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Author Topic:   OMC Loop Charged Induction

jimh posted 02-05-2009 09:39 PM ET (US)
When OMC introduced their loop-charged fuel induction system in c.1968, did they obtain a patent on the method? Typically a patent on a useful invention has a 21-year duration. This would have prevented other two-cycle motors from using loop-charging until c.1989. What did Mercury do for those 21-years to keep up with OMC? Was loop-charging covered under patent? Was it licensed to others?
seahorse posted 02-06-2009 08:00 AM ET (US)
OMC did not invent or patent the loop charge system in 1968. Loop scavenging had been around a long time, especially in motorcycles.
On the back of the 1968 looper 55hp there was a tag that said something like "thru-hub exhaust prop - patent number xxxxxxx". It was the year after OMC won its long court battle against Merc about who invented the thru-hub exhaust prop.
L H G posted 02-06-2009 11:31 AM ET (US)
OMC got their 175HP V-6 on the market about a year before Mercury, but it was a "not very exiting" 90 degree cross charged engine. Having brought out the 3 cylinder 55-70HP loop charged engines as noted, it's strange they missed the "loop charge" boat on the V-6.
A year later Mercury, for the 1976 model year, scooped the market with it's 60 degree V "Black Max" LOOP CHARGED V-6 2.0 liter engine. In 1978 they increased it to 2.4 liter and 200 HP. This engine quickly became the V-6 performance leader for many years, and is still in production in it's 2.5 liter version 33 years later. That's how good it's design was. (TBirdsey just found one of these 1978 loop charged 200's N.I.B. and put it on his Ribside Whaler)
I think Jim has it backwards, it's more like "What did OMC do to be able to keep up with Merc's loop charged 60 degree V-6's"? They brought out the larger 90 degree 3.0 liter loop charged 200's and 225's, still carbed with no EFI, to try (not very successfully) to outrun it. At the 2.5/2.6 liter level, the answer is "nothing" until 1991, when they brought out their copy of the Merc 60 degree design when MERCURY'S series of patents expired, but still carbed and no EFI. Mercury brought out EFI in 1987 I believe, and in racing versions was able to get 280HP out of those 2.5 EFI's! My loop charged 200 EFI's have been incredibly reliable engines and get better fuel economy than the carbed versions.
jimh posted 02-06-2009 11:43 AM ET (US)
I was not aware that Mercury had a loop-charged motor prior to 1968 when OMC introduced their loop-charged engine. What Mercury motor preceded the 1968 OMC motors with loop-charging?
L H G posted 02-06-2009 05:12 PM ET (US)
Jim, I am not aware of any either. I was just wondering why OMC did not continue using loop charging when they introduced their first V6 in 1975, and let Mercury beat them to that technology on the V6 engines? Maybe they didn't know how to incorporate the "loop" technology into a Vee design?
jimh posted 02-06-2009 08:44 PM ET (US)
Larry--Why OMC did not have a loop-charged V6 in 1968, too, is a good question. At least they got one by 1992, when they made my V6 225-HP motor.
Seahorse--Thanks for the clarification on the 1968 introduction of loop-charging in a two-cycle outboard. I was not aware that in 1968 loop-charging had been in prior use in two-cycle non-marine motors.
Peter posted 02-06-2009 09:15 PM ET (US)
At the time that the OMC cross flow charged V6 came out in 1976, they had 18 years of experience with their successful cross charged V4, which started out at 50 HP and was up to 135 HP by 1976. So why mess with success. Go with what you know. Since they shared parts with the V4 cross flow motors, like connecting rods, pistons and the like, there were economies of scale to be had going with the cross flow format rather than creating something from scratch.
The OMC V loopers came out in 1985 with the 90 degree V4 and the V8. The 90 degree V6 looper came out in 1986. The 60 degree loopers came out in 1991.
Mercury, on the other hand did not have any V motor legacies and so they had a blank slate in which to design their V motors in the 1970s. Had OMC's V4 motors been loopers initially, its quite likely that their initial V6 motors would have been loopers.
jimh posted 02-07-2009 08:55 AM ET (US)
There is good information in this discussion, and let me try to put into chronological order some of the milestone developments in the field of outboard design and manufacture.
