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#15
by
libbydiesel
on 01 Sep, 2014 13:42
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My concern at those pressures would not be EGTs, but rather rods and rod bearings from excessive peak cylinder pressures.
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#16
by
Alcaid
on 01 Sep, 2014 13:47
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How many TD/TDI rod failures have you seen with wastegated turbos?
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#17
by
libbydiesel
on 01 Sep, 2014 14:10
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Great, if there's an issue with the rod bearings wearing out in the next 30,000 miles or the block getting a viewport, Gizmo will know exactly who to blame...
I have known of half a dozen AAZ and AHU vanagons running boost in that range and none of them lasted very long. ALL of them had wastegated turbos.
How many TD/TDI vanagons have you built? How many have you even driven?
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#18
by
Gizmoman
on 01 Sep, 2014 14:42
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I don't plan on running boost over 20 psi - As mentioned, I am running 14 when the EGT gets too high. What would be great is to see 18-20 when EGTs are high - not 14.
Would stretching the spring in the LDA achieve that?
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#19
by
libbydiesel
on 01 Sep, 2014 15:27
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You could remove the attmospheric bleed fitting (weird rubber cap on top of 17mm fitting) and run boost to the LDA while watching to see what pressure bottoms out the pin.
If the pin is bottoming out, then you could add pre-tension to the spring (no need to stretch it out) by rotating the 'starwheel' which is accessible with the atmospheric fitting removed.
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#20
by
410
on 01 Sep, 2014 15:41
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The adjustment screw on the top of the LDA increases fueling under no boost when the screw is turned in. If you see a ton of black smoke before the turbo spools you want to back this screw out. It's a very sensitive adjustment so a quarter turn at a time is enough to notice a difference.
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#21
by
libbydiesel
on 01 Sep, 2014 16:29
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You could...run boost to the LDA while watching to see what pressure bottoms out the pin.
I meant to say, regulated pressure rather than boost, so that you can see the pressure where the pin bottoms.
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#22
by
Gizmoman
on 01 Sep, 2014 17:07
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Funny, I thought I'd read all the related pump stuff in the FAQ. So I went to Google and did a search for "BOSCH LDA" which linked to this. . .
. . .
which led me to a clear explanation in the forum FAQ (including this very helpful diagram)
The star-wheel (item 5 above) is RH thread I assume?
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#23
by
410
on 01 Sep, 2014 17:11
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Yes the starwheel is right hand thread. The LDA like Alcaid mentioned bottoms out quite early in relation to boost. If you put too much tension on the LDA spring it causes the spring to bind and not allow the boost pin to reach its full travel.
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#24
by
410
on 01 Sep, 2014 17:23
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Gizmoman, your goal from what I've read is lower EGT's. You've done a great job increasing the airflow and the efficiency of the motor. As long as your air intake temps are reasonable then increasing boost is the way to go. As long as you're not fueling excessively, raising the boost pressure won't raise cylinder head pressures enough to worry about. I would try and disconnect the waste gate all together and take it for a spin. Your right foot will be your regulator at this point. If boost increases over 20 psi with less throttle input then you need to work on your boost controller.
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#25
by
Gizmoman
on 01 Sep, 2014 17:35
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Gizmoman, your goal from what I've read is lower EGT's. You've done a great job increasing the airflow and the efficiency of the motor. As long as your air intake temps are reasonable then increasing boost is the way to go. As long as you're not fueling excessively, raising the boost pressure won't raise cylinder head pressures enough to worry about. I would try and disconnect the waste gate all together and take it for a spin. Your right foot will be your regulator at this point. If boost increases over 20 psi with less throttle input then you need to work on your boost controller.
410, thanks for trying to assist with my "goals" - It can be hard to pin down, even for me
. libby and everyone else here has been very helpful. The other goal is to improve the low end torque as well. I am running a DK tranny and 1st is a bit tall (as are my tires). Turning in the fuel screw seemed to help quite a bit with that goal but it did nothing to increase boost at the top end. It seems I'm getting too much fuel relative to my boost pressure so with everyone's help, I think I'm on the right path.
As soon as the new fuel return hose shows up, I'll do a few test runs after tweaking things a bit.
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#26
by
410
on 01 Sep, 2014 17:47
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For low end torque the screw on the top of the LDA is perfect for that. It adds fuel in "off boost" conditions but it is also nicknamed the smoke screw. Screw it in too much and you'll be billowing out black clouds before the boost kicks in. This adjustment won't have any effect on the top end whatsoever. I've been following you project from the beginning. Keep up the great work.
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#27
by
Gizmoman
on 01 Sep, 2014 18:01
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For low end torque the screw on the top of the LDA is perfect for that. It adds fuel in "off boost" conditions but it is also nicknamed the smoke screw. Screw it in too much and you'll be billowing out black clouds before the boost kicks in. This adjustment won't have any effect on the top end whatsoever. I've been following you project from the beginning. Keep up the great work.
Thanks Mr.
I always thought (for the last three years) the "smoke screw" was the fuel enrichment screw. A simple misunderstanding can really mess you up.
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#28
by
libbydiesel
on 01 Sep, 2014 21:27
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Yes the starwheel is right hand thread. The LDA like Alcaid mentioned bottoms out quite early in relation to boost. If you put too much tension on the LDA spring it causes the spring to bind and not allow the boost pin to reach its full travel.
A stock 1.6TD pump will bottom out the LDA pin around 5psi which Gizmoman is certainly exceeding, but I don't know what Giles has done to the LDA. A Cummins 4BTA LDA will bottom out around 20 psi and it is certainly possible to swap the cummins boost spring and pin or similar.
If you crank the star wheel WAY up it could feasibly coil bind, but the stock 1.6TD spring and Cummins springs are nowhere near coil binding at the aforementioned pressures. Further, if Gizmo wants lower max-boost EGTs, one of the easiest ways to achieve that is to limit the total range of motion of the boost pin.
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#29
by
Gizmoman
on 01 Sep, 2014 21:40
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Thanks libby.
So, are you saying that I should be able to raise the star wheel enough with the stock spring or should I look at getting the Cummins spring?
To answer you question myself - I can almost hear you saying to "try the test mentioned earlier to see what I have now, then go from there".
I'm also hoping Giles will give me some pointers in the next few days.