Venturer

I didn't do a compression test from several years.
What i would like to know is if an immediate rotary engine start when hot (and even cold) is a good symptom of a good compression.
My engine starts faster when hot (about 0.5/1sec) than when was cold (1/ 1.5 sec).

That means the rotor compression is good and can i avoid to do a compression test?

Thank you!

Copeland

iTrader: (42)

Typically a good hot start is a positive sign for engine compression. If you're just doing it for peace of mind, I would call it good with that.

j9fd3s

iTrader: (3)

+1, quick start and a smooth idle = good compression

Venturer

idle is smooth and good, but when the engine is cold i "hear" some random misfires like some "thump" sound from exhausts.No strange sounds when the car is hot. But the rpm gauge hand is fixed even when i hear the "thump" sound. Someone told me this is normal for the wankels. Is it true?

Barnahadnagy

I would be interested in the general consensus on that, but the cars I checked out and my own all do it to varying a degree. I would not concerned about this as long as its only an occasional gentle thump (the engine also shakes once a bit when it happens if you happen to check in the engine bay).
Although there are some factors contributing to this as my car does it a lot less than some other I checked...

mazdaverx713b

iTrader: (91)

I would not be concerned at all and quick starts when warm are typically indicative of good compression.

marclong

iTrader: (1)

Yes the thumps will be there until it revs down. It is normal and music to my ears.