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Thread: Annotated ORTS Diesel Engine Block

  1. #21
    Join Date
    Jun 2004
    Hastings, MN, 55033


    Yeah, honestly, I didn't even consider making any current or future sounds MSTS compatible. Once I saw all the new triggers, I just decided I didn't care if anyone would be displeased with it. The upshot is that I've become somewhat dependent on the audio when testing locomotives. I don't bother reading the brake gauges, for example, I just listen for the air to stop flowing and the cylinders to release. That's probably a bad habit, but nobody's really at-risk here.

    I will say that I am building all of my sounds similarly to the way I did in the past, with a core folder of samples that most things will use, a folder for horns, and then folders for the specific engine I am working with. The 645BC/C sounds, for example, share the same core sounds as the 567, so the folders in my personal common folder look like this:


    You can imagine that the 645E, when I get to it, will use most of the same core files. The approach I am following is somewhat modular. I wanted the basic structure to be extensible, so I decided what minimum engine speeds could represent the entire range (275, 355, 515, and 835 RPM), determined the correct pitch envelope for samples that are transposed to the correct pitch for those speeds, then created a volume envelope that will always yield the correct dynamic range with respect to the horn (people are going to hate it, because almost every MSTS sound set is way too loud, and that's what they're used to, but it will be much more accurate). In the core folder go the transition exhaust clips (hopefully we'll get a load variable at some point so I can get rid of those), roots blower sounds, and exhaust sounds, so that if I have a set of clips that is light on roots blower noise or exhaust, I can use pre-fab streams where appropriate. All I have to do is grab appropriate looped samples from the right engine speeds, change the pitch so that the fundamental of the roots blower is in-spec for each speed (I have a text file listing the proper fundamental frequencies), name the clips using my convention (such as X_EMD_645BC-1_515.wav), set the volume where I need it to be depending on the content (exhaust-heavy clips at 0dB, exhaust-free clips at -2.5dB), copy an existing SMS, insert the blower or exhaust streams as required, change the filenames as required, and I have a new set. If I get a nice full run-up like Shawn sent me, I can transpose off-notches up or down to create multiple sound sets from a single runup. If the person who recorded the sounds pauses at every notch, up and down, and I can loop each clip, I can create up to four discrete sound sets from one recording. With the 567 (and its derivatives like the 645BC/C), you can double this number, because the 567U/V/A/B and 567C/D run at different speeds, so I just copy the SMS files, rename them as appropriate, and multiply the maximum frequency of each RPM-dependent clip (I set two curve points, one at idle, the other at maximum) by 800/835. Presto! An 800 RPM 567U/V/A/B/AC/BC.

    It really colours a consist when each locomotive sounds slightly different (and GP7s and 9s have different pitch envelopes, as they should).

    Incidentally, I've been experimenting to see if I can make include files work within the SMS structure. Does anyone know if there's a method that works? None that I've tried do. I was thinking of creating some SMS files for things that never change, like the control samples (recorded from MNTX 559), coupling/uncoupling sounds, and so on (obviously, anything unit-specific, such as the bell and horn, and anything engine-dependent, such as the compressor, would go in the individual SMS). The more I think about the modular way of dealing with file structures, honestly, the more I like it.

  2. #22


    Quote Originally Posted by derekmorton View Post
    The es44 quotes 4400/4520 and the ac6000 quotes 6000/6250.
    The sd90mac-h quoted 6000/6250 as well.

    I suspect that the 6250 was to claim the highest power and therefore a marketing number.
    I would tend to go for the 4400/4520 as being reasonable.

    You can check on power at the wheels in the HUD and make up your own mind.

    For me that means an extra 120hp or 90kw
    Thanks, will give it a try.
    "Honk if you demand satisfaction"

  3. #23
    Join Date
    Sep 2006


    Quote Originally Posted by Donell View Post
    I have been using traction horsepower and since reading this I have tried to look for actual gross horsepower for the modern diesels with no success. I used to have GE specs in pdf from their site but no longer available. Anyone with gross horsepower for modern diesels like SD60 - SD70ACe? Thanks for the info on the horsepower Derek.

    Honestly, I don't really care about that difference, or hunting up values that may or may not be widely known outside of locomotive design circles.

    After all, who really knows which value that the 3000 hp or 4400 hp values for real life locomotives reflect. I don't really care if a C44-9W is 4380, 4400, or 4520. I just use 4400 and use that directly as an HP value or convert to KW.

