9 psi max boost
 

Is that on the low side? What is the max boost I should shoot for with the stock IP fueling for best performance /economy?

Is this on your 300D? I have the same question...

Don't quote me on this, but I'm thinking 12-15

12-15 sounds like the right area. we have a 300sd running around with 20 and a bit more fuel and it seems pretty happy. but... you have to watch out for overboost protection at about 16 psi

The boost air pipe is provided with a pressure switch (3) At a boost pressure above 1.1 ±0.15 bar gauge pressure, the pressure switch will close and will connect minus (negative) to changeover valve (2), which is connected to plus (positive) via terminal 15. The changeover valve interrupts the connection boost air pipe to ALDA aneroid capsule on injection pump. The aneroid capsule is connected to atmosphere and the injection fuel quantity is thereby reduced. If the pressure drops to below 1.1 ±0.15 bar gauge pressure, the pressure switch will again interrupt the minus (negative) connection and will connect the ALDA aneroid capsule again to boost air pipe

http://sphotos.ak.fbcdn.net/hphotos-..._5133570_n.jpg

Hope that worked, last time i tried to post a pic it went very wrong...

:o oh no... you mean ive been wasting energy this whole time?

... unless you have added fuel.

:D sarcasim is hard to get across it text.

Only to those of us who aren't paying attention (me).

If you've removed the Full load fuel limiter then the max boost you should run is about 15. If you have a intercooler then up to 18 or so- after that the air is still heated quite a bit. You need a egt placed properly as well as a good boost gauge. If you have a IC and both gauges with the stock turbo then no more than 17-20 and make sure you keep the temp under 1200 on a regular basis, and 1350 for no more than 20 seconds, never above 1550. Better safe than sorry and these figures are very liberal- go on the conservative side and drop them all a hundred degrees really. I run up to 25 psi boost with my myna pump and get to 1400 for perhaps 15 seconds after a hard pull ending in 90 mph- but my exhaust manifold is coated with a jet hot type process and I have a IC. I also have some of the best junkyards in the USA to pull spare parts from. I have 1978 300SD intake and exhaust manifolds- pre EGR stuff with larger tubing.

Thanks for the helpful replies. This is the second boost gauge I tried with the same reading so it is unlikely a gauge issue. I am gonna check and make sure I have no leaks in the boost lines. What other things should I check? What are the usual causes of low boost in a 28 year old 300D turbo?

I vote wastegate spring. If it was a fuel issue it should still climb above 9 under full load. If it reaches 9 early and levels off it is your wastegate. Just to be sure though let me check my crystal ball ;)

"Less boost is needed with an intercooler"

More boost is possiable with a intercooler

Boost is air.
Fuel is fuel

More fuel without more boost is more energy, but without more air it has diminishing returns.
More boost allows more fuel.

More fuel and boost creates more heat, an intercooler/aftercooler allows more fuel and boost than is possible without by keeping the charge temperature down. The intercooler also creates a more dense charge (cooler) so that more gasses are introduced into the combustion chamber for more power.

It is generally accepted that an intercooler added to an engine that does not need it, wastes energy through more intake restriction. The three are best designed in together.

agreed.

My engine needs more than the 25 psi I make at full throttle going 80 mph or the 22 I make at 70 mph. That or I need a much much better IC and many other "tricks" to burn all the fuel I put in. But then I'm one of a very few with a pump that can put out way more fuel than stock. If you are blowing black or dark smoke you need more boost until the egt readings tell you to back it off.

Im still smoking pretty bad at 20 lbs... maybe a intercooler would be a good addition :P

I'd like to have the fuel to smoke, ...

id rather have the power without the smoke, but if i have to deal with smoke to make power then i shall. :D

Agreed, sort of. I'm building a 603 rignt now, trying to SWAG the fuel increase, boost increase, timing, and turbo size so that I will hopefully get good power with reasonable smoke and EGTs at full-throttle. I wouldn't be betting on me getting it right the first time, wish I could afford 7mm elements.

getting close or not getting close the first time is better than never trying at all.

I went through the winter with a weak starter and replaced it a month ago with one I rebuilt and no more starting problems so I have time to deal with other issues such as boost.

