So it's been another one of those life gets in the way situations. Long story short, sold a house, built my mother in law a detached apartment on her property then moved into the main house which hasn't had any major updates in... 30 years? So yeah, been super busy making a house a home. 2 bedrooms, one bathroom and the living room finished, 2 more bathrooms, 2 more bedrooms and the kitchen to go. Plus all the landscaping etc etc. The plus side is that now I reside under the same roof as my car!
Now onto the fun stuff. As I've been super busy with house stuff (and half the garage is currently a workshop for house projects) I haven't had time to really bolt things together. But I HAVE had time to spend money on parts!
Most of the progress has been on sizing components for an EFI system. And I finally bit the bullet and got a pair of Borla 2700 SU replacement throttle bodies with built-in injector bungs.
The plan is:
Bolt in replacement for the SUs with 1 injector per 2 cylinders.
Modify the distributor and add an optical encoder inside the body.
Run a wasted spark smart coil (VW style, I believe Daryl is using it?). Haven't purchased that one yet.
Map sensor mounted on balance tube in intake manifold.
Intake air temp mounted on inside of air filter box.
Coolant temp sensor mounted in the usual spot with adapter bung. (And heat shield)
Mechanical water pump and electrical fan. No thermostat and 240sx housing.
Microsquirt ECU running siamesed port injection code, Alpha-N and MAP blended tuning. Also controls fan on/off.
In tank fuel pump and primary filter with 10 micron filter down stream. 3.5 bar pressure regulator (I believe from a late model honda?).
PCV with 90 micron filter mesh (same as used in high pressure air lines) mounted where the low pressure fuel pump typically sits. Oil catch can between valve cover breather on air filter box.
LiIon battery mounted up against the firewall for reduced weight and more rearward weight distribution.
Uprated Denso single wire Alternator on passenger side.
4-2-1 exhaust header with two O2 sensors (needed for tuning the injector control). Once it's tuned I'm hoping to be able to remove one and put a single O2 downstream for closed loop control purposes. High flow catalytic converter under the driver's seat and muffler out back.
PWM 2-wire Idle Control Valve mounted to the air filter box with a split hose going to the throttle bodies.
What am I forgetting?
Something for sure. More pictures as parts come in and I have a chance to draw everything up, test fit things etc.
Some potential issues that may need to be addressed during tuning:
The accuracy in crank angle measurement using an encoder inside the distributor housing may not be good enough for spark and injector timing. If that happens then I'll have to put a sensor on the crank as well.
The fuel pressure may not be high enough to capture the full range of fuel needed from idle to WOT and max engine speed. May need to purchase an adjustable regulator to better dial it in.
In case it ALL fails then I will need to build a new intake manifold from scratch (or modify a stock one) and 4 injectors as the good lord intended!
So what's the motivation for all this? I'm interested in developing a simple, robust, bolt on EFI solution using a minimal number of parts and OEM equipment which is easily available. I decided to start with the SU manifold as they are plentiful and inexpensive compared to the more desirable DCOE style. (At least from what I can tell). So let's see how this goes! Still very much in the design phase and my engine still needs to be bolted together so a long way to go but it should be a learning journey!
If this works it could theoretically be applicable to any number of 4 cylinder twin SU engines from the same Era. Volvos, MGs, Triumphs etc. If not then it'll be a fun exercise anyway.