OMC
1958 Cross-flow V4
1968 Loop-charge Inline 3
1975 Cross-flow V6
1985 Loop-charge V4 90-degree
1985 Loop-charge V8 90-degree
1986 Loop-charge V6 90-degree
1991 Loop-charge V6 60-degree
Mercury
1976 Loop-charge V6 60-degree 2.0-liter, later 2.5-liter and larger
Regarding patents, please give the patent number for the Mercury patent which is mentioned as being in effect until c.1991 and somehow constrained use of the angular dimension of 60-degrees in manufacture of V-block outboard motors. Since most patents are for 21-years, this implies the patent would have been granted c.1970.
jimh posted 02-07-2009 09:02 AM ET (US)
From the above it looks like there was a period of about nine years, from 1976 until 1985, when Mercury had V6 motors with loop-charging and OMC did not.
seahorse posted 02-07-2009 09:24 AM ET (US)
jimh,
To add to your looper history chart, OMC developed the 2 cylinder looper for the 1972 50hp market. That design was used until 2006 in 40, 50, 55, and 60hp configurations.
Peter posted 02-07-2009 10:00 AM ET (US)
Patent terms lasted 17 years from the grant date back then. So if the patent expired in 1991, then it had to be granted 1974. Unfortunately, the Patent Office records are not text searchable for patents granted before 1976.
What I was able to find within Brunswick's portfolio of text searchable patents that mentions 60 degree V6 is No. 4,092,958, issued June 6, 1978 (17 year term would have expired in 1995). It's abstract says
quote:
A sixty degree, V-6 engine for an outboard motor includes loop scavenging and charging with a pair of oppositely located input passageways with differently angles sidewalls and which provide progressive, smooth constriction to the charging port to establish a highly effective velocity pattern across the top of a flat piston. Cast "Blister" cylinder liners with integral ports are integrally cast into an aluminum block. The block is cast with a single manifold between the two cylinder blanks. A milling cutter is located within the manifold to open the exhaust passageways. A T-shaped manifold is secured to close the manifold and define a pair of separate exhaust passageways. The cylinders are rotated to align the upper and lower inlet ports and particularly to locate the exhaust port projecting downwardly into a center manifold. Adjacent piston rods are mounted upon a common crankshaft pin. In high speed racing outboards the engine is fired with an inverse firing order from the lowermost to the uppermost cylinder.
Claim 15 defines a 60 degree V but is more narrow in scope than simply a 60 degree V as it also requires a particular arrangement of exhaust and inlet ports. Given that this patent had an expiration date of 1995, it would appear that this patent had no application to OMC's 60 degree V6 design issued in 1991.
There is a companion patent No. 4,184,462 issued January 22, 1980 (expired January 22, 1997), that lays claim to a T shaped manifold cover. No claim to 60 degree V per se in this patent. Given that this patent had an expiration date of 1997, it would appear to have had no application to OMC's 60 degree V6 design.
Within the References Cited section of the first Brunswick patent is No. 3,166,054 issued to OMC on January 19, 1965 (expiration date would have been January 19, 1982). This patent discusses and claims a 90 degree V6 internal combustion engine where the pistons on one side of the bank are moved opposite to the pistons on the other side of the bank. I suspect that this patent basically cut off Mercury from making a 90 degree V6 powerhead until 1982. Since OMC was already commercially ahead of Mercury in the V outboard market, I suspect that to match OMC's mid 70s introduction of the V6 outboard, Mercury was left with no choice but to go with a 60 degree (or other angle) design block to avoid infringing this patent.
Interestingly, Yamaha came to the U.S. market with a 90 degree V6 in 1984. Yamaha has never made a 60 degree V6. I speculate that it did not want to copy its U.S. joint venture partner's design where it needed to maintain positive relations with its joint venture partner and also because its joint venture partner was not the U.S. market leader at the time.
jimh posted 02-07-2009 10:39 AM ET (US)
Peter--Thank you for your research on the patents which affected the design of outboard motors. It appears from your findings that we have a complete inversion of the usual legend of patents and manufacturers, and that, in fact, it was Mercury was was constrained by an OMC patent with regard to V-block engine design, not the the other way around.
