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Engine Specific Info and Questions => IDI Engine => Topic started by: VWRacer on May 28, 2004, 07:50:09 pm
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I noticed that there is a screw in the top of the BOV. Does anyone know if it is for preloading the spring? It would be very convenient if we could just "dial in" the desired boost... ;)
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that's what i've been wanting to know as well.... i tried messing with mine back and forth just a tad.... didn't notice any change...... still running 10psi
i thought i had read somewhere that it only adjust .7psi +/- ??? anyone?
it would be nice to just dial it in from there.... afterall it is a pressure regulating valve
d
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From what I remember that screw is only a cap, but you can then remove the spring and change it out for a stiffer one I would asume. This may be completely wrong, but it seems like I read that on a post long ago on the old hostboard site.
Now that I think about it if that was the case then you should be able to just stack washers or some other spacer in there untill the spring is preloaded to the point you want, assuming there is enough space for this and the spring has enough travel. :?:
If this is the case you could get the best of both worlds as far as boost control, you could have a gated boost controler, with this as a way to control creep, and sudden extra air pressure.
If some one doesn't beat me to it when the wife gets home I will open it up and see what I can see. :)
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Even if you do this, your turbo is still spinning at/beyond full speed. Better to block off the BOV and control boost at the turbo.
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The screw in the bov has a spring under it holding down a clapper. When the pressure rises enough it lifts the clapper. Simple! To raise pressure, change to stiffer spring. Or, to block, replace spring with a sawn off 1/4" bolt. Clapper no move. :)
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I'm really getting a lot out of this thread, and am really enjoying it, so thanks to all who have made inputs! :D
After Dr Diesel's comments last night I took the BOV off and snapped a couple of pics, which I share here for those who are iterested but not inclined to tear up their engine... ;)
I've labelled just about everything, so it should be pretty much self-explanitory.
(http://home.earthlink.net/~rps1976/Images/Diesel/BOV1.jpg)
And here is the BOV with a brake cleaner can cap inserted. The idea is to prevent the BOV releasing air pressure from the intake manifold.
(http://home.earthlink.net/~rps1976/Images/Diesel/BOV2.jpg)
Then I took the car for a test drive... :twisted:
Surprise! The engine still hit a max of 12 psi. :?
What's up with that? I am pretty certain that the cap is effectively blocking off the BOV, so at this point I'm scratching my head. And yes, I did a post-test tear down to ensure the cap hadn't moved, melted or otherwise failed.
I guess the next step is to make a real block-off plate to test.
Cheers! Stan
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You don't want ot block off your pcv or you will blow the seals in you car or at very least have oil shoot out your dip stick hole (actually saw that once :shock: ) what I found works well as a catch can is a 1L oil bottle, as the tube that used to return it to the intake is almost exatcly the same size so you just slide the bottle in and titen it up with the same hose clamp. THen you cut out the flat section on the top of the bottle, and Shazam you have a cheap effective catch can. :D
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Oh, by the way thanks Stan for the break down 8)
Dr. D, I had advocated using a manual boost controler inconjunction with the BOV to control compresser surgess, as well as boost creep commonly found with gated type controllers.
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I should have specified that I am venting the PCV to the atmosphere while conducting these tests. Not to worry, the hose is not blocked!
I did, however, plug the line to the compressor's intake hose to prevent unfiltered air entering the turbo. (Blue plug in the photos above.)
[Edited for clarity.]
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Stan, that is most definitely a suprise.
In my early diesel tuning days, I had maxed out a wastegate bleed valve, only to get 12 psi. As soon as I plugged the pop-off valve's outlet line, it jumped to 27. I suppose it's possible that your inj. pump's setting is anemic enough to limit boost to that level, though it seems unlikely. I think you said that the wastegate is disconnected. If it's a garrett, there are two lines going to the wastegate. Are they both disconnected? Perhaps the wastegate valve is getting blown open by the exhaust pressure... I wonder what would happen if you routed boost pressure to the wastegate line that normally senses pressure at the compressor inlet? would that act to help keep the wastegate valve closed?
