Anybody have experience with a failed Suburu Head gasket.
 Milo was on the way from Washington to Texas and made it as
 far as SZP. Then the Soob engine had a mysterious over heating
 problem towing a trailer.


 Paul Lamar


 No experience with Soob and blown head gasket, but with a Dodge Minivan, I
 had an overheating problem that seemed 'mysterious'.

 It would overheat, and when you checked the coolant reservoir it would be
 full. When the engine cooled, the reservoir would go down as expected.

 The problem was a small leak in the head gasket, which would put
 combustion
 gas into the cylinder space, driving the coolant out of the engine and
 into
 the overflow reservoir.



 Bill Schertz
 KIS Cruiser #4045
 N343BS


 Bill, did you try any chemical sealants such as duraseal or steel seal?

 Paul Lamar

 Yes I have as that is my business and I rebuild 3 to 4 engines a week, no
 none of those sealants will work as the problem is the combustion pressure
 is pushing past the gaskets into the water system and pushing the water
out
 the burp tank and so there is no way to plug the leak unless you could get
 the sealant into the combustion chamber to shove it into the hole thats
 leaking, hate to say it but you are best to go for a whole engine as you
can
 mill the heads when you replace a head gasket but you cannot mill the
block
 and the block warps as much or more than the heads so if you put a new
 gasket on a straight head and a warped block it wont last long, I can do a
 compete long block for $1500 to $1600 depending on which engine it is and
I
 fix all the problems that Subaru had to make it better than new.
 Give me a call if you need more info.
 Ken


 360-834-4089


 I don't know which engine is in that Subaru, but my sister has one and it
 had a bad head gasket and this is a known problem.  They have an improved
 replacement gasket that fixes it but they didn't do a recall and replace
it
 on their dime.

 Steve Brazil


 The good news is as far as Milo and family are concerned is they were
able to plug
 the leak with goo. After the engine cooled off it sucked all the coolant
back
 out of the over flow can. That would not have happened if the leak still
existed.
 That is part of the process. If the exhaust valve and intake valve is
closed
 hot air in the cylinder cools off causing a low pressure in the cylinder
drawing
 the sealant into the leak. This is somewhat of a crap shoot as the leak
must
 occur around the cylinder that happens to stop in that sealed condition.
 Also of course the coolant itself also contracts drawing coolant in from
the
 over flow can.

 There has been several recent breakthroughs in these stop leak type
 fluids.
 Prior to these breakthroughs most stop leak type products required you to
purge
 the engine of antifreeze coolant. This is no longer true of the better
products.
 The other breakthrough is a chemical reaction that is triggered by the
high
 400 to 500 F metal temperatures that causes the goo to solidify in the
area
 of the leak but not in the radiator.

 Here is the web site that claims to be the best.
 It is called Steel Seal. It is a clear liquid with no particulate matter
 at all. It is rather expensive at $70 and they claim to have an iron clad
 patent. "The product is drawn into the damaged area and seals the crack
 with a thermo-chemical bonding process."

 I have not tried it on a leaking rotary yet but
 it sounds promising to fix the shrunk rotor housing problem due to
extreme over
 heating of the rotary. Milo has some on order to test it on the soob if
the
 stuff we actually used fails.


 https://secure.steelseal.com/**index.php/t2b<https://secure.steelseal.com/index.php/t2b


 Paul Lamar

 The reason the water is pulled back out of the burp tank is that the
coolant system is full of air and it contracts and I still say there is no
stop leak that will plug the leak it is combustion pressure going going
into
the water not the water going into the combustion chamber so you would have
to pour the stop leak into the spark plug hole to get it where you want it,
there is no way no how that stop leak will fix the problem.

 Well while we are on the Subaru subject I may as well make a confession
and
I know that is probably a capital sin and I will probably go to hell for it
but I have a 6 cylinder Subaru SVX 3.3 engine sitting on the floor that is
going to find its way onto the engine pylon of my coot.

 Ken

Life is sometimes like that. One takes one step forward and has doubts and
then
takes 2 steps back :) What PSRU ratio will you use with the Soob?
You are currently using a 3:1 PSRU ratio with the Rotary.
My guess is you  have about 480 foot pounds at the prop at 6000 RPM with
the rotary.

 231 HP at 5400 RPM  Max torque  228 at 4400 RPM.

Torque times rpm divided by 5252 = HP

So HP times 5252 = torque times RPM

So torque = HP times 52542 divided by RPM

So max soob engine torque is 228foot pounds.

But the max PSRU ratio you can use to keep the prop under
2700 is 2 to one. So torque at the prop is 456 foot pounds.

Running a piston engine at full load max HP RPM is like
standing next to a hand grenade. You need to try it sometime.
A real experience to say the least.
My guess is the life expectancy will be about 300 hours
unless the head gasket goes first or a valve burns :)

Since the last flat six they made was in 1997 you may have problems
finding parts.

The final question is what is the weight. Search as I might but
many say it is heavy. My guess is 3 to 4 hundred pounds while
the rotary weighs 200. The double over head cams and four valves
per cylinder do little for the weight.

IMHO you would be better off with a p-port.

So you save 1 gallon an hour with the Soob for awhile.

Interesting experiment Ken. Keep us informed on how it goes.

Paul Lamar



I work on both porsche and sube engines. The svx is nearly identical to the
last aircooled 911 engine in its geometry. The bore to stroke ratio, rod
length to stroke ratio, deck height, and bearing sizes are almost
identical. I believe the same is true compared to the first gen water
cooled 911 engines.

While these may be the best overall automotive piston engine designs for
transferal into aircraft, they are also, each of them, very flexy engines.
The sube cylinder walls are hollow. There is space between the iron liner
and the alum casting. This is also the case for the rest of the EJ sube
engine line. The 911 aircooled cylinders flex independent of the adjacent
cylinder. The water cooled 911 engines are a much better design and are
designed, at least in the lastest versions of them, to handle a good 50%
more power than SVX. Recently showroom floor engine output for the 911
carrera S is over 400hp, from a 3.6 liter.

There are tricks for the sube engines to make them rigid, but it requires
eliminating the stock iron liners, and supporting the cylinders at the top
of the bore. A rather expensive set of operations.

There is one big drawback of both the porsche and sube designs, that is,
the rod angle is really too steep to be considered durable in constant
output operation. The rod angle problem is directly related to the low deck
height of these engines. In the case of the porsche engines, the engineers
have not raised the deck height since 1963!, when they were only 2 litre
engines. So they have stuffed all of that extra displacement within the
original 2 liter package confinements.

The angle of the rod dips down far enough to put excessive load on the
piston skirt, and on the cylinder wall when under heavy load. In the case
of the sube, the wall cracks, then shortly thereafter, everything breaks.
In the case of the porsche aircooled cylinders, the lower cylinder snaps,
ending your; ah, porscha driving privileges for the day, with a large hole
in the case.

Now I have a couple SVX engines in my garage. And perhaps 5 or 6 porsche
engines here too. (Not counting the water cooled ones). For obvious
reasons, my two rotarys' are for the cozy4. I paid almost nothing for both
of them. Selling the peripheral parts from the rx8 paid for the initial
cost of the purchase, leaving $ sufficient to pay for my next rotary engine
purchase. I am p porting both of them, which is a relatively inexpensive
task when compared to the cost of necessary piston engine improvements on
the above two H6 configurations.

Cut the fat, use a rotary.
More space
Less drag
etc, etc.

Ed Carver


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