82 300CD - performance/power modifications possible??? - PeachParts Mercedes-Benz Forum

derherr65 · #1 09-16-2006, 02:11 PM

An odd question on a Mercedes, I know, but how can you get more power out of properly running 300CD?

My thoughts so far:
More turbo boost by replacing turbo. If so, which turbo and how much will the engine safely and reliably handle? A variable turbo would be wonderful wouldn't it!
Perhaps an air-to-air intercooler?
More cubic inches would be a normal thought, but I suspect that a stroker kit cannot be had.

Also, how much power will the transmission and rear axle handle?

bgkast · #2 09-16-2006, 02:56 PM

Please do not replace your cam.

This guy seems to think this is the fix for evry problem.

You could add an intercooler and adjust the max load to get some more power. Choosing a different turbo requires some knowledge and calculations to do correctly. There are a few people working to adapt a variable vein turbo to these engines.

derherr65 · #3 09-16-2006, 03:05 PM

I concur. While you can make some gains, power changes from cams are mostly due to changing the rpm at which the engine peaks. I'm happy with that aspect, just looking for more area under the power curve.
Could you explain "adjust the max load"?
Does anyone have pictures and information on adding an intercooler while retaining stock AC etc?

Johnhef · #4 09-16-2006, 03:13 PM

These engines aren't limited by the turbo, but by the full load setting inside the injection pump.

easiest things to do:

adjust the alda screw, ccw.
check boost pressure/clean out alda lines, overboost switch and cut-out valve.

13psi is plenty for this engine. overboost is set at 15psi, anything higher and you better be monitioring exhaust temps.

if you play with the full load adjustment screw in the pump, again, keep an eye on egt's.

if you're unsure of any of the things I just mentioned- do a search, this subject has been beat to death many times in the past.

#5 09-16-2006, 04:39 PM

Quote:

Originally Posted by RAYMOND485

1984 300d Turbo 140,000
Replace The Camshaft $175.00, 4 Tower Bearing $150.00, 10 Rocker Arms $280.00, 10 Valve Springs $50.00, 10 Valve Stems Seals $12.00 Buy A Valve Stem Kit From **************.com $75.00, 10 Turbo Seals, Guide Book, Push On Tool, 5 Extra Lock Nuts $75.00 Power Improvement, Fuel 20 To 28 Mpg, 30 Percent Gain, No Smoke

HE DOES NOT NEED TO REPLACE HIS CAM. QUIT POSTING THE SAME

IN EVERY THREAD.

"Power Improvement, Fuel 20 To 28 Mpg, 30 Percent Gain, No Smoke"
That CAN'T happen by replacing the stock cam with another stock cam.

First things firts. Get a pre-turbo pyrometer before you do any kind of performance mods.

derherr65 · #6 09-16-2006, 05:32 PM

Quote:

Originally Posted by ForcedInduction

First things firts. Get a pre-turbo pyrometer before you do any kind of performance mods.

Pre-turbo? I guess it is hotter before the turbo isn't it. What are the maximum sustained and peak temperatures you'd recommend on a daily driver?

#7 09-16-2006, 05:42 PM

Quote:

Originally Posted by derherr65

Pre-turbo? I guess it is hotter before the turbo isn't it. What are the maximum sustained and peak temperatures you'd recommend on a daily driver?

1250*f is what I think is safe.

I say get a pyro first because I can already get 1400*f without any internal injection pump adjustments, just external changes without an intercooler.

TheDon · #8 09-16-2006, 05:45 PM

Quote:

Originally Posted by derherr65

Pre-turbo? I guess it is hotter before the turbo isn't it. What are the maximum sustained and peak temperatures you'd recommend on a daily driver?

1220.58 °F is the melting point of aluminum, which what the pistons are made of, id stay at 1100*F to be safe, add more fuel and more boost than you need the extra boost will keep things cool

#9 09-16-2006, 05:50 PM

Quote:

Originally Posted by TheDon

1220.58 °F is the melting point of aluminum, which what the pistons are made of, id stay at 1100*F to be safe, add more fuel and more boost than you need the extra boost will keep things cool

Remember that the pistons are an aluminium alloy, not pure aluminium.

#10 09-16-2006, 05:53 PM

From Ford Truck Enthusiasts Forums

EGT questions answered...now you're confused!!
This is a totally coherent rambling of the apparent inaccuracy of the so-called "safe EGT" threshold that has been disputed and talked about on nearly every diesel and performance car oriented website and forum on the internet. This weekend a friend and I removed the pyrometer from my 2001 Powerstroke and installed it in his 1989 F-150 with a turbocharged 300-6. This is an accurate and truthful collection of findings that came from this experiment. I feel that this totally debunks the "safe EGT" limit that we have all heard about. The magic number I'm referring to is 1240 degrees or thereabouts.

