CamaroFreak87

These are the rods I'm considering:
Aluminum- Manley 7075 aluminum rods
Steel- Eagle ESP Rods 4340 steel
Steel- Eagle SIR Rods 5140 steel

I don't know what the numbers mean. I don't know if higher is better. The SIR rods are about $200 less than the ESP and Manley rods. I'm looking at about 700 flywheel hp with forced induction. I would like to take suggestions please. or if you know any other brands that are comprable in quality and price. Thanks.

Ryan

Mark305TBI

Those numbers refer to the SAE alloy designation.

43xx 1.83 nickel, 0.50 - 0.80 chromium & 0.25 molybdenum
51xx 0.80 - 1.00 chromium

xx denotes carbon content. I'm not to sure what the numbers mean on the aluminum. 4340 is stronger than 5140.

Hung Start67

Hey bro if this engine is a daily driver..pretty sure you need to go with a steel rod..dont believe the aluminum rods were made for daily use...could be wrong thou...later...

johnsjj2

Aluminium rods will last on the street, under normal use. There have been numerous articles about this in car mags. I wouldn't run them on the street due to the fact, no matter how you use them, they will stretch. If you don't keep an eye on this, they could potentially smack a valve if the clearance is low. The main benefit of aluminum rods is the weight reduction, and therfore a faster winding engine. This won't matter much on the street.

Dragula

go with the 4340 steel rods.

ronterry

We all know that stock rods are forged steel, but I wonder what grade?


Ron

Dragula

Stock rods are not forged steel. Chevy made some forged rods for production cars but not in our years.

ronterry

Not my LT-1 rods in my TA.

So are you saying 3rd gen rods are Cast?

Ron

Dragula

Neither are the 4340 H-beams in my IROC

I believe they were all cast

johnsjj2

LT-1 rods are forged, but they are made of powdered metal. They really don't have any other way to make them. These are a lot better than cast, or pink rods, but 4340, or 5140 rods would be a better bet.

Morley

7075 is about the strongest alumnium alloy you can get. One thing to keep in mind is the expansion rate of alumnium. I know in the older alumnim rods they had a problem with them "growing" when in use, due to the expansion of the metal, and you had to be careful with the piston to valve clearance because of this. This may or may not still be a concern in newer alumnium rods, I haven't kept up with the design changes in them.

johnsjj2

I know aluminum still expands at a different rate than steel. If you fire up a cold aluminum rod equipped engine, and sing it to 7 grand, it just might see fit to leave town. This is why some pistons chatter until warmed up. Still, for regular street use, I wouls stay with steel. They will provide a long service life as long as they are properly taken care of. I guess aluminum will too, but its a lot more time consuming to check rods every 3000 miles or whatever the interval would be.

CamaroFreak87

Okay, thanks everyone. I'll be going with the Steel 4340 rods.

BIG_MODS

iTrader: (9)

All the SBC rods were forged steel up until the recently. I wouldn't call powdered metal rods forged.