Found this on CL tonight ...
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Good OMC Looper Tech Info Here
Information about the different eras and model changes that have evolved through the production run of the V-6 90 degree looper.
The design was released in 1986 as a 2.7 liter motor in 200 and 225 HP versions.
The motors had great potential but had teething problems relating to being over carbureted for large, heavy boats.
If you had one on a light ski boat you had a rocket on your hands!
The blocks were open deck with bridged exhaust ports.
Most people only know of the wildly popular Merc 2.4 liter "Bridgeport" motors and the 2.7's have mostly been over looked by the performance boat crowd.
The 200's had the smaller, medium bore (approx.1.450") carbs and worked way better on the bigger boats than did the 225's which had the vaunted "big bores" (approx. 1.640") that the racers worship.
One of the great thing about these motors is that the stock cylinder sleeves are 3.500" and are thick enough from the factory to bore to the 3.658" 3.0 spec's.
Add finger ports to it and you have one of the best "sleepers" on the lake/river
In 1988' they went to 3.0 liters and to a new, smaller single oval exhaust port and a new ignition which cranked in some initial timing to aid cold starts and also a safety which dropped the motor to an idle in the case of over heating.
The porting configuration itself was also much more conservative most likely due to the poor reception of the 2.7's under heavy load.
They were great motors but pretty much shut off at 5000 RPM.
The big bore carbs were gone for good and now we only had the small (approx. 1.290") bores and the mediums. The good thing was that the only real difference between a 200 and 225 of that era were the carbs.
And yes to those thinking it you can bolt 25 HP's onto your 200 by swapping your small bores for a set of mediums!
In 1992' we got a much need and improved/faster trim system as well as an upgraded lower unit. The lower unit went away from the older two giant circlips in the housing retaining the prop shaft bearing carrier housing to two bolt in lock tabs that were easily accessible from the outer lip of the unit and made disassembly much easier.
1993' was kind of a banner year and gave us a brand new "closed deck" block and the two additional intake ports called "finger ports".
Now we had a pretty descent package to work from. Great trim, a descent lower unit, tons of low end and mid range grunt and on light boats set up properly you could turn them into the mid 6000 RPM range and approach their 6700 rev limiter.
In 1998' they gave us something special and it's name was the "225 HO" which was also release as a 250 to the big boat crowd.
These motors had all the good stuff from above plus we got as bonus in the way of horsepower and lots of it for a JohnRude.
They made 254 HP's at the crank and 247 at the prop on 87 octane! (I would still run hi-test)
That is approx. 30 HP above what we were used to getting up to that time.
In 1999' they were forced by the EPA/Carb to go to direct injected technology and their first version was the Ficht which ran from '99 to '01 before switching to the new and current E-Tech motors of today.
There Ya Go...some info to chew on tonight.
