12 a
It has been such a busy year for me, no time free and a baby due in 3
more weeks. I am taking 3 weeks vacation coming up and want to plan
things out to make the most of it.
Sachs 40hp rotary is running on a carb but i want to make it fuel
injected. I am still working with the maximite trying to come up with
a program for the EFI.
My question to you is about temps for the rotary. I have the manuals
for the Sachs, both repair and parts. No where can I find anything
about the temps this engine should run at. I was thinking of using a
cylinder head temp probe under the spark plug and a bayonet J style
thermal couple in the exhaust to monitor the EGT.
What temps do you think I should be running at for the head and
egt's? I only have one of these ready to run, it is air cooled, no
fan like it had in the snow mobile I am hoping prop wash and airflow
over the engine during flight will help keep the temps down, but I
need to figure out what those temp limits are?
Any help you can give Paul, or anyone else would be deeply be
appreciated.
Thanks David M. San Jose, CA
Well the head should be 500 F absolute maximum. 400 F would be a lot better.
The EGT'ts could be a max of 1800 F but that is not as critical.
This is a charge cooled engine so you will not be able to run at full power for long.
I think 10 seconds might be OK. The rest of the time less than 70%
I am guessing based on the AIXRO specs.
Paul Lamar
The 10s limit applies to a karting engine, which has a bypass and runs at >10000rpm.
The bypass leads cold, fresh air directly into the combustion chamber, so does not
contribute to cooling the rotor and main bearing while it runs at peak power. When
our engines are used for flying and similar applications (many engines currently go
to unmanned helicopters in Asia), the bypass diameter is restricted and can be open
for a few minutes at a time, so it is useful when a little extra power is needed.
The most important parameter for a charge cooled engine is the charge temperature
after passing the rotor /main bearing and before entering the combustion chamber. Use
a small probe to have the sensor reacting quickly, e.g. a small EGT sensor. We prefer
to keep it below 130°C peak. 266 F
Attached is a photo that shows the transfer port in the side plate incl. the bearing
temp sensor (red circle). The arrows indicate the air flow from the rotor through the
transfer port (red) as well as through the bypass (blue).
On an air cooled engine checking the casing temp e.g. in the spark plug area makes
much sense. The Sachs air cooled housing are known to come apart under high thermal
load, so the Snowmobile application is a good one for these.
Poul (Aixro)
266 F wow that is high Poul. Your apex seals are shorter than the Mazda.
I think that would destroy a Mazda with steel or iron apex seals.
Are they using Iannetti or silicon nitride seals in Asia?
Paul Lamar
------------------------------------------------------------------
Please add your questions or comments at the end of the thread. Not the beginning.
I am going to enforce that rule. If people don't do that it will not be forwarded. My
ISP changed the rules.
The Rotary Engine free News Letter. Powered by Linux. If you want off the list PLEASE
let me know and I will remove you.
ACRE NL web site.
http://www.rotaryeng.net You Tube
http://tinyurl.com/beqqxas or
PaulLamar2 Copyright 1998-2018 All world wide rights reserved.
