Compression Numbers.. and new battery?
 

Hey there everyone,

So today I took my beloved to have a compression test (my warranty ends 8/14/13) and I wanted to get some feedback on the results. I know the basics of what they mean but I wanted to check here to make sure. Here are the results:

Rotor 1: 7.5, 7.4, 7.7
Rotor 2: 7.7, 7.8, 8

All cranked at 225 RPM. To me these seem like awesome numbers. According to the rotary calculator on foxed.ca the normalized numbers come out to the following.

Rotor 1: 8.1, 8.0, 8.4
Rotor 2: 8.4, 8.5, 8.7

I did not count for testing altitude because I have no idea what that is (Im in PA) Does my rotary math seem to make sense?

Also, the tech mentioned that my battery would need replacing soon since its "undersized". I had the battery replaced at a local no name shop (probably a mistake) after my battery died after coming home from a vacation. How important is it that I replace the battery? Is it an ASAP type situation or can I wait a month or two? The car starts up fine every time hot or cold. Thanks for the thoughts.

Yes, that is a fantastic set of numbers. Great engine. Starter is a bit low, so think about replacing it before long to avoid starting problems in the future.

The battery size isn't critical, though a bigger battery has starting advantages in cold weather and if you have to start multiple times in a row.

Awesome, thank you for your thoughts! Would the smaller battery have any effect on the starters cranking speed?

Only at lower charge levels, which it will reach faster than a larger battery. A combination of a slower starter and a smaller battery are stacking things against you when it comes to flooding risk, but nothing alarming. Just noting the only real impact it may have. With those compression scores you should be starting up quite quickly as it is. A 280+rpm starter and healthy ignition would make them nearly instant starts I expect.

Yes, The starts are very good as is. I just changed all my ignition components (Plugs, wires, coils) so I will make sure to upgrade the battery and starter before the winter comes as precautionary measures. Thanks!

Your numbers are good, especially when you accounted for the slower cranking speed. Spec is 250 rpm. If the car cranks without hesitation and starts easily, I wouldn't worry about the battery.

Those are good numbers...congrats!