BMW Luxury Touring Community banner

1 - 15 of 15 Posts

·
Registered
Joined
·
1,316 Posts
Knowing next to nothing about engines one has to ask, How is the wankel 'dicey'?
 

·
Registered
Joined
·
279 Posts
rixchard said:
Knowing next to nothing about engines one has to ask, How is the wankel 'dicey'?
I guess it depends on the writer's definition of 'dicey.'

To me, the Wankel rotary engine is a proven design has been around for many years and has been successfully marketed in production automobiles (Mazda) and motorcycles (Suzuki.) The design produces a good amount of power from a small package, but in the past, there were reliability problems and they were not very fuel efficient. I believe the newest Mazda engines have improved on both points.

From what I can get from their web site, the Revtech engine is not a major technological breakthrough, but just a different combination of existing technology. Unfortunately, it is still designed to use fossil fuels, when new engine technology should be directed at something more renewable, such as alcohol or bio-diesel.
 

·
Registered
Joined
·
1,281 Posts
Discussion Starter #4
Wankels have difficulty meeting modern emmission standards. I also seem to remember their sliding seals being problematic or difficult to service. But, technology may have surpassed my understanding I will admit...
 

·
Registered
Joined
·
1,281 Posts
Discussion Starter #5
Drunken Engine

From what I can get from their web site, the Revtech engine is not a major technological breakthrough, but just a different combination of existing technology. Unfortunately, it is still designed to use fossil fuels, when new engine technology should be directed at something more renewable, such as alcohol or bio-diesel.
Ethanol is starting to appear. The first E85 Ethanol pump appeared this week in San Antonio (85% ethanol, 15% gasoline). Some existing vehicles can use it as is. Would be a tremendous step towards reducing gasoline usage and dependence on foreign oil. Would also greatly benefit the American farmer. Sounds like a no brainer to me. The down side - E85 gets about 10% poorer gas mileage.

Check this website to see what vehicles can use E85: http://e85fuel.com/index.php

BTW, "fossil fuel" is a misnomer - oil formation is no longer blamed on decaying plant and animal matter. Many believe oil is formed abiotically deep in the earth from methane. Two representative articles:
http://www.enviroliteracy.org/article.php/1130.html
http://www.voicenet.com/~wbacon/documents/newoil.html
 

·
Registered
Joined
·
564 Posts
I was looking at and reading about the Mazda RX8. Seems Wankels still give relatively poor fuel economy, high oil consumption and have weak low end torque.

Too bad, kinda like that car.
 

·
Registered
Joined
·
1,492 Posts
... on the RX8, you have to put about a pint of oil in, every time you top up the gas tank - still haven't got those tip seals sorted yet :(
 

·
Registered
Joined
·
2,406 Posts
:confused: Thought I looked over the site pretty close ... Saw NOTHING stating Rpm range engine will tollerate or type of head / valve lay out.

Pictures did show what looked like a DOHC and whimpy intake runners ... Like a Subaru flat 4 ?

And with NO rpm info, no way to even get an idea on horse power figures ?

Any insight from you folks ?

Scott
 

·
Registered
Joined
·
1,281 Posts
Discussion Starter #9
motorhead said:
:confused: Thought I looked over the site pretty close ... Saw NOTHING stating Rpm range engine will tollerate or type of head / valve lay out.

Pictures did show what looked like a DOHC and whimpy intake runners ... Like a Subaru flat 4 ?

And with NO rpm info, no way to even get an idea on horse power figures ?

Any insight from you folks ?

Scott
I had the same problem not finding data. Must be classified "Industrial Secret", or else it's not as good as their hype would lead you to believe.
 

·
Registered
Joined
·
12,165 Posts
I have seen many "revolutionary" engine designs touted over the past 40 years, all claiming to be the internal combustion engine for the next century. There have been at least 4 that I can remember that had cam arrangements to harness the piston motion. None have ever come close to making it to market.

This one has been written up in aviation journals more than any other that I can remember, but it seems to have been in about the same stage of development now for about 5 years. http://www.dynacam.com/Index.htm
 

·
Registered
Joined
·
1,134 Posts
Hmmmmm...

Please take into account the 'Major' players whenever you see new and interesting technology being evaluated.

