jaconst

saw this little tidbit and thought wonder where else the others cheap out on?
http://www.fordcummins.com/connecting%20rod.jpg

dodgezilla04

you gotta remember the dmax and psd have the same displacement as a ctd but with 2 more cylinders, so their components will be smaller. still, to the uninformed, our rods look huge compared to the other 2.

jaconst

I always thought bigger and thicker is stronger?

Jfaulkner

bigger and thicker isn't necessarly stronger, but is almost always heavier. Especially at high rpm.

dodgezilla04

heavier is one of the reasons our engines redline earlier.

Begle1

Do they redline earlier?

The bottom end is good all day for 4,000 RPM, correct? And the sled pullers launch at over 5,000, but I don't know how much the bottom end likes that. Can Duramaxes and Powerstrokes be spun that high?

I've never even heard of a bottom end failure in a Cummins. I think that those connecting rods equate to a higher mechanical redline than the V-8's...

jaconst

not to mention the I think the inline design equates to more power anyways

Willy91

My new injection pump redlines at 5,500 RPM, I have a mainstud kit for it and PDR said with the mainstud kit I could rev like that for a long time, I try not to rev it that high unless playing or pulling.

wheelo90

I would honestly say that an 8 cyl would redline at a higher RPM range than a 6 cyl. Due to the fact that an 8 cyl is more balanced than a 6 cyl.
Wheelo

Begle1

In general, but due to the bad engineering on the V-8's and the fantastic engineering of the Cummins, I believe that our L-6 can actually out V-8 their
V-8's.

Right?

dodgezilla04

yes the properly modified CTD can run 4K all day long and the pullers are running in excess of 5K. stock, the CTD tach redline is lower than the other 2, for the simple reason that a inline makes more power lower than a V so there really isnt any reason to spin it faster. the V is balanced better, the greater the V, the better the balance. I am seen alot of abuse dished out to a CTD, and havent seen a bottom end failure either, I have seen some bent push rods though, the valve springs(stock) will float the valves.

Berak

Wrong. I6 engines are inherently more balanced than V8 engines. Lower redline is most likely due to more reciprocating mass in general.

wheelo90

Hey, thanks everyone for telling me the way that things are. I really did not know that about the V-8. I had heard this many times around many different people, Now I know.
Thanks,
Wheelo

Begle1

V-8's are better balanced- as one piston is going that way, the other piston is coming that way, so you have better balance.

I-6's are bulletproof and simple, but in general don't like to rev like a V-8 does, where reciprocating mass helps to increase RPM.

The Cummins vs. Powerstroke debate, however, is an exception to the general rule.

And if the airplane was on the conveyor belt, the airplane wouldn't take off.

Northern Light

Hi!

I always thought a I6 or V12 is more balanced compared to a V8
I´m a bit confused right now

I6 in a car engine for example is a totally different animal, those can rev high if stroke and piston weight is reduced, for example BMW diesel I6´s. But it only has 3 l of displacement and a by far reduced stroke compared to the Cummins. Those rev to 5000 RPM easily because of lower mass. The only way for big displacement and (reliable) high reving is IMO a V12 like in the Audi R10 racecar. But for a truck application I think the 5.9 or future 6.7 Cummins is the way to go as you just won´t need to rev high, except the sled pullers maybe. Power down low is where it´s mostly needed for pulling.

Put two turbos, bigger injectors and some other parts on the (hopefully soon to be released) 6.7 Cummins, raise the redline a bit and let the begin