91 Civic DX head swap

My friend wants to wants to put a d16z6 head on his 91 civic dx (aka
"mini-me" vtec.) Newer D16 intake and exhaust manifolds will be used.

Theres a few options we have considered for the ECU.

The easiest route is to use the same year Si ECU and add the wiring
for the extra injectors, and use an RPM switch for the VTEC solenoid.
This is easy, but the downside is the fuel maps arent matched to the
secondary cam profile. Possible power loss ?

The more expensive option is to use a 92-95 OBD1 ECU, although it is a
bit more expensive for the conversion harness, which further drives up
the price, the VTEC control and fuel maps will already be taken care
of.

How much power is going to be lost by using the Si ECU and the RPM
switch ? I'm thinking the OBD1 conversion is the way to go.

Also, will the D16 exhaust manifold bolt up to the stock exhaust ?

 

The best way is to have a 90-91 Si ecu chipped and let the ECU control VTEC
operation. That way, the ECU will adjust the fuel and timing for the cam
changeover.

The exhaust should be fine, might wanna upgrade the exhuast after the cat
though.

The main issue will be the distubutor mounting. The Z6 uses it's own
patteren, The Y8 (96-00 SOHC VTEC) uses the same mounting pattern as the
current DX/Si distubtuor. You'll have to use a Si dist. and add 2 wires for
the crank angle sensor.



Come over to my place, www.sohchonda.com

 

From what i've read, the vtec control mod uses the auto lockup
solenoid output for the vtec control. My friends car is an automatic.
Is the modifed Si ECU still going to work for this car ?