Originally Posted by hondatech
Nobody's babbling here, what you are saying is wrong. Seriously do you know what detonation is guy? I don't think posting a quote from somebody else makes your theory correct either. Try again, maybe enlighten me by explaining detonation then go into why octane is somehow changed or made less effective by oil vapors....Please use details and explain yourself instead of using someone else's quotes.
I recommend you do some research (i.e., search) regarding this topic before you try to tell people how their setups work or give advice on making them better. The spread of misinformation (like what you're doing nere and now) is a huge reason why honda owners get such a bad rap: they blow their motors by listening to all the things "they've heard" on the internet or elsewhere. In regards to my first quote, if you haven't yet heard of
Endyn, you probably haven't been in the honda modification field for long.
I have no idea what detonation is, it's not like I tune other people's cars professionally or anything like that.
Oh wait,
yes I do. Here's the last car I tuned (I'll give you a hint: its owned by a respected, long-time member of this board):
91 octane pump gas.
Do you understand what an octane rating is? Its a fuel's ability to resist ignition.
Here's where you can really learn about detonation
I'll give you a hint: oil vapors have a lot lower octane rating than fuel. What happens if you mix a lower octane combustible with a higher octane combustible? Say, for example, you decide to mix in 1/2 a tank of 87 octane fuel into your gas tank whish is 1/2 full of c16? The final octane rating of the mixture is significantly lowered.
Boosted Hybrid (Jeff Evans of Evans Tuning) is one of the nation's best EFI tuners.... here's his description of the typical catchcan system (
taken from here):
Originally Posted by Boosted Hybrid
The purpose of a catchcan is to "catch" the oil vapors that are typically passed into the intake manifold with the exhaust gas recirculation system on engines. Oil degrates the octane quality of the fuel that you are using. If you can seperate the oil vapors, you can actually run the full amount of octane of the gasoline that you are using and inturn squeeze 1-2 more psi safely from a pump gas setting.
Another aspect of a catch can system is that it relieves crankcase pressure. The freeze plugs in the back of the block are removed, and you vent the crankcase vapor directly from the back of the block instead of forcing it through the stock oil vapor seperator. The key is that you are taking the vapor from two seperate locations on the block, this allows for double the "breathing" of the crankcase thereby relieving more pressure.
Its a two fold system. The filter on the valve cover breather just doesnt let the oil vapor from the head breathing system to pass back into the intake stream. Again, this saturates the incoming air with oil vapor dropping air density and octane level of fuel being used. Its best to have a can "catching" the two locations on the block, and the valve cover breather.