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I haven't seen a diesel thread in a while, and even while searching never saw a title with the d-word in it, except about a specific make/model, so I figured I'd start one. I've also got a question that might be over a lot of heads, but I'm hoping I'd luck out and bump into the right person. Anywho, I saw the configuration in the animated gif below and saw how it puts the con rod under tension for the most stressful part of the cycle by basically extending the wrist pin past the crank, giving it more dwell time and a more sinusoidal movement, among other things. But then there was a claim, and an animation for a proof of it, that the dwell time is actually so pronounced that a motor with that configuration at 6000 rpms had the same dwell time as a regular 'pushing' con-rod motor at 4500, meaning you can rev diesels higher.  Do Diesels really have that much time dependency on their burn speed? Every time I've looked up or asked the question you get a group that confuses power with torque, a group that says that its the physical limitations of the motor being under square and heavy and with a long rear end con rod, and then a few who say its just the burn speed. Does anyone here KNOW for a fact? That's one thing that's driven me nuts for a long time and I'm sure a few others. Anyway, as much as I like to digress, lets have a diesel thread. Here's a beautiful slow-mo video of diesel cycle combustion in-vitro (or in-crystal for that matter) http://www.youtube.com/watch?v=_IFCubco95w
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| # ? Nov 04, 2009 02:07 |
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| # ? Nov 21, 2009 11:25 |
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Man I bet that block would be a pain in the rear end to machine. Other than that the mechanics are over my head.
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| # ? Nov 04, 2009 02:59 |
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Seems like that rod would be awfully brittle.
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| # ? Nov 04, 2009 03:02 |
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I was always under the impression that diesels (at least in the performance world) never really reached much higher RPM's than stock because the injection systems couldn't keep up with the flow rate vs frequency of feeding a diesel.
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| # ? Nov 04, 2009 03:09 |
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angryhampster posted:Seems like that rod would be awfully brittle. Naw, not brittle, but if that was in a diesel and the diesel was putting some psi into the bore with super/turbocharger, I don't see how it could keep from getting really short, really quick. The new diesels with their stupid high injector pressure of like 3000 bar might do better at high rpm.
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| # ? Nov 04, 2009 03:14 |
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From the looks of it, it would probably add enough friction and weight that it wouldn't be worth it, not to mention what (without actually calculating it or anything) appear to be higher piston and bearing speeds and acceleration rates. I thought that being made out of big heavy parts to deal with compression ignition and high static compression and relative loads of torque was what made them not like to rev as high, not the amount of time it spends at TDC.
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| # ? Nov 04, 2009 03:25 |
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Nihilanthic posted:Do Diesels really have that much time dependency on their burn speed? Every time I've looked up or asked the question you get a group that confuses power with torque, a group that says that its the physical limitations of the motor being under square and heavy and with a long rear end con rod, and then a few who say its just the burn speed. Does anyone here KNOW for a fact? That's one thing that's driven me nuts for a long time and I'm sure a few others. According to the Audi R10 team, they could have hit 6krpm with the R10 but the efficiency would be poo poo due to the time it takes diesel to burn so they stayed at 5krpm.
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| # ? Nov 04, 2009 03:37 |
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1. It's bigger and heavier than a standard conrod. 2. It would require a split block in order to install it, making the block weaker. 3. It would add a second friction surface, increasing drag and worsening fuel efficiency. 4. It doesn't provide a marked benefit over a conventional style.
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| # ? Nov 04, 2009 03:44 |
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Muffinpox posted:According to the Audi R10 team, they could have hit 6krpm with the R10 but the efficiency would be poo poo due to the time it takes diesel to burn so they stayed at 5krpm. I know a guy who shifts his TDI around 6k but with the size of the turbo he is running its still making power, 30 pounds of boost changes the powerband significantly.
