Adjusting the IP to match the Holset

[Gizmoman]

Hey all, been a while since I've been here. Good to see the board's still running strong
Ok, I have an 82 Vanagon with a 1.9 AAZ, Holset turbo and WAIC. The engine runs fantastic thanks to much of the help I received here over several years during the rebuilding process, and the wife and I have enjoyed several long camping trips without a single issue. The transmission was worn then and now it's time to move up to a 5 speed which I recently purchased used.

I have sent an AAP 5 speed off for rebuild and have instructed Bill at AZ transaxle to change 5th gear to 0.77 from the stock 0.82.
I am running a 26.7 diameter tire and my excel spreadsheet shows I will be at 70 MPG @ 3100 RPM.

With my current DX transmission with an 0.86 final ratio, EGT's can exceed 1100 F (my warning setpoint) if I am going up a moderately steep grade of around 3-4% and trying to maintain 70 MPH. The Holset turbo is running around 12-14 psi at that point and while it can easily hit 20 psi if I floor it, I can't because I'm already hitting my EGT warning. It just feels like the relationship between how much it fuels and how much boost I have is off a bit. Giles had set the pump based on a K-14 which is what I had at the time.
I believe this relationship can be adjusted using the star wheel in the IP but I'm not sure which way I would turn the wheel or if there are other adjustments that would provide more boost and less fuel. I have turned in the fuel screw

In short, do you think the 0.77 is a bit much of a ratio change as I will hit high EGT's sooner as it is now, or is there a possibility my IP is simply adding too much fuel and not enough boost and if I can get it set properly, the 0.77 will be fine.

Any info someone could provide would be very helpful. The transmission ratio change is expensive and if it causes me to downshift sooner than I do now, it would be quite disappointing.

If the star wheel adjustment is the ticket, can someone tell me which way to turn it (CW or CCW) looking into the top of the LDA.

Thanks all

[RunninWild]

You would loosen the screw (counter clockwise) to lessen fuel. Does it smoke at all as is? I would expect your egt to be lower with the awic. Maybe you should try adding a bit of boost? I was under the impression the holsets were factory set closer to 30psi. What is your timing set at? 1100f is still fairly reasonable. I usually let off around 1250 and occasionally push it over 1400f for a split second.

My Pump was built for closer to 26psi If I remember right and at stock boost levels on my k24 once the lda opened I would make a smoke screen and egt would go through the roof. Disconnecting the line to the lda made the issue go away and I could pull faster up hills without hitting a temperature wall. I'm not saying thats your issue, but I'm kind of thinking the lda is cut too agressively or the springs are a bit weaker then they could be. A stiffer spring would bring the fuel on after more boost is built and in turn have less of an effect on cylinder temps. Or a 1.6td boost pin might workout better if you dont want to play with the boost.

[vanbcguy]

LDA adjustments don't really come in to play for steady state cruising - it only delays full fueling when the pump is operating close to full power. There's nothing you can adjust on the pump that will change the amount of boost you have at cruise. The LDA is a pollution control device which deals with changes in engine load more than anything.

Boost pressure is a function of turbo geometry and exhaust flow. If the wastegate isn't open yet (which it shouldn't be given the boost settings you are describing) then the only way to get more boost with a fixed geometry turbo is to add more fuel, which increases the exhaust pressure.

1100F is a pretty low EGT to be limiting yourself to. The engine and turbo can handle more than that safely. 1400F would be a safe place to set your EGT alarm.

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[Gizmoman]

LDA adjustments don't really come in to play for steady state cruising - it only delays full fueling when the pump is operating close to full power. There's nothing you can adjust on the pump that will change the amount of boost you have at cruise. The LDA is a pollution control device which deals with changes in engine load more than anything.

Boost pressure is a function of turbo geometry and exhaust flow. If the wastegate isn't open yet (which it shouldn't be given the boost settings you are describing) then the only way to get more boost with a fixed geometry turbo is to add more fuel, which increases the exhaust pressure. Apparently I just don't understand how it works at all but do find it hard to believe I cant change the fuel to boost ratio.

Thanks all for the replies. The reason for the 1100F setting is to warn of over-temp approaching. I do take it to 1400F for short stints.
My old head had broken heat shields and from what I've read, this is quite common. It may be "common" because everyone thinks 1400 is OK

It's not so much needing boost at cruise

1100F is a pretty low EGT to be limiting yourself to. The engine and turbo can handle more than that safely. 1400F would be a safe place to set your EGT alarm.