Tom W Clark posted 02-07-2009 12:48 PM ET (US)
To correct some more of misinformation from "The Legend Maker" above, when OMC brought a V-6 outboard to the market for the first time it was a 200 HP outboard, not the mere 175 that Mercury could muster.
I remember the summer of 1975 seeing the new Johnson and Evinrude 200 HP outboard for the first time and being amazed they could make an outboard as powerful as a sterndrive! It seems quaint now, but it was a REALLY big deal back then.
While Mercury was playing catch up with their 200 HP motor a few years later, OMC had moved on to the 235 HP motor.
L H G posted 02-07-2009 08:06 PM ET (US)
Peter's THEORY is pure baloney, and ridiculous speculation. No proof whatsoever that Karl and Mercury even wanted to do a 90 degree V. Why would they, they are dogs even to this day, and even the new 4-stroke V-6's are no longer designing 90 degrees? Even when OMC brought out the 3.0 liter block in 1985, they were evidentally blocked by Merc's patents and had to go with the old fashioned 90 degree block. To this day, OMC's best block designs were the 3 cylinder 70's and 1991 60 degree V-6's ala Mercury, when they finally "saw the light". 90 degree 2-stroke V-6 engines consistently need more cubes to match a 60 degree V engine, which is why BRP had to bring out a 3.4 liter 250HO to run with a 3.0 liter 250XS Optimax.
As for that OMC 235, those were marketing decals, not ponies. OMC never even rated their larger 3.0 liter block at 235HP. A 3.0 liter Merc 225 EFI/Optimax would blow one of those old 235 dogs out of the water. They have a REAL 235 HP.
seahorse posted 02-07-2009 08:33 PM ET (US)

This thread has drifted as many of them do here at CW. The original post by JIMH was asking about patents and loop charging. The following is a brief history of 2-stroke scavenging.

A brief Loop Scavenged 2-stroke history lesson
In 1925 Gasmotorenfabrik Deutz in Germany introduced a two-stroke Diesel with a newly patented cylinder port design, the three-channel reverse flushing combustion chamber for 2-stroke diesel engines. Instead of a deflector on top of a piston, the looper design used a flat piston and 2 intake ports facing away from the exhaust port. The intake fuel charge was aimed to the opposite side of the cylinder and slightly upwards, thus causing a looping action which expelled the exhaust gases from the combustion chamber more efficiently than in previous designs. The research for this engine was performed by engineer Adolf Schnurle (1897- 1951). Schnurle's focus was on the development of big stationary engines, not small motors.
With the German military buildup during those years, Deutz did not want to produce small gasoline engines, so it had no problem allowing DKW to use its designs under license. Working with the Schnuerle-ported engine designs that were further improved upon by Dr. Herbert Venediger, DKW was building little two-stroke motorcycles that were more powerful and more fuel-efficient than their competitors.
In 1932 the firm become part of Auto-Union and continued building cars and bikes until after the war. The Auto-Union consisted of DKW (Zschopau), Wanderer (Chemnitz), AUDI and Horch (Zwickau) with the trademark of four connected rings denoting the four companies.
1950 with his long time co-worker Otto Elwert, Dr. Schnurle he applied for a US patent on a V-8 2-stroke cylinder design. The patent #2681050 wasn’t awarded until after his death so his daughter Gertrud’s name in on the patent along with Elwert’s.
The motorcycle industry of the 50’s and 60’s further developed the loop scavaging. In 1957 Walter Kaaden (MZ, E, Germany) added a third transfer port opposite the exhaust port. An engineer named Erns Degner defected from East Germany to join Suzuki and In the 60's Suzuki the World Championship using exotic porting and rotary valve developed by DKW and MZ. Yamaha added a pair of auxiliary transfer ports (finger ports) along side the main transfer ports and later developed a pair of small auxiliary exhaust ports at the side of the main exhaust port.
In 1968 OMC came out with the first loop-scavenged outboard, the 3 cylinder 55hp called the Triumph or TR-10.
They were also going to introduce a 1.5hp looper single cylinder, but could not get it to idle well. At the last minute, they used the crossflow design from the successful and long running 3hp twin as the new 1.5hp single.
http://s213.photobucket.com/albums/cc281/originalseahorse/?action=view& current=Loopscaveging-Schnurle.jpg
Peter posted 02-08-2009 08:07 AM ET (US)
"Even when OMC brought out the 3.0 liter block in 1985, they were evidentally blocked by Merc's patents and had to go with the old fashioned 90 degree block."