    All I care about is making sure the parasitic load is not deducted twice, the first time manually by a previous MSTS-era "efficiency" multiplier upon the Maxpower value that users calculated themselves, and a second time that Open Rails does within its operating chambers. That "double dipping" that comes from using MSTS-era Maxpower values really reduces the max HP produced in Open Rails when in the eighth notch and underpowers the unit immensely.

    And even if you could read a computer screen that shows only 4380HP on a C44-9W, you certainly don't have access to those "off values" for any older units that don't have such computerized feedback. Unless you were a GE or EMD design engineer from the 1970s, it would be a total stab in the dark for just about every older model. And I have better things to do with my time. And to me, it would seem awfully dumb to design a sim around needing values that are not pedestrian knowledge.

    Just about any unit class on any railroad can be altered by mechanical governor or EFI software to generate a different (higher or lower) HP. There are instances like where Conrail C36-7s came with 3700 HP, and NS or MP C36-7s came with 3750 hp just from buyer preference or from the fact that the MP and NS units had more hybrid Dash-8 features in their C36-7s whereas Conrail's did not.

    If there is a book somewhere like a Diesel Spotters Guide that lists these types of HP differences for every buyer, then I will use those published figures. If there is a difference in parasitic load between DC traction and AC traction (like where a C44-9W is 4380, but an ES44AC is 4520) and those values are widely published and/or known, I will use them. If not, I stick to the model-based generic values and do not go by other peoples best guesses.

    The very last order of C40-8Ws for UP and ATSF came with 4135 HP, and only the last 3 units of the last order of CNW C40-8s came at 4150 HP (called C42-8 by CNW) . I believe the one previous order (9406 and up) on UP had been built capable of being uprated to 4135 and were, the rest were not. But none of the NS, CSX, and CR C40-8s and none of the C40-8Ws for CSX and CR ever came at 4135 or 4150 nor were they ever uprated.
    Last edited by geepster775; 01-17-2018 at 11:38 AM.

  4. #24
    Join Date
    Jun 2004
    Hastings, MN, 55033


    You're not going to find brake horsepower in any publication outside of journal articles or test data from the manufacturer. You're just not. I think the OR team assumed that the published numbers are brake horsepower and real output is that minus some load. It's not. The published numbers are guaranteed horsepower available for traction. Here's an example:

    This is from a paper I found at about the history and development of the EMD 567 engine. Note that the 12-567B is used in a variety of locomotives with designations that include "1200" because the power available for traction at 800 RPM is 1200 HP. The actual gross horsepower is somewhere around 1300, as you can see by the graph. Good luck finding a graph like this for any other diesel engine ever made. I've been trying to extrapolate it to the 16-567B to mixed results - do we figure out the traction horsepower per cylinder at each speed and multiply it by 16? Well, then you get 1600 HP, and the 16-567B is only guaranteed to make 1500. Does the 16-567B have a higher parasitic load? Doubtful, the auxiliary load is given for the 12-567B in that graph, and it's comparable to the equipment on a GP7. Is the compression ratio different? Nope. RPM? Nope. So, on the assumption that maybe somehow the added frictional forces of four more cylinders was the X factor here, and using the nominal figures for both engines as a guide, I ended up dividing 1500 by 16 to produce a coefficient to multiply the per-cylinder horsepower ratings at each speed by to create my curve for the 16-567B. But, even then, I still end up with a gross horsepower figure of 1624. Well, we subtract the 100 HP accessory load from the graph and end up with 1524 HP. That sounds about right. But what does OR subtract from the gross horsepower? And is that accessory load the same on an SD40-2? Because now I have to figure out how much extra power the 645E needs for the sim to deliver the right amount.

    So how does OR deduct accessory power? A percentage? That would, of course, be unwise: the GP7 and GP9 have different power ratings (the 16-567C runs at a higher maximum speed) but have the same parasitic load. Or is it a constant number? Does the sim assume that all locomotives lose 100 HP (or some other number) for accessories? Well, does the 45-tonner have the same accessory load as the ES44? I assure you, they do not. Nor do they lose a similar percentage of total output.

    Either way, the reality we are left with is that almost every source on the internet is only going to give you traction horsepower. And instead of using a number to reduce power like we did in MSTS, now we need to know how much power OR deducts so we can add it back in. It's the same process, just a bigger coefficient.

    Don't get me wrong, when I observe the forces in the HUD, OR seems to come close when I add in my guesses, but... it seems like we're making the same kind of guesses but with coefficients above one instead of below.
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    Last edited by Erick_Cantu; 01-20-2018 at 10:01 AM.

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