This is unadulterated BS. There are many, many Mazda RX7's and other
rotary powered
cars out there with well over 300,000 miles. 500,000 kilometers. I
see many 25 year old
first gen RX7's on the freeways of Southern California almost every
day. I saw one
this morning.
I have owned six rotary powered cars. A new RX2, an RX4 station
wagon, a two rotor Cosmo,
two 2nd gen RX7's and I currently own an RX8. Some with over 300,000
miles. None of them
ever had any problems with apex seals or problems with the chrome
plating.
Some Mazda rotary aircraft applications in gyro copters have over
2000 hours with no troubles.
Rotary engines have been used in aircraft since 1973 with stock
Mazda chrome plated
rotor housings. Further more chrome plated cylinders were specified
in WW II by the US Navy
for all their aircraft engines for salt air corrosion reasons.
Chrome plated cylinders
were also widely used in general aviation air cooled cylinders and
still are.
http://jhbperformance.com/technical.php
IMHO the credibility of this company is zero.
Paul Lamar ...No rotor no motor.
Interesting that they offer a re-chroming service.
John
I think this topic came up before - take a look at rx7club.com and
nopistons.com
Here are pics of one JHB failure:
http://www.rx7club.com/showpost.php?p=7342066&postcount=18
A local fellow described a similar failure.
Cheers
Cary
Paul, Cary,
On this RX- forum Eric makes a fairly good argument on why the thinness of
ceramics not insulate very well. They were mostly used to reduce friction
between the seals and the housings.
http://www.rx7club.com/showthread.php?t=691725
----------
Q = kA / t * dT or dT = Qt / (kA)
Q = heat transfer
A = area
k = material constant. 200 W/m*K for aluminum, 1 W / m*K for ceramic.
t = THICKNESS
dT = temperature differential across the coating.
A super thin coating cannot insulate. Period. Anyone claiming such is
stealing your money. The poor convection in that thin layer of air is a
better insulator than that coating. With piston engines that layer of air
isn't so thin, hence the better thermal efficiency.
The combustion chamber temperature can get up to ~2000 C. The coolant
temperature is about 80C. So dT from the engine to the coolant is huge. But
the engine walls are less than 150C. Otherwise the aluminum would soften and
fail (that's probably why the rotors are iron). In reality the aluminum
temperature is probably very close to the coolant temperature. So the dT
from the coolant to the engine walls is less than 70C and the dT from the
middle of the combustion chamber to the combustion chamber walls is over
1930C. That goes to show right there how much insulating is done simply with
air.
Here's a way to illustrate. Pour coffee in an aluminum, paper cup and then
plastic cup. Even the plastic does next to nothing to stop the heat. Yet
it's 10 times better than ceramic and 10 times thicker than most coatings.
Now go to Starbucks where you'll get a cheap paper sleeve on a paper cup,
with folds in it to create a tiny air gap between the two papers.
__________________
'87 white N/A RX-7, 115k miles, cone intake, TII front springs, RP standard
clutch kit, Racing Beat sways
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Last edited by ericgrau : 09-27-07 at 08:46 PM
http://www.rx7club.com/showthread.php?t=691725
Follow the link to the bottom of the page and you can see a good insulator.
Aerogel I believe it is called. Of course not used in an engine:)
Good for survival emersion suits no doubt.
DougFir
"Even the plastic does next to nothing to stop the heat. Yet
it's 10 times better than ceramic and 10 times thicker than most coatings."
Got it; I understand.
So, any comment on these guys: http://ceramicrotaryengines.com/ ?
Les Nordman
Les
I ran across this site about 2 years ago and checked it out again recently.
It seems they are slowly making a small micro rotary. There is another
group out there proposing a larger all ceramic rotary engine. All of this
talk is fine and great but it is a part of a long research road that even
the big firms are slow to enter. Coatings yes, but parts few. I was surprised
to find out that the industry didn't jump on, IMHO, a great idea of the
ceramic turbine used in the Datsun roadster. Ceramic ICE bottom line is it
will take many more years to perfection.
DougFir
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