Larry let's get the facts correct. The V4 and V8 loopers were initially launched with 1.8L and 3.6L displacements in model year 1985. The V6 looper was launched in model year 1986 with a 2.7L displacement. The displacement of the V loopers was increased for model year 1988 to 2.0, 3.0 and 4.0L, respectively.
What Merc patents blocked them such that they had to go with the 90 degree block? Recall that the 60 degree V6 looper came out in 1991, 4 and 6 years prior to the expiration date of the patents discussed above. If those patents didn't block OMC on the use of the 60 degree angle in 1991, they didn't block OMC on the use of the 60 degree angle in 1985 either.
If Mercury had a patent on the broad concept of the 60 degree V6 loopcharged 2-stroke, it is highly likely that it would have been mentioned among the patents in the References Cited section. No such patent appears in the References Cited section of either of the two Brunswick patents mentioned. Of course, you are certainly free to do your own research and identify the mystery 60 degree V6 "blocking" patents for us.
fourdfish posted 02-08-2009 10:56 AM ET (US)
The title of this thread was "OMC Loop Charged Induction"
I find it interesting to read about the history of this technology since I owned several of these engines. Both Peter
and seahorse offer factual posts which show the evolution of these engines. Patent numbers and dates back up their opinions.
This thread is not about which engines are faster or how much horsepower an engine actually posted!

Tohsgib posted 02-09-2009 11:00 AM ET (US)
Patent blocking is BS....OMC did everything possible to be the oposite of Mercury to set themselves apart. When you only have 1 competitor, you need to do this. Probably why they went white which is opposite of black, V6 instead of straight 6, etc. OMC came out with a V6 a year before Merc, why not patent that? Loop charging has been in the motorcycle industry for decades, way before outboards. There are benefits to both induction systems but loopers are more efficient and hence why they won the battle.
Peter posted 02-09-2009 11:45 AM ET (US)
OMC went V4 and V6 to keep multi-cylinder powerhead height down (a fishability thing). Water pump doesn't have to pump water so high as it does on a straight six. Also keeps the center of gravity of the outboard lower. Mercury finally discovered the advantages of the V configuration (probably after tens of thousands of lost sales to OMC) and got their first V6 product launched in 1977. The straight six 2-stroke eventually went the way of the buggy whip.

Tohsgib posted 02-09-2009 12:04 PM ET (US)
Correct also Peter. If anyone here has a library of old engine brochures, please go through them. You will see(just like today) that each company is arguing their point as to why their engine is better than their competitor. OMC will show how much smaller it is compared to everyone else. Mercury will show how much narrower it is to everyone else...and so on. Again I strongly believe it is a balck/white thing and both had to stick to their guns. After 40 years of research and development, it is easy to be a Monday morning quarterback. Both companies had certain great designs that shined through, others failed. But that is the way it goes, look at any industry. We could debate which is better, the staple or he paperclip until we are blue in the face. Then somebody will throw in how the new laser stapleclip is far superior(I made that up).
L H G posted 02-09-2009 07:25 PM ET (US)
...But the Black company is still here and still bringing out newly designed high tech engines, and the White company is gone.
jimh posted 02-09-2009 09:33 PM ET (US)
I don't understand the difference between Mercury being taken over by Brunswick, which came long ago, and OMC being taken over by Bombardier. It seems to me that neither Mercury or OMC remain; they are both now subsidiaries of other companies. Since Mercury's take over came many years prior to OMC's, it seem even harder to conclude that Mercury remains and Evinrude doesn't.
fourdfish posted 02-10-2009 09:16 AM ET (US)
WHITE company is still here. Of course some just don't like
it. Black company may again have some problems in the future.
fourdfish posted 02-10-2009 10:08 PM ET (US)
BTW-- 4 strokes engines are not high tech! Even if those engines have a supercharger, they are still old technology.
Workable computer assisted DFI with brand new improved
fuel injectors is high tech.
itl posted 02-11-2009 08:07 AM ET (US)
"Workable computer assisted DFI with brand new improved
fuel injectors is high tech."
