Fuel Rail Pressure Gauge is here for bombers

[SRadke]

How high of drive pressures do you look for?

In a perfect situation it will track 1:1 with boost pressure or less. If you're running a lot of fuel through a tight turbo it could be double your boost pressure at WOT. That is a poor situation.



-Scott

 

[Matt400]

In that case how about using one SPA boost channel for both?

You could run 2 identical SPA transducers with a toggle sw. to flip between Boost and Drive displays rather than using both channels on the gauge.

Seems once you have dialed in the 1:1 ideal or as close as you could that you wouldn't monitor both on a continued basis.

 

[gbartels]

I don't post much,but don't the outlook moniter from B. D. have this feature? no wire t taps or soldering of wires plus all of the other things it does.

 

[Matt400]

Its my understanding Outlook reads the "fooled" pressure rather than the actual pressure.

 

[rbattelle]

Off the transducer I couldn't get any AC but off the SPA I was able to get . 002v

I think (Dleno, correct me if I'm wrong) the most effective way of reading the AC component is to use an oscilloscope. Of course, you'd have to do it while driving so you'd need one of these.



Man, that Vantage tool is nice!



It seems the answer to my earlier question is "something in between". I believe you can achieve the measurement you're looking for by carefully setting the time averaging function. I assume the 100ms sample rate (I assume that's 10Hz sampling frequency) is not changeable...



-Ryan

 

[DLeno]

In a perfect situation it will track 1:1 with boost pressure or less. If you're running a lot of fuel through a tight turbo it could be double your boost pressure at WOT. That is a poor situation.



-Scott

I've been measureing drive pressures with the SPA guage for about a month now. works real well. use copper refridgeration tubing to cool the gasses. then use nylong tubing to break the conduction heat transfer. the sender body sees no elevated temps.



steel tubing would be better for a more robust, long term install.



drive pressures on the stock hy-9 are approximately 1-15 psi higher than boost pressures. with boxes up to around 100 HP.

 

[DLeno]

I think it will depend on the level of modifications. Myself am interested in pressures that could possibly push open the limit valve.

An example is the ramifier box I tested, a super nice strong power delivery that seemed to work real well. However If I were to choose to run this box all the time I would fix a way so the in cab power knob would not rotate to a pressure zone I am not comfortable with. With this gauge set up I could basically defuel based on pressure.

Others with more mods and big HP may be interested to see if the rail is loosing pressure under WOT runs. I remember reading a post a while back where the TST was capable of lowering the pressures below what it should be from long durations. Folks with stacked boxes could use the gauge to dial in duration, then pressure, then duration and pressure again till they find the best settings.

As for the lift side all I want to monitor is how it gets depleted under WOT runs and set a low level alarm in case diagnostics on the lift ckt is needed. Don't want to starve the CP3.



I did do a WOT run tonight on the way home but due to road conditions I had to back out. The SPA registered 19,500 (mine is an SO) with the box off. The gauge is very fast reading of all the pulses and at idle if I stare at it I will see anything from 4,200 to 5,200 but remember this is using a temperature channel where averaging time cannot be changed. The Boost channel should work much better.

I think its average pressures that are of interest. the reason is two fold:



1. the pressure relief value will sustain short spikes beyond its set point, and is designed to respond to average pressures.



2. if you are concerned about pressure changes from stacking boxes, again you are concerned about averages.





the rail is characterized by a very pulsy pressure behavior riding on top of an average pressure. indeed the compressability of diesel (which isn't much but does contribute) and the rail itself serve to average out pressure spikes and store fuel under high pressure. So I would suggest that any meaningful performance metric that is influenced by rail pressure can be measured by average pressure. the peaks are only artifacts of the CP3 and the propogating pressure waves caused by injectors.



the pressure side of any SPA gauge can be used as a voltmeter or calibrated for custom senders. if you want to do a temporary study, use the boost channel for a period of time until you understand rail pressure and how to correlate it with truck performance and box settings. then you can hook it back up to boost. in other words, moving the gauge face around to different senders instead of buying separate gauge faces for every parameter of interest. unless of course you really do want to watch them all in real time.



rail pressure and low side fuel pressure, drive pressure, are examples where constant monitoring is not necessary for diagnostics. hook it up and learn how the truck behaves; then monitor boost and EGT constantly. when the truck behaves differently or you want to re-check those parameters, move the gauge around again.



just a thought for the cost concious. for the hopeless analytics, the more gauge faces the better

 

[rbattelle]

for the hopeless analytics, the more gauge faces the better

Amen to that!



[My Fluke 189 should be here today... it's like Christmas all over again!]



-Ryan

 

[Matt400]

I found out the temperature channel updates at 400ms and without the averaging feature this makes for another good reason to use a boost channel.

 

[BHaner]

Using the temp channel I see 4. 3-5. 5 at idle, and a max of 21. 5 at WOT (without pressure box) Is this low for an HO??

 

[ceaman]

I am still trying to locate the connectors I have found several common sources for the male plug but no female donors yet! so i am trying to find a way to contact AMP directly.

 

[Matt400]

One option is to splice into the center wire- but using the fueling box connector, that way the trucks harness is left un disturbed. A simple female/male spade connector could be used to attach the SPA's harness to the fueling box harness but you will need to cut the cannon plug off the SPA connector.

 

[Matt400]

max of 21. 5 at WOT (without pressure box) Is this low for an HO??

I think it is, where did you splice in at?

The first time I did this I spliced in on the wrong circuit as the fueling box was fooling the gauge. I see you mention "without" fueling box but what about your TST? Don't those plug into the pressure transducer also?

 

[SRadke]

TST doesn't plug into the pressure sender. They make no pressure adjustments.



Who makes and sells all the pressure boxes that the diffrent companies market? There's got to be a source out there for the two rail pressure sensor plugs.



-Scott

 

[BHaner]

Yep, Scott is right. No plugs between the factory connector and sensor. I am tapped into the center wire on the factory wire harness about an inch up from the connector.



Anyone with an HO know what the stock max pressure is?

 

[qzilla]

Shoot me an email. We mold our own plugs for the female side. AMP does not have it either, it is built onto the sender. Anyone that use the female side makes their own plug or buys it from someone else that makes it. So far I think I am the only one that molds the plug, everyone else uses abs or poly carb and then pots the pins into it.





Quad

 

[DLeno]

Using the temp channel I see 4. 3-5. 5 at idle, and a max of 21. 5 at WOT (without pressure box) Is this low for an HO??

you should see close to 23. 5 at 3000 RPM WOT

 

[Matt400]

The manufacture of the SPA gages agreed to create a new gauge for this application.

This is what they just emailed me:

We have created a new part number for this gauge DG217W/215L for white and

DG217B/217L for black.



This will be a DG217 fitted with a 215 dial, and only one sensor. What they mean by the white/black part numbers is the gauges face color.



This gauge will have on the face plate- Fuel / Oil for monitoring Rail and Oil Pressure and will come with the gauge, oil pressure sending unit and harness that will bring cabling out to fuel rails transducer and supplied engine oil pressure sensor.

 

[SRadke]

To clarify a little Matt...



-This is a white or black face digital gauge.

-Rail pressure/oil pressure combo

-Comes with oil pressure transducer (I assume you screw it a port in the top of the oil filter?)

-Has the proper plugs to unplug/replug in factory rail pressure harness.



Is this all correct? Would you be so kind as to post or PM me a ballpark price? Thanks.



-Scott

 

[rbattelle]

Wow, good work Matt! If they weren't so expensive (and came as a standalone instead of a dual gauge with oil pressure too), I'd snap one up!



-Ryan