Hi Volker,

how do you know about the 155 bar limit?
I don't doubt the fact but I am curious.
Would you say the 150 bar setting is already risky?
Practically you are right... take the RIV light, rotate the IP to 12deg and move on. But I like the fact that I could understand and adjust the timing like on a gas engine. It seems so more direct.

Here is another point that bothers me. My EGTs (exhaust temps) are too high if I hit the gas. My EGT gauge is very sensitive and I don't know but others report that they can hardly reach the 1400 F. I can easily.

What would the advanced timing (2 deg advance) do to the EGTsx (is there a connection?) and how would the engine respond differently in terms of power supply?

Martin

Hi Martin,

regarding EGT: Advanced timing will decrease but on the opposite you increase easily with maxed out IP.
I can go WOT and EGT rather go down to 500 degC as the governor already pulls back fuel at 4200/min.
Approx. 700 deg C is max EGT continuously according to MB.
617 maybe a bit more, 603 a bit less.

Tom

You need some data like spring length, spring rate, spring pretension, maximum needle movement, needle surface, pop pressure, shim thickness, ....
and then you can do the math what is the maximum before permanent damage occurs.
Or the funny version:
I had asked a spring manufacturer about a harder spring for more pop pressure. After he had the data he said: "If you want something harder than that spring in your nozzle holder, pour it out with concrete!"

No, measurements and calculations say it is safe at 150bar based upon a 135bar turbo nozzle holder.


Gruß
Volker

Thanks Tom,
good information that EGTs go down with advanced injection timing.

I have never experienced that EGTs went down at WOT. My gauge keeps going up with rising rpm.
700C is roughly 1290F or 1300F. I really try to avoid going higher. This prevented me to test out the final speed of the car. Never could go beyond
170 km/h or my pistons would melt?The engine easily could go faster.
Probably my EGT is faulty and I can't imagine that with stock IP setting I would not have reached these speeds.

Hi Martin,

welcome on the bright side of the tunnel.
Would your coolant temp increase dramatically on WOT?
Now we should know:
- timing
- IP adjustment (ccm at what rod position) and pull back rpm
- max. boost pressure

We can guide you to see some improvement but at the end of the day you will understand that bigger element diameter and different geometry will open the next level.

EGTs go down by advancing because you inject less fuel when the piston is far beyond TDC (cylinder pressure drops=cylinder temperature drops, how can this package of fuel burn to push the piston?).
Cam shaft angle for max delivery of approx. 54 ccm with 5.5mm plungers is about 50 deg.

Tom

Speaking of pop pressure, I'm about to rebuild my injectors for the second time 18k miles. I suspect my injectors are set too low because the engine is extremely quiet. By the sound you would be hard pressed to guess its a diesel at idle. From what I've read this is a symptom of pop pressure being too low. It also tends to smoke a bit above 3500rpm. I'm guessing I set the pressure too low because the 5800psi gauge on my Bosch pop tester isn't accurate enough. I picked up a $15 Wika 2000psi gauge on Ebay which hopefully should help me set the pressure more accurately. I think I'm going to aim for exactly 2000psi.

Has anybody else run into this problem?
http://i.imgur.com/F3a0OGT.jpg

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it is easier to advance timing a bit and see if the smoke disappears.
What is wrong with a smooth and quiet running engine?

Tom

Nothing unless the pop pressure is below spec and its burning more fuel than it should be. Timing is already advanced.

Some reading to go along with the subject.
I.C. Engines And Combustion - Google Books

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Hi Tom

1) Would your coolant temp increase dramatically on WOT?
You should know I was driving in the deserts of Oman the last 2 years with my SDL...probably the only one in the country. Not much of a speed limit there and HOT... winter 85-100,in summer 100- 120 F.
In the beginning I had a massive overheating problem, then I installed a new radiator and new water pump and coolant temps were absolutely stable (I had a new fa clutch before.
So finally coolant temps were stable and good!

2) Now we should know:
- timing
- IP adjustment (ccm at what rod position) and pull back rpm
- max. boost pressure

Timing: 14 deg ATDC according RIV (set couple years ago 50K miles ago together with a new timing chain)
IP adjustment: I opened the stick IP 1 3/4 turns ...almost maxed out, adjusted idle accordingly and adjusted Alda.
max boost: 12.5 psi, no smoke, except for WOT acceleration.

I'll attach a document for experienced EGTs/boost and speed

What can you read from this table. Please let me know.
Martin

Attached Files

131207 EGTs, boost and speed.pdf (24.4 KB, 134 views)

good reading.
To follow this correctly you need to measure combustion pressure over crank angle. Plus the matter Volker mentioned that pop pressure is limited by the injector spring to about 150 bar unless you have custom made nozzles.
Up to 150 bar there is no real need for measuring but you might not see that much of a difference.

Tom

in my opinion the maxed out IP is the only reason for high EGTs due to late end of injection.
During the next couple of days we try to collect some data on my 603 turbo with 160 bar injectors.
(combustion pressure over crank angle and some other things).

Tom

Thanks Tom,

what you are saying is that my timing is off (too advanced due to higher pressure) and this in combination with the high amount of fuel from the open IP will create the high temps.
I thought for some time that high boost would cause the trouble (I had 14psi as max) but then I realized that there was no change with lower boost of 12.5psi.

So all I can do (and that is what you all are saying) advance timing 3 or 3 degrees and test EGTs once again and watch out for changes motor characteristics.
What I'll do is get the RIV light and advance from 14deg to 12 deg.
Does this sound like the correct plan?

I was also thinking to get a digital pressure gauge for the pop testing.
What if the calibration of the one gauge I have is off? Sure this is unlikely but I don't know for sure.
best, Martin

I did not say that. Late end of injection because of maxed out IP is causing high EGT.

yes, advance some deg and test.
More important is that all injectors pop within a small range. If this is 142 or 147 does not change much.

Tom

I've been playing around with a spare injector to try to increase the pop pressure from the stock 135 closer to 145 simply by polishing the mating surface where the 2 halves meet using 2000 grit paper (no spare shims). So far I have it popping just a hair under 2000psi. The nozzle is old, worn out and pissy so I put a dab of polishing compound on the tip and spun it by hand inside the nozzle body. It stopped pissing completely and pops repeatedly with a distinct high pitched buzz. I'm going to try to capture some high speed shots of the tip on the pop tester with my GoPro.
http://i.imgur.com/UolXY7E.jpg

I don't think I have balls to try increasing the pressure past 2100psi but I'm interested to see your results.

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Hi,

the edges of the needle cones are sharp-edged to get optimum atomisation.
Polishing helps to close the nozzle but kills the edges.
Waiting for you high speed shots.

I am also curious about our results...

Tom