Cast Iron Engines vs Aluminum Engines, which was/is better? (vehicles, idle)

[burdell]

Originally Posted by rbohm

very true, but those engines are rebuilt after every race. an aluminum block with no liners in the cylinder bores will not go 100,000 miles, as those that owned a vega can attest.

Simply not true, I've seen Nikasil coated aluminum blocks with upwards of 200K on them with virtually no wear, the Vega was just an early, poorly executed example of a different technology. IIRC they weren't coated but made of a high silicon level alloy that required a very specific honing process to function well.

Originally Posted by rbohm

and i made no assertions as to which one was better anyway, i merely pointed out the advantages and disadvantages of each material, and which one i would prefer if i were building a race car, or other vehicle, and if the rules allowed it.

You stated: aluminum = lighter weight, flexible blocks, requires steel sleeves for long wear


Properly designed aluminum blocks are neither flexible nor do they require any type of ferrous sleeve to obtain longevity.

[burdell]

Originally Posted by StealthRabbit

but... audi has an unlimited supply of these lightweight diesels and the time / money / labor to change them between each race. Glad they are paying for the research on this!

regretfully, I spend plenty of time 'fixing' / deal with the burden of Al heads on Cast Iron blocks. Not a pretty solution (differential Thermal expansion).

Physics is Physics... some things will not change (thermal expansion can only slightly be mitigated by alloys).

Flexible (stretch) bolts (torque to yield) have helped, but stuff is STILL moving between every heat cycle, that stuff will eventually leak (highly probable).

General heavy service, I will stick with CI. (dozers / trucks / work horses) but... I appreciate AL engines on my racing motorcycles!

AL heads on a CI block is a whole 'nother ball game. I knew someone with > 200K on an all aluminum BMW motorcycle engine that had never been apart and still ran well, and that's not uncommon.

Somehow, when it's done correctly, aluminum can be made every bit as reliable and long lasting as CI.

[Seafood Junky]

Originally Posted by Felix C

MOPAR Hemi blocks still cast iron.

MOPAR also offers aluminum HEMI variants...

[Felix C]

Originally Posted by Seafood Junky

MOPAR also offers aluminum HEMI variants...

not in production cars

[Hoonose]

Jaguar had serious problems with Nikasil, I forget the specifics, but our 2001 was after the trouble was corrected.

[Grumpy ol' Man]

Originally Posted by Felix C

MOPAR Hemi blocks still cast iron.

Because of the $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$'s

[rbohm]

Originally Posted by burdell

Simply not true, I've seen Nikasil coated aluminum blocks with upwards of 200K on them with virtually no wear, the Vega was just an early, poorly executed example of a different technology. IIRC they weren't coated but made of a high silicon level alloy that required a very specific honing process to function well.

in other words these aluminum blocks have a liner, whether it is a steel liner, or a coating, there IS STILL A LINER in the block, not bare aluminum.

You stated: aluminum = lighter weight, flexible blocks, requires steel sleeves for long wear


Properly designed aluminum blocks are neither flexible nor do they require any type of ferrous sleeve to obtain longevity.

ok so where did i say that cast iron is better? the fact is that i didnt. and again, bare aluminum cylinder walls are not going to wear long, you were talking about coatings which is still a liner on the cylinder wall.

so again i am right.

i will say that given the opportunity, as i noted in my original post, if the rules allowed it, i would use aluminum blocks and heads for building an engine for the reasons i stated. but that doesnt mean that aluminum is better or worse than cast iron. just different.

[eddie1278]

I'll take good old american iron.

[StealthRabbit]

Originally Posted by burdell

AL heads on a CI block is a whole 'nother ball game. I knew someone with > 200K on an all aluminum BMW motorcycle engine that had never been apart and still ran well, and that's not uncommon.

Somehow, when it's done correctly, aluminum can be made every bit as reliable and long lasting as CI.

yup. my whimpy gas engine compression ratios are perfectly fine with CI and AL.

...Diesel Compression ratio and turbo pressure and temps... not so robust.

I do a lot of aluminum welding, and some of the Al combustion chambers I see have been brought to the 'melting point'. (Not a pretty sight) 660c vs 1200+c for CI.

There are 'perfect applications for each!' I have run a few antique chain saws with cast iron engines! We would all look like Hercules if we were packing them around!

[armory]

I am an average guy driving Detroit iron powered by iron blocks. I do not plan on building a supercar which requires $$$$ aluminium block/heads so the iron V6 stays in my truck and iron V8 stays in my car. If I were going to build up a muscle engine it would be a SBC based on a 350 iron block. What can't it do? 200 mph for 500 miles at Daytona or Talledega speaks volumes.

Put me down for iron unless it's a motorcycle engine. Harley had to eventually go aluminium in that regard as they were being killed off. I still prefer an air cooled 80s Suzuki GS in line 4 engine.