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Stan - when the BOV opens, the effect is very noticeable. Once opened, it will stay open continuously, bleeding off large quantities of air until boost pressure drops quite low, and at that point it will finally close. The resulting drop in performance when this happens is very noticeable - it is not a smooth boost pressure regulation effect like a wastegate gives.
If you did wastegate modifications but you haven't turned up your fuel level any bit from stock, I would guess that is what is limiting how much boost pressure you are getting.
FYI: If you just screw the BOV adjustment in all the way in, it won't open until a little bit over 14 psi. You can get the opening point higher yet by adding shims or a thicker spring. (Shim is solid, and it won't open at all.)
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It sounds as though the waste gate is still functioning. and i had a simular problem on my 86 jetta td, it turned out that for emission reasons vw used a 1.50" exhaust pipe from the flange to the resonator then 2" from there on. with that setup i could get no more than 12 to 14psi.
so when i modded the car i got an intake off of a eco diesel because it has no safety valve :) and i made an electronic boost controller using a fast acting pressure switch adjustable and set it at 19psi (best power whithout smoke) and a idle up solinoid from a 88 a1 cabriolet gasser to send pressure to the wastegate when the 19psi was reached.
the setup has been great and dead on 19 psi. if anybody wants plans on building the setup let me know i can post it.
about running the turbo whithout the wastegate connected, well your nuts cause when the turbo lets go it is a bit $$$$ to fix. unless gils did a pump for ya there is no need to go above 20 psi. there is not enough fuel from a stock pump turned up a bit. if you dont want to buy a boost conyroller you can make one with a brigs & straton fuel valve for a lawnmower. put it between the compressor out and the wastegate with a length of hose, crack it open a bit, take it for a spin and check your psi. adjust as needed
just adding boost without extra fuel wont do anything except raise your egt and shorten the life of your engine.
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Thanks for adding your insights, Chris. :)
When I took the car out I was concerned about overboosting it without any protection, so accelerated very smoothly, keeping a good eye on the boost gauge. I first got 5 psi, then 7, then 9 and finally 12 when I ran it out in 3rd after about 10 minutes of driving. I added 5-bucks worth of diesel since the fuel gauge barely rose off dead empty after engine start, then came home, working my way up on boost. I was very surprised that it wouldn't develop more boost than it did.
However, now that I think about it, there are a couple other observations I should mention, in case they may be affecting my results. First, I noticed that although the engine revved quite freely, it seemed to be a bit down on seat-of-the-pants power, so I stopped and hooked up the G-Tech. It recorded just 40 max hp. Clutch...? :?
Second, the engine now puts out a lot of black smoke once the boost gets above about 5 psi. It's not blue "oil smoke". It is the classic diesel looking black smoke...maybe very dark grey. Ideas?
Finally, I just now took this pic. It shows the disconnected hard line to the wastegate, the compressor scroll plug and the compressor wheel. (I disassembled everything to take the pic - I don't run it this way.) Notice that the blades are pretty chewed up. Bad as it looks, I somehow doubt this is what's keeping me down at 12 psi. Any ideas?
(http://home.earthlink.net/~rps1976/Images/Diesel/Compressor%20Intake.jpg)
Thanks! Stan
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Stan, that is most definitely a suprise.
In my early diesel tuning days, I had maxed out a wastegate bleed valve, only to get 12 psi. As soon as I plugged the pop-off valve's outlet line, it jumped to 27. I suppose it's possible that your inj. pump's setting is anemic enough to limit boost to that level, though it seems unlikely. I think you said that the wastegate is disconnected. If it's a garrett, there are two lines going to the wastegate. Are they both disconnected? Perhaps the wastegate valve is getting blown open by the exhaust pressure... I wonder what would happen if you routed boost pressure to the wastegate line that normally senses pressure at the compressor inlet? would that act to help keep the wastegate valve closed?
