2.0l engine with 1.8 heads - what FI set up to use? Options

[Tdskip]

Counter to popular belief I do not stay up late inventing hairbrained questions for you all, although that is tempting sometime given the wealth of knowledge here. As of around 10:30 AM today this will be a real life scenario.

Let’s imagine I have a 2.0l case running 1.8 heads with a single Weber that runs but I want to convert back to FI.

Let’s further image that I have both a 1.8 FI set up and a 2.0 FI set up sitting in the shelf.

Which FI set up would I be best advised to use on this engine, and for bonus points and adding to the community knowledge here, why?

BTW - planning on doing a tech day on this with/for the SoCal mafia once I get a plan together. Given what seems to be a trend back to FI (or at least renewed interest) I think it could be a useful tech day for the community.

Thanks!

[Dave_Darling]

I would go with the L-jet setup, for the reasons above. It can cope with the larger displacement, and probably will not need nearly as much tweaking to work as the D-jet will. D-jet makes more assumptions about the engine's air needs than L-jet does, as L-jet directly measures the air coming in.

Since you would be using 1.8 heads, use the 1.8 intake parts. They are made to go together, so it's a total no-brainer.

The 2.0 plenum (the intake manifold box thing) is wider than the 1.8's is, so the intake runner pipes for the 2.0 are shorter. There is the different bolt pattern, as mentioned several times. Both of those can be dealt with one way or another, but they are things you have to be aware of. It would be interesting to fit the L-jet's air flow meter onto a 2.0 throttle body; different ducting would be needed and the 912E parts (which use L-jet on a 2.0 914 motor) are hard to come by.

The L-jet and D-jet injectors are operated differently (D-jet supplies power to open them; L-jet supplies a ground to open the injectors) and I think may use different power levels and have different impedance. I recall the late Cap'n Krusty telling us that the Bosch reps cautioned to never switch L-jet and D-jet injectors, as that could cause some electrical issues and possibly even fry something.


So: Use the L-jet, complete. It fits what you have, and it should cope with the larger displacement just fine. No mix-and-match of parts required, no machining required, just bolt it all together. (And spend however long it takes to fix all of your vacuum leaks!)

--DD