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Poor performance

After reading a number of different poor performance posts, whether it be power or fuel mileage it may be prudent to have the charge air cooler, aka intercooler and interconnecting tubing pressure tested. May be able to be done diy with common inflatable  plumbing sewer test bladders. Compressed turbo air leakage costs money and most may leak slightly. I will let other more experienced members weigh in on this subject.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Poor performance

Reply #1 –
Quote from: Old phart phred –
...it may be prudent to have the charge air cooler, aka intercooler and interconnecting tubing pressure tested.
I know some members have fitted a boost pressure sensor to their inlet tubing.  Been thinking of doing the same to ours, mostly as a fun project.

Wouldn't monitoring boost pressure accomplish the same thing - that is, tell you if you had a leak somewhere in the system?
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Poor performance

Reply #2 –
And, later model electronic engines (such as the Cummins ISL) do have a boost reading that one can access on a Scan Gauge D or Silverleaf.

And, keeping an eye on it does two things:

1. Absolutely the best reference to fuel MPG, as even a little more boost calls for more fuel.
2. If max boost goes down, SOMETHING IS WRONG.  Find out what it is and fix it.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Poor performance

Reply #3 –
Yes, all the electronic engines have a provision for reading out boost. With a mechanical engine, you can install a sensor and then use one of the extra wires most all Foretravels have to send the reading to a gauge mounted on or near the dash.

The last time I checked, we got about 20 psi at 5000 feet when I went to WOT on a grade. You can see how easy it is to take your reading and compare it from time to time.

A dirty air cleaner, crack in your exhaust manifold or in the intercooler can cause low boost and poor performance. Especially on the mechanical engines, black smoke out the exhaust is another sign of low boost.

When we manufactured turbo kits for non-turbo Mercedes diesels, we noticed that while the turbo was providing boost, the cars were only slightly faster. When the injection pump was recalibrated, the engines started to really live. If you have a mechanical engine, the lack of boost may only add smoke out the exhaust because most don't change fuel in relation to the amount of boost  while the electronic engines will cut down the amount of fuel injected as the boost sensor is connected to the ECU so there is a direct correlation between boost pressure and the amount of fuel injected. For example, our Detroit is VERY limited on the amount of fuel injected until the boost pressure is up so, with a 4.xx first gear, it's a real dog off a stop light, especially at altitude. Several modifications can be made to trick the ECU to inject more fuel coming off the line but at the expense of black smoke in the face of the car behind.

Pierce


Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: Poor performance

Reply #4 –
Pierce, you need a $25,000 in-frame rebuild. <grin> Seriously, mine has only a slight lag before we're moving out quickly. The feeling is almost  "Are you sure? Ok, let's go!" It does take a bit of effort to get 30,000 pounds (plus towed) moving from a standstill, but once everything is going, a matter of maybe two seconds, we can really move out if necessary. Most of the time, though, my foot isn't that heavy.

Re: Poor performance

Reply #5 –
Quote
With a mechanical engine, you can install a sensor and then use one of the extra wires most all Foretravels have to send the reading to a gauge mounted on or near the dash.

Anyone installed one of these on the 8.3? I do miss seeing the boost pressure on the Silverleaf. Thanks.
jor
93 225
95 300
97 270
99 320

Re: Poor performance

Reply #6 –
Quote from: jor –
Anyone installed one of these on the 8.3?
Found this thread by Barry & Cindy.  Looks like the most recent info on adding boost and EGT gauges to C8.3 Cummins.

Digital Pyrometer & Boost Gauges - VEI Systems
1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: Poor performance

Reply #7 –
It shows up on my silverleaf display but honestly I don't really know what I am looking at there. Sometimes high, sometimes low. Dont' know the norms so it makes no sense to me and I haven't had the time to figure it out. Someone know the norms on a M11 450 hp cummins?
'99 U320 40 WTFE
Build #5462,
1500 Watts Solar 600 amp Victron lithium
2012 Jeep Grand Cherokee Overland Hemi
Instagram bobfnbw
Retired

Re: Poor performance

Reply #8 –
Followed most of B&C's advice, used VmSpc for derived boost but used same VEI for pyrometer readings.
Use it to determine engine load and shift and use throttle accordingly. Many big trucks come standard with boost gauges and pyrometers. Pyros react immediately to engine load, you have to wait for engine coolant temps to rise.
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.

