looking to build first kit car
 

Hi there I'm looking at spending around 10000-11000 on a kitcar I'm quite like the westfield with mx5 kit car can u use the 1.8 engine

really?

You can do what you like of course. The ford duratec 1.8 in the mx5 is a solid unit, but the 133bhp available wouldn't be the first choice.
You have a decent budget so could easily step up to a larger capacity duratec out of some mondeo or similar.

Great idea

1.8
 

The 1.8 BP engine in my 2004 NB2 actually makes 152bhp in its standard form, not 133. They are meant to work quite well with aftermarket turbos, without needing to upgrade much else. The big brake conversion is always a good idea tho.
The problem I've seen with it, is that it's now quite old, so isnt well-suited to running the latest E10 petrol, and I believe it's a Euro3 emissions class, so isnt allowed into ULEZ areas (without a hefty fee).