What are the pros and cons of cast iron vs. aluminium barrel

[shocky]

I've never had an issue with running in an iron barrel and certainly don't do 100mls. It's how you run them in,not how long.

Hard and fast through the gears for me 4 thou clearance never had a rebor sieze through lackof tolerance I did have a rapido sieze in 4 places after 1000 miles running in on stripping it had 2.5 thou clearance
it got honed by harry barlow and I stuck a mahle 3 ring in to replace the really fcuk asso ...

[eden]

the best analogy for ali V cast iron is this:

Cast iron barrels are like an old friend, they will tell you when your abusing them and they will let you know when they aint happy with how you are behaving.

ali barrels are like your wife, they will pretend everything is just fine and bottle it all up for ages until the day they blow their top, leaving you wondering wtf happened there!

[nelson pk]

Not another ally versus iron arguement!
Plausible arguements on both sides here but i still prefer ally. The heat dispertion arguement is not old hat, its fact, due to the nature of the two different metals. Also ally can run tighter tolerances giving more power although i know someone will say that the ally piston heats up quicker than the iron in an iron barrel so the tolerance will get tighter which maybe true to an extent.
I dont doubt that its cheaper to maunfacture ally barrels but then add the cost of plating on top.......
Ally barrels did become popular after the TS1 but Vespa also turned to ally with their more sporty T5 model just before this so it wasn't all about the advent of the TS1.
I am sure you will find that car manufacturers did not just start using ally blocks over cast due to cost and weight saving, i think you will find efficient cooling came into it and i think you will find that cast iron blocks cracked easier on certain engines and also i bet there was thinking behind the fact that the headgasket would be between two parts of the same material with even expansion properties rather than two different metals that expand at different rates.
If heat dispertion is not a relative arguement why not make a head from cast iron??????
Ally for me all day long.....

[B-Race Tuning]

the best analogy for ali V cast iron is this:

Cast iron barrels are like an old friend, they will tell you when your abusing them and they will let you know when they aint happy with how you are behaving.

ali barrels are like your wife, they will pretend everything is just fine and bottle it all up for ages until the day they blow their top, leaving you wondering wtf happened there!

FCUKING A

[eden]

the ally piston heats up quicker than the iron in an iron barrel so the tolerance will get tighter which maybe true to an extent.
.....

to an extent?
Its THE reason the tolerance is bigger on a cast iron barrel,

As you brought up car manufacturers, I see you didn't mention the problems Jaguar and BMW had with coated ali bores regarding fuel mixed with water eating the coating and resulting in both manufacturers replacing the engines on affected models with iron bores at huge cost.

funny too because it affected cars much more that didn't do many miles due to condensation, the cars that were used ever day didn't suffer as badly. and lets face it most scooters aint used every day, some are only used on the 3 or 4 sunny Sundays we get through the year.


one thing I agree with you about though nelson..... this topic has been done and done over and over, the people who prefer which ever will stick to what they prefer no mater what the opposing arguments are. Stubborn old farts is what we all are

[B-Race Tuning]

As with my best friends and my wife, I love them both, just in different ways, for different reasons. And wouldn't be happy without either. S

[nelson pk]

the ally piston heats up quicker than the iron in an iron barrel so the tolerance will get tighter which maybe true to an extent.
.....

to an extent?
Its THE reason the tolerance is bigger on a cast iron barrel,

As you brought up car manufacturers, I see you didn't mention the problems Jaguar and BMW had with coated ali bores regarding fuel mixed with water eating the coating and resulting in both manufacturers replacing the engines on affected models with iron bores at huge cost.

funny too because it affected cars much more that didn't do many miles due to condensation, the cars that were used ever day didn't suffer as badly. and lets face it most scooters aint used every day, some are only used on the 3 or 4 sunny Sundays we get through the year.


one thing I agree with you about though nelson..... this topic has been done and done over and over, the people who prefer which ever will stick to what they prefer no mater what the opposing arguments are. Stubborn old farts is what we all are

By saying that the piston expands far quicker than the iron barrel and that is why the tolerance has to be bigger you must surely agree then that its tolerance for seizure due to overheating is far lower than ally?

BMW did have problems with their lined bores years ago.....must be 10 to 15 years ago at least but this was a manufacturing defect not a general result of all lined bores and they haven't gone back to iron blocks (granted, they probably use iron liners).

When they start making heads out of cast iron i will go with cast iron

You are right in that there is one thing we do agree on and that is that our opinions are not likely to change in the near future and yes i am a stubborn, grumpy old fart and i just seem to be getting worse with age

[eden]

i am a stubborn, grumpy old fart and i just seem to be getting worse with age

its great isn't it, you know its bad when you find yourself moaning about your own moaning.

[nelson pk]

i am a stubborn, grumpy old fart and i just seem to be getting worse with age

its great isn't it, you know its bad when you find yourself moaning about your own moaning.

I know, i'm getting more like Victor Meldrew every day

[onthelam]

^ I'm more of a Last of the Summer Wine man!

Aluminium has better heat dissipation qualities than cast iron so it makes sense for smaller engines which produce more power. Which is the way cars are going now. Add this to advances in casting where now the ports in a cast head are almost perfect from the foundry.

Apologies if I dragged up a subject from the past but my OP was really about a buying decision. I live way out here at the end of the supply chain, OK not as far as NZ but... My Honda NSR250 has plated alloy cylinders but I have a local place where I can get replacements if needed. As Vespas are more common here and i have yet to see a T5 that might also tell me something.

It seems the jury is out and the choice is a matter of personal preference.