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VMSpc readings

Yahoo Message Number: 56092

Hey Gang

This is a question for those of you that have a silverleaf. I am seeing 319 HP as 100% HP. Is that normal for a 330 ISC? What should I see for turbo boost?

Dave

ddtuttle

aka Billy Byte (trusty hound)
2000 Allure #30443

Re: VMSpc readings

Reply #1 –
Yahoo Message Number: 56093
Dave,

My ISC 350 has shown 350 HP (and slightly over 1040 lbs of torque) on the VMSpc. It does not always show that high when really pulling a steep grade in gears below 5th. I have assumed that is because on those steep grades the RPM never gets up high enough. When it is showing 350HP, it is usually when RPM is around 1700. Boost is commonly at 23.5 when pulling hard in any gear.

Jim M.

Re: VMSpc readings

Reply #2 –
Yahoo Message Number: 56096
Dave, why don't you search the Cummins website for reported performance specs? In my case, my Silverleaf does read out very close to the Cat specs.

--

Lee Zaborowski
07 Intrigue 12153

Re: VMSpc readings

Reply #3 –
Yahoo Message Number: 56108

To the best of my knowledge the Silverleaf systems don't actually measure anything versus engine performance. They can't because they are not designed to measure hp, only indicate the probable value based on parameters programmed into the system which are obtained from advertised ratings by each manufacturer. Horsepower can only be measured against a known resistance to the torque being generated by the engine. There are dozens of other variables such as coach weight, drivetrain losses, etc. ad infinitum. All the performance systems offered for cars, RV's, trucks, etc use the computer they are based on to calculate likely values based on what is known but they don't actually measure HP.
A call to the company would verify this but I am pretty sure not much more is happening than a reading on the throttle position is compared to an engine speed/RPM to horespower table. The software then looks up the corresponding rating advertised by Cat or Cummins and provides a number. This is why there are numerous files, one for each type of engine installed.
While there are probably numerous explanations of why Dave's is showing a llittle less than full advertised HP one guess is a little resistence has built up in the electronic throttle system and the Silverleaf is reading a bit less than 100% of the expected value for the throttle = less than 100% horsepower.
My VMSpc system is smart enough to know that the as delivered table was incorrect versus my C9 Cat. When I installed the new USB system it asked that to install the proper file for my engine. For those with factory installed systems this was done during installation. A few years ago an owner posted messages about his rig showing much less horsepower than that he had paid for. A visit back to the factory and installation of the correct file found the missing horsepower. Nothing was done to engine itself. I suspect that if I was to install a 500hp Cat file my computer screen would show 500hp at 100% full throttle even though my engine is rated 400.
Dave's reading of a few horses less than expected should not be considered a problem with the engine because the Silverleaf really has no idea what horsepower is being generated.
I am not trying to knock Silverleaf or any of the systems on the market, they provide tons of valuable information that used to, as the sci fi author Arthur C. Clark said, resemble magic to us. In the end the system reads the sensors available to it, interprets what they mean according to the programming and provides us with information we would not otherwise have. However, they don't actually measure horsepower. There would be a need for at least an accelerometer system and I don't believe the VMSpc system incorporates such a system and there is nothing in the specs for other Silverleaf systems to lead me to believe they do either. It isn't easy to get accurate HP readings and even sophisticated dynos will vary location to location and by type of system used to measure the HP.

Bob (rthandren@...)
'05 Inspire 51178

Re: VMSpc readings

Reply #4 –
Yahoo Message Number: 56118
I am sure that Bob is correct regarding the function performed by the Silverleaf monitors.
As to why the monitor is showing less than full horsepower. We would need to know the RPM at which the monitor is showing the less than full power. The reason, of course, is because full rated horsepower will not occur except at rated RPM.
If the 319 HP is all that is reported at peak HP rated RPM (which is probably somewhere around 2,250 RPM for the ISC) than there is something interesting going on.

George in Birmingham
'04 Allure 31038
George in Birmingham
2003 Magna 6298

Re: VMSpc readings

Reply #5 –
Yahoo Message Number: 56122
On my 2004 Allure I always felt that it seemed underpowered and the fact that the Silverleaf never read above 280 Hp reinforced my feelings. So I made an appointment with Cummins Northeast to put in on the Dyno for a test. To make a very long story short they found that it was not up to snuff. The numbers from the Dyno are measured at the rear wheels and included losses in the drive train so a direct comparison to the Silverleaf is difficult. They tightened some clamps on the turbo etc., put it back on the Dyno and said it was were it should be. I can't remember the numbers but the brake hp should be around 80% of the rated flywheel hp. On the road the Silverleaf still read low by a lot.
So a few months later I made another appointment in Charleston, SC with Cummins to put it back on the Dyno. Just before I left I checked the parameters in the Silverleaf. Guess what? It was set to a Cat engine. I switched it to a Cummins 370 and on the way to the appointment it showed 370 every time I pulled a reasonable grade with the rpm at 1800rpm or above.
I cancelled the Dyno test and now I know that my 2004 Allure is indeed underpowered. Oh well.
Bob is right on, The Silverleaf is calculating the hp from the info available. Mine never shows a hp above 370 no matter what I do and that is the rated theoretical value.

Don Seager

2004 Allure 31046

Re: VMSpc readings

Reply #6 –
Yahoo Message Number: 56132

The one thing I found odd was it said 100% HP at the 319 HP readout. Whether or not it ever gets to 330 HP shouldn't it read 96% at the 319 figure? I have the 330 ISC engine selected.

ddtuttle

aka Billy Byte (trusty hound)
2000 Allure #30443

Re: VMSpc readings

Reply #7 –
Yahoo Message Number: 56136
If you are looking for a good answer, call SilverLeaf at 888 741-0259. I have found them very willing and able to answer all my questions.

Don Hibbs

2000 Allure 30565