Engine efficiency

[NeilBlanchard]

Here's a different sort of engine:

Green Car Congress: Tour Engine has Prototype II split-cycle engine running

[Ecky]

Originally Posted by drmiller100

Rough Engine Horsepower Determination Program

FWIW< the calculator is shockingly accurate as an upper goal.

Fun calculator but it isn't really applicable to the Honda engines I'm familiar with. For instance it predicts my engine to produce 107HP, when the spec is for 145HP.

Love this discussion!

What's the relationship between more smaller cylinders, and fewer bigger cylinders with the same total displacement, and FE? Would the larger cylinders typically be better due to reduced friction?

[drmiller100]

Originally Posted by Ecky

Fun calculator but it isn't really applicable to the Honda engines I'm familiar with. For instance it predicts my engine to produce 107HP, when the spec is for 145HP.

Love this discussion!

What's the relationship between more smaller cylinders, and fewer bigger cylinders with the same total displacement, and FE? Would the larger cylinders typically be better due to reduced friction?

Hey Ecky,

I took an 1800 cc engine, at 9.5 to 1, at 7200 rpm. It came back with 137 horsepower, which is about what I would expect from a B18 at full chat.

Which Honda engine do you have?

[Ecky]

B18B1, Wiki states 9.2 CR, 145HP @ 5800rpm. The older B18A1 is rated 140@6300.

Peak torque is pegged at 5200rpm but the torque "curve" you get back from a dyno on this motor looks more like a flat line.

I just spent an hour and a half reading about the new SAE rating system, I wonder if Wikipedia revised these ratings or if they are under the old system?

EDIT: What sparked my interest in this was comparing Honda's latest Civic engine, the R18A1, to the B18B1 which was standard in 1994. They both have similar horsepower and torque ratings, with the R18 being a much more complicated engine (mostly to improve efficiency at part throttle). However my reading leads me to believe the horsepower number pegged on the R18 of 140@6300 is using the new SAE numbers, so that's 140 at the wheels with power steering, A/C, and drivetrain losses, while the 145 pegged on the B18 is at the crank with nothing attached. I expect the R18 is probably closer to 160hp at the crank, while the calculator spits out an expected 132 for it.

[Frank Lee]

Some time ago I saw a siamesed B&S on Youtube... wonder if it was the same guy?

[shovel]

I hadn't previously been exposed to the Gnome engine from earlier in this thread, Animated Engines - Gnome Rotary - and some of the discussion got me thinking, what would happen if this idea was modernized, and then applied to a gas-electric hybrid configuration (i.e. Prius-style) to capitalize on its necessary small displacement and likely high operating RPM

Broken down for clarity:
Benefits

• Very little reciprocating mass, just the "wagging" of the piston skirts and connecting rods as they accelerate/decelerate, and the movement of the valvetrain.
• Could return impressive volumetric efficiency if modernized
• Should run very smoothly, and be capable of very high RPM due to lack of significant reciprocating mass

Drawbacks (and how they may be addressed)

• Gyroscopic effect (when used as a WW1 aircraft engine) -
  1. Probably not relevant in a car. Mount it on a vertical axis and this effect may actually improve vehicle dynamics, rather than detract from it. This then becomes a packaging problem, which is easier to solve.
• Total loss oiling system
  1. This is a tough one - perhaps because there is no piston reciprocation it's conceivable that a "permanently lubricated" design may offer suitable lifetime - you could probably get away with ball or roller bearings on both rotational axis' (piston axis and cylinders axis) because of the elimination of reciprocation.
• Management of exhaust gases
  1. This is also tough... I suppose on the airplanes, exhaust simply left the 'head' into the atmosphere and that was that. Unacceptable on a car, of course. What if the cylinders were "headless" and rotated within a single, stationary ring shaped head? Clearances/scrub seals would be a nightmare, but you could have one spark plug, and the exhaust 'valve' could be just a slot in the "ring" head that the top of the cylinder moves past during its circuit. Like some sort of wankel-gnome amalgam.. thing.
• Management of fuel
  1. I'm thinking, you could mount a fuel injector in a stationary position at the center, that fires past the open intake valve same as a familar automobile engine... they didn't have that 100 years ago.

It also seems to me that somehow the space between the cylinders and the fact that the whole assembly is rotating, could be used as a duct to supercharge the engine as it runs, "ram air" so to speak.

