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How hard could it be???

I currently have a stock 1990 1.6 with 220,000kms on it and have come across a 1.8 to replace it with.

What sorts of problems am I going to come up against in this changeover?

At a rough guess there will be:
Mounting issues
Clutch/gearbox probs
Fuel pump not keeping up
computer not compatible

Does anyone have any specific info for this change?

Also, does anyone know what the fuel efficiency of a 1.8 is roughly?
I usually get 550kms out of my current 1.6 engine.

FM do a 1.6>1.8 conversion kit that should give you an idea of what needs changing in the conversion:

http://www.flyinmiata.com/index.php?dept=67

ebola wrote:Does anyone have any specific info for this change?

Hi there, MX-5 Plus also have a kit for this conversion.

The complete MX-5 Plus Kit includes the following components (customers can less off the components that they don't require):

(1) BP Engine with engine mounts

(2) BP Alternator Pulley (if BP alternator not available - Multi V pulley in lieu of Single V pulley on B6)

(3) B6 Throttle Body to BP Manifold Adaptor, Gaskets and Fasteners

(4) M8 tap and pilot hole drill bit

(5) BP Thermostat Cover with port for B6 thermofan switch

(6) B6 Coil Pack to BP Engine Bracket

(7) BP Top Radiator Hose

(8) BP Air Intake Plumbing

(9) BP Exhaust Header to Catalytic Convertor Pipe

(10) IAC Hose (Modified to suit)


The following is a summary of the modifications that are necessary for the installation of the BP engine using the B6 engine management system.

(1) Drill and tap BP manifold M8 x 1.25 - 12mm minimum deep in two positions as determined by the throttle body adaptor. This service can be provided (ie. exhange your manifold for one already modified)

(2) To reuse B6 Plug Leads - Swap coil positions and wiring in coil bracket to allow use of B6 leads.

(3) Fit B6 CAS (Crank Angle Sensor) to BP head. Extend the CAS wiring loom as necessary

(4) Extend the B6 temperature sender loom to reach BP temperature sender (back of head).

(5) Extend thermofan switch wiring loom to reach new switch position in modified BP thermostat cover.

(6) Remove triangular lug on B6 throttle body to allow fitment to BP manifold.

Please send and e-mail to service@mx5plus.com.au if you require more information.


Here are some images of the throttle body adaptor. The transition from the B6 throttle body to the BP inlet manifold has been perfectly matched.

















Cheers,
Danny

also a good how to in Keith Tanner's Mazda Miata MX-5 Performance Projects pages 53-54:
http://books.google.com.au/books?id=gSt ... CBQQ6AEwAg