Honda F20 engine

All this family is supported by VEMS v3 ECU firmware and hardware including VTEC control

Note: Hi-side PFET-s come handy, see [v3 ECU product options] when VTEC (or VTI) control solenoid needs +12V (grounded to engine block).

F20c 2000 to 2005 12 tooth on crank no extra/missing + 3 cam pulse required for sync

Configlet for this engine available in VT -> primary trigger -> "4cyl_c012_Honda_F20C_00_05_Camsync"


F20C 2005 and up is same trigger wheel as K20X

=== OLD - historical (use the configlets, see above; and anything below should not be needed) ==

Honda F20

From the S2000, this is now a popular engine conversion into older cars and Lotus 7 replicas as it is an RWD engine.


This pic actually shows the late type (2005 and up, see InputTrigger/HondaKTwentyTrigger ).

There are 12 equally spaced teeth 30 degrees apart, with an additional tooth positioned (20,10 deg ??? Or rather 10,20 deg which makes more sense ... And confirmed below and elsewhere).

The engine turns clockwise (apparently this is the only Honda VTEC engine that does) so the trigger pattern is:

..., 30, 30, 10, 20, 30, 30, ...

Now the proper 30, 30, 10,20, 30 ... setup is implemented (along with any similar "extrapulse setup"), also with camsync in 1.1.96 and newer.

DONE: Configlets made for all these since than...

In factory applications the missing tooth wheels are better choices (and actually mostly used: better timing and diagnostics can be achieved without stricter wheel-precision requirement), but for home-made setups the low toothcount (often bolts) are usually appealing.

Bench test results

'Test on real car

Car is honda type R ep3, 2.0 vtec(also vvti) k20a2 engine.

Vems is connected as pigyback, so stock ecu manage the engine.

Primary trigger:12+1(extra pulse)

Sec: exhaust cam(4+1)

Log and trigger log:

Rpms are good and stable(tested till 8000rpm) only at cranking rpms aren't 100% stable

And for TDC settings are:

TDC after (60deg, not 100% sure, but error is max +-5deg)

first trigger tooth:3

but firing 3. cylinder, not first

Then i connect intake cam to secondary trigger:


It's clear form logs that intake cams move 30deg max with stock ecu.

Connect both cam sensors to vems(sec and third input) for best result (see sectrig and thirdtrig position in log).

Primary trigger: crank 12+extra pulse

Secondary trigger: Exhaust(4+1) needed for cam sync(working well)

3th trigger: intake(4pulses), needed for campos for intake cam

trigger log of intake cam(for logging is connected to secondary trigger input)

update 15.8.2011

Car is now running on vems ecu(not mapped).

first ignition coil is connected to vems pin 12, 2nd to 24, 3rd pin 35, 4th to pin 33.

Coils work with logiclevel output 0/5V with stock 510ohm series resistors.

And now tdc is 100% correct.

All three cam sensors are logged good.

Also VVTI control solenoid needs +12V (grounded to engine block). So added P-FETs mosfet(irf 9540) with gate pulled to 12V with 10k and gate connected to p259 chip. And diode for protection.

Car is mapped on dyno, 242@8500rpm. Vtec and VTI are working.