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  What is a Looper (engine)

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Author Topic:   What is a Looper (engine)
cjd posted 03-21-2002 10:23 AM ET (US)   Profile for cjd   Send Email to cjd  
I recall reading an offhand comment about a Looper (Bigshot i think)and i was curious if someone could enlighten me as to what this is, and the merits of the design. i am specifically asking about a 1989 evinrude 140 VRO (still connected) that has been decribed to me as a Looper.
No predictions on life here, but was this considered a solid engine? Compressions checks out good, and I am praying for a couple years before repower.


Thanks in advance

chris

hauptjm posted 03-21-2002 10:40 AM ET (US)     Profile for hauptjm    
If I remember correctly, it's a reference to the LOOP Charge ignition system.
Whaletosh posted 03-21-2002 11:13 AM ET (US)     Profile for Whaletosh    
A looper is slang for a 2-stroke motor that has loop charged induction (not ignition). Basically, the shape of the cylinder and pistons are made so that as the fuel/air/oil mix comes into the piston it flows to the top of the piston then loops down to push out the exhaust gas. Most larger outboards made post late 1960's are loopers. Loopers perform better at high RPM due to lighter pistons (which a typically flat topped or closer to flat) and are more fuel efficient than cross flow motors.

Cross flow induction is a motor that has a single induction port so that the fuel/air/oil mix flows in laterally across the cylinder to push out the exhaust gas. Cross flow induction is used in smaller motors because it producesd better idling characteristics. Motors that are used for sailboats, kickers, and small fishing boats typically are idled a lot so good idling is important.

Bigshot posted 03-21-2002 11:24 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
that 140 is a good engine and if everything checks out, could go another 13 years no problem.
hauptjm posted 03-21-2002 11:35 AM ET (US)     Profile for hauptjm    
I knew someone would get you the correct answer.
peteinsf posted 03-21-2002 11:41 AM ET (US)     Profile for peteinsf    
I recall a 1984 ad that had a tornado inside the cylinder head. I guess the intake gasses swirled.

From 1984 on the "Loop Charged", "Big Block" motors were the 120, 125, 140, 200, 225 and the V8s all were very similar. The all used the same maintenance manual.

The 80's "Cross Flow" (flat head looking) motors date back to the original V4s (40HP I think) and they are the 88, 90, 100, 115, 150 & 175. Later the 150 and 175 switched to the 60deg Mercury configuration that Larry likes.

I just sold my 86 120 with my Montauk, great motor still running strong!

Pete

cjd posted 03-21-2002 01:29 PM ET (US)     Profile for cjd  Send Email to cjd     
You guys never dissapoint. Thanks so much for the info. The good news is my 1.5 year search may be coming to a close (this weekend), the bad news is an 18 Parker may have edged out the 18 outrage I seek. All things being equal, I would rather have the Outrage, but all things are rarely equal in my world. Thanks and please don't mind my lurking, I will have a whaler someday.

chris

chris

vdbgroup posted 03-21-2002 08:55 PM ET (US)     Profile for vdbgroup  Send Email to vdbgroup     
Chris,

Blessed are the meek for they shall inherit the Boston Whaler. (but only if there are any left).

A Parker? Come on! Retract your cranium now and see the light. Once you get Whaler, you never go back..Ask the man that owns one!

Come on. Think twice, thrice. Just do it!

Regards,
RVdB

vdbgroup posted 03-21-2002 08:57 PM ET (US)     Profile for vdbgroup  Send Email to vdbgroup     
Oh yeah, I forgot.

The V-6 loopers w/ oil injection made in the 88-89 years were noted for the cylinders coking up and the engine blowing.

Also they ran hot, and many mechanics simply removed the thermostats to increase cooling.

Just something to be aware of.

peteinsf posted 03-21-2002 09:09 PM ET (US)     Profile for peteinsf    
Is that why they retro-fitted the VRO system? Or are 88/89's just bad?
cjd posted 03-22-2002 10:43 AM ET (US)     Profile for cjd  Send Email to cjd     
Is it true that you can usually see discoloration on an engine head that has been run real hot?
Bigshot posted 03-22-2002 11:39 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
If it is white, it can turn brownish. If it was run real hot the paint will peel off. I have also seen engines discolor from age and from Wd-40,etc. If she cooked real good the wiring around it would have some telltales.
cjd posted 03-22-2002 11:58 AM ET (US)     Profile for cjd  Send Email to cjd     
Thanks Bigshot.
Maybe it will fall through, and i'll be back on the outrage hunt, but i suspect a running $5000 outrage might be a little much to ask. I am starting to understand the 0 down crowd a little better. damn

Chris

lhg posted 03-22-2002 05:50 PM ET (US)     Profile for lhg    
The term "Looper" was first used as part of OMC's advertizing for the 3 cylinder 55-70Hp engines (I believe the first loop charged engine introduced), and even today generally refers to OMC loop charged engines.

Mercury never used the term, and Yamaha wasn't even around back then. When the Yamaha's came out, they were all copies of the US products. The powerheads were OMC based, including the 90 degree V-6's, and the lower units were from Mercury.

whalernut posted 03-22-2002 06:19 PM ET (US)     Profile for whalernut  Send Email to whalernut     
I can attest to the inefinciency of a cross flow engine. My 1975 85h.p. Johnson eats a ton of gas at any speed, it is just a pig on useing up 2-6 gal. cas cans!! And this is on a light weight `16 Currituck. Jack.

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