3rd party Proof that retarding a diesel leads to cooler engine/higher boost

[TylerDurden]

Hrrmmm...

125:155  (bar) is only ~20% difference. If memory serves, it takes about 5hp to drive the IP, so a difference of 1hp or ~750W. I don't see that making much impact on fuel economy.

[libbydiesel]

I believe I've seen Mark post of pressures lower than that.  105 bar?  How much HP is required to make a Quantum cruise at 35MPH?  Approx. 5 or 6...  Regardless, the point of my post was to say that 0.6mm lift w/ 105 bar(?) injectors may well equate to the same start of combustion as 1.05mm lift with 155 bar injectors...

[TylerDurden]

I believe I've seen Mark post of pressures lower than that.  105 bar?  How much HP is required to make a Quantum cruise at 35MPH?  The point of my post was to say that 0.6mm lift w/ 105 bar(?) injectors may well equate to the same start of combustion as 1.05mm lift with 155 bar injectors...

No argument with that... Mark may have actual gauge vs. piezo data.

[TylerDurden]

How much HP is required to make a Quantum cruise at 35MPH?  Approx. 5 or 6... 

Takes about 2 hp to make a bicycle go 35mph, so I rekon it might take a little more than  5 or 6 for a 3000lb wagon.

[libbydiesel]

2,800 lbs, 25 sq. ft. frontal area and 0.35 cod @ 35MPH = 5.86 hp. 

[Gizmoman]

2,800 lbs, 25 sq. ft. frontal area and 0.35 cod @ 35MPH = 5.86 hp. 

That's some good info - can you break down your equation a bit?

[TylerDurden]

Neglecting rolling resistance, driveline, etc...

"During stop-and-go city driving, it's estimated that overcoming inertia is responsible for about 35% of the vehicle's resistance. Driveline friction is about 45%; air drag is about 5% and tire rolling resistance is about 15%."

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=29

[libbydiesel]

2,800 lbs, 25 sq. ft. frontal area and 0.35 cod @ 35MPH = 5.86 hp.  

That's some good info - can you break down your equation a bit?

Sure.  Punch them into a HP for speed calculator...  E.G.  I was making educated guesses on the frontal area, cod and unladen weight.

Neglecting rolling resistance, driveline, etc...

"During stop-and-go city driving, it's estimated that overcoming inertia is responsible for about 35% of the vehicle's resistance. Driveline friction is about 45%; air drag is about 5% and tire rolling resistance is about 15%."

http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=29

Yup.  I'm aware of those factors.  I was only attempting to show that a saving of 1 or 2 HP may be a little more than insignificant as you initially proposed.  I think I succeeded.  

[TylerDurden]

Yup.  I'm aware of those factors.  I was only attempting to show that a saving of 1 or 2 HP may be a little more than insignificant as you initially proposed.  I think I succeeded. 

If 5hp (guessing) is 5%:

5 + 45 + 15 = 65hp total cruising P-in (ignoring inertial losses)  for 35mph... less 1hp  (a reduction of ~1.5% ).

A 1.5% increase in efficiency if not factoring inertial losses.  1% or less in the real world.

[libbydiesel]

Are you trying to say it takes 65 engine horsepower to go 35MPH?  I wonder how I've managed to go 90 on flat ground with an engine that puts out a peak of 52hp...  I do not think it is reasonable to use Tire Rack's estimates of the average driver's energy use to calculate the potential fuel savings of a hypermiler with injection mods, if that's what you're doing.  

[Gizmoman]

2,800 lbs, 25 sq. ft. frontal area and 0.35 cod @ 35MPH = 5.86 hp.  

That's some good info - can you break down your equation a bit?
[/quote]

Sure.  Punch them into a HP for speed calculator...  E.G.  I was making educated guesses on the frontal area, cod and unladen weight.

Neglecting rolling resistance, driveline, etc...

Cool - thanks for the link libby.
I usd .44 CD (from the Samba), a frontal area of 30.25 (5.5' x 5.5'), and 4000 lbs for the van. Here are the results.
Using your vehicle Speed of 65 MPH takes 24.95 HP to overcome air drag.
Rolling resistance is 9.01
For a total of 33.97 HP to run 65 MPH
There may be a bit of data missing from the calculator

[libbydiesel]

It does not include drivetrain losses which are typically calculated at 15%.  The CoD for a Westy is 0.51 (largely due to the luggage rack).  Frontal area is also larger.  Spec is 3.17m^2 = 34.1 sq. ft.  Floored, a well-tuned 48hp 1.6 non-turbo westy will make it above 65 on flat ground with no wind.  With drivetrain losses, that engine is peaking at 42HP to the wheels.  Try those numbers again...

[Mark(The Miser)UK]

I'm back...
OK here's some limited data. Alas I don't have current pietzo info as I dropped the SUN strobe, and it doesn't light up. Probably repairable. My other strobe is a Dieseltune one that clamps inline on the output of the pump and measures pump timing.

