VWDiesel.net The IDI, TDI, and mTDI source.
Engine Specific Info and Questions => IDI Engine => Topic started by: fspGTD on December 02, 2005, 11:59:07 pm
-
Note: this procedure can be done with the blow off valve removed (as shown) or with it mounted on the engine.
Step 1: using a flat-head screwdriver, unscrew the brass pressure adjuster completely from the center of the blow off valve and temporarily set it aside. Permanently remove the spring that's behind it:
(http://www.imagestation.com/picture/sraid195/pcf84fb1bc0a7de4e6bc595adf68b748b/f1369cc4.jpg)
Step 2: Get a 6mm allen-head bolt of about 20mm total length (from tip to tip.) You can hacksaw or grind down the threaded end if the bolt is too long. Also sand the OD of the bolt head if necessary so that it fits down and into the hole of the blow off valve:
(http://www.imagestation.com/picture/sraid195/pa70852443517fec58e2f648eaef9e711/f136b2fc.jpg)
Step 3: Install the bolt and make sure it seats down all the way squarely. The protrusion that was underneath the spring should now engage into the allen recess of the bolt head.
(http://www.imagestation.com/picture/sraid195/p1ea96cc35576a225d0777c04f6293d23/f136b2f1.jpg)
Step 4: Screw the slotted-head adjusting plug back in over the bolt. Only light torque is needed. From the point where it touches the bolt, only add about 1/4 of a turn. Cranking it down with excessive torque unnecessarily strains flimsy plastic and rubber parts of the blow off valve.
(http://www.imagestation.com/picture/sraid195/p20476ad37708902db6c275e5d95db6f1/f1369c44.jpg)
If you stick you finger down into the hole from the intake manifold side and aren't able to move the rubber diaphgram with a good push, it should be good to hold about as much boost pressure as you can spool at it. :twisted:
-
So, why would you want to disable your BOV? Isn't this designed to relieve potentially damaging pressure build up under undesirable engine load times?
-
So, why would you want to disable your BOV? Isn't this designed to relieve potentially damaging pressure build up under undesirable engine load times?
Only if the wastegate stopped working. Plus the BOV opens at around 12 PSI, which makes boosting above that impossible. Only in a gasoline powered car would this be a big mistake :)
-
And now I know.....
-
As always Jake, you bring diy to a whole other level. Keep it up :D
dubCanuck1, not to worry, I asked the same question like 3 or 4 years ago on the old hostboard when I was starting out, its a bit of a learning curve but its worth it.
-
A couple of weeks ago I used the exact same method except instead of a bolt I used an aluminum spacer of the correct diameter and length from the hardware store. Worked like a charm. I also screwed the wastegate closed on my K14 and the boost jumps right up to 17 psi. What a joy, except now I'm having tranny trouble. :cry:
Andrew
I was having huge tranny trouble on my car... So I had the transmission oil changed and after a few trips it was easier to put into gear, and the shifter was a lot looser in cold weather :D I guess 380'000km on the tranny with no oil change will do it :lol:
-
There are definitely a few ways to disable the 1.6TD blow-off valve...
* You can use a plug that replaces the blow-off valve. It also nicely cleans up the engine compartment a bit:
http://www.vwdiesel.net/phpBB/viewtopic.php?t=107
http://www.vwdiesel.net/phpBB/viewtopic.php?t=2511&start=2
* You can block off the blow off valve outlet...
...by capping it with an appropriately-sized rubber cap:
http://www.vwdiesel.net/phpBB/viewtopic.php?t=781
...or by plugging it with the cut-off end of a broomstick handle:
http://www.vwdiesel.net/phpBB/viewtopic.php?t=346
* You can swap to an eco-diesel intake manifold, which doesn't have the blow off valve.
-
I wanted to keep mine active as I thought vw probably put it there for a reason, so I just put a slightly stiffer spring in and screwd it down untill I got the desired blow off pressure, it now blows at around 1.3 bar with my manual boost controller set at 1.2 bar so it will still work if theres a problem - just as easy as disabling it and I get peace of mind :)
-
I thought vw probably put it there for a reason
HA :roll:
-
so by disabling the BOV, you get more boost? So if i did this to a very very stock 1.6TD, what exactly would be the outcome?
-
so by disabling the BOV, you get more boost?
No. The BOV is a safety device in case the wastegate fails. As noted elsewhere, only adding more fuel will increase boost.