Re: Poor performance

Reply #9 –
Check with silver leaf for a compatable sender, hopefully there is a gauge tap on the intake  manifold. Thought my coach had a boost gauge that was not functioning when I brought it home, turns out it is an exhaust pressure gauge for my lever adjustable exhaust brake redlined at 29 psi to keep from floating the exhaust valves. Would like to add a boost gauge also but don't what's max boost for my cat engine, bluebird forum indicates 25-30 psi. Cat RV engine tech support can't seem to find any specs for maximum exhaust back pressure or boost pressure for my engine. Local Cat dealer can't find my serial number on record so there may be a typo.
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: Poor performance

Reply #10 –
Quote from: Old phart phred –
Check with silver leaf for a compatable sender, hopefully there is a gauge tap on the intake  manifold. Thought my coach had a boost gauge that was not functioning when I brought it home, turns out it is an exhaust pressure gauge for my lever adjustable exhaust brake redlined at 29 psi to keep from floating the exhaust valves. Would like to add a boost gauge also but don't what's max boost for my cat engine, bluebird forum indicates 25-30 psi. Cat RV engine tech support can't seem to find any specs for maximum exhaust back pressure or boost pressure for my engine. Local Cat dealer can't find my serial number on record so there may be a typo.
https://www.wanderlodgeownersgroup.com/forums/showthread.php?t=20439
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.

Re: Poor performance

Reply #11 –
As Chuck noted, we added boost & pyrometer gauges.  Always use pyro gauge & tach to drive uphills, downshifting & letting up on throttle to keep pyro from increasing above mid 900 degrees, and engine around 1100 to 1800 RPMs.  We never overheat coolant any more with staying around 180 degrees.

Re: Poor performance

Reply #12 –
Quote from: Barry & Cindy –
As Chuck noted, we added boost & pyrometer gauges.  Always use pyro gauge & tach to drive uphills, downshifting & letting up on throttle to keep pyro from increasing above mid 900 degrees, and engine around 1100 to 1800 RPMs.  We never overheat coolant any more with staying around 180 degrees.
Also keep coolant around 180, but with ISM can normally run exhaust about 1200 F. max. Cummins says 1350 F. is pushing it for my engine. My normal cruise on flat land is about 900 F. at 75 mph.
Jim C.
coachfree, previous 1997, 1999, 2000, and 2003 Foretravels.

Re: Poor performance

Reply #13 –
Quote from: Bob and Julie –
It shows up on my silverleaf display but honestly I don't really know what I am looking at there. Sometimes high, sometimes low. Dont' know the norms so it makes no sense to me and I haven't had the time to figure it out. Someone know the norms on a M11 450 hp cummins?

Bob,

If you are asking about boost, call Cummins with your engine serial number.  They can tell you max boost PSI. And, you will notice that boost is VERY related to your right foot.  Small throttle changes and/or grades result in significant changes in boost.

Max boost is achieved at higher RPM at WOT. If boost is more than a couple of PSI below spec, look for a leak.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Poor performance

Reply #14 –
My M-11 runs 29psi max boost at sea level.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R

Re: Poor performance

Reply #15 –
Quote from: jor –
Anyone installed one of these on the 8.3? I do miss seeing the boost pressure on the Silverleaf. Thanks.
jor
I have a mechanical boost gauge and a EGT gauge on our 8.3, The boost gauge line taps into the tube just out of the turbo and the small air line runs to the dash gauge. The EGT sensor (probe) is installed just past the turbo wastegate and uses a couple of spare wires up to the dash. i can post pics when we return home.
Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota

Re: Poor performance

Reply #16 –
The pyrometer probe is best installed in the exhaust manifold.  The cast iron is easy to drill and tap.  The probe there shows the highest reading.
Regards,
Brett

'99 42' Foretravel Xtreme
'14 Brown Motorsports Stacker
'05 Chevy SSR
'02 BMW R1150R
 

Re: Poor performance

Reply #17 –
Quote from: amos.harrison –
The pyrometer probe is best installed in the exhaust manifold.  The cast iron is easy to drill and tap.  The probe there shows the highest reading.
Brett
I have a spare pyrometer, been thinking about adding another probe to the manifold.........
Thanks
Justin & Cathy Byrd
1995 U280 "Old Faithful"
36' Build #4673
C8.3 Cummins
Allison MD3060R 6 speed - retarder
Powertech 10KW  4cyl Kubota