Thinking out loud, flame all you want

[user removed]

http://www.youtube.com/watch?v=2BQwB...jUV36T-b0mi_o=

Freeze the video at the very last few seconds. The cylinders and pistons are reversed from the original. This is one of the basic modifications of my design which started out as an IC engine in 2004. This is a fixed displacement pump which could be used for a split cycle with on pump for intake, a combustion chamber, and one pump for power.

The present design is one with an adjustable stroke position through the fixed hub, with hydraulic fluid providing power to the outer rim, and variable displacement and neutral and reverse as well as forward positions. This would work as a drive system with an accumulator, the engine would only have to resupply pressure to the accumulator which would also serve to recover deceleration forces. A fully charged accumulator would be capable of providing the energy for a single 0-70 acceleration or a single 70-0 braking event.



regards
Mech

[drmiller100]

Originally Posted by Ecky

B18B1, Wiki states 9.2 CR, 145HP @ 5800rpm. The older B18A1 is rated 140@6300.

Peak torque is pegged at 5200rpm but the torque "curve" you get back from a dyno on this motor looks more like a flat line.

I just spent an hour and a half reading about the new SAE rating system, I wonder if Wikipedia revised these ratings or if they are under the old system?

EDIT: What sparked my interest in this was comparing Honda's latest Civic engine, the R18A1, to the B18B1 which was standard in 1994. They both have similar horsepower and torque ratings, with the R18 being a much more complicated engine (mostly to improve efficiency at part throttle). However my reading leads me to believe the horsepower number pegged on the R18 of 140@6300 is using the new SAE numbers, so that's 140 at the wheels with power steering, A/C, and drivetrain losses, while the 145 pegged on the B18 is at the crank with nothing attached. I expect the R18 is probably closer to 160hp at the crank, while the calculator spits out an expected 132 for it.

I "fixed" the wiki - 5800 is just flat wrong. Various sources say 6300 to 6800 - i suspect 6800 is closer.

The K series engine is actually closer to the replacement for the B series. The K is about the same weight, and a LOT bigger and stronger engine. I talked at length to the Hondata guys at Bonneville - 600 plus horsepower out of a basically stock bottom end other then rods and a ton of boost.

The R series is more of a replacement for the D series. Better mileage. The exhaust manifold is truly creative. For pure mileage, pretty tough to beat an R series but I'm just a bit scared of the wiring harness - looks pretty complicated.

[some_other_dave]

Originally Posted by shovel

I hadn't previously been exposed to the Gnome engine from earlier in this thread...

The Gnome Monosoupape engine had low compression, unbelievably poor valve timing, a total-loss oiling system, ran its intake through its crankcase, and dumped its exhaust straight out into the air. It also could not effectively be throttled.

Its only real virtues were dependability through simplicity (fewer moving parts than most engines of the day), and that the major mass of the engine spun around and acted as a flywheel; engines of the day needed pretty sizeable flywheels to run and that added significantly to the weight. Since the rotary engine used the engine itself as the flywheel, it did not need the extra weight.

Check the Wikipedia article: Gnome Monosoupape - Wikipedia, the free encyclopedia

"...the Gnomes exhibited even poorer fuel economy than other rotaries because the inlet valves opened at times that were not efficient..."

Checking the main article on Rotary Aircraft Engines shows similar comments about their efficiency.

-soD

[user removed]

All true SOD, but you should also look at other engines in the same time frame. One of the best was the Mercedes 200 HP grand prix engine. It ran 2300 RPM compared to the gnome at 1300 and was twice the displacement of the gnome, about the same as the Merlin used in Spitfires and Mustangs in WW2. Low compression was a product of the fuel used.

Actually the later Rotaries used in the Sopwith Camel even had a carburetor that would work when the plane was inverted, solving a problem that even plagued the early Spitfires 20 years later.

Where were auto engines in 1913, compared to today.

The rotary is not a reciprocating engine and every refinement made over the last 100 years could be applied to the rotary today. A modern rotary configuration would be a low RPM torque monster, ideal for electrical generation or for hydraulic hybrids. Bury the engine in the front cross member for packaging and have a trunk in each end of the vehicle.

Comparing 1913 technology to today's, is like comparing the Deperdussin racing monoplane to the Space Shuttle, or maybe a F18 Hornet. Let's make sure we make relevant comparisons.

Would you want to Captain the Dreadnought against an Aegis Destroyer?

regards
Mech