im planning on buying an evo and it came up in our dicussion. ok so heres the deal. me and my friend have been aruging over this.
He says if you have a turbo putting in a blowoff without a recirc will make the engine run rich, i said this is only the case because the MAF sensor is behind the blow valve and will give a false reading. He said its better not to have a valve at all which i said is just plain stupid if you plan on having a big turbo and for long term use and opt performance.
My solution is you can have a recirc at 50-50 and move the MAF sensor after the valve for opt performance. ofcourse he doesnt think so. I ask my fellow evo enthusiast for their wisdom or a better solution.

 

a "blow through maf" is what you speak of i imagine ? not really a good idea for any evo... many will agree im sure... the stock recirc valve still works in excess of 400+hp on my own car... if thats not enough i would suggest removing the maf and converting to some type of speed density sensor (MAP or manifold absolute pressure) there is many advantages of this setup especially if you speak of a "big turbo"... but in turn this also involves some type of engine management ... hope that helps...

 

Keep the bov recirculated... if you opt to delete the maf (which has been proven to make a TON of power with) then do it right and go with an EMS like AEM with speed density.. Do not use a blow through system, they are no better than stock maf.. and just more hassle to tune..

 

when u say recirculated bov, do mean that it doesnt dump to atmosphere? There would be know "Woooosh" sound that way right? Stock, we have a diverter valve which reciculates. What is different between this and the recirculated BOV?

Also, ii have heard claims that a cold air intake can cause problems, as the maf gets confused and provides inaccuarate readings.. is there any truth to that?

 

Most aftermarket intake pipes (ETS & Buschur) affect the maf readings which will cause inconsistent readings at idle.

 

keep it recirc or go with a standalone like previously mentioned.

 

Many people have success with the GM maf and it works well. There is also the option of running speed density on the stock ecu. There's a nice long thread in the ECUFlash section of the forum

 

speed density = map?
i thought u had to run a seperate ems to interprate the the map signal?so if it just changes the idle, that doesnt sound like a bad problem, but when i move up to UP michigan, where it get to -Farenheight temps on a regular basis during the winter, is there any chance that it will misread and overlean and blow? ( does the evo compensate for temperature?)