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Greddy Type-S BOV

pitbullowner_2

Probationary Member
205
4
Dec 22, 2005
ashton, Illinois
I have posted this ? about 3 months ago and for the most part it was a dead end thread. i say for the most part dead end is because the people that did answer said "i think" or " thats what i did". Here it is on the greddy type-s bov does the bottom nipple have to be plugged into something? If so where? If not read the last paragraph before the blue writing in this link i found. Is this correct that if i dont use the bottom nipple i cant adjust it at all? But most importantly if your not for sure where would be the best place to hook the bottom nipple up just in case.

http://herpetology.com/dsm/bov.html
 

DGajre777

DSM Wiseman
4,773
111
Jul 16, 2004
Orlando, Florida
You can leave the bottom nipple unplugged.

Some people who have had issues with boost spike have connected it to a boost source on the intake side, this would be the J-pipe on a 1G or 16G install on a 2G, or the compressor nipple on the T25 turbo. Put a T connector on the hose coming out of the nipple on the intake side and hook it up to the bottom nipple of the Type S. If you have a boost controller, hook it up on this line too. The other hole of the boost controller goes on the wastegate actuator nipple.

There's a big thread on here about this with pics, if you search for it, you'll find it.

EDIT: I have my bottom nipple unplugged/open and I don't have any issues.

On another note, having boost sources on both the nipples on the BOV makes it hold less boost, but at the same time, it makes it easier for the BOV to blow.
 

diablos991

15+ Year Contributor
1,370
20
Mar 8, 2006
Washington, Oregon
I was more impressed with it plugged into the pressure source. I would say try both ways out and see what works best for your setup.
I have friends who have experienced the boost spike. But mine didn't.
 

siceclipse

15+ Year Contributor
1,681
12
Jun 26, 2003
FFLD County, Connecticut
leave it unplugged.
most likely you dont need your Type-S reacting/ opening THAT fast.
 

scottsopko320

Proven Member
101
1
Jan 3, 2006
mentor, Ohio
pitbullowner_2 said:
I have posted this ? about 3 months ago and for the most part it was a dead end thread. i say for the most part dead end is because the people that did answer said "i think" or " thats what i did". Here it is on the greddy type-s bov does the bottom nipple have to be plugged into something? If so where? If not read the last paragraph before the blue writing in this link i found. Is this correct that if i dont use the bottom nipple i cant adjust it at all? But most importantly if your not for sure where would be the best place to hook the bottom nipple up just in case.

http://herpetology.com/dsm/bov.html

yes you can leave the bottom nipple unplugged. that is a secondary vacum nipple, very useless.:cool:
 

ericbev

15+ Year Contributor
770
49
Oct 18, 2004
Coal City, Illinois
On larger turbos, compressor surge at light throttle lifts can be further reduced by connecting the lower fitting to a pressure source. Typically a fitting is added to an I/C pipe between the turbo and the BOV to use the trapped pressure to help push open the valve during these low pressure change conditions. Although slightly more involved, this method allows for crisp on/off transient response inbetween gears without the reoccurrence of surge.

Typically when your BOV is set "tight" you can really feel the boost come right back on inbetween gears, but you get compressor surge at lower throttle releases. Most cars that have their BOV tuned for everyday driving are set a little softer then they would like just so they aerent getting the dreaded compressor surge. I usually tighten up my BOV a little when going to the track to ensure that the spring closes as fast as possible to help pressurize the intake tract with maximum efficiency. The above mod will allow you to run a slightly "tighter" spring tension setting in an everyday setting without allowing compressor surge to rear its ugly head.

I know alot of people (mainly EVO guys) that have had to "single spring mod" their type-s just to get rid of surge at these low pressure releases because their BOV was as loose as it could get but still fluttered (stalling as they call it) a bit. They consider the above mod the easier install route then utilizing the bottom nipple but to each their own. Here is the EVOmoto link for some good information.

http://www.evomoto.com/tech_info.php?tPath=1&tech_id=7
 

thilaksharma

Proven Member
310
12
Jul 3, 2006
Evo City, Asia
so guys,
give me a advice
i run a greddy type-r
as i know its even stiffer than type-s
i am on a t04e now , i get a surge when i boost low or in the case that i do not floor down to gain high boost
so will plugging the bottom nipple help ?
 

