Cast iron verses aluminum blocks

[I am Technoman]

What are your views on both of these blocks? I like cast iron.

[MadSideways]

Aluminum is lighter and dissipates more heat, but cast iron can handle more pressure and abuse...

[I am Technoman]

Aluminum is lighter and dissipates more heat, but cast iron can handle more pressure and abuse...

Ok but what about when you change sleeves to stronger ones?HKS claims you can get 50psi of their SR sleeves.

[MadSideways]

This question would probably be better suited for the SR20DET forum....

[YamaOni]

Well the weight difference is next to zero because aluminum is not as strong. (CA Vs SR) If you want punch up a cast block you do it if you want to do the same to the aluminum you need to put in sleeves. The aluminum block does heat up and cool down quicker. Cast iron + water = rust. I like cast because it is stronger (As far as I know there is no tin can RB20 to test with) ... but I have seen RB shoot pistons out their sides before. In the end it comes down to the amount of green you want to lay out to get what you want.

[themadscientist]

Are you referring to the "air cooled" RB?

[YamaOni]

The air cooled A31 and the air cooled stutter box

[voltron]

Here are my opinions on this subject; Aluminum resists corosion better and weighs less. It weighs less regardless of the metals tensile strenght. So I would prefer that the engine in my car is made of aluminum. The rest of it? Engine tuning is a factor way before the metal used to build the motor out of. Say you have two race cars one with an iron block and one with an aluminum block, both motors are runnning 20psi on c16. Lets say then that detonation occurs at the same time in each motor, what breaks? Probablly the ring lands if you are lucky. Maybe you melt a pistion. Whatever. Maybe the question should be what metal will fare better in the instance of catsitrophic failure? I guess then that the iron block has a better chance of being re-used.

[KSee777]

Here are my opinions on this subject; Aluminum resists corosion better and weighs less. It weighs less regardless of the metals tensile strenght. So I would prefer that the engine in my car is made of aluminum. The rest of it? Engine tuning is a factor way before the metal used to build the motor out of. Say you have two race cars one with an iron block and one with an aluminum block, both motors are runnning 20psi on c16. Lets say then that detonation occurs at the same time in each motor, what breaks? Probablly the ring lands if you are lucky. Maybe you melt a pistion. Whatever. Maybe the question should be what metal will fare better in the instance of catsitrophic failure? I guess then that the iron block has a better chance of being re-used.

[themadscientist]

no the tensile strenth is an issue. The aluminum block has to have extra external webbing cast into it for it to approach the strength of the cast iron peice. I have a stripped CA block at the shop next to a fully assembled SR. If I could talk the SR guy into pulling the engine apart we could weigh them. I am sure the SR is lighter but I doubt it is more than 10lbs, not a race-winning difference. If somebody has a stripped SR weigh it and let us know and I will weigh my CA.

[voltron]

Ok I misunderstood the statement above. You are saying that because aluminum is not as strong there has to be more of it, thus making weight diffrence negligable. I did not think of that.

Ksee777: you have a question? I would be happy to clear up anything I typed that does not make sence to you.

[Open4Cycle]

The weight difference between the KA and SR may not be that much of a weight difference but aluminum is stronger than steel by weight! Steel is stronger by volume! One perfomance advantage for cast is not only is the block stronger but the thermal expansion rate is lower therefor the cylinders and other machined surfaces will stay aligned better.