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Its not so much needing more boost at cruise, I'd like to have more boost when under load like climbing a 3% grade, common on West coast freeways. I have wired the wastegate shut and I suppose I could hit 30 lbs if I kept my foot into it. The boost I have at cruise is around 6-8 psi at 70 MPH. Remember, this is a breadbox in the wind.
I've tried just stabbing the pedal to the floor when climbing these grades but EGT's can go well over 1400 very quickly.

Thanks all for the replies.

[RunninWild]

I know boost is relative to load and the amount of fuel going in. I'm thinking the wind resistance and weight of the van is enough to load the engine enough to engage the lda, but because he is just cruising the boost isnt raising enough to properly burn the fuel for the amount of load. I think the lda is just too aggressive. In a lighter car with better aerodynamics this issue probably wouldn't exist. I'm experiencing the same thing in my samurai, admittedly my turbo wasn't set to make enough boost to burn the fuel but it was too much fuel regardless. Turning the fuel screw out made it that if I didn't raise the rpms enough before dropping the clutch the engine would lag and just crawl until it got to 1500 or so then start to accelerate, and still have unsafe egt temps at high rpm and high load. It was either too much fuel at boost, or not enough when off boost. Disabling the lda and increasing fueling gave significantly better exhaust temps (like 1200f max), and although it didn't accelerate as fast, the top speed and hill climbing speeds were increased because I could actually push the pedal enough up long hills to maintain speed without my egt going through the roof.

I would suggest just trying to disable the lda. Pinching the vacuum line doesn't cost you anything and it will quickly tell you if the on boost fueling is your issue. If it is, I would suggest getting a less aggressive boost pin, like one from a 1.6td that is adjustable. That way you can de-tune your higher end fueling without disrupting your preboost acceleration.

In my opinion the LDA needs to be cut in a way that off boost you have maximum fueling for the amount of air, and then at full boost you have maxium fueling for that much air. The slope on the lda would ideally be the same shape as the efficiency map of the turbo with a spring that allows them to raise at the same speed. This would ensure optimal fueling for the entire torque curve and wouldnt allow the egt to get out of control assuming the intake temperature is within reason.

A stiffer spring on his lda would allow him to have the same fuel potential but it wouldn't kick in until more boost has been made and could potentially be burned efficiently at lower temps would it not?

I just read the 1.6td lda spring is stiffer then the aaz one. Maybe it would work better for you?
http://vwdiesel.net/forum/index.php/topic,32848.0.html

[vanbcguy]

The LDA isn't going to change anything. Disabling it will reduce the power available with the pedal to the floor, but it's won't change anything at part load.

This is a diesel, not a gasser. It always takes a full cylinder of air, then varies fuel to control acceleration. Unlike a gasser there's no management of the fuel:air ratio. If the LDA were "enriching" things the engine would just go faster, exactly the same as if you pushed the pedal down further. The LDA is literally a movable stop for the "pedal to the floor" fuel delivery inside the pump. The governor lever only ever touches it when the operator is asking for maximum fueling - any time you are not requesting the maximum fuel delivery the pump can achieve the LDA doesn't come in to play. It's only job is to prevent the pump delivering 100% of its configured maximum fuel until there is boost present purely to control smoke.

If you believe your EGTs are too high at anything less than "pedal to the floor" and you have a fixed geometry turbo with a closed wastegate your only choices are to change to a turbo that is more suited to your needs (one which produces more boost in the conditions you are experiencing) or find a way to reduce the intake air temperature. Every 1 degree reduction in IAT generally results in a 3 degree reduction in EGT.



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[Gizmoman]

... Turning the fuel screw out made it that if I didn't raise the rpms enough before dropping the clutch the engine would lag and just crawl until it got to 1500 or so then start to accelerate, and still have unsafe egt temps at high rpm and high load. It was either too much fuel at boost, or not enough when off boost. Disabling the lda and increasing fueling gave significantly better exhaust temps (like 1200f max), and although it didn't accelerate as fast, the top speed and hill climbing speeds were increased because I could actually push the pedal enough up long hills to maintain speed without my egt going through the roof.

