI to handle. But yes, with the FI's long runners, and better plenum, a stand-alone tunable ECU would work very well. But you need the money for an ECU, bigger injectors, fuel pump, regulator and high pressure lines (assuming it's not already a 1975 Opel), a laptop to tune it (unless it's SDS or Luminition which has its' own controller), and TIME to tune it. Preferably on a dyno. So there's a sizeable $$$ investment just for the induction system, probably $1500-$2k.
-What kind of compression ratio would we be dealing with here? How much lower would it be with a 1.9 head and the same set-up?
Depends on the valve sizes, head milling, unshrouding, but again, usually 10.5:1 to 11:2:1. A stock 1.9 head with 2.0 pistons gives 8.45:1 compression, with Chevy 1.72/1.50 valves an even 9.0:1 compression. With milling, you can approach 10.0:1, but then the valve notches need work.
-You didn't mention fly-cutting the pistons. Are the valves safe with that combo of piston and lift?
With the Venolias I mentioned, you have clearance (at least to 8400 rpms..that's as high as I've run that combo). Unless you mill the head appreciably, and then the intake notch of the pistons needs clearancing for diameter, rather than for depth.
Bob
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