Go Back   EcoModder Forum > EcoModding > General Efficiency Discussion
Register Now
 Register Now
 

Reply  Post New Thread
 
Submit Tools LinkBack Thread Tools
Old 12-03-2010, 12:26 PM   #71 (permalink)
Master EcoModder
 
Join Date: Jul 2008
Location: Silly-Con Valley
Posts: 1,479
Thanks: 201
Thanked 262 Times in 199 Posts
Well, the point of maximum pressure is usually reached when the mixture has been burning for some time, which does occur after TDC, but your point is well-taken.

The friction/oil pumping losses are, IMHO, not "closing the barn door after the horses escape". They are ways to very slightly reduce some of the losses in a system of (at best) modest efficiency. Not pointless, exactly, but likely of small enough benefit that you'd never recoup the costs of performing them.

-soD

  Reply With Quote
Alt Today
Popular topics

Other popular topics in this forum...

   
Old 12-03-2010, 02:26 PM   #72 (permalink)
Master EcoModder
 
NeilBlanchard's Avatar
 
Join Date: May 2008
Location: Maynard, MA Eaarth
Posts: 7,907

Mica Blue - '05 Scion xA RS 2.0
Team Toyota
90 day: 42.48 mpg (US)

Forest - '15 Nissan Leaf S
Team Nissan
90 day: 156.46 mpg (US)

Number 7 - '15 VW e-Golf SEL
TEAM VW AUDI Group
90 day: 155.81 mpg (US)
Thanks: 3,475
Thanked 2,950 Times in 1,844 Posts
The Revetec design doubles the efficiency of a crankshaft design. If some of the other major losses could be addressed, then could the efficiency go above 50%? Is 60% possible?

The major problems with most current ICE designs:

Poor geometric / mechanical torque due to the inherent limitations of the sinusoidal motion of the piston and the connecting rod's angle relative to the crankshaft (vs a rotary design or an electric motor)

Long time periods between power strokes, requiring relatively large flywheels.

Large mechanical drag from the valvetrain having to work against the springs.

The acceleration and deceleration of the piston and connecting rods.

The brief / momentary pressure buildup of the fuel burn (vs the constant pressure reserve of a head of steam, for example)

The need to pump oil through tiny passageways, and to generate electricity.

The need to warm up to reach ideal operating temperature.

The amount of waste heat requires a lot of "stuff" and requires a lot more aerodynamic drag to be able to dump it out of the vehicle.

The relatively narrow torque band, requiring a multi-ratio transmission -- basically as many gears as possible. Seven or eight gears would be better than merely three to five.

The need to idle while not actually being used.
__________________
Sincerely, Neil

http://neilblanchard.blogspot.com/
  Reply With Quote
Old 12-03-2010, 04:42 PM   #73 (permalink)
Basjoos Wannabe
 
ShadeTreeMech's Avatar
 
Join Date: Apr 2009
Location: Arkansas
Posts: 870

The Van - '97 Mercury Villager gs
90 day: 19.8 mpg (US)

Lyle the Kindly Viking - '99 Volvo V70
90 day: 25.82 mpg (US)
Thanks: 174
Thanked 49 Times in 32 Posts
Quote:
Originally Posted by autoteach View Post
pretty sure that your wife is sitting on it. 4DSC.com : Articles
Ah, that is the VG30DE. It is very similar to the engine in my Villager, but it isn't the one in my 98 Max. Wonder if I could track down one of those intakes for the Villager. FWIW the intake runner, and I'm certain the distributorless ignition, boosted the power by 40 hp over the one in my Villager.

My Max has a VQ30DE, which had a variable intake available in the Middle Eastern Maxima, but not in the US.

That is a good pic of our car in the Wiki article!

__________________
RIP Maxima 1997-2012


Quote:
Originally Posted by jamesqf View Post
I think you missed the point I was trying to make, which is that it's not rational to do either speed or fuel economy mods for economic reasons. You do it as a form of recreation, for the fun and for the challenge.
  Reply With Quote
Old 12-03-2010, 08:44 PM   #74 (permalink)
Master EcoModder
 
Join Date: Apr 2010
Location: belgium, wi
Posts: 262

Bus - '94 Ford School Bus huge

Stupid - '01 Chevy Blazer LS
90 day: 21.38 mpg (US)

hawk - '00 Honda Superhawk
Thanks: 2
Thanked 24 Times in 19 Posts
Quote:
Originally Posted by ShadeTreeMech View Post
Ah, that is the VG30DE. It is very similar to the engine in my Villager, but it isn't the one in my 98 Max. Wonder if I could track down one of those intakes for the Villager. FWIW the intake runner, and I'm certain the distributorless ignition, boosted the power by 40 hp over the one in my Villager.

My Max has a VQ30DE, which had a variable intake available in the Middle Eastern Maxima, but not in the US.

That is a good pic of our car in the Wiki article!

Well, about the variable length... Tuning is not that difficult. If you were going to invest the time, it would be a day on a dyno to program it. I just am not sure that it would be worth that much.