I am currently running old 293 nozzles @ 130bar. That has been giving me a static timing of 26 thou.
The lowest I actually went down to was 120bar, that liked a timing of 22thou.Winter starts have been fine down to -10C.
I did intend to go loweras I  haveseen nozzles of this type run at 110bar factory on some engines, but my old nozzles weren't good enough.

The only set of 4 new old stock French ones I had, to do the job, had one faulty one and one pin I managed to break on another. Economy was good, so I left it at that  meaning to return in the future.
Physical engine knocking became my obsession.

The big question no-one has asked, is how did I get to these timing figures, that were seemingly so far off the beaten track? I certainly didn't walk into the desert and have a vision, or did I?

Well, I did have a bit of an inspiration, as I was looking for a way of determining 'best timing' I thought perhaps I could look for smoothness of running; so I first listened to engine, and adjusted at idle. Not easy to decide, I then moved on to listening to smoothness of acceleration.

I then combined with finger tips on the shifter, whilst on the road, to feel for smoothness. This was quite good and started giving me lower timing figures. Still this is quite hard in the absence of silky smooth roads. In retrospect, lowering tyre pressures may have helped...

The trouble with these methods is that they required some skill, and time. I wanted something I could do whilst stationary, and with repeatability.

OK another inspiration...

I was looking for maximum economy, so, presumably, by definition that must mean more miles per gallon; so back at the engine surely more revs per gallon.

Thus the jump to the most energy out per injection. This I thought would be reflected in the desire of the engine to want to increase revs.
I just happen to have an analogue rev counter from a truck that  by luck works by the W connector, and is both accurate, and has an expanded FSD of only 3500 revs.

To operate, I have it connected in the engine compartment. I raise the revs to about 1000 to 1100,  [from around 750] by altering the clip on the accn. cable.
I  swing pump until I find a jump in the revs. I then tighten the pump, and hope it stays in the sweet spot.

Strangely, often the revs drop by about 30  when the bottom nut is tightened.

[Gizmoman]

I'm back...
OK here's some limited data. Alas I don't have current pietzo info as I dropped the SUN strobe, and it doesn't light up. Probably repairable. My other strobe is a Dieseltune one that clamps inline on the output of the pump and measures pump timing.

I am currently running old 293 nozzles @ 130bar. That has been giving me a static timing of 26 thou.
The lowest I actually went down to was 120bar, that liked a timing of 22thou.Winter starts have been fine down to -10C.
I did intend to go loweras I  haveseen nozzles of this type run at 110bar factory on some engines, but my old nozzles weren't good enough.

The only set of 4 new old stock French ones I had, to do the job, had one faulty one and one pin I managed to break on another. Economy was good, so I left it at that  meaning to return in the future.
Physical engine knocking became my obsession.

The big question no-one has asked, is how did I get to these timing figures, that were seemingly so far off the beaten track? I certainly didn't walk into the desert and have a vision, or did I?

Well, I did have a bit of an inspiration, as I was looking for a way of determining 'best timing' I thought perhaps I could look for smoothness of running; so I first listened to engine, and adjusted at idle. Not easy to decide, I then moved on to listening to smoothness of acceleration.

I then combined with finger tips on the shifter, whilst on the road, to feel for smoothness. This was quite good and started giving me lower timing figures. Still this is quite hard in the absence of silky smooth roads. In retrospect, lowering tyre pressures may have helped...

The trouble with these methods is that they required some skill, and time. I wanted something I could do whilst stationary, and with repeatability.

OK another inspiration...

I was looking for maximum economy, so, presumably, by definition that must mean more miles per gallon; so back at the engine surely more revs per gallon.

Thus the jump to the most energy out per injection. This I thought would be reflected in the desire of the engine to want to increase revs.
I just happen to have an analogue rev counter from a truck that  by luck works by the W connector, and is both accurate, and has an expanded FSD of only 3500 revs.

To operate, I have it connected in the engine compartment. I raise the revs to about 1000 to 1100,  [from around 750] by altering the clip on the accn. cable.
I  swing pump until I find a jump in the revs. I then tighten the pump, and hope it stays in the sweet spot.

Strangely, often the revs drop by about 30  when the bottom nut is tightened.

Geeze Mark, you are becoming a diesel whisperer . I hope to try out my pulse unit this weekend after I finish putting a new seal on the Westy pop-top. I was a bit under the weather yesterday and didn't get much done. Do you have any data on what 26 thou (.66 mm) does to your EGT and low-end torque? I'm running four new 155 psi Giles injectors. I believe my old ones were 135.
I also need to switch some probe wires around as I'm getting some odd readings from my intake air and oil temp probes.
Your efforts to push the envelope is commendable but I just want dependability, low end grunt and lower EGT's on long hill climbs. I am still way early on the new rebuild to have any conclusive data though - probably only 20-40 miles so far.

[theman53]

If you only have 20-40 miles in a couple trips how did it even warm up? The vehicle will run a little bit off until it is warm, at least mine does.