If its a 95 series filter they claimed 3um, but its actually 10um and there isn't a better one, that I have found.. and I have looked!

 

I guess the only thing I can put out that I am certain of, is that I have had no problems with the unit, I am certain that I do not starve for fuel even at mid 900hp... pressure needle barely moves.

 

Yeah the final fuel filter, FF5712, is rated for 228 GPH so thats good.. Too bad its only 10um absolute. It is 5um at 83%, but still not 7um absolute like the OE specs for.

The f/w sep is only rated at 19.82 GPH thou!

 

AH64ID that could be the original thought of these fuel pump guys. Flow (performance) versus gauge psi. As you know, but for other readers, gauge psi can be the same or higher but flow (restriction) changes....maybe?

 

Flow is related directly to pressure and restriction. So not just one of those can change, 2 have to change. In a given system if pressure drops so does flow. Or if restriction drops, flow can change but pressure might not.

Most of these pumps are constant output, excess just is internally or externally bypassed. So when pressure drops you have exceeded the flow capability of the pump, but if pressure is still in the safe zone your fine.

 

Stated another way, a given relationship of pressure, flow, and restriction is fixed. If you change any one of those, at least one of the others must also change.

Kinda like that old saying about fast, good, or cheap

 

HOHN, can you tell us what the stock third gen (03-10) cylinder compression pressure is and how it relates to timing?

 

No, I can't. Cummins has a cylinder pressure design spec that is confidential.

I can tell you what you already know-- more timing means more cylinder pressure (peak).

BMEP (brake mean effective pressure) is the average pressure acting on the piston through the power stroke. This is what makes power.

For maximum power with a given head gasket sealing capability, you'd want the highest BMEP for a given PCP. That points towards retarded timing and lower compression ratios.

 

Thank's for that HOHN. Hope other's are paying attention.

 

Thread derail ^^^ but good info there.

That is why you see many of the high perf. trucks with big turbos and purposely lowered compression ratios.

 

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Good point soulezoo, except for one thing.............
The high performance Dodge CTD sled pulling trucks and drag trucks definitely have the low compression ratios (10.0-12.0) but almost all of them run very high timing (40-45 degrees) not "retarded" as HOHN had said. That is on the trucks that are running the Cummins 5.9 12 valve engines with the P-7100 type mechanical fuel pumps.

 

Retarded and advanced are obviously relative terms. Relative to what, is the key. RPM is obviously a huge variable.

For the high RPM associated with big pullers and racers, 45deg might actually be "retarded" in a sense.

Keep in mind that timing is a crutch for an incapable fuel system. We don't have a fuel system that can pump in X amount of fuel in Y amount of time if I start the timing at TDC.

By comparison, consider the new XPI system used in the 2010 and newer ISX. We're talking injector flow in the ballpark of what guys are running on sledpulling Dodges. I'm almost certain there is a part of the timing curve were the injector never fires before TDC, because the fuel system can cram in all the fuel it needs in the RPM range without advancing the timing.

Eventually, even a highly capable common rail system will need more timing advance to get the fuel into the cylinder within the needed time.

Big timing is an artifact of low injection pressure and high commanded fueling. If you have higher pressure, you need less timing to get the same amount of fuel in (assuming equal injector flow).

I've heard rumors that the current ISX XPI system can get the fuel into the cylinder in <6deg crank rotation at some portions of the full load curve. That's ridiculous!

This system is the highest pressure common rail system I know of-- we are north of 35000 psi (over 2500 bar).

JH

 

6* of rotation is FAST!!!!!

Awesome stuff HOHN! Since we're de-railing...what are your thoughts on SCR?? Cummins Thoughts??

Chris

 

guys i have a 95 series with a ff5712 on it and want to know if i can put on something else.. and where can i get one.. these 5712's are inposible to find here...!! i've read somewhere u can put on donaldsons, napa and wix filters. i need a part number

thanks
vj

 

The FF5712 is a 10um filter, so its not even enough filtration for your 04.5. FASS sells an adapter to run a Donaldson P553203, I would go that route.