As for Blanchard's comment about narrow torque curve of gas engines, I would disagree. Can you show me a graph of a narrow torque curve.
  Reply With Quote
Old 12-03-2010, 10:27 PM   #75 (permalink)
Master EcoModder
 
NeilBlanchard's Avatar
 
Join Date: May 2008
Location: Maynard, MA Eaarth
Posts: 7,907

Mica Blue - '05 Scion xA RS 2.0
Team Toyota
90 day: 42.48 mpg (US)

Forest - '15 Nissan Leaf S
Team Nissan
90 day: 156.46 mpg (US)

Number 7 - '15 VW e-Golf SEL
TEAM VW AUDI Group
90 day: 155.81 mpg (US)
Thanks: 3,475
Thanked 2,950 Times in 1,844 Posts
I guess I should clarify: a narrow efficiency band. Electric motors do not require transmissions, nor do steam engines.

Surely an ICE can be designed that beats the best we have now? Is an external combustion required? What would it take to get 50-60% efficiency?

'Cuz electrics are up close to 95%...
__________________
Sincerely, Neil

http://neilblanchard.blogspot.com/
  Reply With Quote
Old 12-03-2010, 10:34 PM   #76 (permalink)
MPGuino Supporter
 
t vago's Avatar
 
Join Date: Oct 2010
Location: Hungary
Posts: 1,807

iNXS - '10 Opel Zafira 111 Anniversary

Suzi - '02 Suzuki Swift GL
Thanks: 828
Thanked 708 Times in 456 Posts
Quote:
Originally Posted by NeilBlanchard View Post
The Revetec design doubles the efficiency of a crankshaft design. If some of the other major losses could be addressed, then could the efficiency go above 50%? Is 60% possible?
It really depends on useful work obtained vs. thermodynamic heat input. Try modelling a Carnot cycle, using assumptions for Otto cycle, Miller cycle, and whatever other cycles you want. That'll answer your question in theory.

Quote:
Originally Posted by NeilBlanchard View Post
The major problems with most current ICE designs:

Poor geometric / mechanical torque due to the inherent limitations of the sinusoidal motion of the piston and the connecting rod's angle relative to the crankshaft (vs a rotary design or an electric motor)

Long time periods between power strokes, requiring relatively large flywheels.

Large mechanical drag from the valvetrain having to work against the springs.

The acceleration and deceleration of the piston and connecting rods.

The brief / momentary pressure buildup of the fuel burn (vs the constant pressure reserve of a head of steam, for example)

The need to pump oil through tiny passageways, and to generate electricity.

The need to warm up to reach ideal operating temperature.

The amount of waste heat requires a lot of "stuff" and requires a lot more aerodynamic drag to be able to dump it out of the vehicle.

The relatively narrow torque band, requiring a multi-ratio transmission -- basically as many gears as possible. Seven or eight gears would be better than merely three to five.

The need to idle while not actually being used.
If we're talking about the majority of cars on the road today, you forgot a couple of biggies.

The need to generate an intake manifold vacuum.

The need to suck air past a huge inefficient restriction (namely, the throttle plate).
  Reply With Quote
Old 12-03-2010, 10:57 PM   #77 (permalink)
(:
 
Frank Lee's Avatar
 
Join Date: Jan 2008
Location: up north
Posts: 12,762

Blue - '93 Ford Tempo
Last 3: 27.29 mpg (US)

F150 - '94 Ford F150 XLT 4x4
90 day: 18.5 mpg (US)

Sport Coupe - '92 Ford Tempo GL
Last 3: 69.62 mpg (US)

ShWing! - '82 honda gold wing Interstate
90 day: 33.65 mpg (US)

Moon Unit - '98 Mercury Sable LX Wagon
90 day: 21.24 mpg (US)
Thanks: 1,585
Thanked 3,555 Times in 2,218 Posts
Quote:
Originally Posted by NeilBlanchard View Post
The Revetec design doubles the efficiency of a crankshaft design. If some of the other major losses could be addressed, then could the efficiency go above 50%? Is 60% possible?

The major problems with most current ICE designs:

Poor geometric / mechanical torque due to the inherent limitations of the sinusoidal motion of the piston and the connecting rod's angle relative to the crankshaft (vs a rotary design or an electric motor)

Long time periods between power strokes, requiring relatively large flywheels.

Large mechanical drag from the valvetrain having to work against the springs.

The acceleration and deceleration of the piston and connecting rods.

The brief / momentary pressure buildup of the fuel burn (vs the constant pressure reserve of a head of steam, for example)

The need to pump oil through tiny passageways, and to generate electricity.

The need to warm up to reach ideal operating temperature.

The amount of waste heat requires a lot of "stuff" and requires a lot more aerodynamic drag to be able to dump it out of the vehicle.

The relatively narrow torque band, requiring a multi-ratio transmission -- basically as many gears as possible. Seven or eight gears would be better than merely three to five.

The need to idle while not actually being used.
I haven't really researched the Revetech, but I do know that cam replacements for con rods are nothing new. If they worked I'd think that after all these decades of development I'd at least be able to get one on a lawnmower or something.

