ckennedy

was wondering what is the difference in the injector setup on 3nd generation vs 2nd gen engines - just wondering??

I know running "cleaned up" SVO (straight veg. oil) on 3nd. is questionable - but I found serveral doing it... what are the real diff. in issues using SVO in a 3nd vs 2nd gen engine??
** I am not talking about home brew biodiesel **

phox_mulder

Basically (very basic)

2nd gen, the injector pump pressurizes the fuel to one injector at a time, and the injectors are set to "pop off" as a specified pressure.

3rd gen, the injector pump keeps a constant high pressure along the "rail", and the injectors are electronically told to "pop off" at a specified time.

As I said, very basic.


phox

Supermod56

Greasel says you can run WVO in a 3rd Gen, the 2nd Gen VP-44 don't like it, the heated oil burns up the electronics in the 44.

Tom

ckennedy

if I was to run WVO or SVO (not made into biodiesel) in any truck I would get a FASS or other pump system.. I kind of want to use both homebrew Bio and SVO - so a 2nd gen would/may be better..

I know I may be crazy - but I had the thought of trading off my 3nd for a 2002/2001 2nd gen truck - to get away from the common rail and other issues... also I have a auto - I maybe would like a manual... then I can put a Jacbrake on, etc ,etc....

***DOES THE 2nd GEN INJECTOR SCHEME HAVE A SEPERATE PILOT AND MAIN INJECTION EVENT LIKE THE 3RD GEN. **** thus not flushing injector in one big event ??????

CTD NUT

No...as Phox mentioned, the 2nd gen ISB injector fires by a preset pop-off pressure and are not electronically fired from a common rail....there is only 1 injector firing event - hence, the very loud and uncontrolled pre-ignition on the 2nd gens compared to the 3rd gens.

ramtd02

I also believe the pressures are different.....due to the higher cylinder pressures in the 3rd gens due to the pilot injection.

ckennedy

ok - I got it the second time around ..

thanks CTD NUT, Phox, RAM.. guess I am going in to many directions at once - thats what adult ADD does (adult - Attention Deficit Disorder )

** Following from other post (think it was superduty's work)

First of all, diesels need to run with a load or they carbon up. It doesn't matter what diesel it is, they all do it. Idle conditions and light loads just don't get the combustion chambers hot enough to promote good clean combustion.

Having said this, these new common rail injection systems are much more prone to problems than are the older pump line injector systems. I say this because the injection events are much more finicky and the metering is by pressure time rather than positive displacement in a conventional pump system.

The early Cat 3126 and the early Powerstrokes were very prone to this problem. I've seen PSDs that bent pushrods because the valves got gummed up from too much idle/low load operation.

It doesn't help that the 3rd Gen HPCR Cummins engines are very free flowing engines. Low backpressure on both intake and exahaust means lots of air flow even at idle, which means low combustion chamber temps. Putting a free flowing exhaust on, removing the cat and putting a free flowing air cleaner on will make the problem WORSE.

The new injection schemes, ie separate pilot and main injection events make it even worse because the volume of fuel injected at any one time is smaller and thus doesn't flush the injector nozzles as well as one big injection event might.

*****

question #1 - if the 3nd gen engines where to run a little hotter and one was using SVO (waste veg. oil) cleanup good but not converted to biodiesel.. would not the fact that less veg oil is being injected help in the fact that it would prob. burn better (more complete, less build up, etc).... but then you still have the issue of flushing the injector... so it would be very important to flush out the diesel before turning truck off!

question #2 - on the other hand - the above issues with the 3nd gen prob. makes it better to mess with cleanup wasted veg. oil in 2nd gen trucks... with a good pump like a FASS plus the heating issues ??

ramtd02

As for question #1.....i refuse to run veg. oil in my truck for 2 reasons....one is it is not as readily available, and 2nd and more importantly, these engines were designed too run as a diesel, not a deep fryer

as for the comment of the gumming of these engines without load.....my cummins guy told me too drive it hard, full throttle acceleration whenever the oppurtunity rises, this cleans everything up with the porper conditioners etc.

phox_mulder

I am in no means an expert, just re saying what I've learned being on here for 3 years.

If I was set on running WVO, I would look for a 12 valve truck.

No way would I want to risk a $40,000 investment by running it in a new 3rd gen, they seem to be having enough injector problems as is.

What Supermod56 said about running it in a 24 valve would have me thinking twice about risking my current truck, does that just relate to WVO, but Biodiesel should still be ok?

I'd sleep much better at night risking a $5-10,000 dollar investment by running it in a 10 year old 12 valve.

That's just my thoughts.


phox