OT: Which Engine Configuration has the Most Power?, Curious Minds Want to Know Options

[tat2dphreak]

I want to add one thing about the rotary... it may have already been said, but the engine is Very efficient... part of the reason is it takes only 1 rotation to complete a cycle, whereas piston engines require 2 rotations...

the rotory engine fascinates me

[ArtechnikA]

QUOTE (tat2dphreak @ Aug 26 2005, 02:56 PM)

I want to add one thing about the rotary... it may have already been said, but the engine is Very efficient..

it is mechanically efficient.
its thermal efficiency kinda sucks.

it is hard to make them run clean, and it is hard to make good fuel economy numbers.

big Diesel engines have the kind of specific consumption (lbs fuel/HP) numbers most engines can but dream of.

VW TDI engines actually have issues in the cold - they don't make enough heat to warm themselves to "operating temperature."

[lapuwali]

Rotary engines actually have terrible thermal efficiency, which is why they get such sucky gas mileage. Mazda was nearly bankrupted when they first introduced them just in time for the 1973 OPEC oil embargo, which raised world oil prices by 80% almost overnight.

The main reason they have such bad thermal efficiency is the "combustion chamber" takes up the entire inner wall of the rotor housing. Because its so spread out, quite a bit of the energy in the gasoline goes to heating up the housing, rather than being used in propelling the rotor around the crank. A huge amount of the energy also ends up escaping out of the exhaust, easily seen by looking at the sky high EGT figures on any rotary. Combustion never really quite completes on them, so HC figures are also extremely high (the second nail that nearly did in Mazda in the early 70s).

Rotarys are efficient in terms of power for their overall size and weight, but for efficiency in terms of how well they extract energy from their fuel, they suck big rocks.

[BMartin914]

QUOTE (ArtechnikA @ Aug 26 2005, 11:02 AM)

VW TDI engines actually have issues in the cold - they don't make enough heat to warm themselves to "operating temperature."

Yes. I know a Jetta TDI driver that can drive around for 20 minutes in the winter until the temp needle even begins to move.

[Rgreen914]

QUOTE (flesburg @ Aug 25 2005, 04:11 PM)

...the rotary, such as used to be used in aircraft was theoretically the design with the least inherent (spelling) vibration...

In WWI, the French Nieuport airplane (nick-named "Baby", for its diminutive size) had a radial design engine but it was referred to as a "rotary" because the whole damn engine spun around with the propeller! The exhaust poured out from the cylinders in a cloud and later, a shroud was developed which covered about 75% of the upper area of the engine; this shroud directed the smoke out the bottom of the engine and away from the pilot. These aircraft apparently suffered a number of landing crashes due to excessive vibration combined with their abbreviated length! Film of these aircraft displayed the most bizarre idling qualities and the engines often sounded as if they were intermittently being switched on and off! Some other models of Nieuport aircraft also shared this engine.

Ron

[lapuwali]

It wasn't the vibration that caused the landing crashes. It was the enormous gyroscopic effect of that huge mass spinning at the front of a very short and light airframe. If you banked the plane one way, the nose would climb rapidly, if you banked it the other way, it would dive rapidly. If you pushed the nose down, it would bank violently. Pull it up, and it would bank the other way.

Plenty of novice pilots died trying to turn shortly after takeoff, and finding the plane either nose down, or nose up so much it stalled, because they forgot to apply opposite elevator and rudder to compensate for the gyro effect.

[Rotary'14]

Concerning rotary engines, I feel that mazda has come a long way in regards to the refinement and evolution of the engine. Mazda's latest rotary engine uses an idea that has been around since the 70s (in regards to port design/layout) but efficient fuel control took 30 years to make the idea a reality. Remember the rotary engine is merely an adolesent compared to the piston engine designs that have had over a century of developement. I bet new coating technology would likely help the rotary engine in it's later developement.

On a side note my beloved rotary engine has attributes that make it a good candidate for a hydrogen IC engine. So the engine might be as common as the piston engine in a hydrogen powered future.


Don't get me wrong now, I do not want this to turn into a rotary is better than everything kinda thread.
I think piston engines are marvelous too, really!


(IMG:http://www.914world.com/bbs2/html/emoticons/boldblue.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/boldblue.gif)

[jonwatts]

Is anyone else who's reading this thread thinking lapuwali and Artechnika are twins that were separated at birth?

[redshift]

QUOTE (Rgreen914 @ Aug 26 2005, 09:32 PM)

In WWI, the French Nieuport airplane

Prop torque n p-factor.

