CAT 3116 Boost/egt numbers?

Discussion in 'Downeast Engine Room' started by Toolate, Apr 24, 2016.

  1. Toolate

    Toolate Captain

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    Going to splash this week and will be running my new SBMAR Turbocator gauges fro the first time. Any idea what to expect for exhaust temps and boost pressure?

    Engines are 98 vintage with about 1000 hrs. 300 hp TA models. Roughly?
     
  2. ArchHibb

    ArchHibb Captain

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  3. Toolate

    Toolate Captain

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    I actually posted this on BD as well. BillD thanks.

    I have read that people advise against cruising them at 2400 maybe more like 2200 so I guess the real question is should I just cruise at 2200 or so even if the EGT´s are higher there? Sounds counterintuitive...
     
  4. ArchHibb

    ArchHibb Captain

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    I'll be paying close attention to responses to this. I guess I would start by asking, do lower EGT's translate into less stress on the engine? I would think so. If she runs 50-degrees cooler at 2400 than at 2200, how could that not be a benefit to the engine?
     
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  5. Toolate

    Toolate Captain

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    Ran the boat today light breeze dead low tide and took a couple shots of my tach/EGT/boost gauges. These things are cool as hell. 2200 looks like 750 degrees and 2400 looks like maybe 765 or so. Very slight difference but definitely less. Took these pics after running about 5 minutes at the rpm shown.

    EGT's are about 20 degrees lower at higher rpm (not much but a little) which is strange but the boost is so much higher at 2400 than it is at 2200 that it has to have something to do with that. I didnt push it past 2400.

    Last year with old props, dirty bottom, filthy heat exchanger/aftercooler etc (no service) the boat ran up to 2850+ at WOT so I think its propped well.


    Does this mean higher rpm/lower EGT's are better for the engines or would lower RPM would be better for longevity in general?
     

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  6. El Mar

    El Mar Captain

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    Wow. We saw steady 1100-1200 on the Yanmar yesterday.

    Same brand new gauge.
     
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  7. Toolate

    Toolate Captain

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    Really that high?

    My engines are 300 hp twins in a 36' planing hull.
     
  8. Ol Gilnetter

    Ol Gilnetter Senior Member

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    Isspro has color coded pyro gauges for both pre and post turbo thermocouples. The pre-turbo gauges show yellow starting at about 1050F while the post-turbo gauges show yellow zone starting at about 875F. Certainly temps can be engine specific, but also temps taken pre and post turbo are not equal.

    1200F seems hot though for either side of the turbo, must have had the cooler full of beer that day.
     
  9. Ol Gilnetter

    Ol Gilnetter Senior Member

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    Are those turbocator gauges backlit red or white or green or....? I was looking for a backlit red Isspro pyro but couldn't find one, or didn't look in the right place.
     
  10. HappyHour

    HappyHour Senior Member

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    Engines are 18 years old, with 1,000 hours, and your worried about longevity...?

    Every engine will read slightly different temps as the probe location differs. You cant compare a cat to a yanmar, what a pyrometer is designed to do is let you know how your engine is responding to changes that you've made. More specifically when you've modified the engine. Thus preventing a melt down if you've gone to far.

    Adding a pyro to a " bone stock " engine is kinda " useless" . its one more gauge to stare at.


    Food for thought: Aluminum melts at 1,221 degrees Fahrenheit
     
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  11. WoundUpMarine

    WoundUpMarine Captain

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    Lower exhaust temps at higher RPMs mean the engine is running more efficient. More RPM is more load on the engine which is making more boost from the turbo and feeding more air into the engine. The big engines i used to work on would have an exhaust hump where the temps would go start going down as you reached higher RPMs, until you really gave the boots to her, then the skys the limit for temps.
     
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  12. Toolate

    Toolate Captain

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    My dash has red lights that are very dim which I like so I didn't even connect the lights on these yet. I don't run much at night and never go fast so should be fine. Been so busy too. Can always hook me up later. dunno what color.

    I would give them a call ISSPRO. Spoke to their tech guy and he was very helpful. Probably just a bulb change to get to red.
     