I guess this means that Mercury Optimaxes are high tech.
fourdfish posted 02-11-2009 09:45 AM ET (US)
In my opinion that is true. They are not old technology. It is a fact that 4 stroke engines have been around for a very long time. Supercharging has also been around for quite awhile. Even the car companies are merging DFI with the
old 4 stroke technology.
Peter posted 02-11-2009 10:04 AM ET (US)
Gasoline direct injection has been around for more than 50 years.
Perry posted 02-11-2009 11:10 AM ET (US)
Direct injection has been around for more than 50 years. 2 stroke motors have been around for a very ong time too. I guess that means an Optimax and an ETEC are old technology as well.
Both 2 stroke and 4 stroke outboards recently began using computers to control the engines crtical functions.
fourdfish posted 02-11-2009 08:21 PM ET (US)
Direct Fuel Injection was never WORKABLE nor practical
until the newer fuel injectors were recently invented.
These new injectors were capable of much more significant pressures which made theory into reality. They also could
cycle at a much higher rate and last for an extended
period of time.
Thus old DFI engines were not mass produced nor sold in any
large quantity. The NEWER DFI engines are not old technology.
The fuel injectors themselves are state of the art and
few would say they are not new technology.
The computers themselves made this technology possible.
The computers have advanced to a size and technology which allowed for the use of the new fuel injectors. It was only
recently that the large auto companies started using DFI!
I have heard that 4 stroke outboards may in fact use
these injectors in the future but I have not seen it yet.
Since 4 strokes in outboards are not significantly different
than those that are found in most cars. They are in fact
old theory and technology. Since DFI in 2 strokes is brand
new, I would say your opinion is not valid.
So Perry spew away!

Perry posted 02-11-2009 11:05 PM ET (US)
Oh fourdfish, just because the ETEC has new injectors it's high tech huh? You make me laugh. By the way, what kind of Boston Whaler is your ETEC mounted on?
fourdfish posted 02-12-2009 08:18 AM ET (US)
Thats all that you could up with? Use that search engine again and maybe you will come up with somthing. We have had Boston Whalers in our family probably before you were born. Just because my E-TEC is not mounted on our Whaler is meaningless.
R T M posted 02-21-2009 11:19 PM ET (US)
Mercury didn`t need the V configurations back in the day, becuase in 1958 Charlie Strang started stacking cylinders on top of each other until he got to 6, and created the greatest outboard ever built. It started with the 60hp Mark 75. They figured a shifting gearcase couldn`t handle all that power so they developed the silent nuetral shifting,(dockbuster). Well that didn`t work out too well, so a shifting gearcase was in production two years later.
BTW Mr. Kiekhaefer prefered to have his first name spelled Carl, which was his given name, and not Karl as spelled by "The Legend Maker" above. Of course they are both pronounced the same, maybe Karl sounds more "German", to someone not very knowledgeable about Mercury`s great history.
rich (Binkie)
mobey posted 02-22-2009 04:57 PM ET (US)
I believe I have read that Kiekhaefer Corporation initially went with the "silent neutral" reverse for the Mercury Mark 75 because at that time the company didn't have the funds to design and manufacturer a new heavy duty forward-neutral-reverse shifting gear case that the Mark 75 would have required. In that era, the company was often out of cash. Kiehhaefer Corporation's money troubles were mainly attributed to the major amount of money Carl/Kiekhaefer Corp had put into NASCAR and other auto racing endeavours, and Carl's own personal heavy spending habits.
brisboats posted 02-22-2009 07:41 PM ET (US)
Back to the loopers....why won't they idle as smooth as a crossflow?
Brian
Tohsgib posted 02-23-2009 11:04 AM ET (US)
Who said they don't? In my observations, Loopers idle better than crossflows or at least quieter. Crossflows sound like diesels or about to chunk a rod through the block.
brisboats posted 02-23-2009 08:33 PM ET (US)
Crossflow by design is inherently a better idling engine than a looper. I was looking for some enlightening discussion as to why.
brian
Tohsgib posted 02-24-2009 10:27 AM ET (US)
Show us an article pertaining to your question please. If my buds Crossflow V6 idles smoother than a Loooper I will eat it. If a 115 Crossflow OMC idles smoother than a 115 V4 Yamaha, get me another plate.
newt posted 02-24-2009 03:57 PM ET (US)
In my opinion, a Johnson V6 looper idles much smoother than a Johnson V6 crossflow.