DGajre777

DSM Wiseman
4,773
111
Jul 16, 2004
Orlando, Florida
thilaksharma said:
so guys,
give me a advice
i run a greddy type-r
as i know its even stiffer than type-s
i am on a t04e now , i get a surge when i boost low or in the case that i do not floor down to gain high boost
so will plugging the bottom nipple help ?
NO, DO NOT PLUG THE BOTTOM NIPPLE. Leave it unplugged or connect it to a boost source on the intake side.

If you have a nut to adjust your BOV, try that first.
 

donmagicjuan

Probationary Member
824
34
Jan 21, 2006
Bremerton, Washington
The Greddy blow-off valves are actuated by a differential pressure applied across a diaphragm. The top port is the low pressure side of the diaphragm and the bottom is the high pressure side. When a vacuum line from the intake manifold is connected to the top port and the bottom is left vented to atmosphere, a pressure differential is applied to the diaphragm when the throttle is shut and there is vacuum in the manifold. By connecting the bottom port to the turbo outlet (at boost pressure), the pressure differential across the diaphragm is enhanced when the throttle is shut, allowing for easier and more rapid opening of the valve. This has the potential for reducing compressor surge commonly seen at part throttle boosting, particularly on larger turbos.
 

daren_p

DSM Wiseman
4,608
90
Nov 22, 2004
Newmarket, ON_Canada
donmagicjuan said:
The Greddy blow-off valves are actuated by a differential pressure applied across a diaphragm. The top port is the low pressure side of the diaphragm and the bottom is the high pressure side. When a vacuum line from the intake manifold is connected to the top port and the bottom is left vented to atmosphere, a pressure differential is applied to the diaphragm when the throttle is shut and there is vacuum in the manifold. By connecting the bottom port to the turbo outlet (at boost pressure), the pressure differential across the diaphragm is enhanced when the throttle is shut, allowing for easier and more rapid opening of the valve. This has the potential for reducing compressor surge commonly seen at part throttle boosting, particularly on larger turbos.


:thumb: Good post. If you aren't having any part throttle issues then leave the port vented to atmosphere. If you are having surge issues then hook it up to a pressure source, if this is done it will act like the stock 1g bov. Have you even noticed the small hole in the base of the 1g bov, they are for the same function ;) (apply pressure under the diaphragm, for faster response but will decrease the amount of boost the bov is able to hold).
 

thilaksharma

Proven Member
310
12
Jul 3, 2006
Evo City, Asia
donmagicjuan : sorry my understanding of english is bad

so in other meaning , to make the BOV vent much easier
i should apply pressure from the manifold to the top nipple
and apply pressure from the before throtthle to the bottom nipple

tis will ease the bov to open ?
 

DGajre777

DSM Wiseman
4,773
111
Jul 16, 2004
Orlando, Florida
thilaksharma said:
donmagicjuan : sorry my understanding of english is bad

so in other meaning , to make the BOV vent much easier
i should apply pressure from the manifold to the top nipple
and apply pressure from the before throtthle to the bottom nipple

tis will ease the bov to open ?
Yes to all your questions, same thing I mentioned in post number 2. Do you have a Type R or Type RS? The RS doesn't have a bottom nipple, it has a hole to relieve pressure. You can drill this hole and put a nipple on it.
 

thilaksharma

Proven Member
310
12
Jul 3, 2006
Evo City, Asia
DGajre777 : thanks , i am on Greddy Type-R, i know its an overkill for the 16g setup, compressor surge if i dont go more than 1bar ,

in my country, greddy 2nd hands go for USD$100
 

daren_p

DSM Wiseman
4,608
90
Nov 22, 2004
Newmarket, ON_Canada
thilaksharma said:
donmagicjuan : sorry my understanding of english is bad

so in other meaning , to make the BOV vent much easier
i should apply pressure from the manifold to the top nipple
and apply pressure from the before throtthle to the bottom nipple

tis will ease the bov to open ?


Your understanding of how to connect it up is correct, just the wording is abit wrong. The top nipple would be connected to the intake mani like you said but this is a pressure/vacuum source. The lower nipple if you want to hook it up (to blow off faster/easier) goes to a pressure source usually before the IC, such as the comp cover, jpipe, lower ic pipe etc. With this bottom nipple hooked up you will probably have to adjust the bov again since it more then likely won't hold as much boost as it did before, therefore you will have to tighten the spring.
 
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