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  13. Toolate

    Toolate Captain

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    I don't know if it's useless... I may have learned that the advice everyone gives on these engines is wrong- most people suggest cruising them slower than 2400 which has higher EGT's than 2200- have seen one other case of this on BD) I am no diesel expert so I installed them. Probes are in exactly the same place because I had new dry risers made and the probes are in identical locations.

    Def concerned about longevity. I like that these are mechanical and don't want to replace them any time soon. Just trying to do what I can. The 15 degree difference here isn't much to really debate I don't think but it is interesting.
     
  14. BillD

    BillD Captain

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    Keep the 3116s propped accurately @ 100 rpm over rated WOT with the boat as heavy as you'll ever use it and the engines will last just fine with proper maintenance and alarms.

    Woundup brings up a good point...You gotta keep the engines "freed up"

    Engine load =s heat...heat =s EGT....simple.

    Here's the best example I can give you on EGTs. My 31 Blackfin ( a very heavy hard hull to get up on plane and keep it there) had new Cummins 370s. Engines are rated at 3,000 rpm. I had them propped to 3150 (under propped) with the boat fully loaded. The 370s ran at 875 F @ cruise (2200-2600) or WOT (3150)...BUT if I ran the engines with the boat "on the hump" (just about but not quite on plane..plowing really with the ass digging a hole in the water) @ 1900-2000 rpms just before the turbos kicked the EGTs would shoot up to 925-950 F. Once on plane and the turbos spooling the EGTs settled back to 875 from 2200-3150.

    OK, now lets look @ the Cummins 370 I have in the 25 T Jason. Way too much hp for the hull right? Well I have the 370 propped to 3250 WOT which really frees up the motor, keeps the hp down etc. The EGTs at at any rpm 2000 to 3250 run 750F...why? The engine doesn't have to work too hard to push the TJ around at any speed.

    Your 3116s are good motors @ 300 hp. Keep em freed up...

    FWIW, Bill D
     
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  15. goin4broke

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    Bill I think you nailed both the performance of a boat properly propped and the difference between planing and DE hulls. Haven't seen this explained any better in such a short statement. Good points.
     
  16. Toolate

    Toolate Captain

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    Sounds good and I think I am in good shape. Will have to do some WOT testing to be sure I am still making the same rpms as last year with all the changes I have made but this def helps me understand. Thank you.

    Anyone know if there is any CAT info on boost pressures for these engines? Mine seem low compared to the two other boats I have seen info from on BD. Maybe my turbos are worn?
     
  17. BillD

    BillD Captain

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    I search boatdiesel exhaustively for a 3116 boost spec....nothing nor does CAT publish it.
    I'd call CAT directly with engine SN and ask them.

    If I owned those CATs of yours I'd prop them both @ WOT boat heavy to 2900 with a photo tach.

    btw, ask CAT what the governed no load WOT is for the engine. I'm curious
     
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  18. crabz

    crabz Senior Member

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    I may be wrong but I always thought that there is more than one way to be over propped.
    When you can NOT get the upper RPM's that you should and on a diesel
    the governor is shoving in too much fuel to try and reach that RPM, too much load, too high of EGT.
    I think boost is a byproduct of load, to a certain extent, if you are propped correctly you won't see big boost numbers.
    Toolate I think you are right on , those are good numbers, I am curious how the numbers will change for you when the load changes, more weight onboard, dirty bottom, tide, wind, etc. Are your probes pre or post turbo?
    When I started commercial fishing in the 70's everyone ran their engines
    by the pyro, EGT was everything, RPM wasn't important when loaded. But that was on West coast salmon boats where the total gross weight could be tens of thousands of pounds difference at different times.

    I'm curious about newer computer controlled engines that tell you the percentage of load the engine is under. If your EGT is 1,100 degrees what is the percentage of load?
     
  19. El Mar

    El Mar Captain

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    First time we ran the boat for the season, we were actually pretty light.
    Ran as normal except for the new gauge.

    420 Yanmar 33 Flowers.
     
  20. Madchark

    Madchark Senior Member

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    Yanmar specs are 1300 wot and 35 boost.

    Saw 1140 at cruise with 16 boost.
     

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