First Intake + Fuel Enrichment
-Not having an intercooler means that the piping from the compressor outlet to the intake manifold is very short and simple but also that it has to stick up past the hood line - no problem. I had this rubber boot off of the Volvo CIS setup I had previously bought. It fit just right over the rubber seal & retaining ring off the stock Niva intake. From there I just ran a PVC pipe to the compressor and coupled it up with a few rubber adapters. I drilled the hole for the temp sensor and threaded it in. For my first fuel enrichment attempt I figured I'd just try running a very slow pass and see how the computer reacted to boost. After all, the fuel pressure regulator located on the TBI is sensitive to ambient air pressure, so maybe the rise in absolute fuel pressure would compensate for the boost and everything would be hunkey dorey.
-Although the computer didn't freak out from the boost (no "check engine" lights). It doesn't keep up and the engine runs lean past atmospheric.
-Next I tried an old Porsche turbo rising rate fuel pressure regulator I had scored on eBay, The operation is simple, fuel pressure is controlled by a diaphragm, with one side restricting fuel flow and the other side responding to manifold pressure, as boost pressure rises, it increases fuel pressure exponentially by making the fuel return path smaller and smaller. Higher fuel pressure translates into more fuel passing through the injector as it opens, so you get a richer mixture. This method of enriching the mixture is very common among aftermarket turbo/supercharger applications for fuel injected motors.
-This run was the same as the first, meaning either the Porsche regulator is either calibrated to start at a very low fuel pressure, or that the ratio is not sufficiently high to get any meaningful increase in fuel pressure. It could also be that my fuel pump can't make enough pressure or flow enough to keep up.
-The next thing to try was to put my nitrous setup from my '97 on, but only run the fuel, without the nitrous. It's pretty crude having to activate with a pushbutton but I was planning to change that to a pressure switch once I had figured out my fuel.
-Running only around 4psig of boost, when the button was pushed it would hum along OK for a second then go really rich and finally start to flood the engine because it was injecting too much fuel. The jet was calibrated to inject just over 50HP worth of fuel at 32psi (same as Niva), so obviously 4psig isn't making me an extra 50HP, but it's pretty darn close.
Pictures:
1.Stock rubber seal & retaining ring.
2.Tee in the fuel feed line to run to the fuel solenoid of the nitrous kit.
3.Nitrous nozzle threaded into the intake runner.
4.Fuel & nitrous lines hooked up but the nitrous line is capped just before the filter to keep out debris.
More Intakes.
-With the previous intake having failed, I decided to try using some fuel injectors from another car and firing them at 100% duty cycle (off of a switch) to enrich the mixture. I put in all four because I didn't know how many I'd need to feed the boost and get a good mixture.
-Using some plumbing supplies (PVC pipes) I was able to fabricate something that looked cool anyways.
-I took it for a spin at 4psig and with 2 injectors, and it ran half decent but was erratic and slightly rich. I then did a run with just the one injector firing and it was running lean. So I knew that I'd only need 2 injectors and that the design was crappy for injection purposes. So I came up with a different setup, similar to the first single pipe one but with 2 holes drilled for two injectors.
-With the boost at 4psig and two injectors firing at 100% duty cycle it was still running very rich, but with only one injector firing it was maginally too lean for my taste, so the only solution was to crank up the boost, and thereby make the mixture less rich on two injectors.
Pictures:
1.Four injectors. Notice the test pipe on the exhaust.
2.Another angle.
3.With two fuel lines.
4.Second Angle.
5.With the single pipe intake, but only 2 injectors. Notice the lowered rige height ;)
6.Up-close.
