Author Topic: C-12 Sweet Spot  (Read 15395 times)

Jerry Emert

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C-12 Sweet Spot
« on: August 28, 2015, 11:24:50 PM »
First let me say that I understand that there are a ton of variables including the driver.  For those of you with experience with C-12s, where have you found the RPM "sweet spot" to be.  I always hear that 62 MPH is it and on mine I seem to get pretty good mileage at 62.  I know some of you are a whole lot more experienced and knowledgeable than this old Sailor turned Cop.  So where is your sweet spot (you know what I mean?)
Thanks
Jerry
Jerry, Chief USN Retired
2003 Patriot Thunder Lexington 40' 3 Slides
C-12 Ser#  2KS89983
4000MH

Steve Huber Co-Admin

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Re: C-12 Sweet Spot
« Reply #1 on: August 28, 2015, 11:31:59 PM »
Jerry,
With mine it's ~1475 to 1500 (62-65 mph on my GPS) No noticeable difference in mileage ( ~8) in this range.
Steve
Steve
2015-          07 Contessa Bayshore C9,  400 hp
2013-2015: 00 Marquis Tourmaline, C12, 425 hp
2005-2013: 01 Contessa Naples, 3126B, 330 hp
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Marty and Suzie Schenck

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Re: C-12 Sweet Spot
« Reply #2 on: August 29, 2015, 12:28:17 AM »
Years ago I found a Cat document explaining what you want for the most part. If you were to build a vehicle for best mileage with a C12 engine, gear that vehicle so the engine RPM is at 1350rpm's at the freeway speed that that vehicle will be running at most of the time. My Thunder has 3:55's in it and I am at 1340 at 62-63 mph. I have got as high as 9.6 mpg running solo (no toad). I get 8.7 pulling my Fiat 500 Pop and right at 8.0 pulling my wife's 2005 GMC extended cab full sized pick-up. Those figures are calculated using the speedometer and cross referenced with 2 GPS monitors. I am very pleased. Marty
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Dave Atherton

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Re: C-12 Sweet Spot
« Reply #3 on: August 29, 2015, 02:32:05 AM »
Jerry, C-12 sweet spot, using 2KS27875 S/N,    169-5159 A/R  Test Date: 1999-11-03  Test Results

410 H.P.,  1800 rpm, 20.3 gal/hr, Adj Boost 23.5 psi, Fuel pressure 100 psi, Oil Pressure 49.9 psi,
TQ Cor F RAT 16.7 gal/hr,  low oil pressure 14.6 psi, torq CK Speed 1200 rpm, TQ CK Tor TQ 1552 lb/ft
Hi Speed 2119 rpm, low speed idle 600 rpm , Intake air temp 122 deg f
This may give you some idea where engine sweet spot in fuel & power driving.
Dave Atherton Retired Cat Mechanic
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Jerry Emert

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Re: C-12 Sweet Spot
« Reply #4 on: August 29, 2015, 02:51:45 AM »
Dave, you are exactly what I meant by way smarter than me!    I think I got 1200 RPM!  Is that correct?
Thanks
Jerry
Jerry, Chief USN Retired
2003 Patriot Thunder Lexington 40' 3 Slides
C-12 Ser#  2KS89983
4000MH

Dave Atherton

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Re: C-12 Sweet Spot
« Reply #5 on: August 29, 2015, 02:53:22 AM »
Jerry messed up, did not see your S/N 2KS89983, A/R 198-3653,  Build Date 2002-07-25,  Test Date
2002-07-29,  Test Results:  Corr FL Power 505 HP,  Speed 1800 rpm, Fuel rate 23.2 Gal/HR, CSFC
0.324 lb/hp-hr, Adj Boost 23.8 psi,  Fuel Pressure 87 psi,  Oil Pressure 45.5 psi,  TQ Cor F RAT 16.5 Gal/hr,
TQ CK Adj Bst 22.9 psi, Torq CK Speed 1200 rps,  TQ CK for TQ 1550 lb/ft,  low speed 599 rpm,  low
Oil Pressure 14.4 psi, Hi speed 2121 rpm, Intake air Temp 122 Deg F
Dave Atherton Retired Cat Mechanic
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Dave Atherton

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Re: C-12 Sweet Spot
« Reply #6 on: August 29, 2015, 02:56:29 AM »
Jerry, above 2KS 89983 S/N is your engine build date and test results and date. Dave
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Jerry Emert

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Re: C-12 Sweet Spot
« Reply #7 on: August 29, 2015, 02:59:15 AM »
Now to figure out what that stuff means.  I'm a googling fool tonight.  I really do appreciate it.  Thanks again.
Jerry
Jerry, Chief USN Retired
2003 Patriot Thunder Lexington 40' 3 Slides
C-12 Ser#  2KS89983
4000MH

Fred Brooks

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Re: C-12 Sweet Spot
« Reply #8 on: August 29, 2015, 03:04:27 AM »
      Thanks Dave,

     Discussing the "Sweet Spot" i guess is kind of a subjective statement. If you are into economy and letting your C-12 cruise along then 1350 RPM is the place you want to be. To verify that statement, scroll thru your silverleaf and you will see 6 to 7 pounds of turbo boost and all the ideal temps of the perameters of the engine.
     However if your are asking where is the Power and Torque of the engine is then 1825 RPM is where she goes to work. If your going up a hill, this is where you want to be for max performance and cooling.
      Either way, a C-12 in my humble opinion is the absolute Best of both applications. Regards, Fred




     
Fred & Cindy Brooks
2000 Marquis, Jasper
C-12 Wild Cat (U of A)
2014 Honda CRV
Proverbs 3: 5 & 6
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Dave Atherton

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Re: C-12 Sweet Spot
« Reply #9 on: August 29, 2015, 03:46:59 PM »
Fred, info. off silver leaf really helps in keeping all the numbers in the safe zone. Did not have time
last eve to break out above Jerry's  engine test results. Jerry said he was going a googling last eve,
( did not think Jerry was a ELK hunter but maybe he was meaning something else.)  Let's get started,
Cat C-12 505 hp, speed 1800 rpm, fuel rate 23.2 gal/hr, Adj Boost 23.8 psi, Fuel Pressure 87 psi, High
Oil Pressure 45.5 psi.
Note:  engine running start of test, putting load on engine. Speed 1200 rpm, Boost Pressure 22.9 psi,
Torque 1550 Lb/Ft, Fuel Rate 16.5 Gal/Hr, Intake Air Temp 122 Deg F. What this is telling us along with
info. you mentioned off your Silver Leaf. The  Cat C-12 will preform best at the lower speeds for Fuel
milage and power. Dave Atherton Retired Cat Mechanic
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Jerry Emert

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Re: C-12 Sweet Spot
« Reply #10 on: August 29, 2015, 04:57:06 PM »
Dave, as I'm sure you know I was trying to figure out what the abbreviations, such as Corr FL and TQ Cor F RAT meant.  I was unsuccessful!  I have never been Elk hunting.  No Elk in Florida.  I've spent my time hunting drunk drivers, druggies and burglars.  Elk don't shoot back or fight but I'm not cut out for climbing mountains anymore.  So, 1200?  LOL
Thanks again.
Jerry
Jerry, Chief USN Retired
2003 Patriot Thunder Lexington 40' 3 Slides
C-12 Ser#  2KS89983
4000MH

Joel Ashley

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Re: C-12 Sweet Spot
« Reply #11 on: August 30, 2015, 12:26:09 AM »
Like bad guys, elk do fight back if cornered, Jerry.  Especially if you google instead of bugle them, Dave.

;)  Joel
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