Looper vs. Crossflow

[soup]

What is the difference between a Looper and a Crossflow?

 

[duck64]

Re: Looper vs. Crossflow

The difference between a 60 degree and a 90 degree is the angle of the vee form by the connedting rods as the point toward the heads.<br />A 90 degree motor is much wider across the back of the motor. A 60 degree would appear much narrower if it were setting next to a 90 degree motor.<br />90 degree are cross flow motors (they have domed top pistons which direct the flow of the fuel and air entering and exhusting the combustion chamber.<br />The 60 degree motor is a loop charged motor and has flat top pistons. <br />--------------------------------------------------------------------------------

 

[jimmbo]

Re: Looper vs. Crossflow

Not all 90 degree engines are crossflows, some are loopers.<br />As to the original question... The names refer to which induction design the engine utilizes. Crossflow engines have pistons that have a deflector which directs the intake charge towards the combustion chamber and prevents the air/fuel charge from going directly accross to the exhaust ports. A Loop-charged engine, as mentioned earlier has flat or slightly domed pistons. Carefull location and design of the intake ports ensure the air/fuel charge is directed into the combustion chamber and not towards the exhaust ports. Generally crossflow engines are smooth running, especially at low speeds while loopers are a little rougher but tend to make more power while being a little more frugal with the fuel.

 

[Walker]

Re: Looper vs. Crossflow

Actually 60 or 90 degrees has nothing to do with it. There are some big bore 120's, 130's and 140 90 degree loopers and single bank loopers. <br />Loopers and crossflows have different fuel mixture paths from the carbs to the cylinders. Crossflows simply full the crankcase with fuel mixture and the mixture enters the cylinder through ports above the piston when it is on the down stroke. Loopers pass mixture through corresponding holes (ports) in the lower skirts of the pistons and the cylinder walls. These ports lead to chambers that go around the outside of the cylinder wall and to intake ports higher in the cylinder walls back into the combustion chamber. The mixture "loops" around the piston. Thus the name Looper. That's about as simple as I can put it. I have some diagrams of the flow paths of each type but my scanner is down right now.

 

[Jcrain]

Re: Looper vs. Crossflow

I got a 97 90 hp'Rude, SPL How can I tell which it is?

 

[Dhadley]

Re: Looper vs. Crossflow

All V4 and V6 crossflows have bolt on covers over the intake passages called by-pass covers. They also have bolt on exhaust plates on the block and water jacket covers on the heads. In short, a bunch of bolts and covers.<br /><br />V4, V6 and V8 loopers do not have any of these bolt on covers.

 

[seahorse5]

Re: Looper vs. Crossflow

Jcrain,<br /><br />An SPL version is a crossflow 90, a very good motor, an economy no-frills model, but not a looper.

 

[ED21]

Re: Looper vs. Crossflow

Here are some diagrams that explain it.<br /> http://www.maxrules.com/fixtheory2.html