Peter posted 02-24-2009 06:03 PM ET (US)
My 48 Johnson SPL 2-cylinder looper had a horrible idle compared to my 35 Evinrude 2-cylinder cross flow. I can't say that idle quality was only due to the induction method, however.
brisboats posted 02-25-2009 07:59 AM ET (US)
Break out the plate and forks...http;//www.maxrules.comfixtheory2.html.
Pretty much acccepted that the crossflow design is a smoother better idling engine than a looper. I was looking for a discussion as to why. I believe it has to do mostly with exhaust scavanging. The looper needs rpms to scavange the exhaust efficientcy buy hey I could be wrong. Not going to offer to eat anything metallic though.
Brian
brisboats posted 02-25-2009 08:05 AM ET (US)
Typed that wrong http://www.maxrules.com/fixtherory2.html
I think you can just type in www.maxrules.com and the article(s) will come up.
Brian
TransAm posted 02-25-2009 08:22 AM ET (US)
Your syntax is screwed up; ":" after http and a "/" before fixtheory2. Here's the correct address.
http://www.maxrules.com/fixtheory2.html
I got this picture in my head of Klinger from M*A*S*H trying to eat a jeep to prove he was crazy. I think he used a dipping sauce of 10W40. Enjoy!
TransAm posted 02-25-2009 08:22 AM ET (US)
You beat me too it!
Tohsgib posted 02-25-2009 11:40 AM ET (US)
The 2cyl loopers were not the smoothest of engines at low speed due to the 2 large cyls and dual carbs. The 35 is a lot less complicated and powerfull. My 60, 48 and 40hp were all pretty shaky until warmed up, they could jump around a bit. Displacement I believe has a big role in it. Look at a 1400cc Harley vs a 883 when it comes to vibration.
Backfire posted 02-25-2009 11:54 PM ET (US)
If you think you have a small engine (7.5) that idles better than a 1955+- 7.5 Evinrude, bring it on. Throw in earlier models like the 2.5 for another example. Loop charging is great in larger engines, but in the small engines it is "old tech" that delivers at 24/1 oil, coil, point,and condenser ignition. Maybe computer controlled fuel injection and et al will be the answer. We will have to check out the E-TEC 9.9 when it shows up.
Backfire
Peter posted 02-26-2009 07:04 AM ET (US)
I would put the 2-cylinder 5.3 cubic inch cross-flow 3 - 4.5 HP OMC made from the 1960s to the 1990s up to that challenge.
Tohsgib posted 02-26-2009 09:36 AM ET (US)
Peter..your 4.5 is crossflow.
Peter posted 02-26-2009 10:14 AM ET (US)
Isn't that what I said? "cross-flow 3-4.5 HP". I have a 1-cylinder 3.5 HP looper now. It's a nice, light, torquey portable outboard but it's idle doesn't come remotely close to the smooth idle of the 2-cylinder 4 HP I used to have.
Tohsgib posted 02-26-2009 10:47 AM ET (US)
Yeah I was interpreting both posts and both engines are Crossflows. I meant to say that.
sandhammaren05 posted 03-02-2009 07:13 AM ET (US)
The first loop charged outboard was the /Quincy Mercury' made in a small welding/machine shop by O.F. Christner, as response to the König invasion in alky racing. In 1975 OMC produced the 50 c.i. loop charged 75 hp outboard that dominated OPC racing until it was superceded by the 56 c.i. model. OMC was very, very slow to loop-charge the V4 and V6, the cross charged 235 OMC could not run with the 225 Mercury. OMC 75 loopers easily turn 7000-8000 RPM un tunnels, 7000 RPM on the old Allison V-bottoms. The rumor is that OMC sent the early 55 loopers to Christner.
