Forged engine build – stripdown

A few weeks ago I went to Skuzzle motorsport so that the Westfield could be put back on the rolling road to check all was functioning correctly still. I felt it had run rich ever since updating the MegaSquirt firmware to work with RaceTechnology gear and indeed it was. It was also down 30bhp at the wheels. Nick was able to add more boost and ignition advance to compensate but we didn’t go too far and I left with 210 at the wheels. It was 229 last year. The logical explanation for that is the rods are bent – adding boost and advance is something you’d be able to do if you lowered compression. I’m not 100% convinced as I’m of the opinion that the rods aren’t going to bend a little bit and then be nice and stop, but I’m not dismissive of the idea either.

I’d had a plan to build a forged bottom end and go for more power, and this just kick started it really. I was going to do it over the summer so it’s not that early. I picked up another mk2.5 engine; going for mk2.5 because I wanted the main bearing support plate. The alternative was to get an early mk1 1.8 block with the oil feed under the exhaust manifold which would have tidied up the pipe work but I felt the main bearing support plate was more beneficial.


Mk2.5 engine

I stripped it down, throwing most parts in the bin as I already had a lot of spares from the last engine. With the head off, I was able to inspect the bores which were the important part. They weren’t in as good a condition as the previous engine but still fine


VerticalĀ marking on bores

All four cylinders showed this marking to some degree with cylinder 1 (pictured) being the worst. It’s nothing too sinister as it can’t be felt with the fingernails. It’s marking rather than scoring so should go when it’s honed.

Cracking on, I removed the sump and began removing the crank and pistons.


All looked fine here, and likewise with the crank removed.



I’ll be removing the oil squirters tonight, cleaning it up a bit then dropping it off tomorrow for cleaning and checking… along with getting a second opinion on those cylinder marks. Just in case!

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