any performance gains for a NA diesel? - PeachParts Mercedes-Benz Forum

weird beard · #1 07-03-2011, 04:40 PM

Has anyone here ever increased the output of thier NA diesel? Delivery valves, timing, LPG? Anything direct and somewhat cheap like rob these off this pump etc? I like my 190d with 2.5na (om602.911) but wish it had a bit more power sometimes. Car is total junk pile, not looking to to spend much time or money on it. Longevity not an issue.

Yes I searched. Mostly "NO" is the answer. Should be able to find power somewhere. Very little to no smoke from the exhaust.

oldsinner111 · #2 07-03-2011, 04:43 PM

One guy has propane injection at full pedal.

okto · #3 07-03-2011, 04:53 PM

I haven't ever really seen a good writeup/thread on adjusting the IP, but I know you can make it dump more fuel into the engine than the default settings.
If only I could get to my IP without removing the manifold...

layback40 · #4 07-03-2011, 10:07 PM

Hey weird!!
Havent seen you about here for a while!!

Its all about getting air in & exhaust out with a n/a.
I have emptied out the cat converter & opened up the air feed to the filter a bit. It appeared to help when under load.
You could give it a little more fuel as well. Mine appears to get gutless at higher rpm.
The WVO doesnt help. Is it breathing bad yet?

weird beard · #5 07-03-2011, 10:44 PM

I know it's been a while. Car has exceded my expectations. For $500 it has been great. Had no problems with it. Got the a/c working, did some body work on it, fixed the oil leaks. Cat has been deleted. Cleaned the carbon from the egr system out of the manifold, deleted egr including the throttle plate. Replaced fuel bypass valve.

Haven't run WVO for a while, no longer free, therefore no longer worth it in my opinion. I due however score the occasional batch of contaminated diesel that I mix according to level of contamination with fresh diesel. Right now I am running 25% used engine oil. A rig came in with 20 gallons of fuel in the 20 gallons of oil already in the pan. Mixed it to 25% oil with fresh diesel. Still no smoke. I filter it through a filter setup I scored off a scrap Mack engine, primary and secondary filters. The filters are free too! I grab used ones from the bin and bring them back when they plug up.

Back to the thread:

Im thinking it could stand a little more fuel. All the write ups about the ip's are for turbo applications. I don't know how much is directly applicable to the na pumps. There is little or no smoke under load so it is not at the point of overfuelling, and with no egr, there is more oxygen available so should be able to get some more fuel in without much trouble. I wonder how much fuel is available at the pump to give? How much return is there at full load? Could it may be maxed already? I changed my bypass valve (fuel pressure regulator on the return line @ the pump) with a brand new bosch one ($30 cash from my local diesel shop) so as long as the fuel pump is ok I should have some fuel available.

I need to find out what I can swap out easilly, say delivery valves, to get some of the missing fuel back that was held off due to the egr.

I have looked at full throttle propane, but want to stay with diesel if possible. My crankcase breather splits five ways, entering each intake runner just ahead of the intake valves. I was thinking I could plumb the propane into these ports and vent the crank to atmosphere. It would just be a set regulator, through trial and error, being careful not to hydraulic lock the engine! Activating at WOT only.

I'm really hoping someone will pipe up and say something like "grab these off this pump, will give you 10 more poneys"

barry123400 · #6 07-04-2011, 01:39 PM

Checking and increasing the base fuel pressure in the base of the injection pump will give you more. How much more depends.

Look up the thread on the relief valve for a refference. It still will not blow your socks off. Yet even a little more is usually good. Cheap area to examine and change as well.

47dodge · #7 07-04-2011, 05:15 PM

The delivery valves really should not be messed with unless you have a shop to test it for proper fuel delivery.

barry123400 · #8 07-04-2011, 05:43 PM

Also you have adjusted the valves? Some have not been done for years. When dealing properly with the injection pump base pressure it will indicate if you need new filters or the tank filter cleaned as well.

Some fuel delivery pumps have gone softer with age.Very easy to recondition if indicated. You have to watch out for them as well.

A pressure gauge on the system is your best friend. It is worth it in my opinion. You can even gain a little in fuel milage but the 5 cylinder natural aspired engine is not the most fuel efficient to start with.

The turbo five cylinder does better driven the same way for fuel milage. Also the current fuel milage is somewhat of an indicator of condition but you have to pin it down accuratly. By going through this area properly tends to familarise you with the system as well. That in itself is far from a negative.

whunter · #9 07-04-2011, 06:15 PM