Gez from Australia here.
I have 2008 Mazda 3 2.0l hatchback, manual gearshift and want to know if the timing cover from my engine will fit the 2.5.
I believe that this is necessary to enable the oil pan change to facilitate A/C fitment back to the original position when swapping to the 2.5 . I also was under the impression that all of the timing covers were the same but I read later in the posts on the swap engines subject, that the 2.0l is shorter , is that right? Aren't the 2.0 and the 2.3 timing covers the same ?
The Mazda 3 2.5 litre is called the SP here by the way and I think it can be used up to 2013 I think.
My engine is fine , would just like a bit more power.
Hope this makes sense .
The engine blocks between the 2.0L, 2.3L, 2.5L (mazda / ford) are the same. The heads are not. The 2.0L head is 3/4" shorter than the other two because of the stroke length difference (not to mention bore difference) with the smaller displacement.
With the 2.0L swap with a 2.5L here is what you need to change.
1) Timing cover - source a used, taller 2.3L mazda timing cover
2) Oil pan and oil pickup tube - source a used, deeper 2.3L mazda oil pan (IF your car has A/C) and get a new 2.3L oil pickup tube. The 2.0L engines did not use a balance shaft. The 2.3/2.5 engines have balance shaft hardware that hangs down into the oil pan area. The 2.0 pan will not fit unless you decided to to a Balance Shaft Delete on your new engine. Your choice. Keep in mind it holds less oil too! If you have A/C, you'll need a 2.3L mazda oil pan with the indentation to fit the A/C compressor. If you don't have A/C you can use the ford oil pan from your new engine. The oil pickup tube is matched to the pan shape and depth. You must use an oil pickup tube that matches the oil pan.
3) Passenger side motor mount - get a new 2.3L mazda PSMM. The mount location is on the head. Taller head, taller motor mount needed.
4) Exhaust manifold. There is a beefy metal bracket that bolts to the backside of the engine and supports the exhaust manifold from underneath. The taller head means your exhaust manifold now sits 3/4" higher than it did before. The bracket will be 3/4" too low. A bracket must be used, or your manifold will hang from the attachment point on the engine and put all the stress on those bolts. I got some 3/4" machined zinc-coated spacers from Ace Hardware (about $3 each I think) and some longer bolts. The spacer fits so nicely between the bracket and the exhaust manifold. Longer bolts WERE NOT NEEDED since the original bolts were plenty long. The spacers were available in brass, raw steel, zinc-coated steel, nylon, etc. This is a high heat area so stick with metal. A stack of metal washers could also work. The zinc-coated spacer is by far your coolest option. Except no one will ever see it.