I've heard quite a few things about about venting to atmosphere with Evo's, and not letting your "ricer side" come out and stay recirculated, but what exactly is the deal with Evo's not liking it? Granted this is my first Evo (owned for about 1.5 years now) and I AM NOT venting to atmosphere currently, but I'm finishing my bolt ons and deciding whether or not I will be. Do you have to run speed density to do so? What are the pro's/cons to recirc. and VTA valves, and speed density. I've always vented to atmosphere on my SR20's and never had problems but the 4g63 is a different creature. Help. Thanks

 

The MAF measures air and calculates the amount of fuel to use for that air, if you vent the air that is already measured, you car will run really rich every time it opens.

Also with something like a TiAL bov, to have a reasonable spring force that allows for decent driveability, the BOV may be slightly open at idle, which will mess with your idle characteristics.

 

Because it's throwing out all the air that is supposed to be mixed with fuel, thus creating a pig rich environment. Got it. But that's what tuners are for right? If you're tuned to vent to atmosphere it will compensate...?

 

No, its metered air. There is no way to "tune" it out. ECU doesn't take into account when throttle is increasing or decreasing. If you want to VTA then you need to swap to speed density.

You wont hurt anything venting, but when you lift with the clutch in and let the RPMs drop the engine will stumble or die. If you're rowing through the gears, it will cause a stumble right at tip-in. Basically, it decreases driveablitly for the sake of noise.. Ricer ****

 

Before calling me a "Ricer F*ck", understand that I'm asking these questions because I'm curious as to why everyone talks about speed density. I could care less about the "noise", only what makes my car run better, which is why I'm asking which is the better choice, instead of just throwing it on my car like a "Ricer F*ck" and making a YouTube video of my Evo "BOV'ing it up". Also, thanks for the information. Any reason this is particular to 4G63's though and not other motors?

 

VTA is for SD on the Evo its a MAF no MAP only like the SR20 IIRC. If you want the Sound get a TiAL QR which is a Recuirc BOV and its pretty loud. Then later if you goto SD you can just get the bottom half of the TiAL Q and be VTA. I hope this helps you in the quest of modding and good choices.

 

Hmm, well I guess "****" could be read multiple ways. I was the mod is Ricer $h1t, no point to it on a relatively stock car.

 

Because Nissan uses a hotwire MAFS and Evos use Karman-Vortex MAFS. Not all are the same.

 

If you wish to keep it recirculated, but want the sound, go with a Perrin Intake.

 

Ah, I got ya. No worries. Thanks for the info.

 

Solid point. I had planned the whole time on going with the Tial QR, but was just wondering what the whole deal with VTA and SD were because I couldn't find any info other than "just don't do it" which just isn't good enough for me lol.