I tried adjusting the Alda, had it fully C.C.W. and still getting max 9 psi. I then pressure tested the Alda aneroid and it would not hold pressure for very long. I pumped it up with a mini bicycle pump to 15 psi and it would leak down to 0 within 5 seconds or so. Should it hold pressure longer than that and how much longer?
I had shaving cream around the connections including the banjo fitting at the aneroid and saw no bubbles so I am pretty sure the aneroid is the part that is leaking.

What should I be doing next?

your ALDA is leaking at the seal where the pin goes down to the pump pin.
As the boost pressure source is huge it should not influence much the ALDA work. If you adjust the ALDA all out it does not matter if it leaks.
Or you take it off completely to test boost pressure.

Tom

Thanks Tom,

Anything I have to be careful with so I don't break it? There's no fasteners on the cover other than the slotted screw and 10 mm locknut. There's a big hex nut underneath the cover - looks to be around 27 mm. Is that the nut to remove the ALDA? A link to a good DIY would be appreciated.

I don't have the link right now but yes the hex 27 underneath and a hex ?24? just above the 27 hex to hold the ALDA.
There might be a spacer between ALDA and pump that fall out or stays in.
This spacer is a basic adjustment when the ALDA was put on the pump in the last diesel shop (or by factory). Use this spacer again with the same ALDA on the same pump.
Once removed you can use the shaving foam to see the leaking seal.

Your boost line goes directly from the manifold to the gauge?

Tom

The hard vacuum line from the ALDA banjo was kinked with a pinhole about 6" from the banjo. I fixed it by cutting off the damaged section and splicing a T in with rubber hoses. That T is where the boost gauge is connected.

Could the leaking seal explain the 9 psi max boost? I guess it can ha? With the ALDA off, if I see the leak at the seal with the shaving cream, I'll plug the line to the banjo and my boost should go up along with more power?

Your 9 psi boost is likely a weak spring in the waste gate. If you have a KKK turbo it is easy to adjust, the garret is a little harder. Look up waste gate adjustment on this site and you should be able to find it. On my 300d it was at 9 psi also, and I put it to 12psi. Stock pump settings on this one. Alda is removed, and egr blocked.

oh the leaking seal, it is very unlikely to cause any real lose of boost, the volume is just to small, even having the line to the alda off and venting to the air would not cause a lose of boost. Think large volumes of air.

After getting all the lines cleaned and the boost gauge installed in my 85 300CD I'm seeing a max boost of 8 psi, with a regular boost of only 7. No smoke.

from reading here, It's my understanding that I too suffer from a weak waste gate spring. My boost gauge is tied into the hard line from the banjo bolt also using a Tee.

I have not checked the ALDA yet or done any adjustment to it.

I'm planning on getting out there today and playing with it some more and doing the spring adjustment.

turns out I have the KKK turbo... So I just finished increasing the boost and doing some testing.

Now the boost is around 17 but I saw it hit 19 for a second. I held it at full boost and the over boost protection kicked in at 16 and dumped the pressure... Like it should... So good there.

Now, I need to work on that Alda.. I'm still debating if I should remove it or just adjust it.

I have the Garrett. I found a few good DIYs. I couldn't get the flat spring retainer tang on the wastegate cover to lift. The tang is right under the inlet housing which is in the way of visibility so I was working by feel. Garrett could have installed the tang in a more accesible/ visible spot to make it easier. Looks like they did that on purpose and don't want you to fu*k with it. I used a small flat blade screwdriver but it kept slipping off the tang. Very frustratiing. I will make a special tool with a sharp chisel point to get under the tang in order to lift and hook it and see it that works.

by the way the oil separater came, and is now on the car, thanks

Excellent! I'm glad that parts of my 240D lives on in others 240D's.

I got the wastegate tools made but haven't tried them out yet. Hope they work.

I got a hold of a junk Garrett turbo from a 617 with a seized turbine (been sitting out in the elements) and played with getting the wastgate cover off. The spring was corroded in by the oxidized aluminum groove that it sits in. After a lot of scraping and with the help of penetrating oil, I got the spring off. I then tried getting the spring and cover back on and have not been successful yet. Maybe I'm just clumsy but this job seems to be a royal PITA do do in situ if I am having problems on the bench.

I am going to try a manual boost controller before trying anything else. I think my adjustable fuel pressure relief valve should work just fine.