On the diesel engine, the pyrometer reading at idle hovered between 210 and 275 degrees depending on electrical/AC load. The gasoline engine idles at nearly 640 degrees. Ok, no big deal. The big change comes when cruising and when loaded. While cruising down the interstate at 75 MPH, the diesel consistently runs between 600 and 800 degrees. This is no load, level road surface. Under load, the temps can easily climb to 1200 degrees, which is about 100 degrees hotter than I ever run it (since I've fallen into the 1240 degree myth). On the other hand, the pyrometer is COMPLETELY USELESS in the gasoline engine because the needle is PEGGED past 1500 degrees AT ALL TIMES. When heavily loaded (8400 lb. GCVW trailer, toys, and truck), the EGTs do fall to 1400 degrees due to the 11.5:1 air/fuel ratio my friend has his tuning set at under WOT with 6 psi of boost. Just judging by the ease of "pegging" the gauge, it is safe to assume that an EGT of 1600 or 1650 degrees has been reached. Keep in mind that as I write this, we are on an 80 mile trip and I haven't seen the the pyrometer gauge come "un-pegged" for at least 30 minutes.

Now it's time to talk about the physical differences/similarities between the two engines and why the EGT does not seem to matter.

First off, both engines use a specific fuel and air mixture to cause a controlled expansion of burned gasses by way of combustion. Obvious differences are that the diesel engine uses a precisely metered amount of fuel to control engine speed and power while the gasoline controls both air and fuel. Internet sources (taken with a ton of salt obviously) claim that the BTU of diesel fuel is somewhere between 170,000 and 180,000 while gasoline is somewhere between 120,000 and 130,000 BTU. Air/fuel ratios of a diesel engine vary from close to 100:1 at an idle to anywhere lower than 20:1 depending on tuning. Gasoline engines on the flip side need to run between 11.5:1 and 16:1 to operate. Too rich and she misses, too lean and she misses. Either end of the spectrum creates a loss of power. It is interesting to note, however that the EGT of a gasoline engine rises during LEAN conditions and cooler during RICH conditions. This is completely opposite of our diesel friends. Under a steady cruise with no boost and an air/fuel ratio of 14.5-15.3:1 the EGT of the gasoline engine was NEVER less than 1500 degrees.

Obviously, both the diesel engine and the gasoline engine use ALUMINUM pistons. This fact is where the "magic" 1240 degrees comes from. Sure, the aluminum might just become soft and pliable at a consistent 1240 degrees. However, the ENTIRE PISTON IS NOT 1240 degrees. Not even the head (top) of the piston is a CONSTANT 1240 degrees because every other crankshaft revolution (every time the intake valve opens), you get some nice cool(er) air coming in. Let's not forget that aluminum is great at dissipating heat and transferring it to other places. The skirt (sides) of the piston are in contact with a thin layer of oil and then a water-cooled cylinder wall. The underside of the piston is exposed to air in the crankcase that is not 1240 degrees either. Add that to the fact that most every diesel engine uses piston cooling oil jets that spray oil at the underside of the piston head....again, not 1240 degrees.

The EGT is just that, Exhaust Gas Temperature. The temperature is not an accurate depiction of PISTON TEMPERATURE. I can easily understand that if temperature is maintained too high for too long the heat cannot be dissipated fast enough. However, how much heat does it take and how long?

The 300 maintains a 1500+ degree for a long time. The gasoline piston is thinner and lighter than the diesel piston. The 300 DOES have piston cooling oil slingers drilled into the big end of the connecting rods, but nothing precisely aimed or really pressurized. The engine doesn't suffer any ill effects from running this temperature and like I stated before, I have seen this truck push 1500+ degree EGT for 30+ minutes straight.

Makes you think.

From now on, I'm not going to worry about my EGT.

Cody

TheDon · #11 09-16-2006, 06:01 PM

interesting.. very interesting.. yes EGT is just that, the temp of the gases not the temp of the cylinder.. i wonder...

derherr65 · #12 09-16-2006, 06:13 PM

Another FTE'er! Howdy.

I thought the turbo itself would be the first casualty of high EGTs.

#13 09-16-2006, 06:23 PM

Quote:

Originally Posted by derherr65

Another FTE'er! Howdy.

BTW, I'm not nor have I ever been or will be, a "Ford Truck Enthusiast". I'm a Chrysler/Dodge man.

They just happened to have the best article on EGT's that I (Google) could find.

derherr65 · #14 09-16-2006, 07:13 PM

Quote:

Originally Posted by ForcedInduction

BTW, I'm not nor have I ever been or will be, a "Ford Truck Enthusiast". I'm a Chrysler/Dodge man.

Well, no one is perfect. but I'll let you slide... this time.

Sounds like I may have first bid on an '82 300CD.(signature car, not mine, yet at least) Interior is a little rough, ALDA screw is tuned to max, runs rough cold but seems fine warm, and the vacuum system is on the Fritz, A/C system works aside from vacuum vent control, radio and speakers are toast, body good, paint fair.

Johnhef · #15 09-17-2006, 12:20 AM

Quote:

Originally Posted by ForcedInduction

1250*f is what I think is safe.

I say get a pyro first because I can already get 1400*f without any internal injection pump adjustments, just external changes without an intercooler.

just curious, have you done any brainstorming on your personal intercooler designs yet?

I picked up one from a C230, but I'm still far off from incorporating it into any of mine, if I do- it would probabaly be the 124- I'm just about done with the coupe and am thinking about unloading it.