Electric Fans, double nothing

Discussion in 'Engine Performance + Maintenance' started by bobby v, Jul 6, 2020.

Car Parts
  1. Pinger

    Pinger I'm Awesome

    Messages:
    469
    Likes Received:
    569
    Joined:
    Mar 10, 2020
    Location:
    Scotland.
    Both. Clean oil retains its colour visually. Have a look at the thread re oil analysis for an example of a typical report.
    Oil analysis is useful not just for the state of the oil but for pending problems - eg, dirt due to a leak downstream from the air filter, overfuelling, coolant (pending gasket failure, etc. Also gives the wear metals and you can see the compositions of each change eg, during break-in on a rebuilt motor versus a fully run-in one.
     
    HotWheelsBurban likes this.
  2. Pinger

    Pinger I'm Awesome

    Messages:
    469
    Likes Received:
    569
    Joined:
    Mar 10, 2020
    Location:
    Scotland.
    Agreed.
    But with a gasoline engine and EGR there's exhaust products present during all of the four strokes. Without it, only for two. Not major but there nonetheless.

    Not with LPG as it's a gas when introduced to the cylinder not a liquid as per gasoline which will wash down - this being worse from cold start-up due to the necessary enrichment. LPG already being gaseous needs no enrichment from cold. A significant benefit in IMO.

    BIG potatoes - and a massive explosion if there's an inlet backfire!
     
    HotWheelsBurban likes this.
  3. Pinger

    Pinger I'm Awesome

    Messages:
    469
    Likes Received:
    569
    Joined:
    Mar 10, 2020
    Location:
    Scotland.
    There's more to consider re EGR and LPG. Eg, LPG has no cooling properties thus is more heat sensitive re detonation. LPG is fast burning - once lit. It is slow to ignite initially though and exhaust products in the mix don't help (think carbed 2-stroke at part throttle). The presence of exhaust products also limits AFR possibilities (think carbed 2-stroke at part throttle).

    I'll be picking up on this stuff later but meantimes, if anyone can provide info as to when EGR is deployed in a Vortec - eg high load for NOx reduction, part load to reduce throttling losses, etc - it would be very useful to me.
     
    HotWheelsBurban likes this.
  4. smdk2500

    smdk2500 I'm Awesome

    Messages:
    377
    Likes Received:
    112
    Joined:
    Dec 26, 2017
    Location:
    Nebraska
    Ok. I dont have a way of testing my oil but just on the visual "test" my 6.5's oil looks just as dark as my 6.7 cummins did My 6.5 does not have a egr and never did. The 6.7 did. Also on the reefer units I work on some have egr and some don't and the oil looks the the same in both. So with no egr on them how the oil get dirty so to say with your opinion of the egr letting it in. So in my opinion the look test proves nothing unless it looks glittery or has big chunks when it comes out of the pan. Again I am not trying to start a pissing match Im just trying to educate myself to other peoples thoughts and opinions.
     
    Big sack, Pinger and HotWheelsBurban like this.
  5. SAATR

    SAATR /\___/\___/\___/\___/\

    Messages:
    2,393
    Likes Received:
    363
    Joined:
    Dec 16, 2010
    Location:
    Loo E Z an uh
    Lack of fuel dilution and cylinder washdown is certainly a benefit of gaseous fuels, but my point is that they still have the same gapped ring design as any other ICE and will therefore have combustion byproducts that get beyond the rings and into the crankcase. That, in turn, oxidizes the oil and depletes the additive package. Gaseous fuel engines, with a few exceptions, will have cleaner oil and longer service intervals, but aren't immune from the intrinsic properties of the fuel burning piston engine.

    No more likely or worse than your NA engine. I've worked on Caterpillar's and Kohler's version of the 5.7L Vortec in genset application, both running off of CNG or LPG, and haven't had one "sneeze" yet. I've seen several natural gas engines pop back, and while loud it usually isn't particularly destructive. The worst damage was a blown up compressor wheel on the turbo, damaged carburetor diaphragm, and blown regulator diaphragm. I'm not saying it can't be worse, but it's an inherent risk with a gaseous fuel and a flooded intake. A turbo would certainly help take advantage of the inherent knock resistance of the fuel. A NOx or O2 feedback system set up for lean burn would be very effective.
     