So if i did this to a very very stock 1.6TD, what exactly would be the outcome?
You would not see any change with this mod alone. According to my Bentley, the stock boost for a 1.6TD is 0.64-0.72 bar (9-10 psi), while the BOV opens at 0.81-0.86 bar (11.5-12.2 psi), so you can see that there is no point in disabling the BOV on a stock 1.6TD.
The only reason to disable the BOV is to allow boost pressures greater than stock, and the only way to get more boost is to add fuel.
See the many threads on how to add fuel... :D
-
Andrew, what you describe is TWO changes, not one. I did exactly what you describe to my Quantum and saw a rise in max boost of 2 psi (from 10 to 12 psi), but no difference to performance on my G-Tec. In other words the engine was burning a bit cleaner (more air for compustion from a little more boost), but because no additional fuel was introduced there was no increase in performance.
But my answer to Zagarus remains that just blocking the BOV (with NO other mods) will change nothing.
-
so since stock boost is below the release valve of the bov, there is no familiar air discharge that is common with turbo cars right? So by adding more fuel and therefore increasing boost above the specified 12-13 psi, the bov would then acutally be used, and that sweet sweet sound of a bov would be heard?
-
so since stock boost is below the release valve of the bov, there is no familiar air discharge that is common with turbo cars right? So by adding more fuel and therefore increasing boost above the specified 12-13 psi, the bov would then acutally be used, and that sweet sweet sound of a bov would be heard?
I think you have this pop valve confused with a blow off valve on a gas car. It will never make a "sshhhhhhhhh" noise like a gas car because there is no throttle body. Since engine speed is regulated by fuel there is no throttle body and therefore no throttle to slam shut between shifts and cause a back-up of boost pressure which would then be the spike vented when the blow off valve opens. If boost were increased past the breaking point it would simply open and vent the excess boost back into the intake making whatever you did a waste of time.
-
So by adding more fuel and therefore increasing boost above the specified 12-13 psi, the bov would then acutally be used, and that sweet sweet sound of a bov would be heard?
Strictly speaking, no.
That's because if you merely add fuel you will cause the wastegate to open first, bleeding off excess boost before it gets a chance to open the BOV. The "sweet sound" you seek occurs in turbo'd gassers when the throttle closes suddenly as the driver lifts off the go-pedal during gear shifts. We don't have throttles, so the sound of the BOV opening will be masked by the engine noise at full power, and you will never hear it.
-
This is a somewhat interesting angle for the need of a blow off valve on a TD,I've inatslled one before on a twin turbo'd dodge :wink:.
http://www.bd-power.com/ram/product.php?pn=BD%20TurboGuard&tt=ram
-
This is a somewhat interesting angle for the need of a blow off valve on a TD,I've inatslled one before on a twin turbo'd dodge :wink:.
http://www.bd-power.com/ram/product.php?pn=BD%20TurboGuard&tt=ram
I'm still not buying into it. You let off the pedal and fuel flow drops drastically. EGT's fall, turbo slows down. As far as the turbo is concerned, the engine is just slowing down and there is no drastic difference between on and off throttle. There is no such change which would cause compressor surge.
-
while I was adjusting mine to blow at just above where my boost is set to, I had it opening before I reached max boost - you do get a fairly loud 'whoosh' noise similar to a turbo'd petrol cars dump valve - but you also get a pretty silly flat spot in your acceleration as it dumps a load of air out of the intake manifold! :roll: not exactly what you want
-
Andrew, I never stated, claimed nor suggested that my compressor wheel was in "bone stock" condition. But now that you mention it, even in its knackered condition that turbo made stock boost of 9-10 psi. By disconnecting the wastegate I got it up to the BOV activation range. Disabling both got me 12-13 psi.
My point remains that simply disabling the BOV on an otherwise stock engine does nothing for performance - a point confirmed by you.
BTW, I agree with your other points about changes made in isolation. Most do no good and many can make things worse. As we all eventually learn, engines are an integrated whole. Making random changes to isolated bits rarely has the desired effect... :wink:
-
This is a somewhat interesting angle for the need of a blow off valve on a TD,I've inatslled one before on a twin turbo'd dodge :wink:.
http://www.bd-power.com/ram/product.php?pn=BD%20TurboGuard&tt=ram
I'm still not buying into it. You let off the pedal and fuel flow drops drastically. EGT's fall, turbo slows down. As far as the turbo is concerned, the engine is just slowing down and there is no drastic difference between on and off throttle. There is no such change which would cause compressor surge.
