Aluminum Connecting Rods Vs Steel

Jay s tech tips 43 when are aluminum rods right for you.
Aluminum connecting rods vs steel. There are some practical considerations when choosing a connecting rod. This alloy has a higher level of silicon 1 45 to 1 80 and a little more carbon and molybdenum for added strength. Many rod suppliers are making steel connecting rods out of 300m alloy. In a big inch engine steel rods can weigh more 900 grams while comparable aluminum rods would be around 600 grams.
This allows the thickness and cross sectional area of the rod to be reduced so the rod can be 10 to 20 lighter than a comparable rod made of 4340 steel. Steel connecting rods are made with various types of materials and manufacturing processes. For example cast steel. All connecting rods stretch under high rpm use and aluminum rods will tend to stretch 010 more than steel with all other variables being the same.
Engine builders are trying to get more weight off the piston these days and keep the extra mass at the bottom of the rod that s where an aluminum rod is beneficial. A brief comparison of aluminum with steel rods. It s the same thing with a connecting rod. Real street performance duration.
This expansion that aluminum rods endure is attributed to the inherent thermal expansion of aluminum as a material more so than high rpm movement. Aluminum rods are generally 25 percent lighter than steel rods and for this reason theyre very popular with racers looking to shed mass from the reciprocating assembly. Steel rod manufacturers have been able to remove a lot of weight in their modern designs and aluminum rods are about 100 grams lighter in a direct comparison of similar rods. When it comes to connecting rods the main material options are steel aluminum and titanium.
Depending on the material and the application a steel connecting rod might last almost forever or an aluminum connecting rod may last just a handful of passes if you are really making lots of horsepower with boost and nitrous at high rpms with a very heavy piston.