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MODIFICATIONS => Performance => Topic started by: turbo90gp on June 05, 2002, 10:22:39 PM

Title: Blow off Valve
Post by: turbo90gp on June 05, 2002, 10:22:39 PM
Ok, I installed the BOV Onto the lower IC pipe.  Now, when I let off the gas, it still uses the wastegate and the BOV does not open.  What could this be??  Could it be that the BOV is crushed, or do I have to hook it up to something?!
Title: Blow off Valve
Post by: 1trucavalier on August 30, 2002, 11:51:26 AM
when the wgs cuts boost via ecu (rev limit/knock/or eng prob) or taking your foot off the gas the waiste gate dumps the excess air so the bov is not necessary.   You would have to have an aftermarket wg (overiding the stocker) and boost controller for it to work.  In stock form without a bov you can clearly here the wg purge the excess air when you take your foot off the gas especially at wot.  i am sleepy so I hope thats correct :?:
Title: Blow off Valve
Post by: turby on August 30, 2002, 04:49:18 PM
It needs to be hooked to your map sensor. Put a tee on the map sensor line and connnect the B.O.V. to it.
Title: Blow off Valve
Post by: Chris A on September 02, 2002, 02:47:58 PM
Quote from: 1trucavalierwhen the wgs cuts boost via ecu (rev limit/knock/or eng prob) or taking your foot off the gas the waiste gate dumps the excess air so the bov is not necessary.   You would have to have an aftermarket wg (overiding the stocker) and boost controller for it to work.  In stock form without a bov you can clearly here the wg purge the excess air when you take your foot off the gas especially at wot.  i am sleepy so I hope thats correct :?:

Sleepy, SLEEPY! Wake up!

:)

Actually, the WG can't dump the extra air, but the extra exhaust. THe sound you hear is actually the compressor wheel being hit by a pressure wave from the throttle body. When you take your foot off the gas, all the air that WAS going into the engine, has to go somewhere... RIGHT BACK TO THE TURBO. So your compressor wheel which was turning near 150,000 rpm gets slammed to a stop. The BOV gives this air a place to go so it doesn't hit your compressor wheel and try to stop your turbo.
Title: Blow off Valve
Post by: Black Pheonix on September 02, 2002, 10:22:43 PM
that doesn't sound good, i mean really, with an air filte upgrade it sounds like a bomb going off. So would you guys recomend a blow off valve? obvisouly a boost controller is not a recommend way to try to reduce the wear created by our turbo's.    Thanks in Advance,
Title: Blow off Valve
Post by: TGPilot on September 03, 2002, 06:38:38 AM
I just received my BOV ('92 Eclipse) and will be installing it this week. If I go through the gears with the 5-speed with just a filter on the turbo inlet it sounds really cool, but I know I am killing the turbo with the instant spin-down without a place for the compressed air to go! Chris A is absolutely right...you go from 100,000+ RPM to 10,000 in a flash! Our turbo's use a suspended oil bearing, not ball bearings or even a bushings on the shaft. So just imagine how much it torques the impeller shaft everytime there is boost on one side and back-pressure on the other! Auto-tranny cars still cause this condition, but not normally as extreme or as often as a manual tranny car as you are constantly closing the throttle body changing gears. The waste gate only relieves so much back-pressure in the exhaust side only... 8)
Title: Blow off Valve
Post by: turbo90gp on September 03, 2002, 10:12:11 AM
I got the BOV to work a while back, I just connected it to the intake plenum with a t-fitting for the boost gauge too.  Nice "Woosh" when I let off the gas, sounds like a ton of air and feels like it to when I put my hand infront of it.  I will never run a turbo without one again, it shot my bearings.
Title: Blow off Valve
Post by: olds1992 on September 03, 2002, 01:48:10 PM
Does anyone know why it is suggested to use an g1 mitsubishi eclipse or talon BOV?  I have also been thinking about this mod, and after hearing all this great feedback, I am really considering it in the near future.
Title: Blow off Valve
Post by: turby on September 03, 2002, 01:55:38 PM
The BOV's rom '90-'94 Tsi's are of a pretty good construction. The other years were made from plastic.
Title: Blow off Valve
Post by: Black Pheonix on September 03, 2002, 03:13:37 PM
so how much do they usually run? I suppose you have less turbo lag with one then since it isn't forcing to stop, plus you get less wear i'll have to get one.
Title: Blow off Valve
Post by: TGPilot on September 03, 2002, 08:31:51 PM
I have seen them run anywhere from $35-$55. You need to make sure it is a "1g" bov with the mounting flange! 90-94 were the best ones as redturbo90 said they were all metal construction. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=1855105632 Do a search on ebay for "bov". Just realize that we have no mounting on our TGP's for a bov and you will need the flange and to get someone to weld it on for you... 8)
Title: Blow off Valve
Post by: turbo90gp on September 03, 2002, 09:33:15 PM
Junk yard, you'll find a ton.  Or go to DSMtalk.com and do a search for BOV's.  They do not need to be crushed either.
Title: Blow off Valve
Post by: Black Pheonix on September 03, 2002, 10:22:35 PM
cool, thanks guys. I just have one more question can you manually set the blow off value to get rid of all boost?, it might be a dumb idea but i would really like to be able to run my car without boost most of the time. Thanks Again,
Title: Blow off Valve
Post by: Chris A on September 03, 2002, 10:51:23 PM
Quote from: Black Pheonixcool, thanks guys. I just have one more question can you manually set the blow off value to get rid of all boost?, it might be a dumb idea but i would really like to be able to run my car without boost most of the time. Thanks Again,

