WSsick

iTrader: (13)

me and another guy at my college today were talking about cars of long story short we got on the talk of block strength. we both agreed that it is widely accepted iron blocks are strong for boost, nitrous, etc. now what we really didnt know was whether a forged bottom end on an aluminum was just as good as a FBE iron block, under non-extreme power (i.e. 800hp and below). i would assume that, duh, the iron block is stronger but i really didnt know when the differences REALLY start to show/matter. anyone gimme some answers. i know its broad but answer in your expertiece


dont ridcule me, just trying to gain info. sorry for the newb-ish question thanks in advance.

Sunset'01Z

iTrader: (10)

once you add a girdle to the aluminum block, it's just as sturdy as the iron, but you will spend a lot more money on an aluminum engine.

Vicinity

iTrader: (7)

What's a girdle? I thought that made people look less fat.

WSsick

iTrader: (13)

hahahah x2. thats exactly what i was thinking.

Jon5212

iTrader: (2)

A main girdle is like backup for the main bearing caps, keeps them held down. Just like a rear end girdle presses on the bearing caps to keep the ring gear/differential still.

raven154

iTrader: (14)

A girdle just ties all of the mains together to keep the case from flexing under load. Just keeps the block square.

landonew

Iron block is stronger, but slightly heavier (80lbs). It doesn't require sleeves so it can be rebuilt a number of times. For sub 800rwhp, a girdled alluminum block is ideal.

Whether an iron block is significantly stronger than an alliminum block is questionable. Some claim that aluminum blocks are plenty strong and with a good tune (i.e. no detonation) they are capable of 1300rwhp+. Others claim that Iron lq9 block has a clear structural advantage. I have no opinion on this matter.

Now the LSX iron block (gm performance block) is clearily the strongest but also very heavy. The warhawk alm. block is also a nice piece.

SHINER

iTrader: (18)

Well said

Yeajimi

If they use the same tooling during the casting of the two blocks, iron and aluminum, the iron block will be far superior to the aluminum block. You will be able to dyno both built engines and notice missing horsepower at high levels due to the block shifting and creating out of round cylinder bores.
A good manufacturer will have additional reinforcement and add structural rigidity to the block by adding ridges and beefing up certain known weak spots in the block.

99blancoSS

iTrader: (115)

One thing no one metioned is the fact the aluminum expands quicker than iron. What does that do to the bite (clamping pressure) on the mains?

This is why an iron block is better for boost.