Venting to the atmosphere?

larryd · 04-14-2002, 05:16 AM

ok as much as I hate to ask this question ### I know ive read over and over again on dsmtalk when newbies get flamed. Why is it bad to vent to the atmosphere.. why does the car run funny?? Id really like my Greddy BOV to vent to the atmosphere for no other reason then I love the sound of a BOV and it sounds insanely cool.. I did it once for a few minutes and the car ran like crap.. is there any way I can vent back to the atmosphere and get the car to run right??

jdmawd · 04-14-2002, 11:12 AM

the reason its not a good idea to vent to the atmosphere, is because the mass air reads how much air being ingested in to the motor threw the turbo. when the bov dumps back into the intake track the metered air remain consistent with what the meter has already read. the ECU determines how much fuel to add dependent on how much air the mass air recognizes. when you dump to the atmosphere the ECU thinks that air that is being ejected from the intake track is actually being ingested into the motor and supplies a given amount of fuel to match the metered air. but that figure is now incorrect because the air is not going into the motor its going into the air, so now you have a disproportionate air/fuel ratio between shifts. i hope that made sense

extremeprimetim · 04-14-2002, 01:38 PM

Actually JDMAWD that made a lot of sense... thanks for the info for I had a similar question. How would an AFC aid in making sure you have the correct A/F ratio between shifts?

Extreme

jdmawd · 04-14-2002, 01:44 PM

That will only work with hot wire mass air meters, dsms read in karmen . The AFC has a deceleration air mode but it will not work on our cars. you need a vpc or stand alone to vent to the atmosphere without having a rich condition

larryd · 04-14-2002, 06:39 PM

damn.. what is a VPC?

jdmawd · 04-14-2002, 06:47 PM

The HKS VPC is designed to physically and electronically replace OE air metering devices which present a significant restriction to the intake system and offer no adjustment or reprogramming options to take advantage of dramatically higher air flow or larger fuel injectors. The VPC converts both air flow meter and air mass sensor systems to what is referred to as speed density systems by utilizing a 16 bit central processing unit reading its own intake air temperature sensor and absolute pressure transducer (B-MAP sensor) signals. This unique conversion feature not only allows the VPC to replace the factory air flow metering device, but also eliminates the need for a fuel cut defencer. Another benefit of the VPC is the ability to create our own programs to take advantage of larger fuel injectors and new air flow characteristics (larger turbos). In some specific instances, the VPC may be used in addition to the PFC F-Con and larger injectors for the ultimate in HKS plug-in fuel system technology. VPC equipped vehicles respond quicker with improved horsepower. Controls those monster injectors as well!

larryd · 04-14-2002, 06:53 PM

wow.. that sounds like a really interesting thing.. something that would benefit me well

jdmawd · 04-14-2002, 07:01 PM

yeah the vpc is pretty nasty you can expect around 20-30 hp with no other changes. its kinda ruff below 3K but the S-afc will correct that

larryd · 04-14-2002, 07:19 PM

wow.. how much does that bad boy cost?

jdmawd · 04-14-2002, 07:23 PM

best price i seen is 1050 from www.turbotrix.com

larryd · 04-14-2002, 07:31 PM

good lord.. time to keep dreaming

Silent2g · 04-14-2002, 10:33 PM

heres a little tid bit of info regarding a vpc and a dsm

you have two options.
crappy daily driving on low boost, but great at the track
crappy track time, or great daily driver

id suggest a pms over a vpc on a dsm

venting the bov works on some dsm's not a lot fo them, the computer is set up different on all of them. some will take it, some won't. depends on tolerances of the ecm at that time, also weather plays a lot of havoc on those too. id go into detail, but im not all there right now

jw · 04-14-2002, 11:02 PM

This topic has been beaten to death on DSMtalk and you will see pages and pages of why and why not. I have contributed to some of them but get real tired of typing things over and over again. Some of info here are right and some are wrong. In short, dont do it if you are still using the MAS.

Ludachris · 04-14-2002, 11:50 PM

I believe Post 2 from jdmawd answers it best... I'll likely link to this thread in an FAQ section soon.

http://www.dsmtuners.com/forums/show...=5284#post5284

larryd · 04-15-2002, 12:12 AM

would it be possible to split the tube that goes back to the intake in two pieces... so I could semi vent?? I just want to be able to be louder

jw · 04-15-2002, 10:47 AM

The problem usually magnify when you are running high boost with a larger turbo since the amount of aircount loss is larger than a small turbo running low boost. Most of the DSMers seeing less problem venting to the atm are the later.

I have seen some BOV having certain percentage vented to atm and return back to intake. However, I do not know how well that works.

L2RTSiAWD · 04-15-2002, 05:21 PM

I vent to that Atmosphere because I have a RFL BOV. I may have a rich condition between shifts but for that 1-2 sec I don't consider it a problem. My car does not buck during shifting at low or high rpms. I don't have an idle issues venting vs not venting becasue I had a greddy type-s routed back into the intake before the RFL .

Later,

larryd · 04-15-2002, 10:50 PM

so how come some BOVs can vent to the atmosphere and others cant?

L2RTSiAWD · 04-16-2002, 12:17 PM

Some BOV's have different springs if the spring is too soft you will have a hard time venting. With my RFL I add or take away washers to stiffen the BOV to get a combo of good idle+venting+no compressor surge at low boost.

Later,

Violater101 · 04-16-2002, 12:34 PM

Well, if your looking for cool sounds, get a dumptube made coming off your O2 housing. They sound pretty cool. I am going to have one made for my car real soon. They are really LOUD when you are at WOT.

larryd · 04-16-2002, 10:52 PM

but a dump tube is exhaust sound loud, not blow off valve sound loud.. my exhaust is already loud enuf

Capone · 04-17-2002, 12:48 PM

Signal is running a blitz bov , i wonder how his car is running?
I was thinking about going that direction as well.

umiami80 · 04-17-2002, 07:40 PM

I have a HKS Super Sequential BOV and vented that sucker since day one. Loud as helll when I wanted it to, silent when I didn't. I personally believe that it is the best BOV on the market because it his two valves, one for high boost, and one for low. I may have run rich when i shifted but no bogging, no bucking, PERFECT idle, just loud as hell and could scare the crap out of people, it was great.

"problem usually magnify when you are running high boost with a larger turbo since the amount of aircount loss is larger than a small turbo running low boost"

Not my car, i Putt a Mutt on and it didn't get wirse with boost increase, I was litterally flowing twice as much air too. Anywas I was chewed out sooo much on dsmtalk so much that I actually vented back into the intake and was done with it. Now my BOV is silent

but it is all go. BTW I flet NO difference while doing this other then a Huge increase in gas milage, about 50 miles a tank, which is huge but it is only gas.

sophat34 · 04-17-2002, 11:31 PM

hks also makes another ptoduct specificly for the venting to the atm problem. its called the EIDS I dont know if it is avalable for dsm's but it is avalable for the evo,, mabey it would work and its only about $100 compaired to the 1000$ + for the vpc and the problems I have had with it, had I known that this thing was made I would have thought twice about getting a vpc and just stuck with the little box from hks(EIDS) and a s-afc

jw · 04-18-2002, 11:10 AM

Quote:

Originally posted by umiami80

"problem usual