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| # ? Nov 04, 2009 06:52 |
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oxbrain posted:1. It's bigger and heavier than a standard conrod. The rod is shorter! The piston is longer so the wrist pins go past the crank. Its also under tension, and metals are generally much stronger under tension than under compression or shear. This does make the piston into the failure point now, though... and that 2D view was really honestly a crappy representation. http://www.pattakon.com/pre/PRE1.exe <- best animation of it I can find, its not a virus AFAIK, avast doesn't find anything but downloader beware. I wish I could rip a .gif out of that. I'm waiting on some white papers on it but it might be useful for F-1 applications, MAYBE diesel, they're still working on their diesel prototype but the gas motor runs fine. I also don't see why it would need a split block. That gif I showed had a WEIRD rear end shape, I think just to show the crank/rod motions. It doesn't have to be shaped like that. But wow I jacked my own thread go me.
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| # ? Nov 04, 2009 06:58 |
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InterceptorV8 posted:Naw, not brittle, but if that was in a diesel and the diesel was putting some psi into the bore with super/turbocharger, I don't see how it could keep from getting really short, really quick. Its under TENSION under power and compression strokes 
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| # ? Nov 04, 2009 06:59 |
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Muffinpox posted:According to the Audi R10 team, they could have hit 6krpm with the R10 but the efficiency would be poo poo due to the time it takes diesel to burn so they stayed at 5krpm. So I guess it is burn speed because it has to spread around and swirl vs just propagate a flame front like gasoline. Now I wonder why you can't just advance the fuel injection timing though.
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| # ? Nov 04, 2009 07:03 |
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Nihilanthic posted:Now I wonder why you can't just advance the fuel injection timing though. You can to a point. After that it becomes counterproductive. And a lot of the RPM limits are partly due to the massive cranks diesels are swinging around.
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| # ? Nov 04, 2009 07:06 |
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obso posted:You can to a point. After that it becomes counterproductive. And a lot of the RPM limits are partly due to the massive cranks diesels are swinging around. I'm trying to isolate the burn speed variable  but there's probably a reason nobody builds the motors to physically rev higher.So now I wonder why use turbos instead of a supercharger that can just be geared up as high as you want.
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| # ? Nov 04, 2009 07:37 |
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Nihilanthic posted:Its under TENSION under power and compression strokes He's talking about the piece connected to the piston not the conrod.
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| # ? Nov 04, 2009 07:57 |
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You know what you COULD do with a system like that? Opposed cylinders. Stick another dome on the bottom of that thing and get 1 combustion event per revolution per opposed cylinder pair.
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| # ? Nov 04, 2009 09:52 |
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Advent Horizon posted:You know what you COULD do with a system like that? Or go crazy and re-invent the Napier Deltic... Is this what they mean by history repeating itself?
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| # ? Nov 04, 2009 10:17 |
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As I understand it the burn rate in a diesel engine is limited by the evaporation rate of the fuel droplets in the injector spray. In contrast, in a petrol engine the droplets of atomised fuel have a chance to evaporate before ignition. Smaller droplets have more surface area, so the diesel can burn quicker... and the way to get smaller droplets is to increase the injector pressure.
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| # ? Nov 04, 2009 11:26 |
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Nihilanthic posted:I'm trying to isolate the burn speed variable Large static cr causes very quick turbo response. Combined with variable geometry turbos, no throttle plate, and common rail, you have a non-parasitic forced induction system capable of max boost off idle and making as many pounds as the turbine can handle. Also jamming more boost into a diesel is easier than making it rev an extra 1000rpm. Muffinpox fucked around with this message at Nov 04, 2009 around 15:29 |
| # ? Nov 04, 2009 13:53 |
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Nihilanthic posted:Its under TENSION under power and compression strokes No....... The piston/conrod combo, not the other conrod.
