Author Topic: psi of turbo boost?  (Read 5104 times)

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Offline Stuplich

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psi of turbo boost?
« on: October 15, 2012, 07:26:29 AM »
Any idea what the average/normal turbo boost pressures should be, (at idle, highway cruising and at full throttle up a grade)?
When I called the Cat Helpline, they were less than helpful.
They said, "The maximum boost should be around 50 to 55 inches of mercury".
When asked how many psi that would be, I was told "25 or so"......... (I can GUESS without Cat's help)!

Also,  the needle of my boost gauge is steady at low and moderate throttle pressures but when pulling a grade at full throttle, the needle fluctuates rapidly between 22 and 26 psi, (the needle visually "buzzes")!
Is that normal, or an indication of a problem?

Mel
'96 Sahara, 250hp 3126 Cat

Offline Tom Bernardi

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psi of turbo boost?
« Reply #1 on: October 15, 2012, 07:58:30 PM »
Mel,

I just got my Silverleaf VMSpc, and driving through Florida, Georgia, South Carolina and the Blue Ridge mountains of North Carolina, I have not yet seen it over 26 PSI and normally it sits at 10 to 11 at 57 MPH on level interstate or highway. It goes to zero when at idle at a stop sign or rest stop.
Tom

Tom (and Sally & Valentine) Bernardi '07 National RV Tropi-Cal LX 35'/Freightliner/350HP CAT C-7/'06 Honda CRV Senior Vice President, Diesel RV Club, an FMCA Chapter www.dieselrvclub.org Our personal travelogues and life at www.bernardihome.com
Tom
2017 Newmar Dutch Star 4054 / Freightliner 450HP Cummins ISL / Blue Ox Avail / '17 Jeep Wrangler Sahara / Brake Buddy /
Silverleaf VMSpc w/Pressure Pro TPMS

Offline Stuplich

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Re: psi of turbo boost?
« Reply #2 on: October 20, 2012, 08:38:08 AM »
Tom
Thanks
I don't think Liner Logic quite has their stuff together, re: their Scan Gauge D.
(to many variables in these coach and engine combinations)?
Others have told me that SGD boost readings are % of boost put the User Manual states "It is reported in PSI".
Mel
'96 Sahara

Offline wb7auk

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Re: psi of turbo boost?
« Reply #3 on: October 20, 2012, 03:42:30 PM »
From one of Cat's RV spec sheets they state boost pressure normal is   0-28 psi
As to your gauge operation at high boost some where around here I have that
information and as soon as I find it will forward it.
I some what agree on issues of the Scan Gauge D as I am working with them on getting
their system to report factual information on my engine, so far they have done a great job.
And when someone uses one of these diesel chips the whole thing goes south.

Art
99 National Tradewinds.

Offline wb7auk

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Re: psi of turbo boost?
« Reply #4 on: October 22, 2012, 09:01:33 AM »
Mel,
On your boost gauge problem, it sounds like the gauge is not damped.
Have you or anyone changed anything like hoses or connections?
A lot of boost gauges have a restriction placed either in the gauge or some
where in the pressure line feeding it to address this issue.

Art

Offline Stuplich

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Re: psi of turbo boost? UPDATE
« Reply #5 on: October 25, 2012, 02:14:23 PM »
Linear Logic will be sending me a version 9.10 of their ScanGauge D, to see if the boost gauge works properly on my Cat/Allison Safari coach.
I have been told that the SGD Trans Fluid Temp gauge may not work because a trans temp sensor may have been optional on/in the '95-'96 Allison M3060 transmission, and I may not have one.
I do know the trans temp is shown on the old Magnum Intelidrive displays, (forerunner to the VSMpc), that are in some '96 Safari coaches.
Anyone have any knowledge to that affect?
Mel
'96 Sahara, 250hp Cat 3126, Allison M3060

Offline Stuplich

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Re: psi of turbo boost?
« Reply #6 on: November 10, 2012, 09:29:31 PM »
The up-grade to a version 9.10 corrected my 2X boost pressure reading!
Still no trans Fluid Temp reading, (TFT is blank).
Any suggestions how I can find out if TFT should be registering, (Linear Logic, Allison and Cat have been NO help)!
Mel
'96 Safari Sahara
250 hp 3126, Allison M3060, ScanGauge D

Offline wb7auk

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Re: psi of turbo boost?
« Reply #7 on: November 13, 2012, 11:43:55 AM »
Mel,
With the version 9.10 the boost pressure was converted to psi instead of IN HG(inches of mercury)
which is about 2.04 greater than psi.
As to the transmission temp problem, I also have one of those optional / not there kind of deals however
the original owner installed a sensor in the transmission cooling line as it comes out of the transmission
and wired it to the ECM so I have that reading. Do not ask me how he was able to do it but it works that far what
it does not do is indicate to the control shifter panel any of this information.

Art