VWDiesel.net The IDI, TDI, and mTDI source.
Engine Specific Info and Questions => IDI Engine => Topic started by: GTD. on December 15, 2004, 06:17:35 pm
-
I've blocked off my BOV with a bit of reinforced hydraulic hose I had lying around and a 3/8" to 1/4" socket adapter and some jubilee clips.
The BOV vented to the intake pipe so I fitted a breather filter to were it connected to the intake pipe.
Anyone know of a better/neater solution?
Its a SB 1.6 IDI TD engine.
Cheers
-
No need for the breather filter on the blow off valve outlet. It's just a feature to protect the engine from overboost in the event of a stuck closed wastegate, so it never actually lets air flow through it when things are working the way they should.
-
No need for the breather filter on the blow off valve outlet. It's just a feature to protect the engine from overboost in the event of a stuck closed wastegate, so it never actually lets air flow through it when things are working the way they should.
Why would overboost really be a bad thing on a diesel? Wouldn't running infinite boost just continue to cool egt's and increase combustion efficiency, or would the LDA still supply enough fuel to burn up the engine? It's my understanding that they eliminated the pop valve on the Eco Diesel intake which makes me assume that this has to do with the latter.
-
Actually boost = heat. And the turbine creates a lot of heat, because the exhaust gases are compressing as well.
Intercooling would definitely decrease temps though! As for combustion efficiency, you would need an intercooler after 9 or so psi. After that the air's oxygen levels arent good enough to ensure a clean burn (and you can tell when your car is leaving a black cloud behind it... brings back memories in summer time, but not in winter :)
fspGTD mentioned in a book that there was diesel tractors with 200 psi boost. That is some MEAN power right there. If anyone could get 200 psi on a vw diesel, they would be my hero!!! LOL (good luck... its half the pressure needed to ignite the diesel.... w0w intercooling would have to be water spray!!!!!)
-
Actually boost = heat. And the turbine creates a lot of heat, because the exhaust gases are compressing as well.
That's not exactly how I've understood things. Yes, with a gas engine running more boost will create detonation after a certain point due to increased cylinder pressures and decreased air density due to heat. Running more boost when more fuel isn't available will increase heat which can cause engine damage regardless of detonation.
When you consider your standard diesel compression check ought to yeild results in the 400+ psi range, it seems like a drop in the bucket to add a little extra boost. But I suppose in theory if we run 1 bar of boost we effectively double cylinder pressures. Of course this will lessen as boost increases due to the heat generated by compressing the air.
From everything I've read, tuning a diesel is more like an excercise in chasing your tail. Ultimately, excess fuel will melt pistons, not boost. With a lean burn engine like this, adding boost will essentially lean the engine out, or reduce engine load - which ultimately reduces EGT's.
If I'm overlooking something , feel free to chime in :D
-
Why would overboost really be a bad thing on a diesel? Wouldn't running infinite boost just continue to cool egt's and increase combustion efficiency
It would, until the physical limits of the turbo are reached and the compressor wheel bursts due to excessive speed. The other enemy is cylinder pressure. As you said, doubling the intake pressure will double the cylinder pressure. This will catch up to you at some point.
Boost is limited to a safe level on later models by underfueling them. No fuel = no heat = no boost. I don't think a stock 1.9TD with the wastegate tied shut could really hurt itself.
If I'm overlooking something , feel free to chime in
You've pretty much got it, The only limit to the amount of power you can make is the physical strength/heat resistance of the parts. You can compound turbo's to easily obtain 70psi of boost. If you can get the rods, pistons and head gasket to hold then you could make some huge power. :D
-
Why would overboost really be a bad thing on a diesel? Wouldn't running infinite boost just continue to cool egt's and increase combustion efficiency
It would, until the physical limits of the turbo are reached and the compressor wheel bursts due to excessive speed. The other enemy is cylinder pressure. As you said, doubling the intake pressure will double the cylinder pressure. This will catch up to you at some point.
Boost is limited to a safe level on later models by underfueling them. No fuel = no heat = no boost. I don't think a stock 1.9TD with the wastegate tied shut could really hurt itself.