. . .I just read the 1.6td lda spring is stiffer then the aaz one. Maybe it would work better for you?
http://vwdiesel.net/forum/index.php/topic,32848.0.html

I backed off the fuel screw yesterday about 1/2 turn in. The result was identical to your description. My EGT's don't climb as fast but there's some serious clutch slipping required to get it going - especially if I'm starting from a dead stop on an incline, I can imagine this thing would be undrivable in San Francisco

Egt's are lower though once I'm up to speed and they don't come up as quickly going up those 3% grades. I think I'll turn out the screw 1/4 turn and see if the compromise is livable.

As for cooling the intake, I have a probe in it and with my water to air cooler set-up, it seldom goes over 30 degrees ambient.

I need to go back and read up some more on the star-wheel and the spring stiffness as well. Not to doubt those that are more familiar with these pumps/engines and turbos but I just need to get my head around it.

As usual, Andrew Libby once told me that I needed to have a variable turbo to achieve my goals and that the Holset would not be ideal.
I believe he was correct.
I still have to check out the star wheel and or spring stiffness cause I'm obviously hard headed.

[burn_your_money]

The other option that I didn't see mentioned was pump timing. Try bumping your timing 3mm advanced and then 6 degrees (from the advanced setting) retarded and see how that effects everything.

Do you have any boost leaks? Are there any restrictions in your exhaust setup?

With regards to the spring for the LDA, increasing the spring tension will delay at what boost psi the pump starts to add more fuel. I don't know how a Holset spools but I know how a K14 does and I think that's where your issue lies.

Based on what you said about winding the max fuel screw out 1/2 a turn and finding your EGTs to have been improved, I would put it back to where it was and significantly increase the tension on the spring in the LDA.

[vanbcguy]

Advancing the timing a little may indeed help with this situation - advancing the timing reduces EGTs, but it also will cause the turbo to be a little less responsive. Back to that whole "exhaust pressure builds boost" thing...

The comments about needing a variable geometry turbo to achieve your goals is pretty much my point.

You want to push something up a hill, it takes a certain amount of energy from burning fuel to do that. The fuel required to push the vehicle at a particular speed up a particular grade, assuming complete combustion, is essentially a constant. More fuel, more speed. Less fuel, less speed.

To not melt your engine you need enough cool air entering the engine. More air mass, lower exhaust temperature. Less air mass, higher exhaust temperature.

Since you need a certain amount of fuel to do the work required altering pump settings can't really do anything for you, with the exception of timing. Timing adjustments will shift things around a little - advance will reduce EGTs but increase peak cylinder pressure. Retarding the timing does the opposite.

If you saw an EGT reduction after backing out the fuel screw you probably found you needed to press the pedal down more. These pumps have a load dependant timing feature that adds a few degrees of advance when the accelerator pedal is at around 3/4. More than likely that's what you're seeing.

In short, if you can't get your intake temperatures any lower and you can't add any more air the only thing you can do is add a little advance, but too much and you'll blow your head gasket due to increased cylinder pressure. There's not really much room for adjustment...

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[Gizmoman]

Update - I spent the morning turning the starwheel and going for short test runs. I also put the fuel screw back as it was too lean to live with. Actually, I may have put the fuel screw to a tad richer than it was because, the star wheel adjustments seemed to be helping quite a bit. Changing the fuel screw past where I have it now makes the idle adjustment do nothing so I have backed it off a bit.

I have raised the starwheel (added spring tension) by 22 clicks. The thread is so fine that's really not much. I've read where guys say they moved it three clicks and had good results - I find that tough to believe. Possibly they meant 3 complete turns.
My last adjustment was to spin the diaphragm pin 189 degrees so it wasn't so aggressive. This seemed to help a bit more but I think the star wheel needs to go possibly another 12 clicks and the pin needs to go back where it was riding in the groove.

Burn your money - Interesting you should mention boost leaks. I know all my piping and hose connections are rock solid but possibly it's leaking at the intake manifold to head, exhaust to turbo connection or the waste gate is somehow leaking. As I mentioned, I currently have the waste gate held shut with bailing wire and hitting 20 psi should be easier than it is:o.

On one of my test runs I saw the boost hit 20 then drop off rapidly to 3 or 4, It's been OK since but I haven't tried a hard run again.