All other points above are addressed to some degree... but not all on the same piece of equipment.

Con rod torque xfer> turbines
Power strokes> multi cylinders; 2 strokers
Valvtrain power requirements> 2 strokers; opposed pistons
Recip mass> short stroke geometry; small size (think Honda 50)
Intermittent combustion> turbines; is it necessarily a bad thing?
Oil pumping> 2 strokers, splash lube (think old Briggs and Stratton)
Electricity requirement> diesel; glow plug ignition; magneto (as a low drag source)
Need to warm up> heat storage ala Prius thermos bottle; preheat via various methods
Heat rejection> air cooling; water cooling (marine); thermosiphon
Narrow torque> dunno, 2 or 3 gears works for me
Need to idle> no they don't
__________________


  Reply With Quote
Old 12-03-2010, 11:10 PM   #78 (permalink)
Master EcoModder
 
NeilBlanchard's Avatar
 
Join Date: May 2008
Location: Maynard, MA Eaarth
Posts: 7,907

Mica Blue - '05 Scion xA RS 2.0
Team Toyota
90 day: 42.48 mpg (US)

Forest - '15 Nissan Leaf S
Team Nissan
90 day: 156.46 mpg (US)

Number 7 - '15 VW e-Golf SEL
TEAM VW AUDI Group
90 day: 155.81 mpg (US)
Thanks: 3,475
Thanked 2,950 Times in 1,844 Posts
Thanks for the response, Frank. The trick seems to be combining as many of these features in one design, I guess?

This thread has flown along, and my design proposal has been buried:

http://ecomodder.com/forum/showthrea...tml#post206606

In a nutshell: a 2-stroke, rotary disk valve, opposed piston, with an offset that aligns the beginning of the power stroke with the crankpin at 45 degrees past top dead center -- oh, and only a turbo doing any compression; as there is no compression stroke...
__________________
Sincerely, Neil

http://neilblanchard.blogspot.com/
  Reply With Quote
Old 12-03-2010, 11:15 PM   #79 (permalink)
(:
 
Frank Lee's Avatar
 
Join Date: Jan 2008
Location: up north
Posts: 12,762

Blue - '93 Ford Tempo
Last 3: 27.29 mpg (US)

F150 - '94 Ford F150 XLT 4x4
90 day: 18.5 mpg (US)

Sport Coupe - '92 Ford Tempo GL
Last 3: 69.62 mpg (US)

ShWing! - '82 honda gold wing Interstate
90 day: 33.65 mpg (US)

Moon Unit - '98 Mercury Sable LX Wagon
90 day: 21.24 mpg (US)
Thanks: 1,585
Thanked 3,555 Times in 2,218 Posts
I've been looking at the animation on the Revetech site...

I see way more contact points + gears + sliding things + torsion loads per piston than a regular con rod set-up, so if in fact there are gains with this design they have to be from the mechanical advantage more than offsetting the increased internal friction. And then there is the expense and longevity of lobes + gearset vs rod and crank throw.
__________________


  Reply With Quote
Old 12-03-2010, 11:23 PM   #80 (permalink)
Master EcoModder
 
NeilBlanchard's Avatar
 
Join Date: May 2008
Location: Maynard, MA Eaarth
Posts: 7,907

Mica Blue - '05 Scion xA RS 2.0
Team Toyota
90 day: 42.48 mpg (US)

Forest - '15 Nissan Leaf S
Team Nissan
90 day: 156.46 mpg (US)

Number 7 - '15 VW e-Golf SEL
TEAM VW AUDI Group
90 day: 155.81 mpg (US)
Thanks: 3,475
Thanked 2,950 Times in 1,844 Posts
Yeah, the torsion on the flat conrod must be a problem, for sure. But, in theory, there is very little piston slap (if that means the side to side force that the skirts resist), and the valve train is completely standard. They have more or less equaled the Atkinson efficiency of the Prius -- which is the best for any gasoline ICE, is it not?

I wonder what would happen with the Revetec as an Atkinson / Miller cycle? Or, if rotary ball valves could work?

Have you seen the Garric rotary design?

__________________
Sincerely, Neil

http://neilblanchard.blogspot.com/
  Reply With Quote
Reply  Post New Thread


Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Discussion on tire efficiency Ernie Rogers General Efficiency Discussion 69 12-27-2014 01:17 PM
The Easy Leg: Vehicle Efficiency natefish Off-Topic Tech 17 05-19-2010 04:52 PM
Vehicle Efficiency Improvements SVOboy EcoModder Blog Discussion 24 12-07-2009 10:19 PM
World’s cleanest internal combustion engines? blueflame EcoModding Central 6 02-28-2009 08:13 PM
Low-Drag Trucks: Aerodynamic Improvements & Flow Control System Boost Fuel Efficiency OokiiMamoru Aerodynamics 5 06-15-2008 11:38 PM



Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Content Relevant URLs by vBSEO 3.5.2
All content copyright EcoModder.com