If I'm overlooking something , feel free to chime in
You've pretty much got it, The only limit to the amount of power you can make is the physical strength/heat resistance of the parts. You can compound turbo's to easily obtain 70psi of boost. If you can get the rods, pistons and head gasket to hold then you could make some huge power. :D
I haven't actually heard of much of an issue with the compressor wheel coming apart. As Deo stated, they were running over 35 psi on the stock turbo.
-
No need for the breather filter on the blow off valve outlet. It's just a feature to protect the engine from overboost in the event of a stuck closed wastegate, so it never actually lets air flow through it when things are working the way they should.
I think you've misunderstood me I blocked the bov outlet with a bit of hydralyic hose with a 3/8" to 1/4" socket adapter stuck in it as a plug and held it in place with a worm drive clip.
The breather filter is is on the inlet pipe where the bov outlet would connect to, if I didnt use a filter, the turbo and engine would be drawing in unfiltered air.
I was just looking for a neater "Plug", I'll post pics up tomorrow.
I know the BOV is to leak overboost back in to the inlet pipe, I want to up my boost pressure from 0.6 to 1.1 BAR by using a manual boost controller on the wastegat line thats why I've blocked my BOV outlet, also my engine is intercooled as it left Wolfsberg as I said in my post, Its a SB 1.6 IDI TD engine.
Cheers
-
Gotcha, thanks for the clarification. :)
Have you seen this cross-section diagram of the BOV?
(http://members.rogers.com/harryfodder/pic/safety2.JPG)
I found that the stock range of adjustment maxxes out at an operating pressure of about 14psi (a little under 1 bar), which doesn't sound like enough for your needs. I have heard that if you unscrew the adjuster completely, you can install a shim behind it (going between the threaded adjuster and the spring that is behind the adjuster) that can cause it to raise it's operating pressure higher than the stock adjustment range, or if the shim is thick enough, lock the position of the valve completely closed (accomplishing the same thing as capping the air outlet.)
Stock intercooled 1.6lTD... nice motor... you know those weren't available in north america. drool!
-
Gotcha, thanks for the clarification. :)
Have you seen this cross-section diagram of the BOV?
I found that the stock range of adjustment maxxes out at an operating pressure of about 14psi (a little under 1 bar), which doesn't sound like enough for your needs. I have heard that if you unscrew the adjuster completely, you can install a shim behind it (going between the threaded adjuster and the spring that is behind the adjuster) that can cause it to raise it's operating pressure higher than the stock adjustment range, or if the shim is thick enough, lock the position of the valve completely closed (accomplishing the same thing as capping the air outlet.)
Stock intercooled 1.6lTD... nice motor... you know those weren't available in north america. drool!
No worries, no I aint seen that pic before, I might have to make a little test light up. might make it permanant with a LED on the dash.
I never thought of adjusting and shimming the BOV as I thought I'd have to strip it down and replace the spring with a firmer one.
Might be worth doing as a safety feature in case of damage to the hose suppling the wastegate or MBC just in case I didnt notice it on the boost guage.
Yes, although I only found out after ordering a Bentley A2 manual as there isnt a UK workshop manual for a Golf MK2 diesel, this model was only avaliable in the UK for the last year or so of production, I was lucky to find one at the local salvage auction, so I decided to save it by rebuilding it.
Fortunatly the A2 Bentley covers similar US spec A2 TD engines, and is usefull for other stuff.
Cheers
-
I haven't actually heard of much of an issue with the compressor wheel coming apart. As Deo stated, they were running over 35 psi on the stock turbo.
So why doesn't VW run all there diesels at 35 psi boost? At that boost level the 1.6TD could have made well over 150hp and still got 50mpg. Also, nothing improves emissions performance like boost, it helps with NOX, particulate, hydrocarbons, everything. If it can be done with the stock turbo, stock internals and with 100000mile reliability whats the holdup? In fact, why the hell am I not doing this? I had no clue that my 200+hp 1.9TD was just a chopped wastegate hose away... :D
-
Lol QuickTD... Man I would LOVE to have 200 HP and 50 mpg!!! WHERE DO I SIGNUP???
Haha!
-
What size of plug do you need? VW sells a 5/8" rubber antifreeze cap for about a buck. It is like a rubber thimble that goes onto the metal coolant hose...covers the connection for the oil cooler if you don't have the turbo. My rad cap keeps about 25PSI in the system so it ought to be sturdy enough.
