Strength of the stock connecting rods

TurboBob

Resident mad scientist
Staff member
Joined
May 24, 2001
Here's a question for all you engine guru's out there.

There are lots of discussions of girdles vs caps, and forged crank vs. stock.

But what about the rods? At what point should you put forged rods in a stock-block engine?

I don't recall ever hearing about broken rods, it seems that its usually something else that fails.

What is the current wisdom?

Bob
 
Below 10.50 the stock rods get real questionable. I know Billy Anderson broke some rods in a 10.20 engine. One of our shop cars has been 10.30s a few times with stock rods and crank but it hasnt been beaten on THAT much.
 
I have found that they bend real nice when detenated, bent 5 of six due to my dumb *ss, pump and 27psi do not get along, but never broke one.

I would imagine its rpm sensitive more than power. These were in a 10.70s car.

Thanks
Bill
 
we have over 15k miles on Melissa's motor (well its my Mazda motor:p ).. It gets a beating everyday.. NO DETONATION !!!
 
Bob "if" I were doing a new motor I would step up and get new rods. Buy the time ya "do" a set of stock rods I'd save the $$$ and put it towards the new ones :cool:
 
The factory ecm uses fuel cutoff for a rev limit. I ran up on 2nd gear quick on my stk rod motor and hit the limiter. In theory, it shouldn't have enough fuel to fire. Well.....maybe there was just enough in the runner...not sure. But it popped once (28psi:rolleyes: ) on the rev limiter and was knocking on the return road...:mad:

No mo stock rods fo me!!!!!!!

If you're getting that deep into the motor...why not spend the extra $$? Cheap insurance...because you WILL BEAT ON IT. Regardless of best intentions...:biggrin:
 
Bob "if" I were doing a new motor I would step up and get new rods. Buy the time ya "do" a set of stock rods I'd save the $$$ and put it towards the new ones :cool:

X2
Ask your builder how much to inspect, shot peen, add ARP hardware, resize the big end, and if you change the piston pin setup, the total price. That should seal the deal for ya.
 
I, too, feel that same as the rest of the guys on here. If you ever plan on running faster than 10.50, and the engine is being built, run the K1 rods. They are real nice pieces for the money. Cheap insurance. But......if you never plan on leaning on the car past 10.50, then keep the stock rods, they work great as long as you tune it right. They do bend, but I have never seen one brake.
 
I broke a rod once on the Pin end. I never had problems on the crank end. My pin end I believe came from pressing the pistons on/off and the heating of the rod end.

I never messed up a stock end that was never messed with(pressed on/off)

The rod I broke was 7K rpm at 28 PSI on radials. Blew the tires 40 feet out and over rev'd really quick :redface:
 
I ran stock rods with stack sps bolts for years and never broke one. Over the last two years the car ran 10 teens to 10.30s'. Raced almost every weekend. They will bend with detonation but otherwise seem to hold up real well.

John
 
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