Ground loop the crap out of any tail dragger, you have to hold hard right rudder, and apply slow throttle moves.


M

[banksyinoz]

the majour problem with the rotors is that when they are out of the power they use more fuel than a v8 ,however when in the power they use the power
in a peripheral port
ie 0-7000rpm fill up the car behind
7000-14000 they will use the fuel
they also have a low centre of balance as with a boxer

my theory which i have also experienced is that a rotor is not much good without a bug huffer

at the end of the day u use what you want for your given purpose (IMG:http://www.914world.com/bbs2/html/emoticons/beerchug.gif)

[IronHillRestorations]

QUOTE (Britain Smith @ Aug 25 2005, 03:16 PM)

I was discussing the engine layout of a Porsche motor in a horizontially opposed configuration and the question came up on which engine configuration produced the most HP/liter and why? I know that an advantage of a Porsche motor is that the center of gravity is really low, but does its configuration have any power advantages when compared to say a 90 degree V6 or an straight 6? For simplicity, lets keep the discuss focused on normally aspirated motors. What are you thoughts and why? -Britain

In the Porsche normally aspirated boxer engine family (stock), the 2.2S sixes have the best output per liter. This doesn't include racing version, or the four cam four cylinder Carrera engines.

[SLITS]

QUOTE (bd1308 @ Aug 25 2005, 08:11 PM)

the worst engines in my experience balance wise is the Jeep inline series engines.... they are bullet-proof....OHV and strong engines (i had a 2.5L I4) but the balance is horrific.....even with the harmonic balancer it was like chattering my teeth..... i miss that jeep. until i fill up my 914 for $26...

Your "Jeep" 4 was actually a GM engine w/ some mods.

[messix]

QUOTE (Rgreen914 @ Aug 26 2005, 06:32 PM)

QUOTE (flesburg @ Aug 25 2005, 04:11 PM) ...the rotary, such as used to be used in aircraft was theoretically the design with the least inherent (spelling) vibration... In WWI, the French Nieuport airplane (nick-named "Baby", for its diminutive size) had a radial design engine but it was referred to as a "rotary" because the whole damn engine spun around with the propeller! The exhaust poured out from the cylinders in a cloud and later, a shroud was developed which covered about 75% of the upper area of the engine; this shroud directed the smoke out the bottom of the engine and away from the pilot. These aircraft apparently suffered a number of landing crashes due to excessive vibration combined with their abbreviated length! Film of these aircraft displayed the most bizarre idling qualities and the engines often sounded as if they were intermittently being switched on and off! Some other models of Nieuport aircraft also shared this engine. Ron

that is how these engines were "throttled" by intermitently cutting the ingition. other wise they ran wide open, no throttle like carb. many engines of the day ran like this is aviation.

any one care to elaborate with more expertise?

[bd1308]

hmm.

so the only engine Jeep really does have is the 4.0L /6 ?

[flesburg]

In my original reference to a rotary engine, I was not refering to the goofy WWI french engine that had the crankshaft rigidly mounted to the aircraft frame and the engine housing mounted to the propeller, which ment that the entire engine casting spun around with the prop, but I am refering to the rotary engines commonly used in most all commercial aircraft until the age of the turbojet. They were made by many manufacturers like curtis-wright. Look at a B17 or B29 or most Navy fighter craft of WWII.

Sorry I brought it up, but I only did to point out the of all internal combustion piston engines ranked from a standpoint of vibration and theoretical lightness of weight,

best to worst designs;

best: rotary (only found in museums, I think)
next best: horizontally opposed (still used in lighter piston engined aircraft)
in the middle: v engines with the "proper angle" between cyl banks
least best: a v engine with incorrect angle between cyl banks, like my ford 3.1 v6

We certainly got off on a tangent. Sorry I brought it up.

[lapuwali]

QUOTE (jonwatts @ Aug 26 2005, 11:30 PM)

Is anyone else who's reading this thread thinking lapuwali and Artechnika are twins that were separated at birth?

No one's ever actually seen us together...

(IMG:http://www.914world.com/bbs2/html/emoticons/cool_shades.gif)

[redshift]

Uhh... yes someone has..

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[grantsfo]

I know this naturally aspirated rotary made 700 hp. Not bad for such a small powerplant. Here's a bit of Porsche trivia - it was hooked up to a Porsche tranny on the Mazda LeMans car.

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