One thing I can say is these small adjustments have changed the characteristics of the motor dramatically improving the low end torque and reducing the EGT's a bit as well. I also notice the EGTs seem to drop a lot faster when I back off - not sure why but I'm not complaining.

[Gizmoman]

Advancing the timing a little may indeed help with this situation - advancing the timing reduces EGTs, but it also will cause the turbo to be a little less responsive. Back to that whole "exhaust pressure builds boost" thing...

The comments about needing a variable geometry turbo to achieve your goals is pretty much my point.

You want to push something up a hill, it takes a certain amount of energy from burning fuel to do that. The fuel required to push the vehicle at a particular speed up a particular grade, assuming complete combustion, is essentially a constant. More fuel, more speed. Less fuel, less speed.

To not melt your engine you need enough cool air entering the engine. More air mass, lower exhaust temperature. Less air mass, higher exhaust temperature.

Since you need a certain amount of fuel to do the work required altering pump settings can't really do anything for you, with the exception of timing. Timing adjustments will shift things around a little - advance will reduce EGTs but increase peak cylinder pressure. Retarding the timing does the opposite.

If you saw an EGT reduction after backing out the fuel screw you probably found you needed to press the pedal down more. These pumps have a load dependant timing feature that adds a few degrees of advance when the accelerator pedal is at around 3/4. More than likely that's what you're seeing.

In short, if you can't get your intake temperatures any lower and you can't add any more air the only thing you can do is add a little advance, but too much and you'll blow your head gasket due to increased cylinder pressure. There's not really much room for adjustment...

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Clear, concise and to the point ^^^
I'm going to move the star wheel up some more to stiffen the spring as it does seem to be helping and it's easy to do. I should mention that this pump is from a 1.6 and may already have the stiffer spring (it's blue if that means anything). Giles set the pump for a K14 and a max boost pressure of 14 psi. Ironically, 14 psi is about where it gets to when the EGT's start a rapid increase. That said, a variable turbo may be the ideal solution and I'll be on the hunt for something "affordable" to replace the Holset

I did speak to Giles about adjustments I could make for the Holset and he said I'd need to send the pump back to him and he would see what he could do. I don't blame him for that response at all but it's an expensive option that may or may not work as he has no experience with a Holset which he readily admitted.
I'll report back after I make the adjustments. I'm also going to check for boost leaks as there are times when the boost readings act real jumpy - possibly it's my digital gauge but I need to look for possible leaks. I believe the best way to do that nay be to make a fitting and introduce 20 psi where the turbo discharge connects.

[vanbcguy]

Suppose the one other thing to check would be the exhaust side... Was it you or someone else that discovered they had a massive exhaust restriction? The other factor in building boost is of course post-turbo restriction.

The boost gauge fluctuations could definitely be pointing to a problem. You should see a corresponding increase in smoke, a drop in engine performance and a temporary rapid increase in EGTs if the boost leak is real - if the engine performance doesn't change at all then I'd be chasing down a gauge problem.

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[Gizmoman]

It's embarrassing to admit that when I wired the waste gate closed, I was in a campground and didn't do a proper job. The bail wire was wrapped around an object that could flex . This morning I have redone that mess and now the gate is definitely closed. While I was under there, I inspected everything else and there is no sign of any leaks either on the intake, or exhaust side.
vanbcguy, you've a good memory - yes, I had a huge restriction with the muffler the PO had installed but remedied that quite a while ago. Everything is 2-1/2" now.

I have turned the star wheel way up (quit counting clicks) and backed off the fuel screw 1/8 turn. It took 6 test runs this morning to get to this point but the outcome is acceptable now.
I can hit 21 PSI if I floor it and am now getting to 15 before the egt's go over 1200F. I also have much more low end grunt and the changes have greatly shortened the flat spot I had before boost would kick in.
A variable turbo would be ideal but this will do for now.

[vanbcguy]

Ha - yeah that's definitely not ideal. Hopefully you'll be able to work with what you have now that you're getting the most out of it!

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[theman53]

On my holset setup I cannot throw enough fuel to it. The more aggressive you get with it the more boost it makes and in turn I will actually see the egt raise to almost 800f and then come down. I have mine turned all the way up and the pump timing set .94 and I cannot get past 800f. If I baby it the egt stay around 750f...what kind of RPM are you running to get the egt? Do you have a manual boost controller?