Sluggish Pyrometer Response - Page 2 - PeachParts Mercedes-Benz Forum

bgkast · #16 05-11-2007, 09:31 PM

Before I intercooled I hit 1100F climbing a long hill in 4th with my foot to the floor. Now that I have intercooled I never even hit 1000F. The engine runs between 450 and 650 on the freeway, and I don't even think my gauge would move from 250F (the lowest reading) at idle. Guess I need to adjust the full load.

Here is my pyrometer pictorial for installing the thermocouple PRE-turbo: Pyrometer Thermocouple Installation Pictorial

Lycoming-8 · #17 05-11-2007, 11:07 PM

On a 240D, even stuck in the aft end of the tail pipe it is pre-turbo!!

ajrn · #18 05-11-2007, 11:45 PM

Uh..

Mine doesn't have a turbo.. I guess my sarcasm created confusion!

I forgot, some of you guys have grafted one on!

#19 05-11-2007, 11:50 PM

Quote:

Originally Posted by ajrn

My thoughts were of adding propane fogging, for merging onto the highway. A manually controlled button, that would maybe fog, with a relay timed for 30 seconds or so-- then shut off.. Once she's 'to speed' she's okay, for the most part.. Getting there can get spooky, sometimes..

Not worth the time. You won't get much (if any) more power from a non-turbo IDI diesel.

Adjust your ADA about 1/4-1/2 turn CCW and you should get better power.

ajrn · #20 05-12-2007, 12:00 AM

Won't dumping more fuel also increase my exhaust temps??

I guess I'm wondering if I should see this as a project (the car itself) not worth chasing.. I'm going to adjust the valves, and see if that doesn't help some-- Not sure if the PO did an adjustment.. If he did, it's likely wrong, from what I've seen of his repair prowess..

I've got an '84 SD-- and I'm thinking maybe just selling the 240D, and finding another 5cyl turbo would 'fix' the problem..

...Nothing beats displacement.

#21 05-12-2007, 12:09 AM

Quote:

Originally Posted by ajrn

Won't dumping more fuel also increase my exhaust temps??

Yes, but that's why you have a pyrometer.

bgkast · #22 05-12-2007, 01:07 AM

Quote:

Originally Posted by ajrn

Uh..

Mine doesn't have a turbo.. I guess my sarcasm created confusion!

I forgot, some of you guys have grafted one on!

Oops...guess I should read more carefully.

Jeremy5848 · #23 05-12-2007, 01:30 AM

The thermocouple in my '85s EGT is in the manifold, just before the pipe to the trap cat. The '85s came with a tapped hole just after the last exhaust port. I had to use an adapter so the thermocouple doesn't protrude as far into the exhaust stream as I'd like. Add to that my IP is set a little low and I've not yet seen temps above 850F. I'll have to do some hill climbing on a hot day to see what happens.

Jeremy

ajrn · #24 05-12-2007, 01:40 AM

Okay--

Am I right in saying 1200F sustained, is a max, and it can momentarily go over??

#25 05-12-2007, 01:47 AM

Quote:

Originally Posted by ajrn

Okay--

Am I right in saying 1200F sustained, is a max, and it can momentarily go over??

I'd say that 1400*f is a safe max for a few seconds at a time with a few minutes cooling time after. 1250*f is the established safe constant maximum.

ajrn · #26 05-12-2007, 01:53 AM

heh heh heh..

Well, then I'll have to adjust those valves, and turn up the pump....

With an automatic, she'll never be a ball of fire-- I'm looking at making interstate travel a smidge safer..

biobenz617 · #27 05-12-2007, 02:24 AM

Instead of propane, have you thought of nitrous? Increasing the oxidizer going into the engine with nitrous supplement when needed would be like having a momentary turbo if you could also add extra fuel when nitrous is injected. Perhaps the ADA on the injection pump could be used to control fuel delivery limits by supplying a regulated pressure signal from the nitrous injection line to the ADA atmosphere port when nitrous is active, then vent the pressure signal when nitrous is turned off to restore normal fuel limit. That would simulate higher atmospheric pressure allowing the pump to deliver extra fuel. I really don't know if the naturally aspirated injection pumps can vary the fuel like the turbo pumps though. Just a thought.

ajrn · #28 05-12-2007, 05:25 AM

Uh--

I don't think the NA pumps have atmospheric 'correction..'

and.. Hmm.. I'm barely smart enough to understand what you're SAYING, let alone how I'd carry that out..

I realize, having read some of these guys threads, there are some EXOTIC 4 cyl diesels out there.. To the guys who make that happen, I tip my hat-- you are scholars in a world where too many people don't know how to check, much less change their oil..

Like I said earlier.. I'm already considering the merits of more displacement-- THEN doing something exotic..

...a tireburning turbodiesel 123 wagon, for instance!!

#29 05-12-2007, 11:30 AM

Quote:

Originally Posted by ajrn

I don't think the NA pumps have atmospheric 'correction..'

This is the ADA, or, altitude compensator.

biobenz617 · #30 05-12-2007, 06:56 PM

It really wouldn't be that complicated...

Turbos are used to increase flowrate of air (oxygen) going into the engine so you can inject more fuel and achieve higher engine outputs for the same size engine. Turbos do this by compressing the air as it enters the engine. If nitrous oxide (an oxidizer like the oxygen in air) is added to the inlet air of a N/A engine, it too enables more fuel to be used and gives higher outputs.

If you put a hose into your air intake (preferably furthest from the engine for mixing's sake) to deliver nitrous oxide gas from a cylinder in your trunk, now you have a turbo in a tank. Using a switch and solenoid valve for the nitrous (probably comes with a nitrous "kit"), you can select when you want your extra power.

Now, doing this wont really give you any more power until you give your engine extra fuel when the nitrous is on. If your injection pump has the atmospheric adjustment pod (ADA), it should have a connection on it for atmospheric pressure that is probably not connected to anything. I'm not sure what the adjustment range is on these pumps, but if they can respond to pressure above atmospheric and add more fuel accordingly at full throttle, then it could work. A pressure signal could be tapped from the nitrous system and regulated down to say 10 psi and directed to the ADA pod when the nitrous is injected in the intake. That would tell the pump to inject more fuel when nitrous is injected. When you shut the system off, the ADA signal would vent back to atmospheric pressure and normal fuel limit reestablished. Just a couple hoses, solenoid valves, pressure regulator, and the nitrous cylinder.