Q. What is the difference in a 139QMB and a 1P39QMB?
Essentially there is no difference, other than one has a P in the code. What the P actually tells us is that the engine is a horizontal cylinder engine. Some manufacturers may be more likely to mark their engines with or without the extra character, but even the ones without the P are still horizontal engines.
Some have claimed that having a P coded engine designates 69mm long valves instead of 64mm long valves. While it is true that there are many P coded engines with 69mm valves, there are also P engines with 64mm valves so the engine code does not reveal valve length.
Another misconception for a while was that the P code meant the engine was a "secret 63". That's a stock engine with a 44mm bore, making it roughly 63cc instead of 49cc. There were many 44mm bored engines with 1P39QMB coding, but the also existed with 139QMB engine codes. Once again the P code didn't designate what it was hypothesized to.
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The engine code located in front of the oil drain plug and below the CVT.
Just behind the engine mount bolt.
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