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| # ? Nov 04, 2009 14:44 |
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I've got a dumb question I've wondered about. I've never been around diesels except for a driving a diesel uhaul for a day a couple times, but I basically know how they work from books,tv,internet. Why can't a diesel engine run on gasoline? Gas ignites when it's under too much compression and it's thought of as a bad thing in a gas motor. Diesels probably have more than enough compression to ignite it, and they have those direct injectors so they can squirt it at just the right time, so why not? Is gasoline ignited by compression just ineffecient or bad or something compared to ignited by spark? I'm talking like a truck that's meant for diesel but if you can't find any you can use some gas. On a related note another dumb question, the new gas direct injection engines like the CTS has: does the fuel squirt in the intake stroke or compression stroke? If it squirts in the compression stroke why aren't they pushing the compression ratio sky high? couldn't they? Could they do some kind of flex fuel gas/e85/diesel on one of these motors? Wagonburner fucked around with this message at Nov 04, 2009 around 15:15 |
| # ? Nov 04, 2009 15:12 |
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Wagonburner posted:Why can't a diesel engine run on gasoline? Gas ignites when it's under too much compression and it's thought of as a bad thing in a gas motor. Diesels probably have more than enough compression to ignite it, and they have those direct injectors so they can squirt it at just the right time, so why not? Is gasoline ignited by compression just ineffecient or bad or something compared to ignited by spark? They can but it runs like fried rear end and smokes like cheech & chong.
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| # ? Nov 04, 2009 15:16 |
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Wagonburner posted:I've got a dumb question I've wondered about. I've never been around diesels except for a driving a diesel uhaul for a day a couple times, but I basically know how they work from books,tv,internet. Besides that there is the issue of lubrication, diesel fuel lubricates the fuel system and keeps those pricey injection pumps from dying. So not really possible in a conventional engine, usually when someone puts gas in a diesel it gets expensive.
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| # ? Nov 04, 2009 16:39 |
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Pictures of diesels? My truck, 02 Silverado 2500HD w/ Duramax  Doing what it was made to do  '92 Ford F-450 Super Duty (non-turbo) w/ Massey  I should have taken my camera to my brother's shop last night. He's building a twin-turbo Cummins 12v in a '94 Dodge 2500, and also has an old Chevy 6.5L torn apart for somebody.
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| # ? Nov 04, 2009 16:56 |
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The problem with revving a diesel to high rpms is the delay between the injection event and self-combustion. modern diesels are slowly overcoming this with higher injection pressures and injectors with finer apertures. Diesels can't run on gasoline mainly because gasoline does not lubricate, and no lubrication plays hell with the injection pumps. ignoring that, Diesel fuel is designed to self-combust as easily as possible (Cetane rating) while Gasoline is designed to resist self combustion as much as possible (Octane rating) Current-Gen Common Rail Diesels are amazing though..injection pressures are upwards of 1800 Bar (thats 26 000 psi for you imperials) and can inject up to 5 times per stroke!
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| # ? Nov 04, 2009 17:13 |
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SpeedFreek posted:Diesel burns, gas explodes. Lubricity of diesel decreases along with its sulfur content. This can be a Big Deal when you're talking about older diesels with mechanical injection pumps -- something designed for LSD (500ppm sulfur) diesel will experience higher wear when exposed to ULSD (15ppm). Newer diesels on the other hand have crazy moon injection systems that run like poo poo / clog cats / are terrible when run on LSD. Usually when someone puts gas in a diesel, and the diesel doesn't have a mechanical injection pump, it gets expensive. The rest of us add about a gallon of B99 and a gallon of two cycle engine oil and fire that poo poo right up.
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| # ? Nov 04, 2009 17:19 |
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My family does fun stuff with diesels. 35+5 foot trailer with the heaviest motherfucking 5ft sides that I HATE putting on. It's somewhere around 4 cords of firewood and just shy of 40k with split firewood thrown in.   Carrying that got some of the funniest looks from other people on the road.  I can't find the pictures from dragging it onto the trailer. It didn't run and it involved another truck and a tractor to drag it onto the trailer.   Had to cut it down while it was on the trailer, and my older brother and I did it by ourselves in the middle of the night. It was a little hairy. Hypnolobster fucked around with this message at Nov 04, 2009 around 17:28 |
| # ? Nov 04, 2009 17:24 |
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I had the pleasure of driving a brand-new Ram 2500 HD with the Cummins Verdict: 
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| # ? Nov 04, 2009 17:28 |
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 Real men smell like diesel.