    Pinger and HotWheelsBurban like this.
  6. SAATR

    SAATR /\___/\___/\___/\___/\

    Messages:
    2,393
    Likes Received:
    363
    Joined:
    Dec 16, 2010
    Location:
    Loo E Z an uh
    The 6.5 is a Prechamber style diesel engine, vs the Direct Injection of all modern diesels and the 6.5's Ford and Cummins contemporaries. They are inherently a bit dirtier than DI engines, and but don't soot the oil more, if any at all, than other designs. EGR systems on diesels do tend to put more soot in the lube systems, primarily because the soot is recycled back to the combustion chamber instead of being sent out the exhaust. That said, heavily soot loaded oils tend to feel slightly gritty on the fingers and the blackness doesn't wipe off as easily as newer or cleaner oil. Strictly speaking, there is no accurate way of judging an oil's condition by sight alone, save if the oil is heavily contaminated by water, coolant, fuel, etc. "Looks" good doesn't mean it IS good, or vice versa. If the oil has contaminants suspended in it, then it is doing its job, and your filtration simply isn't good enough to remove them.
     
    Pinger and HotWheelsBurban like this.
  7. TheAutumnWind

    TheAutumnWind I'm Awesome

    Messages:
    453
    Likes Received:
    240
    Joined:
    Feb 11, 2019
    Location:
    California
    Why do people go this route when NBS fan/shroud setups can be found for less than $200 new that outperforms that setup
     
    HotWheelsBurban likes this.
  8. Pinger

    Pinger I'm Awesome

    Messages:
    469
    Likes Received:
    569
    Joined:
    Mar 10, 2020
    Location:
    Scotland.
    SAATR answers your question well with the paragraph below and post #56.

    LPG does a good job of keeping the oil clean (I'll say a bit more of that In a moment) and although dirty looking oil isn't necessarily a bad thing (it shows its doing its job keeping the dirt in suspension, preventing it forming deposits in the engine) if you were running on a fuel that doesn't dirty the oil - wouldn't you want to retain that?

    True. But consider for a moment those small engines for model aeroplanes. The earliest (so called diesels) ran fuel mixed equal parts ether, kerosene and castor oil. The castor oil was there purely to seal the ringless piston.
    A gasoline engine will always be compromising the oil film around the rings through dilution whereas a gaseous fueled engine will maintain a more consistent oil film there - to the benefit of sealing.
    Rings (along with the periphery of valves) are referred to as 'crevice volumes' as they trap gasoline and if/when they ever release the trapped fuel it burns so late and lazily it creates CO and UBHC - which the cat has to deal with. The rings just love to trap raw gasoline. I've heard of turbo Subarus here running on LPG and passing our annual emissions test (for CO and UBHC) without a cat. That's a significant difference - and achievement.

    An additional point (a disadvantage of) gaseous fueled engines - the inlet valves can suffer due to lack of liquid fuel. Passing hot EGR past them isn't going to help that.



    I don't disagree with any of the above. It's just much more than I'm prepared to do. All the above is a pretty major project that I just don't have the time or resources for. (I also have a separate 2-stroke project I want to pursue which will soak up my time).
    What I'm aiming for is just optimising the existing system as best as I can to suit the LPG. As far as I would go to gain further advantage from LPG's higher octane is slightly increase the CR. If I have the heads off for any reason I'll consider having them skimmed - or consider the higher CR Roadmaster pistons. But not so far as I lose the ability to run gasoline (with care) as back-up.

    Re the explosion risk. Personally an intercooler primed with fuel is a risk further than I am prepared to accept (a personal decision). Due to a badly configured LPG system (common on mixer systems though) I had a crankcase explosion when an inlet backfire occurred. Blew the timing cover apart. Once bitten, twice shy....
     
    HotWheelsBurban likes this.
  9. L31MaxExpress

    L31MaxExpress I'm Awesome

    Messages:
    1,188
    Likes Received:
    432
    Joined:
    Apr 21, 2018
    Location:
    DFW, TX
    I have datalogged it. Its mostly under mid-heavy throttle to control NOX. It comes on just off-idle to mid throttle at about 2 mph and causes a noticeable hesitation on quick throttle opening. At cruising speeds it is either shut or almost shut depending on the engine load and rpm. Its also open at or very near WOT.
     
    HotWheelsBurban and Pinger like this.
  10. Pinger

    Pinger I'm Awesome

    Messages:
    469
    Likes Received:
    569
    Joined:
    Mar 10, 2020
    Location:
    Scotland.
    Brilliant! Thanks - much appreciated.
     
    HotWheelsBurban likes this.

Share This Page