Steve
-
What size of plug do you need? VW sells a 5/8" rubber antifreeze cap for about a buck. It is like a rubber thimble that goes onto the metal coolant hose...covers the connection for the oil cooler if you don't have the turbo. My rad cap keeps about 25PSI in the system so it ought to be sturdy enough.
Steve
According to the A2 Bentley BOV test procedure the plug is 1"/25mm, but thats for a plug to fit in the hoses.
That thimble like cap might stretch over the BOV outlet, have you got a part number for it?
cheers
-
I haven't actually heard of much of an issue with the compressor wheel coming apart. As Deo stated, they were running over 35 psi on the stock turbo.
So why doesn't VW run all there diesels at 35 psi boost? At that boost level the 1.6TD could have made well over 150hp and still got 50mpg. Also, nothing improves emissions performance like boost, it helps with NOX, particulate, hydrocarbons, everything. If it can be done with the stock turbo, stock internals and with 100000mile reliability whats the holdup? In fact, why the hell am I not doing this? I had no clue that my 200+hp 1.9TD was just a chopped wastegate hose away... :D
I don't know what world of magically exploding turbos you come from, but around here they just wear out faster and start to smoke. I think it's pretty damn obvious why vw didn't have cars running 35psi from the factory, that doesn't mean you can't do it. My Gas Rabbit makes almost triple the stock power output.....sure VW didn't do it from the factory, but I did it anyways.
-
The rubber cap is a real stretch to put over a 3/4" pipe. 1" would not work.
Steve
-
I don't know what world of magically exploding turbos you come from, but around here they just wear out faster and start to smoke.
Working on standby and prime power generator electronics/engine management for the last 5 years or so, I have had the opportunity to see diesel engines destroyed in every concievable fashion. I take a keen interest in the forensics of engine destruction, the controls I work on are supposed to prevent this very thing from happening.
I don't have any exploded VW turbo's (working on it :D ). I have learned by others mistakes. I can show you a stack of "magically" exploded garret T3's and T4's that have paid dearly for making big boost. They usually don't pop on the first trip up, it takes about an hour of unregulated running off the top of the map and some throttle cycling before the compressor wheel succumbs to metal fatigue. Most of these turbo's were on john deere and perkins diesels that the local standby generator guy likes to "uprate". :roll: They once did 2 in a single day. Pretty dramatic when the big ones go. The force of the wheel bursting can break the compressor housing off the turbo.
This sort of turbo failure is extremely unlikely in the gasser world. Gassers do not run at boost levels anywhere near those of automotive or industrial diesels. 25psi is really doing something on a gasser. 25psi on a diesel is routine. So commonplace is the wheel burst problem that diesel turbochargers are now being produced by both garret and 3k-warner with titanium compressor wheels in an attempt to avoid this sort of fatigue failure.
And you are correct, I do know why VW diesels don't run big boost from the factory. It is because the mechanically inept drive cars. They cannot be trusted to act in the best interest of the machinery. They may very well run the thing at full throttle from New York to Los Angeles. The same might be said about some of the people who read this forum. As much as we would like to think that we are all professionals, there are some amateurs in our midst. I don't think it is very responsible to tell them that running 35 odd psi of boost is harmless and will only cool the EGT's and make more power. Fact is, they will go out and try it. Many will do it with their daily driver and many will not have the cash to fix it when it scatters...
I feel its only fair to warn them that, based on what I've seen, there can be consequences...
-
As much as we would like to think that we are all professionals, there are some amateurs in our midst. I don't think it is very responsible to tell them that running 35 odd psi of boost is harmless and will only cool the EGT's and make more power. Fact is, they will go out and try it. Many will do it with their daily driver and many will not have the cash to fix it when it scatters...
I feel its only fair to warn them that, based on what I've seen, there can be consequences...
I can definitely understand that. Maybe on occasion the wheel will blow up on a car.... when I have some free time I was going to run the maps on some other compressor wheels. I thought about upgrading the compressor but I don't know if I'll ever get around to that. I really ought to spend the time on my other projects.
But yes, they will go try and it and then come back crying because something broke. I'm a firm beleiver in education before implementation. If you don't know what you're doing, don't f*ck with it. :D