Difference in motors

what is a looper motor and cross flow motor? I have a johnson 1986 V4 120 hp with VRO written on the cowl. I dont really know what I have.

Re: Difference in motors

The 120 is a looper.<br /><br />Somewhat simplified explanation...<br /><br />Looper refers to Loop Charging - the means by which fuel/air is introduced into the combustion chamber and exits the exhaust. It literally does a loop with the apex near the spark plug. Pistons are usually flat or slightly domed, with holes or gaps in the piston skirt to allow for the flow pattern. The entrance of the fuel/air charge often comes from 2 or three points around the piston as the ports are part of the cylinder wall. The looping is designed so that <br /> the exhaust part of the process is more or less aimed at the exhaust ports.<br /><br />Cross flows are just that - the flow of fuel/air enters one side of the cylinder, hits a sloped crown on the piston dome that more or less aims it at the plug, and exits the other side of the cylinder wall (exhaust). The entrace and exit are through holes in the cylinder wall (ports). <br /><br />- Scott

Re: Difference in motors

You can get more ponies per cube with loop charging. But sometimes there's a sacrifice to longevity. I'd venture to say that crossflows are far more bullet-proof than their loop charged siblings. I see way more old crossflows than loopers. The more horsepower you squeeze out of a block, the shorter it's life.<br /><br />The quick way to recognize the difference is that looper piston tops are slightly domed or flat. Crossflow piston tops kinda resemble Prudential's "The Rock".