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| # ? Nov 04, 2009 17:38 |
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afen posted:
need to take some photos from my schools engine laboratory it has a 5000 kw (ca. 6800 hp) MAN marine diesel
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| # ? Nov 04, 2009 19:36 |
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afen posted:Real men smell like diesel. "poo poo, I think we lost Frank somewhere around the crank" 
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| # ? Nov 04, 2009 19:41 |
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Low speed two stroke cross head engine up in the house
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| # ? Nov 04, 2009 19:55 |
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Blaster of Justice posted:"poo poo, I think we lost Frank somewhere around the crank" "I wonder if my new engine's main bearings are seating in ok, maybe I'll look" "You'd start taking apart an engine just to look???" "s'alright each cap has a ladder on either side of it for me to climb up to look"
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| # ? Nov 04, 2009 20:05 |
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Diesel engine in a coupe? Sign me up  A diesel coupe was apparently too blasphemous to sell in Germany, so it was US market only. 
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| # ? Nov 04, 2009 20:12 |
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Diesel MBs are awsome! I one day dream of owning an early 80s 300(T)D station wagon
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| # ? Nov 04, 2009 20:23 |
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Trench_Rat posted:need to take some photos from my schools engine laboratory it has a 5000 kw (ca. 6800 hp) MAN marine diesel That's a Wärtsilä 6R32E, 3346BHP. We had two of those, and two 8R32E, 4460BHP for 15.612BHP in total. E: The boat I'm on now has two Bergen Diesel BRM-9s, 10.800BHP total afen fucked around with this message at Nov 04, 2009 around 20:29 |
| # ? Nov 04, 2009 20:27 |
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I forgot about this one.  This is probably the only Diesel Deville with 250k+ miles on it, in fact I'm fairly sure that it is. Nobody wanted to fix them after the headgaskets exploded the first time. My dad bought it with 100kish miles many years ago and rebuilt it, and it ran forever, got incredible mileage, and the interior is ungodly comfortable (and man, with that bag phone that used to be in there it was the bees goddamned knees). It was eventually retired and a year or so ago, it got dragged out of the barn to sell to a friend who needed a car. Started on the first crank after throwing in new batteries. The friend did the brakes, exhaust, etc and drove it for a year and the headgasket finally gave out again. It'll probably sit for a few years before it gets some new body panels and another headgasket. The pictures are from right after it came out of the barn. Hypnolobster fucked around with this message at Nov 05, 2009 around 03:19 |
| # ? Nov 04, 2009 21:17 |
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Hypnolobster posted:I forgot about this one. Looks like a Fleetwood Brougham to me, the Eldos were always two-doors.
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| # ? Nov 04, 2009 22:28 |
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miklm posted:Pictures of diesels? Sup, duramax buddy   14,500 miles in 5 months, around half of that towing. Only thing that pisses me off is the in-town mileage - I can't get better than about 14 no matter how hard I baby it. 18-19mpg unloaded at 70mph is no problem, 17 towing at 60mph is easy, but breaking 14 in town is drat near impossible. I'd own a Dodge if everything else in those trucks weren't utter poo poo 
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| # ? Nov 04, 2009 22:40 |
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Savington posted:Sup, duramax buddy My brother has two Dodges with the 12v Cummins and just sold a 24v truck. He's looking for a common rail, but the prices are so inflated on newer 2500 trucks and manuals are rare... I have no disrespect towards Dodge/Cummins. I've been getting 15-17 no matter what I do in mine - in town, cruising, or railing on it. Hooked to that big Gooseneck trailer pictured I get like 10MPG - it is a very heavy trailer. I got 13-14 with that two-car hauler, but it was a miserable ride to pull a long, heavy tag like that. I sold it and am looking for a cheap single car trailer, possibly enclosed. I have a 4" MBRP exhaust on it with something resembling a muffler, and the Edge Juice w/ Attitude programmer. Otherwise it is stock. I have seen tiny MPG gains with the Edge but mainly it does add a ton of power. *edit* Mine had 105k on it when I picked it up at the first of April. If I didn't turn 114k last night, I will the next time I drive it. miklm fucked around with this message at Nov 04, 2009 around 23:44 |
| # ? Nov 04, 2009 23:13 |
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