THAT would be the wastegates job. The blowoff vlave just gets rid of the shockwave when the throttle closes. You can make changes to the wastegate to limit the amount of boost you want.
Title: Blow off Valve
Post by: Black Pheonix on September 04, 2002, 02:55:18 PM
is that pretty easy to do, i know its simple to keep the waist gate closed but to keep it open do you have to like pry it up or something, i would perfer something as easy as a on/off type switch or lever. Any Ideas,
Thanks,
Title: Blow off Valve
Post by: 1trucavalier on September 06, 2002, 08:21:39 AM
i am getting this one http://www.extrememotorsports.com/g1cat/bov3-l.jpg  but I like this one http://www.extrememotorsports.com/g1cat/grtyps-l.jpg

the reg bov is $96 the purple is $225  of course if you go to MIR raceway you can get them for beans!!!!
Title: Blow off Valve
Post by: TGPilot on September 09, 2002, 12:18:41 PM
I installed the BOV on mine on Saturday. What an improvement in spool-up time between shifts! :P  It sounds pretty damned cool too...kind of like an air dryer purge sound on a 18-wheeler.  8)
Title: Blow off Valve
Post by: 1trucavalier on September 10, 2002, 08:31:23 AM
this is viscous but its to much $$$$$$$ $429


(http://www.spwusa.com/images/products/RYTBLOF01.jpg)
Title: Blow off Valve
Post by: TGPilot on September 10, 2002, 09:05:20 AM
Just my opinion but...do yourself a favor, don't get caught up in the "if it is more money it must be worth it" attitude. For $50 at the most you can get a 1g BOV from a Mitsu or an Eagle Talon. No matter what BOV you buy you will need to have a flange welded onto the intercooler pipe and then hook up the vacuum line to the intake plenum. So for $75 at the maximum you can be on your way. The 1g BOV has more than enough relief flow and is very reliable. It is funny that the newer cars are going back to this BOV because of it's reliablity. Like I said though this is just my opinion, but I am a best bang for the buck kind of person... 8)
Title: Blow off Valve
Post by: 1trucavalier on September 10, 2002, 02:07:08 PM
lol! I assure you I already know.  I just had a totalled a fully built budget racer. :cry:
Title: Blow off Valve
Post by: 90TGP on September 17, 2002, 04:15:37 PM
$50? I just picked up a 1stgen Talon BOV from my local pull-it place for $20. :)
Title: Blow off Valve
Post by: TGPilot on September 18, 2002, 06:32:09 AM
$20 is a great price! You could put it on Ebay and sell it for $40-50... 8)
Title: Blow off Valve
Post by: turbo90gp on September 18, 2002, 07:50:52 AM
I got mine for freeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee
Title: Blow off Valve
Post by: no1kicker on March 21, 2003, 10:09:48 PM
Just wondering, I don't have welding tools, about how much would it be to have someone weld it for me?
Title: Blow off Valve
Post by: eclipse5302 on March 22, 2003, 01:42:47 AM
Call some local welding shops.  It's not hard to do, so they shouldn't charge much.

And the 1G BOV will hold up to 20psi before "exploding".  They are very nice, and extremely reliable since they are made of metal instead of plastic like the newer ones.

Jason
Title: Blow off Valve
Post by: turbo90gp on March 22, 2003, 01:23:00 PM
If you crush the BOV, it can handle even more then 20lbs w/out leaking.  BUt I do not think we need to worry about that on our cars.  Maybe someday though.
Title: Blow off Valve
Post by: eclipse5302 on March 22, 2003, 10:53:42 PM
Yeah, I heard about that.  I guess they do that to FPRs also.