Brison 3.2-will a 23-8 prop be too much for it?
02-01-2015, 05:23 AM
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Brison 3.2-will a 23-8 prop be too much for it?
I have this engine on a 50cc size pitts s-12 biplane.I don't care at all about 3D type flying, I fly IMAC style and have been running a 22-8 on it. I've heard some say that this engine does better with a smaller diameter prop,, just wanted to hear from some RCU guys. Thanks
02-01-2015, 09:24 AM
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You don't say what brand of prop you are using but a quality 22-8 is pretty much what that engine likes. Being a Sachs based engine, it likes to turn up and its not quite the torquer the newer rear intake engines are. I think you'll find the performance will drop off quite a bit if you go to something like a 23-8. If you had the engine in a warbird, I might recommend a smaller diameter, higher pitched prop but your higher drag biplane will like as much diameter as the engine will pull .... which pretty much puts you back at the 22-8.
I prefer the wood Bolly or Menz 22-8. The Xoar 22-8, Beechwood or laminated works well but being a higher drag prop, RPMs will drop by several hundred compared to the other two props. Of course, the Menz is really a 21 1/2" prop.
I prefer the wood Bolly or Menz 22-8. The Xoar 22-8, Beechwood or laminated works well but being a higher drag prop, RPMs will drop by several hundred compared to the other two props. Of course, the Menz is really a 21 1/2" prop.
02-01-2015, 03:19 PM
#4
I have only been able to get good RPM(7000) on a Zoar 23x8 on my highest time Brison 3.2 . It is a blue case well broken in with probably a hundred gallons through it. The other 4 newer 3.2s run at their best on a Zoar 22x8 laminated for aerobatic or a 21x10 for speed.
02-02-2015, 04:23 AM
#8
The A&M is close to a pound heavier than the true Brison . Now Brison did convert some A&M's to the Brison
cantelever crank and did reduce some of the weight. The only way to tell is examine the crankshaft. If the A&M has a good crankshaft (either sachs or Brison) it is as good as a Brison except for the extra weight.
cantelever crank and did reduce some of the weight. The only way to tell is examine the crankshaft. If the A&M has a good crankshaft (either sachs or Brison) it is as good as a Brison except for the extra weight.
02-02-2015, 08:00 PM
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Just looking at the A&M Sachs engine, it has on the cylinder head a designation "Mahle"and the numbers " 44zn18 ". Does this give any indication of the crank, or just the cylinder type? Thanks
02-02-2015, 09:03 PM
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That is just the cylinder casting number.
Do some searches here on RCU. There was quite a lot posted about the older Brison and pre Brison engines. The author was Rcignition or under a different name, Antique. That is Ralph Cunningham and he could tell you every detail of those early engines, which ones had the good crank, etc. Its all archived here on RCU if you look a bit. AFAIK. all the Brison cranks were good. All the Brison engines use a Cantilever crank with an aluminum rod.
Do some searches here on RCU. There was quite a lot posted about the older Brison and pre Brison engines. The author was Rcignition or under a different name, Antique. That is Ralph Cunningham and he could tell you every detail of those early engines, which ones had the good crank, etc. Its all archived here on RCU if you look a bit. AFAIK. all the Brison cranks were good. All the Brison engines use a Cantilever crank with an aluminum rod.
02-03-2015, 06:29 AM
#12
The original Sachs 3.2 was a Dolmar 115 or Makita 520 chainsaw engine. I have one of these I use as a chainsaw. It is a 1997 model and is as reliable as chainsaws get. This saw was discontinued back in 2003. In 2013, Makita/Dolmar discontinued the cylinder. So parts are getting scarce.
The Brison 3.2 only uses the cylinder and piston from the Makita Dolmar chainsaw.
There are old Sach's 3.2's that are a cut down chainsaw engine. They are the original chainsaw engine with un-needed parts removed. They are very reliable but heavier than a Brison.
This was a very popular engine for many years. There are a lot of conversion combinations. Some of the cantilevered crank versions didn't hold up so well?
The Brison 3.2 only uses the cylinder and piston from the Makita Dolmar chainsaw.
There are old Sach's 3.2's that are a cut down chainsaw engine. They are the original chainsaw engine with un-needed parts removed. They are very reliable but heavier than a Brison.
This was a very popular engine for many years. There are a lot of conversion combinations. Some of the cantilevered crank versions didn't hold up so well?
Last edited by w8ye; 02-03-2015 at 09:11 AM.
02-03-2015, 09:20 AM
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There is also the Taurus 52 which is an extremely good engine in my opinion. It uses the whole Sachs / Dolmer rotating assembly - crank, rod, piston and cylinder. Having a (2) counterweight crank supported fore and aft in the custom machined case, it is one of the smoother running of these conversion / custom engines and there is no weight penalty.
Quite a few Sachs based engines out there ..... and don't forget the FOX that is almost a twin to the Brison. Of course there is also the FPE which is its own unique use of Sachs parts ..... though later engines have gone away from the now scarce and expensive Sachs parts.
Just about anything you read about the Brison, FOX or FPE engines pretty much applies across the board. Add the Taurus to the list regarding running and tuning though as mentioned the crank assembly is different.
Quite a few Sachs based engines out there ..... and don't forget the FOX that is almost a twin to the Brison. Of course there is also the FPE which is its own unique use of Sachs parts ..... though later engines have gone away from the now scarce and expensive Sachs parts.
Just about anything you read about the Brison, FOX or FPE engines pretty much applies across the board. Add the Taurus to the list regarding running and tuning though as mentioned the crank assembly is different.
Last edited by Truckracer; 02-03-2015 at 09:23 AM.
02-04-2015, 05:56 PM
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Just looking closely at the A&M sachs 3.2 and this engine looks great, I don't know what oil mix the previous owner used but the piston and cylinder look just like new. The compression is great and the outside of the engine looks just as good. Is there anything distinctive about the crank that would tell me whether it is the better cantilever crank? Thanks
04-29-2015, 03:47 PM
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I picked up an old (what looks to be an) A&M engine a few years ago and am getting ready to use it (on an 84" RV-3). Has the mechanized ignition advance, as seen in the pictures. Sachs head. When I started this engine with a starter it ran great, sounds like a powerful engine. But when I tried hand-starting it the thing backfired a bit - scared the crap out of me. Does this mean that the timing is off? Is it firing too soon? But it does sound great when it's running. However, I prefer to start my gassers by hand - just not sure if I should on this one. Any advice? Also, I saw the previous posts on the different cranks. If mine has the lesser crank, what are the negative affects? Also, I need a muffler. Anyone know where I can get one? I ready somewhere about Kangke, on Long Island. Thanks in advance.
Mike
Mike
04-29-2015, 05:40 PM
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With mechanical advance, you want to avoid flipping the engine as you normally would, either choked or unchoked. They can bite you! For starting any engine of this type, I usually go choke on, full throttle and ignition off. Flip the prop briskly until you see fuel and maybe hear the sloshing sound of fuel in the carb intake. If you place a finger in the intake, it should be just wet with fuel. Just be careful and don't overchoke. Once you have fuel, open the choke and retard the throttle to just above idle, ignition on and flip as you would for a normal start. Should have a running engine in a few flips and no fear of getting bit by the prop as you only have the ignition on at low throttle settings.
