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I've seen many supercharged and turbocharged cars run only an FMU with no problems at all. The FMU that comes with most kits are 12:1 to stay on the rich side. Like any mod you want to keep an eye on the A/F ratio to make sure it stays rich under boost. You won't be able to tune for max HP like you can with a stand alone ecu but the FMU is cheap and simple. I would suggest running both an FMU and some type of timing/knock control to be extra safe. The best part about the FMU is that it only adds fuel pressure under boost so while your cruising around the car runs normal and doesn't wast fuel.
If your looking to run higher boost you can also add an adjustable FPR and bigger injectors. You should have a wideband O2 to keep an eye on the A/F so you can lower the base fuel pressure to compensate for the bigger injectors during idle and cruise conditions, then when under boost the FMU will dump in the extra fuel needed.
Remember to always keep your timing conservative and your A/F ratio rich under boost.
If I were to attempt a "cheap" 5sfte this is what I would do:
- Use 3sgte ct-26 turbo/manifold/piping plus an extra elbo for TB (add bigger turbo if cheap enough)
- ebay downpipe
- ebay exhaust
- misc oil and water lines
- 3sgte intercooler
- 3stge oil pan
- would not use 2 bar map (too much timing from tricking ecu) keep stock map.
- add a 12:1 FMU
- add bigger fuel pump
- *maybe add adjustable FPR and NA supra injectors then reduce base FP (could be added later)
- reduce base time by 2-4 degrees for safety
- get a wideband o2 or borrow one and keep an eye on the narrow band o2 after tuning
- see how much boost I could run before A/F drop off
Its fun to daydream...
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