Pop pressure of old 6.2 injectors vs. 6.5 turbo related to timing?

[WarWagon]

Going to open this can of worms for discussion as I already have on my engine. 6.2 IP with 6.5 injectors.

Looks like if you change injectors you also change the timing of the engine. New vs. old injectors may not be that big of a difference.

It is like pressing on the brake pedal more to get more stopping power relates to more rotation of the engine/timing for pressing on the pedal, and pressure related to pop pressure.

So changing the pop pressure of the injectors changes the timing.

Low pop 6.2 injectors changed to to the high pop turbo 6.5 injectors retards the timing. I noticed less diesel clatter after dropping in my 6.2 with a 6.2 IP and 6.5 injectors.

The same may hold true for marine injectors.

 

[bk95td]

I would agree. It should take longer to make more pressure. A degree is a lot in timing a diesel. The advance in your 6.2 ip may be not working properly too. Do you get a good rattle at cold start when the advance is engauged?

 

[WarWagon]

Push in on the lever on the side of the IP just about stalls the engine. Unplugging the cold advance switch kills some of the clack. So 6.2 IP is all working best I can tell. Just retarded from the higher pop injectors...

 

[Matt Bachand]

It would have too. Math proves it. It must take longer for 1800psi will always be made in less time than 2200psi.

Now if that same IP had 2 fuel pressure going into, vs that IP having 12psi fuel pressure going into it, would that be a CH off too?

Like I say to people at work, 1 / 16th of an inch may not be alot, but before you know it it will start to add up into measurable values.

What about the same systems running dry #2 diesel, vs Nicely lubed and additives diesel? Another CH there?

 

[midniteplowboyy]

I was going to post a similar thread about what I discovered yesterday. Sorry for the highjack, but it fits well here.

This is on both my mechanical trucks timed line to line, both fully cranked DB2's. The 92 seems timed about right. My 93 I always thought was timed slow, but ran good, I compared timing yesterday and the 93 has 9.6º less timing than the 92, both IP's line to line. Turning up a DB2 also advances it, so I was surprised to see the 93 was so retarded.

The 92, 13.4º BTDC @idle
New IP
New stock Bosch injectors
timing chain (350k miles)

The 93, 3.8º BTDC @idle
IP(around 50k miles since new)
Bosch Marine Injectors(30k miles)
Gear drive (30k miles)

This is with pulse/timing light, not a lumi/mag. This reads the actual pulse in the line, not the actual combustion. Looks like a there could be a 20º variance using the line to line method and different parts. Then add the variance of pop pressure on top of that. I wonder how much more retarded the timing is I'm not seeing on my 93 with the marine injectors.

I need to put some advance in the 93 and see what she will really do, ought to increase the fuel mileage some from the 15-16mpg local I'm getting, best I ever seen highway was in the low 19's a few times.

Something to make you go hmmmmmmmm.

 

[buddy]

There is certainly a difference in injection timing, however ignition timing is hard to grasp. the amount of time spent increasing pressure 400 more psi may be well rewarded with better atomization such that combustion happens faster and more complete than had you injected a less atomized stream earlier.

 

[cub124]

I know I'm pulling this out of the graveyard but I had the same thought as Buddy but how much of an increase in power would there be? The Duramax uses around 23,000 psi common rail if I recall right. What about increasing injector pop pressure to 3,000 psi and timing the engine to the correct degrees?

Im not real familiar with the IP but if timing was retarded and IP flow increased I think its possible. This may not bring HUGE HP numbers but it would probably bring better millage.

Thoughts? :thinking:

 

[turbobill]

The one thing I would wonder about is the increased stress on the plungers and cam ring with such an increase in pumping pressure.

 

[tanman_2006]

3,000 will likely kill the pump from IIRC. I know others know the numbers better than me but somewhere I remember reading the truck wont crank over with over 2500psi.

Also at 3,000 psi I'm not sure if the IP will build the pressure needed to pop the injectors at high RPM.