The Big Boys DO NOT WANT competition. They have amortized their development a LONG time ago. And, will do anything to keep upstarts from developing new mousetraps.

With all due respect to our member engineers, MOST engineers I have worked with are taught to think 'Within the Box" not outside it.

If some of these newer ideas were given the time of day AND the dollars they deserve, we might NOT be in the present energy quagmire! :mad:

BIG OIL + BIG DOMESTIC AUTO COMPANIES + BIG GOV'T = F**K YOU!

Of course, this is just, My Humble Opinion...
 

·
Registered
Joined
·
12,165 Posts
If any big company saw a design that was truly better, bets are they would buy it out and produce it. No large company can sit back and gamble that one of their competitors won't buy out a better design and beat them about the head and shoulders with it.

Believe it or not, a company that ignores something that is likely better, will die when better minds prevail and use the better approach.

There are many of these "better" approaches that have been touted over the past few decades, but proved to be non feasable for sound engineering or reliability reasons or just plain too expensive to produce compared to current engines, for small possible overall gains.

There have been cries of "keeping it out" related to engines, fuels, etc. (anyone remember the "Fish" carburetor?) for decades, but still, the better technology for the time and purpose usually wins out regardless, with very few exceptions. There have been a small number of cases where a large corporation will buy out a patent, and then sit on it to protect their investment from a competitor getting the patent and using it against them, but still, these types of cases are exceedingly rare.
 

·
Registered
Joined
·
279 Posts
dshealey said:
If any big company saw a design that was truly better, bets are they would buy it out and produce it. No large company can sit back and gamble that one of their competitors won't buy out a better design and beat them about the head and shoulders with it.

Believe it or not, a company that ignores something that is likely better, will die when better minds prevail and use the better approach.

There are many of these "better" approaches that have been touted over the past few decades, but proved to be non feasable for sound engineering or reliability reasons or just plain too expensive to produce compared to current engines, for small possible overall gains.

There have been cries of "keeping it out" related to engines, fuels, etc. (anyone remember the "Fish" carburetor?) for decades, but still, the better technology for the time and purpose usually wins out regardless, with very few exceptions. There have been a small number of cases where a large corporation will buy out a patent, and then sit on it to protect their investment from a competitor getting the patent and using it against them, but still, these types of cases are exceedingly rare.
This may all be true in the automobile (or motorcycle) industry, but I can say for certain that in the aviation industry, 'status quo' has been the only accepted practice for decades. That's why most "modern" piston aircraft engines are still using technology that was developed in the 1920's. With a few notable exceptions, magneto ignitions and antique carburetors or mechanical fuel injection systems are still being installed in brand new Cessnas, Pipers, Mooneys, etc. While unleaded gasoline has been the standard for automobiles for more than 30 years, most new piston airplanes are still designed to use gasoline containing lead as an octane booster.

The main reason? The aviation industry is (for good cause) deathly afraid of trial lawyers! The installation of any new technology is justification for the sharks to start circling. The "logic" is that if the manufacturer adopts a new technology, then the old technology must have been faulty. Therefore, the faulty old technology must have caused the airplane to crash and kill the poor innocent pilot and his passengers. Therefore the aircraft manufacturer is on the hook for millions of dollars of product liability claims.

As long as trial lawyers are allowed to bring (and win) huge product liability law suits based on junk science and sympathetic juries, the aviation industry will be stuck firmly in the first half of the last century.
 

·
Registered
Joined
·
12,165 Posts
Yep, I flew GA for some time, have private and instrument, but have not flown now for about 4 years.

One of the main reasons avaiation engines have stayed where they are is the extreme cost of certification. There have been a couple of nice piston engine developments, but the costs were huge to get them certified. Even Toyota developed piston aircraft engines, and actually went through certification, only to decide against marketing them at the time. Liability? Probably. Surprised they did not sell them in other countries that do not have the overzealous litigation attorneys we are "blessed" with.

There are also Diesel aircraft engines now becoming more available. The big advantage with them is no gearing required to get the prop speed down, as converted auto engines require, and most of all they can use jet fuel instead of the increasingly more expensive AvGas. Europe has been the leader in diesel development.

Here is a nice article about aircraft engine development. Don't know when it was written though, not dated.
http://www.prime-mover.org/Engines/GArticles/article2.html
 
1 - 15 of 15 Posts
Top