So, last Friday I exploded the engine in my Miata. Well... that might be a bit of an exaggeration. I lost power and found that there was a catastrophic amount of blow-by. I had to go out of town for the weekend, which was torture with my car all sad and 'sploded, but I got to work first thing Monday night.
Leakdown numbers on 1-4 were: 4, 36, 7, 40; with lots of air coming out of the crank case. Yup, that's new engine time.
I tore the engine and transmission out and took the engine apart down to the short block and this is what I found:
A little errosion and a crack in piston #4, I attribute this damage to the fact that this engine had 240k miles on it when I dropped it in two years ago.
The cylinder bores in #2 and #4 were both pristine:
So, with all good guts in the engine, I'm thinking rebuild time! I have been pricing out connecting rods and pistons, likely going to go 'forged' on the bottom end to not worry about power anymore.
In the meantime I arranged to buy a used 80k mile driveline for $425, so I'll have that to drop in and drive around with while I build my serial racecar engine.
On a related note, my clutch was almost worn out completely, so time for a new clutch too.
Edit: finally uploaded some pictures from an autox last year:
Leakdown numbers on 1-4 were: 4, 36, 7, 40; with lots of air coming out of the crank case. Yup, that's new engine time.
I tore the engine and transmission out and took the engine apart down to the short block and this is what I found:
A little errosion and a crack in piston #4, I attribute this damage to the fact that this engine had 240k miles on it when I dropped it in two years ago.

The cylinder bores in #2 and #4 were both pristine:


So, with all good guts in the engine, I'm thinking rebuild time! I have been pricing out connecting rods and pistons, likely going to go 'forged' on the bottom end to not worry about power anymore.
In the meantime I arranged to buy a used 80k mile driveline for $425, so I'll have that to drop in and drive around with while I build my serial racecar engine.
On a related note, my clutch was almost worn out completely, so time for a new clutch too.
Edit: finally uploaded some pictures from an autox last year:

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