Doc, my turbo is a k24, and I can only find one line to the wastegate. Anybody know for sure that there are two lines?
I think I'm going to have to fab up a solid block-off plate to completely replace the BOV. I just don't trust that it's not somehow releasing pressure.
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Thanks for putting up with me, guys, but I've been having fun with this all day... :D
Anyway, I took some scrap plate aluminum and made a block-off plate for the BOV. Using the stock collar-clamp I RTV'd the flange then clamped it all together to completely block off the BOV port. Here's what it looks like...
(http://home.earthlink.net/~rps1976/Images/Diesel/BOV-cap.jpg)
Then I took it out for another test drive. Well, first thing was that I discovered that I had left the cold-start knob out last night...I wonder if that affected my results? Second, after pushing the cold-start knob in most of the smoke went away. There is still a bit at higher boost, but most of it is gone.
The bottom line, though, is that there was no change in max boost. It is still hitting 12 psi and then backs off to about 11 if I just hold it in gear at max revs (the pump is pulling fuel out, isn't it?).
In the photo below, one can see that there is an EGR system plumbed from the exhaust manifold to the intake. There is something at left which appears to be some sort of blow-off valve. My Bentley doesn't mention the diesel's EGR, but I wonder if this could be the source of my limited boost?
(http://home.earthlink.net/~rps1976/Images/Diesel/Engine1.jpg)
I realise that I am grasping at straws here, since Dr D and DV8STR got 20-plus psi by simply blocking the BOV. Any ideas?
Thanks! Stan
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Stan,
Ditch that whole EGR setup immediately. Have a good look inside the intake manifold, and make sure it's not all carboned up inside. TDI's are NASTY for this problem, due to having an EGR system. I saw one where the inlet elbow diameter on top of the intake was reduced by 50% from carbon/soot buildup!! Perhaps the same deal has occured on your engine.
The coldstart knob should only be noticeable below ~2000 rpm. After that, the internal advance mechanism takes over. If you notice a difference in power at any rpm (especially higher) when you pull the CS knob out, then it's likely you're not getting any inj. advance at all. This happened to me last year, when I'd installed a pump with an "IN" banjo bolt on the "OUT" side of the injection pump. The car was a complete dog.
That turbo looks terrible too. If it's munched something, maybe it's axially rubbing on the scroll walls? I'd wanna replace that if it was mine.
Dieseltech,
That's the same boost control system i've been using too! It's worked great since last fall. I'd monkied around with several other types with nowhere near the satisfaction of this system.
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My guess is that the Garrett and KKK turbo's max boost is different if both were non wastegated and since the Garrett is capeable of higher psi this is what is happening ,I got the same results with the K24 as VWRacer. both as we know run the same stock psi but are totally different when modified :D
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Okay, I'm making some progress! :D
I took Doc's advice and removed the EGR system completely. Here a photo with the blockoff plates in place. The intake plate is 1/8" aluminum. I reused the old undamaged gastket with orange high-temp RTV. I chopped off the exhaust-side elbow and made a crude 80-thou stainless blockoff plate. Both held very well! ;)
(http://home.earthlink.net/~rps1976/Images/Diesel/EGR%20Removed.jpg)
The boost is still maxing out at 12 psi, but the smoke is nearly all gone - just a tiny bit as the engine hits the fuel limiter. Horsepower is back up, too. I did two back-to-back runs through 3rd and got 58 hp on each run. Up over 10 hp! :D
Someone mentioned that they couldn't get more than about 12 psi with the stock exhaust, so I took a look at the pipe on my car. The downpipe has a HUGE crimp right after the turbine section outlet! :cry:
The pipe appears to be a nominal 1.5" OD, but crimps down to about 1" right after the outlet.
(http://home.earthlink.net/~rps1976/Images/Diesel/DownPipe.jpg)
This has got to have a big impact on boost production. I have some 2.5" elbows and bit and pieces to build a test system, and will get to it this week. Right now I gotta go do the family thing...back tomorrow night!
