Contour Enthusiasts Group Archives Forums Modifications Duratec Performance long rod motors

i follow the mustang crowd too. lots of guys are running longer connecting rods in their motors. from my understanding it improves the rod ratio. this helps increase piston speed and helps promote cylinder filling at lower rpms. this modification is especially beneficial to intake systems that have limtited breathing capacities, such as factory feul injection. has anyone else out there done any research on this for our motors? seems to me like this would help give us that low end punch that we lack...any increase in torque would abviously be beneficial, and we would still have complete use of our rev range.
custom rods would be obvious. pistons with a custom compression height as well. because it does not change the crank throws, as does stroking, i wouldn't think that there would be any block clearance issues.
just wanted to throw my brain storming out there, see if anybody else had thought of something similar. i would rather do this than a 3L swap. its is fun to tell people that my V6 is smaller than their 4 banger and watch their foreheads wrinkle in confusion

a longer rod will not at all change the speed of the piston. It will however make the piston reach further up the cylinder, effectively increasing he compression ratio, a well known method if improving performance.

To increase piston speed a longer throw crankshaft is needed.

Actually increasing the rod length would hurt low rpm scavenging.

Also shorter rods are more beneficial to low lift camshafts (I.E. like our DOHC engine has) & it also allows for longer duration without backflow.(again drastically to our benefit!)

Also the only time the shorter rod will have lower piston speed is around Bottom Dead Center. Not really a major concern IMO.

I personally do not see any benefits on our engine architecture.

actually...the piston speed does increase with the longer rods but it is only at TDC and BDC(this is because of the increased rod angle) unlike in a stroker wich increases speed throughout the cranks rotation. this is what helps cylinder filling on the long rod motor.
thanks for the input Demon...*POP*...that was my bubble.

Our engine have a pretty ideal rod ratio of 1.6, that's what gives it it's rev happy demeanour and at the same time also gives it's long and flat torque curve. You could stick in a longer rod and have a custom piston done with a different pin hight to keep the pistons from protruding the block. But I doubt it will do any good for the amount of money that it would cost to have this one.

thats directly from the 3 liter GOD!!

Well, if you are going through the trouble of custom rods/pistons, might as well offset-grind the crank to get a larger stroke. That would be very beneficial.

Different rod ratios are really insignificant when compared to bore stroke ratios, i.e., long stroke vs short stroke cranks.

A longer rod ratio effects dynamic compression, effectively making an engine build compression longer--Good when you have static compression limitations from racing rules.

It depends on the nature of the engine which rod ratio is better....but again, it really isn't that significant in terms of power production to lose any sleep over.