I removed my plastic throttle body a few days ago to re-seal the butterfly plate as I have been chasing a long standing air leak/idle issue. Whilst it was removed I noticed that my TB had been restricted. The butterfly plate was restrained from fully opening to the normal 90 degrees. By design it had been limited to around 70 degs . Curious as to what was going on I did a little investigation and found that this appears to be the case on the 1.8 engines only. On the 2 litre Duratec the butterfly plate opens fully. These two engines are virtually identical and even use the same plastic TB moulding. The subtle difference is the little metal bracket on the side of the TB assembly that the throttle cable attaches to. On my car the bracket restricts the movement.
Why did Ford chose to do did this I wonder? Was it to ensure a meaningful difference between two similar products?

Whatever the reason it presented the tantalising prospect as to how the engine might perform if the restriction was removed? Fortunately I had a second hand 1.8 TB that I had previously picked up just in case I couldn’t seal the air leak in my original. Curiosity got the better of me and just had to go get the saw.
Here’s the original 1.8 TB
Bracket modified to match the 2 litre. I wouldn’t recommend anybody doing this. It would have been so much easier to just to have picked up a 2 litre TB in the first place.
Here’s the difference with butterfly fully open - before and after.
Today I put it back on the car, re-adjusted the cable and out for a quick of blast. Early days yet but all working very well indeed.

I was anticipating disappointment thinking that the engine would “bog” when the throttle was fully open owning to insufficient fuel but not so at all. This may be attributed to having a performance remap installed recently and that may be adding a little extra fuel anyway. Whether the standard 1.8 calibration would perform the same I can’t say.
This mod might be here to stay