Actually, a longer rod will usually provide more torque, all things being equal. There is more leverage with a longer arm. The draw backs are of course the higher wrist pin location. There are even kits to run a slightly longer Chrysler rod in a 5.0 and the "rod of choice" for SBC's is the 6" rod as opposed to the 5.7(??)

 

That's what I've read too. FWD. Engine built around car. 5.4 is a wide engine. 5.4 is about the same width as a 460 if I'm not mistaken. Call me old fashioned, but pushrods work fine for me.

 

The "arm" is the crank pin on the crank. All things being equal, the shorter the rod, the more the angle of attack against the crankpin right after TDC. This results in a more direct "push" on the crank pin. That's the argument for short rods.

However, there are many other factors and it seems to be that the consensus has been towards longer rods lately. It puts more load on the big-end bearing right after TDC though.

I know the current trend has been going with longer rods... old-school is that shorter rods help low-end torque.

Things change

ak

 

krewat


I respectfully disagree. I'm almost think you're thinking stroke??? I know the bores have been shrinking lately while the strokes are increasing(GM 5.7/6.0 Ford 5.4/6.8) which helps control flame travel/emissions.

This is a post from 302/351 etc ...thread that I believe explains it perfectly.

"Originally posted by Quantrex
Rod length directly effects how an engine breathes because it controls the speed of the piston during both the intake downstroke and exhaust upstroke. Longer rod motors also tend to run cleaner as the piston dwells longer at TDC, creating a more complete mixture burn and increasing combustion pressure efficiency. A side benefit of that is that the motor becomes less detonation prone for a given fuel octane. Longer rods also decrease piston thrust against the cylinder walls during the power stroke so more force is sent to the crankshaft. The horsepower and torque ranges of a motor are more dependent on camshaft timing than rod length, however."
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This is great!!! Even though I was taught the above post was correct, I did a little research because the other theory made sense.

Turns out both ways have there merits and both increase torque during different parts of the revolution. http://www.chevytalk.com/tech/engine/rod_angle.html

The TDC explanation was explained different to me in that the longer dwell would give more time to charge the cylinder(of course the cam must be correctly matched)

Good call though, learn something new everyday.

 

Yet another view! (courtesy of EPNCSU2006 from the 221/260/289/302/351 thread)

http://www.grapeaperacing.com/grape.../rodslength.cfm

 

THE TERM TRITON IS A MARKETING THING FORD USES TO DISTINGUISH IT ENGINES FROM OTHERS. JUST LIKE CHEVY USES VORTEC AND DODGE USES MAGNUM. BY THE WAY, THE 5.4 AND THE 6.8 HAVE THE SAME BORE AND STROKE. I READ A WHILE BACK THE 6.8 IS BASICALLY A 5.4 WITH TWO EXTRA CYLINDERS AND SHARE MANY PARTS. THIS IS DONE TO KEEP THE COST DOWN AND AVOID HAVING TO DESIGN AND BUILD AN ALL NEW ENGINE FROM SCRATCH.

 

ok sorry if someone spoke up but i couldn't read anymore

i own the original(well i doubt it but maybe that what the m REALLY stands for) modular 351m i know wha??? two engines are i dentical but the crank & piston (flywheel & balancer they work fine but are slightly different)

so i can tell you first hand stroke and deck height are not directly related.
like they told me in school if a+b=c and d+e=c a or b does not nessicarily = d or e

how bout the 240 & 300

well as far as the I6(or is the proper term L6 eh)
all they have to do is look to aussies and licence theres
or could turn to the cosworth side and leave the rice burners the heII out of it let em make tranny for the mustang and rangers
then have ZF(i know there germans but what coumpany is it??) mate a tranny pref a 3 cv awd six full sync

now for cosworth you can get a ford cosworth in about any country but the US and a recall a chevy vega cosworth pretty sure ford has had a lot of their stock for a long time so shall we say fordfunked up??

but alas neither could replace the 300 or the 351m/400 guess all you can get a "heavy duty towing motor" with a torque peak @3500-3750rpm what do you pull at that rpm i tend to put it in gear before that

hey guess what i will never buy a new truck at this rate nor would i want to