seahorse posted 03-02-2009 08:24 AM ET (US)
The following is an excerpt from the Quincy Looper website about their going to looper technology after Konig did:

Although Quincy Mercs were still doing well in the early 1960's, Dieter Konig would soon raise the bar in racing technology. To combat Quincy Welding's Quincy-Mercs, Konig radically changed his motors from the cross flow or deflector piston design to the flat topped "loop charged" design being used by other European competitors at that time. Quincy Welding's deflector piston Mercs could no longer keep up with the redesigned Konigs without literally melting the dome off of the deflector piston itself due to the intense heat from the Quincy Welding modifications. Christner's technological advancements had finally surpassed the structural durability of the deflector piston itself. O. F. Christner went back to the drawing board and created what became known as the Quincy Looper racing engine. Chris designed a loop scavenged block that would allow the use of a flat top piston design for better heat dissipation. The inlet ports "looped" the intake charge away from the exhaust ports. These Loopers had exhaust stacks out both sides of the engine. The first production Quincy Loopers from Christner's patented design were produced in the fall of 1963.
R T M posted 03-02-2009 09:00 AM ET (US)
sandhammaren05 Interesting post. I assume the OMC 50 and 56 cu. in. motors are the same one being run in OPC SST-60 class. I assumed that this is a stock class run with a standard shifting gearcase with a nose cone. Can you give me more details on this engine. I was thinking of running an engine like this on my Desilva F runabout at the Classic Raceboat Assoc, and AOMCI meets, instead of my Chrysler Stacker which is overweight for my boat.
I would love to own a Quincy Looper, if I could afford, and find one.
rich(Binkie)
I Am Papasmurf posted 01-08-2010 12:54 PM ET (US)
[I] have enjoyed the knowledge you guys have brought to life. [I] am a 65-year-old male ASE-certified technician. I love looper engines of all kinds. [Goes into his personal history with engines other than the OMC outboard engine, such as go-cart engines.] Looper engines have made history. [I] am sad to say they will soon be history. [Long sidebar deleted.] [Misstatement of federal regulations deleted.] I think ten years will end production of all two-cycle engines and 30 years there won't be any on the lakes. As for me [I] am buying all the OMC 55-70 hp loopers. [I] hope you guys keep up the fine work and keep the facts coming. It [is] ok if someone lets me know [I] am just a crazy old man, because [I] know it already and [I] love it--Papa
brisboats posted 01-08-2010 02:32 PM ET (US)
No worries Papa, you [are] not a crazy old man. Like you I have sought out and purchased some motors that maybe be very scarce in the years to come.
Brian
seahorse posted 01-08-2010 02:58 PM ET (US)
Papasmurf,
Like you I raced the old Mac-10's, West Bend-820's and even the old Clinton A400 and A490's on go-karts back in the mid 1960's. Those were crazy fun days for a kid like me.
Read the link about the EPA low emission award give to the Evinrude E-TEC a few years ago. Even with the emission regulations that are in the works, there will be 2-strokes that are direct-injected and computer-controlled for quite a few years to come.
http://www.epa.gov/air/caaac/2004awar.html

I Am Papasmurf posted 01-09-2010 10:25 AM ET (US)
You guys got it all together. After reading [the link given above regarding the E-TEC two-cycle engine] there is a glimmer of hope. [I] have always been a two-cycle fan and loopers were the poor man's way to compete. [A four-cycle engine] is nice but at least four-times the moving parts, means money now and money when repaired. In this case less is better, at least for me. [I] can only learn from this forum. [I] know it was started for loopers. [Keep] the knowledge coming. Again thanks for that bit of information--Papa
jimh posted 01-09-2010 02:29 PM ET (US)
[The purpose of the website has always been to collect and organize information on the topics it pursues. To that end, we do not collect and organize misinformation, and, accordingly, I have deleted some misinformation regarding the federal regulations as they apply to loop charged two-cycle engines which were presented in the course of this discussion.]
ssv posted 08-03-2011 11:14 PM ET (US)
Just for information about implementing loop scavening in outboards.
First loopers in Soviet Union:
"Neptune", 18HP, displacement 346 sm3, weight 43 kg, mass-production started in 1967.
"Privet" (means "Hello" in english), 22HP, diplacement 346 sm3, weight 38 kg, mass-production started in 1973.
Also I read somewhere that Yamaha produced outboards with loop scavenging in late 50s for domestic market.

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