I have a 1995 honda del sol si with a b16a2 swap and I realized today when I take my oil cap off alot of air is coming out of it when its idling. My friend told me it was excessive blowback? Can anyone please explain what it is? What causes it? And if it will harm my engine??

 

During normal operation, a small amount of unburned fuel and exhaust gases escape around the piston rings and enter the crankcase, referred to as "blow-by". It depends on how much is coming out of the valve cover. Honda's normally tend to have this. If your motor seems like it is running properly, I wouldn't worry about it.

 

ya it is running perfectly fine. Just kinda worried me...

 

i have minor blowby on my rebuilt b16a and ran 15.13 in a 1/4 completely stock..if its minor its nothing to worry about.