Vacuum at WOT

[rodbolt]

Re: Vacuum at WOT

off topic but I gotta say it specking of constant volume fuels.<br /> I was about 18 when down in south texas a 36 inch natural gas line rupthred and burst into flames. was quite amazing with natural gas under pressure shooting flames several hundred feet into the air. we all thought well just close the valve, wrong.<br /> Red Adairs team came in and detonated a charge that extinguished the flames, then they cut off the pipe. then some crazy engineer calculated the volume of gas flowing and told the welder how fast he had to weld the cap on in inches per minute so the mix would stay rich enough then go lean enough not to reflash. we watched the weld job on the TV feed to our work center. two welders and a fitter but no engineer but it worked.<br /> now you tell me who would be crazy enough to weld a plate on a gas pipe that big spewing thousands of cubic feet per hour of natuaral gas?<br /><br /> but it worked, the welder never created enough flame to light a smoke.

 

[QC]

Re: Vacuum at WOT

rodbolt,<br /><br />We should talk on the telephone . . . You continue to confirm my points but you are just missing one little tiny thing. With an Otto cycle engine, to maintain that constant volume (stoic) at anything but full load, you must choke off the air (throttle). You say it over and over and miss that it costs fuel to suck air (or push air if you prefer) past a restriction (throttle). Frankly, it is like running with a dirty air cleaner. What do you get from that? Low Power! Increased Fuel Consumption! It is huge. You need to trust me.<br /><br />Most diesels don't get altitude sickness for only one reason . . . turbochargers. Naturally Aspirated diesels suck arse at high altitude unless they are derated or you can live with solid black smoke (insufficient air). Turboed engines are usually rated to 9000 ft. because the turbo spins faster at higher altitudes due to lower air density, hence giving the engine magically the same air density as sea level. This is as old as the 50s.<br /><br />I am dead serious man. Everything you are saying about constant volume confirms my assertions, except for one thing: Throttling losses absolutely make Otto engines less efficient than compression ignition engines (diesels). Higher compression contributes and so does the fuel's inherent energy benefits (if you are talking volumetric efficiency vs. energy efficiency), but the number one contributor to the efficiency benefits is the lack of throttling losses. These are not QC's theories or ramblings. These facts are well known by every engine development engineer on the planet.<br /><br />We currently take perfectly good high compression diesels and convert them to run on a combination of natural gas and diesel, it is called Dual-Fuel. Like gasoline, natural gas has a narrow band of air to fuel ratio in which it will burn (not as narrow as gasoline, but still narrow). Internally, we argue constantly about adding a throttle to allow us to burn more natural gas at light loads (too lean so we run 100% diesel). We don't add the throttle because of the efficiency penalty. No other reason except that diesel ring packs are not designed for vacuum and they end up with higher oil consumption than a stock diesel. But again, the main reason is the efficiency penalty. If we could add a throttle without efficiency penalties our lives would be sooooooo much easier it is hard too imagine. But we insist on maintaining diesel efficiency because we are selling to commercial operators . . .

 

[rodbolt]

Re: Vacuum at WOT

Originally posted by QC:<br /> Yes, I know your head is spinning, but it is true and it is the main reason that diesels are more efficient. They ain't got no stinkin' throttle.<br /><br />ya changing the subject matter, you have also stated the throttle plates are the cause of the inefficeny which is not the case, its the fuel type.<br /> http://www.diesel-central.com/News/cackle.htm <br /> for those that wish to see the ratio's VOLUMES that a powerstroke diesel runs as well as the wimpy ares RPM.<br /> if I side stepped the clucth on my 455 in my old 442 at 2400 and shifted at 2400 shifting would not be an issue as it would most likly stall. however if I side steppeded it at 33oo and shifeted at 6800 I could traverse the 1/4 mile in roughly 12.5 seconds yet could ilde all day in ft worth TX traffic.<br /> try that with your powerstroke or 3208 cat.<br /> on a single speed constant volume fueled motor there is no throttle nor fuel bowl,normally, however in a very narrow RPM band it works well.<br /> and QC tactfully ignored my HPDI comment which DOES NOT rely on anything to move fuel other than an engine drivem mechanical high pressure pump very similar to a diesel injector pump. yet it still has to have a restrictor. why does it need a restrictor?<br />QC<br /> if I am injecting gasoline and gasoline only no oil, directly into the combustion chamber from a high pressure,1100PSI pump, why do I need throttle shutters to control engine speed ?<br /> a hint<br /> at 100-1 air to fuel you could not light gasoline with a torch.

 

[QC]

Re: Vacuum at WOT

I didn't intend to side step HPDI. I understand HPDI. I apologize. Jeez. I am apologizing to jimonica on DC and rodbolt here . . . What my life has become . . . oh, the horror <br /><br />Again your points prove my assertion. As you continue to say "constant volume" engines require a throttle. Yup. I do not understand your performance comparisons as I don't understand why you believe we are disagreeing. Diesels are more efficient, at full load less so, because the Otto engine is at WOT. At part load diesels are extremely more efficient as illustrated by the chart above. Believe it or not we have data (so does CAT, Cummins, GMC, Ford, Volvo, Mercedes, Scania, Detroit Diesel, Isuzu, Toyota, Orbital, Bombardier etc. etc. etc.) to back it up. HPDI does not eliminate it, although it improves on the issue.<br /><br />I can see 3208s in my nightmares. They are piles and I would never mention them when discussing diesel performance. You have no idea how many times I have been beaten over the head with 3208s . . . and those of you outside of CA do not know the half of it LOL

 

[rodbolt]

Re: Vacuum at WOT

hahaha we see a bit of the "drawbacks" to the supercharged/turbocharged marine versions here. seems it was a very good motor in the 220 HP normally aspirated version, tends to get dicy with pressure over 300.<br /> we tow a few in each season.<br /> we are not actually disagreeing just you said the ineffeceny was due to a shutter and I say its due to fuel type. can ya imagine trying to run a gas motor at a A/F ratio of 100-1?<br />or 10_1?<br /> niether would run yet a diesel will.<br /> its the fuel type not a carb.<br /> thats why even though the HPDI,in my view, is almost a diesel it MUST have an air restrictor or RPM becomes fixed and could only vary a few hundred up or down.<br />and its rare that any outboard has an air cleaner, I tell my customers if you need an air filter you also need to check your depth finder and GPS.<br /> one of the major drawbacks to a "otto" cylce motor has always ben the vlve train. its a terrible comprimise.<br /> me and a buddy are working with a soliniod actuated push/pull valve arrangement that would allow infinate lift,duration and valve timing while eliminating the paristic drag of a camshaft and valvetrain.<br /> dont know that it would ever work.<br /> however if you look at the competition cams book under oldsmobile adjustable rocker arms that was My Idea.<br /> I sent them what I did, they sent me a cam kit and 2 years later it was in the hot rod magazine.<br />they refined it and made it a bolt on and mine required redrilling the heads to accept big block chevy screw in studs.<br /> got a buddy right now that thinks he has a killer tripple stage twin injector setup for a low compression high speed diesel.<br /> while I like to chat theory with him I aint gonna finance that either .<br /> however I do understand the concept of most engine designs and have worked with conventional gas, rotary valve,just a bit, rotary(mazda) and gas turbine.<br /> if ya wanna see wild boost pressures look at the 4 rotor mazda.<br /> some of the boost pressures are exceeding 45 PSI.<br /> the rotary was a great concept, however it took from 1924 to 1985 or so for the technology to make it viable. 2 issues, one was rotor apex seals, or lack of and 2 is fuel economy at normal asperation. however I had a racing buddy that launcehed at 11K and shifted at 16K and other than apex seal failures never broke anything.<br /> sounded like a weed wacker on the starting line.<br /> back in the 80's I worked by night for GOEX setting up and programming CNC lathes and mills, by day I worked at dutch branch marina I also worked for Dan's automotive machine shop some as well as crewed for Bob's auto supply's 68 camero.<br /> in my spare time I tried to get as much out of a stock olds 455 that I could without resorting to exotics cause thats what I also drove to work each day. some days I actually went fishing.<br /> then after a 6 year stint as an FC I went into bidness for myself and became a work o holic. I study about anything.<br />QC<br /> your about my age I think, I am 45.<br /> could you imagine a 375HP 350 CID chebby with AC power steering power brakes and a rock smooth 650 rpm idle in 1980?<br />one that would turn key start in any weather, need no real maint for 60,000 miles and do it day after day.<br /> well we have them now.<br />my 455 in my 70 w-30 car made 370 HP at 5600 and shook like a dog passing peach pits at idle, intake vacum was so low that the w-30 option could not be had with power brakes and shook so bad they dropped the power steering option.<br />todays 8.1 makes a conservative 420 HP and comes with a rock smooth 650 RPM idle and any option you desire and actually weighs less and gets better fuel to HP margins.<br />so its not a shutter VS non shutter issue. its a better understanding of how the air is put in the cyl, how the fuel is added, how the exaust is scavenged and most importantly how the fuel characteristics dictate the rest of the design.<br /> but never bet a motor pool guy that a 7.4L multi fuel motor cannot be started on JP-5. it can I saw it and it cost me a case of refreshing beverages, was an ingenious starting procedure but it started.

 

[QC]

Re: Vacuum at WOT

Agree with all again. Let's say that diesel (and other heavy fuels) allows the elimination of the throttle . . . Maybe we are closer then.<br /><br />Funny thing, in a truck the 3208 NA is the POS . . . We had EGR 3208s in CA in 1976. I was the first US Cat Dealer Parts and Service rep dedicated to truck at 20. The reason they started the program in L.A. was the 3208 NA EGR. It's about a two sixer conversation . . .<br /><br />Yup, close, I am 46. I agree on the performance stuff now. That's why I have argued against the old adage that you have to have a big block. It is just not true anymore unless you want close to 400 bhp.<br /><br />Thanks Tony!! Fun discussion.

 

[rodbolt]

Re: Vacuum at WOT

man I would have never imagined a stock 4.3 V6 with a smooth idle and all weather turnkey starting at 225 HP in 1979.<br />absolute reliability and no stall converters or slipping the clutch coming up the ramp.<br />ya shoulda seen me trying to pull a 19ft 1968 johnson ebbtide up the ramp with that w-30 olds <br />only way I could do it was slip the clutch above 3000 until I could make the tires spin then feather the throttle.<br />saltwater ramps at low tide sometimes took a few tries.<br /> now the guy with the 4.3 EFI in the s-10 blazer can do it and the idle speed hardly changes.<br /> if you think the land based 3208's had issues try the pressureized 300+hp marine versions.<br /> I no longer work on diesel period. the smell of the fuel makes me sick and the exhaust makes me toss in a few seconds.<br /> them parts are just to dang big and heavy.<br /> ya think the heads on that big truck are tough to get off, try doing it in a sitting position then taking it up 2 decks and aft 40 ft to the salon. all the while if you leave a fingerprint or dent the cherrywood flooring in the staterooms or passageways the mate,capt and owner are on the phone with the attorneys.<br /> the money is good but not woth the aggrevation.<br />I have been in engine rooms where we wore the hospital type shoe coverings, takes 6 hours to lay down the padding on the ladders and passageways and hatch frames then cover that with plywood and another layer of padding before the first tool is brought aboard.<br /> whaen ya start humping the big nasty parts through a stateroom with 30,000 dollar floors and 10,000 dollar cabinets ya cant afford to bump it.<br /> its all one off custom stuff and scratches,much less dings, are NOT acceptable.

 

[FreeBeeTony]

Re: Vacuum at WOT

You guys need to get some sleep.............<br /><br />Seems like you are enjoying yourselves though....