Chatting it up with a friend a little while ago and CAIs came up.. he brings up that CAIs get your engine dirtier over time than the stock setup. The logic being it brings in more air, thus more contaminants, and that the filter really doesn't compensate for the extra contaminants for the sake of performance... any insight??

 

Well, he is right, but for not quite the right reasons. A CAI will generally allow more dirt into the engine because the filters on a CAI are designed to flow as much air as possible, filtration is secondary. They sacrifice flitration for airflow.

The stock cellulose panel filters do an excellent job of filtering the dirt out, but don't flow very well because of that. The more filtration, the less air flow.

 

yeah, thats the logic. but sometimes something can be perfectly logical but still be off-base. dont hear that too often about increased dirt with CAIs. how do you feel about more dirt and engine longevity?

 

Higher octain burns up and gets rid of more gunk on your engine anyway, along with certain brands of oil

 

Sorry if I am asking a stupid question, but how does higher octane burn to get rid of engine gunk? I was under the impression that higher octane doesn't burn hotter than lower octane. If higher octane is more resistent to ignition, then how would putting higher octane in your car help it burn better.

 

Higher octane burns hotter, therefor more stuff is burned up, due to the higher temps.

 

It's not that it burns hotter it's that it burns slower.

 

do a search on that it burns hotter according to everyone out there

 

if it burned slower it would get much better mpg and it doesnt I have tried before

 

sorry, but i think you are wrong on this one. unless i am misunderstanding what you mean by "burns hotter". i know high octane fuel takes more compression before it will ignite spontaneously... whereas lower octane fuel will prematurely ignite in a high compression engine, and that is where the knocking comes in.

i dont think it has anything to do with burning hotter or cooler.

 

I'm not about to try explaining everything I just read on the subject... but you can read it here...

http://www.faqs.org/faqs/autos/gasoline-faq/part3/

 

tried reading it, but there were too many words for me. gave me a headache. LOL!

 

That says that heat is a product of the octane rating being too low and creating combustion because of compression rather than because of spark. Therefore moving up to a higher octane fuel will stop early combustion and stop the creation of heat. So it burns cooler and slower (which is more important).

 

Exactly, octane rating has nothing to do with energy content of the fuel. Higher rating makes it more resistant to premature detonation of the fuel (i.e. burning before the spark plug fires). Race engines can use up to 116 Octane fuel because the compression ratio is so high (12,13,14:1). More compression = more power which requires more octane. higher octane itself does not = more power, or burn hotter.

 

Anyway, back to the question of dirt in the engine...as long as you use a good oil filter with quality syn oil and change it regularly, you should be fine. If you are worried about dirt getting into the engine with a CAI, look into Amsoil's EaAU air filters for the CAI's. www.amsoil.com I'll be ordering one within a week or so for my CAI that I haven't even installed yet. I did quite a bit of research and they look to me like the real deal and worth the investment.

 

Thanks edge67, this is exactly what I have been thinking for years. I thought the only thing that can make gasoline burn hotter is ethanol.