Author Topic: supposed larger flow...and what about breaking pressure? (Read 2886 times)

carrizog60 · « **on:** July 26, 2007, 02:46:01 am »

hello

i have ordered the merc 261 nozzles to do a freshen up to my very tired stock ones and now i was thinking what should i do when i go to diesel shop...
should i mantain 155bar or increse/decrease it?
and about pump timing?

i would like the best performance and the less temperature as its a N/A engine converted to TD(without oil squirts.)

searched the forum but have find many post without any conclusion...

foxracer1 · « **Reply #1 on:** July 26, 2007, 07:24:43 am »

I have some new merc injectors waiting to be set also. I'm unsure whether to go 130 or 155.

carrizog60 · « **Reply #2 on:** July 26, 2007, 09:03:29 am »

i was told that it would be better to use higher pressure(180bar for example) as i sometimes use SVO. :idea:

Black Smokin' Diesel · « **Reply #3 on:** July 26, 2007, 01:43:35 pm »

I'd go with 135bar, less pumping loss from the injection pump and better fuel economy. 180 is wayyy too high.

carrizog60 · « **Reply #4 on:** July 26, 2007, 02:20:46 pm »

but wound that mess with timing?
and what about runing SVO with that pressure?
and performance wise,whats the best? :idea:

Black Smokin' Diesel · « **Reply #5 on:** July 26, 2007, 03:07:53 pm »

Quote from: "carrizog60"

but wound that mess with timing?
and what about runing SVO with that pressure?
and performance wise,whats the best? :idea:

Timing should be at 1.0 or 1.05, no matter what breaking pressure (except 180 :? )

No idea about SVO, shouldn't be a problem if the oil is hot enough.

Performance wise, I don't think there's any hard data on that matter. Only thing we know is that there is less pumping losses (somewhat debatable though as we don't know if it changes much).

Vincent Waldon · « **Reply #6 on:** July 26, 2007, 04:04:30 pm »

The higher the breaking pressure the more the injectors will retard your timing (think of it as taking longer for the pump to build up enough pressure to overcome the injector and therefore delaying the opening)

So were you run 180 (not sure where you'd find the shims for that) in my mind you'd need to significantly advance the pump to compensate.

I run 140-150 with my injectors... smart money seems to be that somewhere in between the stock NA and turbo pressures is the sweet spot for economy, timing, and power, and I believe Mercedes runs these exact nozzles in that pressure range as well... they probably know a thing or two about diesels.

SVO ?? Haven't played with it on my pop tester, but my wild guess would be to not do anything special from a breaking pressure... rather make sure the viscosity is as close to normal as possible.

Vince

carrizog60 · « **Reply #7 on:** July 26, 2007, 04:26:49 pm »

it will retard the timing but if we compensate that wouldnt the higher breaking pressure make better spray and in result better combustion?(and fuel economy,power...)

Black Smokin' Diesel · « **Reply #8 on:** July 26, 2007, 06:51:31 pm »

Quote from: "carrizog60"

it will retard the timing but if we compensate that wouldnt the higher breaking pressure make better spray and in result better combustion?(and fuel economy,power...)

In theory yes but it's not that simple. Someone on here did some tests and it showed that a lower breaking pressure resulted in better fuel economy.

foxracer1 · « **Reply #9 on:** July 26, 2007, 07:51:32 pm »

145bar it is! timming 1.05mm!

carrizog60 · « **Reply #10 on:** July 27, 2007, 02:09:29 pm »

any benefit on running more pressure than emissions? :idea: