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Author Topic: Which would you choose????  (Read 30790 times)

apogee_man

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Re: Which would you choose????
« Reply #45 on: February 01, 2009, 07:18:52 AM »
Wouldn't it be interesting if she paid for a 12/2 and was actually shipped a 20/2 by mistake?

Would explain what she is able to do...

oliver90owner

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Re: Which would you choose????
« Reply #46 on: February 01, 2009, 08:48:34 AM »
diesel guy,

Not looked at the power curves but to suggest that these slow revving engines have an exponential power curve is fairly wide of the mark.  Power from uprated engines (increased speed) does not seem to bear that out.

The power curve for the 6/1 From Lister was fairly linear when they increased the power by20% with a simple increase in rpm of 30%.  Agreed not directly proportional but linear on their power graphs, certainly not a square function.

On that basis a 12/2 should be about 10HP  at 500RPM and maybe around 7HP at 350RPM.

Results reported seem to be more reasonable than your assumptions, so I am with Sara and Bob on this one.

Sara has the data and Bob is more practical with the figures.  Your assumptions may hold better for higher speed engines where they run 'off the cam' once below maximum torque.  Modern engines, short stroke, low torque.  Entirely, well nearly, different.

Regards, RAB

The 'brain' of the engine is the cam.

mobile_bob

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Re: Which would you choose????
« Reply #47 on: February 01, 2009, 01:56:46 PM »
another engine comes to mind that likely is fairly linear, that is the old mack endt673 and 675
massive torque rise engines

both high speed engines which doesn't make it an apples to apples thing, but if you can get a high speed engine
to deliver a torque band that is relatively flat from 1000rpm to 2000rpm you certainly can tailer a slow speed engine to
deliver at least half power at half rpm.

it takes some tweaking but it can be done.

bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

sarawnw

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Re: Which would you choose????
« Reply #48 on: February 02, 2009, 06:16:41 PM »
Hi All,

Thank you for the support,  I only know what I have done and trying to understand how it relates to the big picture.   
I really do need to understand injection timing and how to do it methodically. 
This 12/2 runs  better at lower RPM, smoother, to be descriptive.

The pointed bolt sounds llike a great idea, thanks

have a great day

sara

diesel guy

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Re: Which would you choose????
« Reply #49 on: February 04, 2009, 06:11:48 AM »
I’ve been away for a few days, here’s what it comes down to. A little background about me that was never spoken here and helps explain my point of view.

I have many Patents granted and Patents applied for and Provisional Patent Applications applied in the following fields:

I designed and patented, an extremely fast Sterilization system (45 seconds, worlds fastest to date) for Med Units for domestic and military use. It uses a sterilizing chamber, cryogenic liquid nitrogen system, vacuum pump, quartz heating element and a vacuum controller expansion valve. Liquid nitrogen kills only about 85% - 90% of micro organisms, I place equipment into the chamber then close, a vacuum draws the chamber down to 1/10 of an astrosphere at the same time a quartz heating element heats an air tank, when the vacuum reaches 1/10 of an astrosphere the cryogenic liquid is drawn through the expansion valve, this increases the evaporation rate of the liquid nitrogen, producing even lower temperatures in the vacuum, sterilizing the components, then the heated air is injected into the chamber to rapidly raise the temperature, an infrared sensor detects the internal temperature of the equipment until it reaches room temperature, then the door automatically opens.

I designed and patented, an anti-roll/flywheel energy storage system for sport utility vehicles, which uses counter rotating moveable permanent magnet rotors, computer controlled split stators and gyroscopic sensors, that sense the vehicle’s angle and acceleration of roll and the information from the gyroscopic sensors is processed to manipulates the magnetic field from the split stators to the moveable permanent magnet counter rotating rotors, converting the stored kinetic energy potential into a downward twist in the opposite direction of the roll to reduce rollover susceptibility. It operates as a electrical storage system (battery) in normal driving.

I have two patents applied for and worked 9 years on an advanced Maglev train research lab perfecting and comparing Linear Induction motors and Linear synchronous motors. Advantages, disadvantages. Using advanced 3-D models and simulations to calculate structural integrity and alter the design where required, then use advanced 3-D models and simulations to perform complete power requirements calculations for the propulsion, lift, guidance and all on board electronics, then use advanced 3-D models and simulations to calculate the capabilities. The finished product was an advanced 3-D simulation with all the thermal and dynamic forces produced by the train.

I also have one patented and one patent applied for in wind turbines. They use a special variable flux density permanent magnet alternator. This system enables wind speed to automatically control the amount flux to the stators from the permanent magnet rotor/s and eliminates the need for a turbine blade pitch control system. This advanced alternator allows the turbine blades to operate at maximum tip speed at the widest wind velocity range by precise flux control simular to an electromagnet design with the increased efficiency of a permanent magnet design.

I also have one patented and three patent applied for in Heavy Hybrid propulsion systems. I spoke to Bob about one of these in the past. My designs offer very high power densities and fuel efficiency. There are four types of hybrids today, Series, Parallel, Series - Parallel and Hydraulic. I have one for each design. I can’t display details of my unique designs as I have International Patents being applied for.

This leads me up to the engines in the forum. The Series hybrid propulsion system that I developed uses “generators” to power electric motors placed in the driveline. We have used independent university studies to enable us to build the most reliable, powerful and fuel efficient system, to date. Generators that run at 1,800 rpm have an X amount of stored kinetic energy within the rotor and flywheel. Our engines operate between 1,400 and 1,800 rpm when over the road highway speeds and 1,200 rpm in low output mode and 900 rpm in stop and go mode. When the engine speed is slowed to 1,200 rpm the programmed horsepower is set at “½” of 1,800 rpm, this allows the engine to maintain proper X amount of stored kinetic energy potential.

When the engine speed is slowed to 900 rpm, the programmed horsepower is set at “½” of 1,200 rpm, this also allows the engine to maintain proper X amount of stored kinetic energy potential.  So even if an engine could power more than that rating, engine wear would be “dramatically increased from the lack of stored potential”. This is stored potential imperative because we are using highly efficient medium duty engines in a heavy duty class, which is achievable, if excessive amount of stored kinetic energy potential is maintained.

For instance, if you were driving a car with a standard transmission and in 4th gear at low speed approaching a hill and you pressed the accelerator, instead of downshifting. The engine would start to lug. Do you know what causes the lug? It happened when the engines output torque “exceeds” the stored kinetic energy capability of the flywheel and begins to “hammer” the pistons, rods and mains. When you down shift, the engine torque is multiplied so less output torque is needed and the engine speed is increased, so stored kinetic energy within the flywheel again exceeds the engines torque output and the engine smoothens out, so the engine can safely produce greater output power without damaging the engine.

The 12/2 operating at 325 rpm has ¼ the stored kinetic energy potential as operating at 650 rpm. So how can one think an engine can make a level of torque and not address this important requirement, you can’t. Lister designed these engines so the flywheels stored potential was never exceeded, that’s where you get reliability. The 12/2 at 325 rpm is like taking off both cast iron flywheels, and make two lightweight flywheels out of aluminum and there mass would equal ¼ the total of the two cast iron flywheels. Now run the engine at 650 rpm and put it at “full load” with ¼ the stored potential, the engine will come apart in short order. That is exactly what this person is doing to the 12/2 at 325 rpm, but the torque would be much lower.

Bob you state: “hp to rpm on these engines is surprisingly linear to a point, until
you get outside the geometry and spring that controls the governor”.

You are correct when you talk about 500 rpm and above, but lower and it is a whole new ball game. You need torque to produce a liner hp output. You need hp to produce Kw. Hp is the amount of work done in a given time, so how can the hp output be liner when the torque output and the rpm “drop together” under 500 rpm? Therefore it is not liner.

Bob you state: “take for instance an 855 cummins, they are built from ~230hp all the way to at least 475hp all the same engine, same block and same crank there are also the old formula engines that had a deep torque curve and all sorts of variants”

That also is correct, but if you pushed these engines hard for an extended time at low rpm they will come apart and that is a fact. The only way to increase engine life when an engine is working at maximum load at low speed (900-1,200 rpm) is to install an “extra” heavy flywheel, plus retard timing and lower compression.  Me and a few friends built three Cummins 855’s for drag racing, so I know the engine quite well. They are very fast engines, all had 6 speed Allison transmissions in them, 13 - 15 second trucks.

Oliver90owner you stated: Not looked at the power curves but to suggest that these slow revving engines have an exponential power curve is fairly wide of the mark. Power from uprated engines (increased speed) does not seem to bear that out. On that basis a 12/2 should be about 10HP at 500RPM and maybe around 7HP at 350RPM.

Is that so? “I have the power curve of a 10/2”. These are the exact figures: a 12/2 is a 10/2 but operates at 650 rpm and the 10/2 operates at 600 rpm. At 650 rpm = 12 hp, at 600 rpm = 10 hp, at 500 rpm = 8 hp. But don’t read totally into these numbers, “the torque curve rises after 600 rpm”. If you operate “under” 500 rpm, the power will fall rapidly and the power is far from liner and on a downward spiral. So you power esimates are far from accurate.

oliver90owner you stated: “Your assumptions may hold better for higher speed engines where they run 'off the cam' once below maximum torque. Modern engines, short stroke, low torque. The 'brain' of the engine is the cam”.

You are exactly correct about the cam as the brain of the engine but you have it totally backwards. We’ll take Bob’s 855 Cummins with a torque peak of 1,200 - 1,400 rpm. The proper engine speed when cruising down the highway is 1,450 rpm - 1,650 rpm. When a hill comes up and the engine begins to loose rpm, the engines torque “increases” as it “fall onto the cam”. The operator needs to downshift to elevate the internal pressures to maximize engine/transmission life. 

Now the so called “low speed’ 12/2 that everyone thinks is liner, the profile don’t “come on the cam" until guess what? 600 rpm and this is the “beginning of the torque rise” and pulls on up, then flattens out and then falls. Therefore when you operate below the set torque curve in a mechanical engine, vacuum will be dramatically reduced and “torque and vacuum” go hand in hand. So any engine speed under 600 rpm, is operating “off the cam” and will have exponentially diminishing power output as speed falls.

How do I know? Because I have been designing and cutting my own cam grinds for 25+ years in gas and diesel engines and fully understand the working dynamics of internal combustion engines and you kind of get the hang of it after a while.

About three months ago I spoke to Xyzer just about this subject. I have exactly calculated two cam grinds that moves the torque curve down to approximately 475 rpm and 350 rpm. My cam grinds (I call them the Chugger series) produce the maximum vacuum and appropriate cylinder pressure needed to meet the exact torque curve displayed. Also, it would be mandatory for the flywheel mass to be increased proportional to the torque increase so the stored kinetic energy within the flywheels always exceeds the engine torque by a reasonable margin. I will have one or both of these cams installed by next Winter on my 14/1 and 16/1.

I’m going to finish my prototype Heavy Series hybrid System for display and I can’t be distracted by this any more. You people have been a great help when I was perfecting my system and I’m shutting down and back to the grid. Everyone new here should listen to these experts and learn from them as I have done. See you next year. God bless.

Diesel Guy

mobile_bob

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Re: Which would you choose????
« Reply #50 on: February 04, 2009, 06:42:55 AM »
DG:

you dropped a load and now you gotta run?

well to much to respond to for now, so i guess we can pick this up when you get back...

NEXT YEAR

there simply is so much to argue it boggles the mind.

your chugger series cam, gotta love that
that alone tells me all i need to know about your capabilities and knowlege of diesel engine's

cya next year

bob g
otherpower.com, microcogen.info, practicalmachinist.com
(useful forums), utterpower.com for all sorts of diy info

billswan

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Re: Which would you choose????
« Reply #51 on: February 04, 2009, 01:03:10 PM »
Hello diesel guy

I hope you come back asap, want to here more about your cam grinds for 16/1's.

Good luck on your Hybrid systems. ;D

Billswan
16/1 Metro  in the harness choking on WMO ash!!

10/1 OMEGA failed that nasty WMO ash ate it

By the way what is your cylinder index?

Roark

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Re: Which would you choose????
« Reply #52 on: February 04, 2009, 01:15:44 PM »
Can you give me the patent number on the anti-roll/flywheel energy storage system for sport utility vehicles?  One of my (many) goofings is in self-guided robotics, and one of these projects could REALLY use this sort of an arrangement.  Rover has to be stable on hills, and getting the CG low enough is problematic.  I've been looking at doing something "active" and came across your post.

Roark
What?!? No engine parts at the dinner table?  C'mon, Hon...