I made a MBC from an old (weak) fuel pressure relief valve, a 3/8 brass tee, a 1 " L 3/8 hose and some clamps. It tested at 12 psi opening pressure w the cap all the way in (spring fully compressed). By loosening the cap till it almost falls off (spring least compressed) pressure is 5 psi.

I am still getting max 9 psi boost (with the MBC valve cap all the way out @5 psi opening pressure). The boost comes on earlier with throttle input but max boost remains the same, There is a definite improvement how it accelerates. Should I shorten the spring in the MBC to get a lower opening pressure than 5 psi?

What should I do next to get it to 12 psi boost? What will that extra 4 psi give me in performance?


.temporary plastic bag & twist tie to catch the parts if the cap comes off http://i31.photobucket.com/albums/c3...042211_001.jpg

deffinitly get it up to 12 lbs :) <- you'll get that

Lets look at basics, generally speaking more fuel will give more boost,less fuel less boost. So boost is limited by two things fuel, and wastegate. Assuming your manuel boost controller is keeping the wastegate closed, then there is a lack of fuel. If I were working on this the next step I would take to install a fuel pressure gauge, and see if it is at least up to specs. Think around 18- 20 psi. If not get it up, and see what improvement you get. next remove alda at least for now. If you get into ip adjustments later you may want it back on. But now is not the time to get into ip adjustments. If this does not work then I would really expect that the wastegete is dumping, and getting it working right will be required. I have a spare for the garrett. I'll look and see what condition it is in.

Or the turbo could be unbalanced and not spin up as easily... though I'd imagine you'd hear that.

A rather general statement, but a lot of things work into the P=V/T equation there Lance.

If the intercooler is dropping the temperature by 1/3, then yes in theory the pressure will also be lower by 1/3 for the same mass. However, this also depends somewhat on where the pressure measurement is taken as the pressure pre-intercooler will be higher than post-intercooler due to the temperature drop and to the restriction that the intercooler might pose to airflow. You're also making a pretty big assumption that the temperature will drop by 1/3.

Now I beileve that the previous posts are providing information regarding how much more boost the enigne can handle at cooler temperatures (and thus add more fuel) rather than how to calculate P=V/T

So apparently you've already chosen his intercooler, Lance.

Funny though, because I see most of these guys who are adapting and installing used/junkyard-find turbos, also adapt and install used/junkyard-find intercoolers (ex: Saab) and aren't necessarily getting optimum cooling nor optimum pressure drops, even finding optimum locations for airflow nor plumbing, ... thus my comment that it's a pretty big assumption.

Pardon me All:
Where does the intercooler go? Before or after turbo? Thanks

There is no intercooler on the 617. If you want to add one, it goes AFTER the turbo.

An intercooler goes after the turbo, between the turbo and the engine's intake manifold to cool the compressed-air charge.

That's what I meant to say. ;)

Just got the ALDA off. I only had an adjustable wrench to fit the large locknut but had a hammer and a 12" 3/8 drive ratchet extension which rested on the nipple of the ALDA and hit with a hammer to loosen then I was able to use my fingers to loosen it all the way. I put a bicycle pump on the ALDA and at first there was no movement but after a bit of fiddling with it it started to move as I pump. It would not hold pressure though. Once the pressure drops, the plunger retracts. Is the ALDA ok per my description? I haven't taken it for a drive yet with ALDA removed.

http://i31.photobucket.com/albums/c3...042611_002.jpg

If it does not hold pressure the diaphram may have a small leak. Not moving to start with sounds like it could well be most of your problem. Test drive and see how it is without it. It will hold back fuel being stuck, so you should see a noticable differance without it.

With ALDA removed, I took it for a short drive and for the first time I was able to get smoke with the peddle to the metal from a standing start. Not black dense smoke but a gray haze. But the boost is still maxed at 9 psi. Is there a way to check if the wastegate is leaking w/o removing the cover or removing the turbo?

It's nearly 30 years old, the wastegate spring is probably weak and needs adjustment.

Shouldn't he manual boost controller I have installed prevent the wastgate from opening? I would love to adjust the wastgate but I have been unsuccessful in getting the wastgate cover off. I will remove the MBC next and see if boost goes past 9 psi. With the ALDA removed and more fuel, boost should go up.

I missed the MBC part.

If the wastegate is not opening and you are only getting 9psi boost it could be air intake/exhaust or fuel or even rack travel. Do you get smoke?