I agree that a VW TD for that matter does not need a BOV.I just wanted to show you guys that they have been used on a diesel.This option seems Ok with with the use of an automatic transmission.With the automatic when you back off on the Go petal real quick with the Torque convertor unlocked under full load conditions (high HP) the engine returns to idle almost instantly causing the turbo(s) to spool down quicker than they would like to which can possibly cause the compressor wheel to fly apart or even the shaft to break.I've never actually seen or even heard of any such explosions before so It's likely not needed anyways :roll:
A little off topic but somewhat related :oops:.
-
Can't a person buy a modded Blow Of Valve that is set at a higher level? What would be a decent max PSI?
What about the blowoff valves that make noise when they blow off?
-
my wastegate is stuck shut, and when i first put my td in my jetta, i would always get to 12 psi and then boom acceleration was gone, i had actually made threads about how my old engine could rev better, but really it was just that the blow off valve was creating a dead spot in acceleration, so a car with a wastegate set below the bov's release pressure would actually be faster, kinda like how my friends vr4 is faster at 13psi than 14 psi because he has fuel cut off and almost blew his motor with the gtech and too much boost. haha that car only ran a 14.1, after running a bunch of mid 14's, that's hillfolk territory
-
alright now that i have increased fuel and have a boost controller, im thinking diasbling the BOV so i can run say 15-17psi is an ok thing? no intercooler or exhaust or EGT gauge...YET. but intercooler should be this week, already have my muffler, just gotta save some money so i can goto PP for that.
-
it only takes like 10 minutes to disable it.... not a major step or anything
-
sounds good to me. what would you suggest, stiffer spring, or allen bolt?
-
alright so im gonna keep it at 15psi until i get my intercooler this week. Sound safe?
-
15 psi is totally fine with no intercooler.
-
oh and dave, i stil wanna get my exhaust system done, but im not sure if its completely affordable for me right now. I mean i do have enough money, but im wondering if theres anything i can do to prep thatll make it cheaper, and plus i could only come down on weekends, but i doubt you're open sundays.
-
I can do the exhaust on the weekend if necessary. The downpipe is the trickiest thing to make, I would say you should buy a downpipe than just get whoever is installing your intercooler to make the rest of the exhaust.
-
im thinking that will be the case. But mandrel bent, they dont do. :( they can weld all the pieces so it isnt crush bent.
-
Than don't get them to do your intercooler either. I would much rather see a crush bent exhaust than crush bent charge piping.
-
nono, im gonna do the intercooler, its the exhaust system i want done.
-
i used dall rod cut to length..
-
I don't know
The other day i heard a dodge diesel that had a very loud blow off valve. Has anyone tried one and can conferm they won't give you the cool pssssst sound?
ATD
-
What would be a decent PSI to turn the boost on my turbo up to? Can't I get a aftermarket BOV that will allow for higher PSI and yet keep me from over pressure and enging damage?
I want a quick diesel that I can drive everyday without worries.
ATD
-
got this mod done at the weekend to my car, plus a bit more fuel, and its like a different motor, well recomended.
-
I have a 1.6 TD in my Samurai. I did the gov mod and the advance spring mod to the Lime Green spring. Just put boost and pyro on and get 9psi boost and in 4th and 5th pulling hard the EGT goes to 1400° and would probably go higher if I was pulling a long hill. I blocked the BOV with a bolt with no change in boost. I have a T-3 turbo. I added a manual boost control and before I got it set it would bury the 15 psi boost gage. I set it at 12 psi. This seems to keep the EGT down some. I have never seen smoke. At what boost pressure does the increase in boost cause higher air temperature out of the turbo to the point it doesn't do any good to raise boost? I do not have a intercooler. I am not looking for more power. In a 2100 pound Samurai its plenty. I just want to cool the EGT.
Jim
-
Does anyone have any pictures to replace the ones that are missing from the original post please?
-
Does anyone have any pictures to replace the ones that are missing from the original post please?
I would also like to see the pictures! Im a little confused to be honest, i think i need to see a picture of the BOV..
-
Scott,
PM me your email, I've got the whole thread and more saved into one word.doc,
Easiest way is to undo the screw in the plastic cover, with a slotted screwdriver. Under that there is another screw which applies pressure to the valve via a spring.
Tighten this screw down - job done.