Cheers! Stan
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Yeoww!
Stan. Are the blades totally trashed on your compressor wheel or is that just the photo? Looks pretty bad.
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The leading edge of every other blade is pretty chewed up... :?
At least I don't see any sign of the compressor wheel touching the scroll housing.
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hey Stan, just for shizens and giggles, why not unclip the downpipe from the toilet bowl and take it up the street, Gtech on?
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I'm no turbo expert but I think you need to take a closer look at your compressor wheel. I looks to me like something has gone into the turbo and damaged the wheel quite severely. It looks like about 3/8" of every other blade is missing. That thing must be very out of balance at the very least and could explode at any time. Check this pic of a good wheel showing that every other blade sticks out further than the adjoining ones. Also notice the part that's missing on yours is at a shallower pitch than the rest of the blade. I believe this is designed to bring the slow moving air up to speed without stalling the airflow. Without this part of the blades your compressor may be having a real problem working, kinda like starting out in third gear. You turbo is probably not getting up to speed and boost, maybe that's why is hasn't blown up yet. :shock:
Course, I could be full of crap too. :lol:
(http://www.fostertruck.com/images/Imagetank/turbowheel.jpg)(http://www.fostertruck.com/images/Imagetank/CompressorIntake.jpg)
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i vote full of crap! :twisted:
oh wait, no that sounded like an intelligent point. hehe
I vote for buggered impeller! :wink:
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Hey guys...I'm back from Holidays! :)
Yeah, I agree that the compressor wheel looks pretty well knackered. :cry:
DieselsRcool, is that new looking one a spare that might be available? ;)
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Unfortunately no. I wish I had an extra wheel to help you out. I just happen to have one of my turbos apart for rebuild and took the shot for your ref. It may be best to pick up a used turbo rather than buying a new wheel.
There is one on ebay now. You could recoup some money by re-selling the manifolds. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2480111643&sspagename=STRK%3AMEWA%3AIT&rd=1
Larry
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Stan - I always thought there was something "odd" about your intake manifold setup - with the 90 degree "el" on top! (Usually, the quantum intake manifolds I've seen have a block-off plate on top and a straight inlet on the side - where in your case, it has EGR going into the side!
Well, looked in ETKA and it was verified there are 2 versions of the quantum intake, and yours has the EGR! I did not know EGR was a possiblity on a 1.6lTD - so I learned something new from you! (I wonder if it's a california-only kind of thing.) Anyway, good job figuring that one out. That compressor wheel does look kind of bad. Looks like debris was making it's way past the air filter... So, you've got a few things to try at this point: 1. widening out that restrictive exhaust (it sounds bad in your case!) 2. fixing the chewed-up compressor wheel (looks like maybe a bolt was rattling around in there, something too big to make it's way past the wheel. Dinged up the sides of the compressor inducer bore as well, I see.) 3. up the fuel level (can't remember if you've got an EGT gauge already. Be weary of the EGT levels resulting from increasing the fueling without doing both #1 and #2 above first! An intercooler sure doesn't hurt either but I'm sure you can safely take the fuel up quite a bit without intercooler, if you just get yourself that big exhaust and efficient comrpessor blades.)
Nice progress... keep up the good work and nice reporting job with the pictures keeping us in the loop! :)
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By the way Stan - nice looking blow off valve block-off plate too. :)
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By the way Stan - nice looking blow off valve block-off plate too. :)
Yeah, sorry about the ugly workmanship. The round one I made on the mill and is a good close fit. The others I simply cut from scrap...the one on the intake manifold is plate aluminum. The odd looking one under the sawed-off EGR elbow is 80-thou stainless. Ugly...but effective. :oops:
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My guess is that the Garrett and KKK turbo's max boost is different if both were non wastegated and since the Garrett is capeable of higher psi this is what is happening
In experimentation, I've seen 28 psi with my k24. 32 with the N2O on. :wink: