I currently own a Mk3 Fiesta RS1800 track car that is in need of re-shelling. I'm aware that there are what's considered Mk3 and Mk3.5 shells with the latter being used on the Si. What I need to know is are there any limitations as to what shell I can use in order to house the Zetec engine?

I know the FRST only has a rear engine mount whereas the RS1800 has front and rear, but can the chassis leg of a FRST shell simply be drilled to accept the Zetec front mount?

Also are there any other issues that may come up transfering RS1800 components (suspension, lower arms, rear beam) to a FRST shell? The engine management/loom, electrics and fuel system are completely aftermarket so they're not an issue.

Any advice would be greatly appreciated

 

All 3.5's will take a zetec

 

i had a mk 3 shell the bought a 3.5 rs1800 but wanted to fit a cvh lump the top rear engine mount on the chassis is further back on the 3.5 so i had to make a plate 1 inch longer to bring the cvh engine further forward the chassis leg hole is the same ...

 

I'm working with a similar conversion though mine goes other way around. Here is a short summary of the differences:
- there is two different flavours of the front mount. The one found in XR2i 16V and the one in Si. The Si one has an additional support which bolts onto the inner front wing. The bolt pattern in the chassisrail is not compatible wirth the latter type in pre -92 chassis.
- the rear engine mount mounting place is in different location. You can just drill an extra hole into the 8V version and off you go.
- The bulkhead is quite different. The cutout and seal for the steering column is in different location and different shape. The steering racks mounting points are in different place because mk3,5 chassis have more clearance and strenghtened mounting points compeared to mk3 one. This is required to house the PAS setup.
- lower ball joint, suspension arm, outer CV, hub, bearings and strut are all different desing and none of those are interchangeable individually with the corresponding mk3 items. You can change the suspension as a whole though.

There is nothing major, but lot of details to take account when fitting 16V engine into 8V car or other way around.

 

There are 2 versions of the MK3 shell & MK3.5
MK3's - 1 for the lesser models & 1 for the XR2i & Turbo.

The mk3.5 are similar however as I think after looking on Microcat that there are 2 different shells as well.
The base 1100 & 1300 will also accept the CVH lump as a straight fit but is the shell strong enough to handle the power from say a 200 bhp tuned turbo lump?
The other shell is for all Zetec engined cars so the Si is the same shell as the RS1800 which can deffinately handle 130 bhp so my advice would be to go for this one.

hope this helps.

 

Mk3.5 shells are much stronger/stiffer, so would be a better choice for a track car. Shouldnt really have any problems putting a zetec from a 3 into a 3.5.