I think the theory about aluminum blocks have changed since the demise of the Vega back in the 1970s.

 

Depends on how good the cooling system is.

 

I am sure that the high power AL blocks have IRON sleeves. They would have to.

 

Aluminum blocks cannot hold as much boost as cast iron blocks can. Cast Iron is much more durable. Aluminum blocks are good for NA motors...not boosted.

 

Yes. Many VTEC blocks have been assigned to the junk yard for this very reason. While thisis true, we're talking real overheating here, like properly fried and not just a bit of steaming in traffic. Say if you puncture your radiator but decided to carry on the next 10km to the end of the Special Stage at race pace, that sort of thing.

Al blocks can't take insane boost levels because of the lower stiffness of the material and virtually all its alloys. They also distort more at high temp, if i recall correctly.

However, there are some very exotic aluminium alloys that are very very stiff. The cost of casting and maufactuing these particular alloys I'd imagine to be astronomical. But I think you can design them to be as stiff as the cast iron while still weighing less. That would be nice... In any case, if they designed the thing to work at xxpsi boost, I'm sure it will work fine at that level. There are other ways of getting more power from your engine other than increasing boost. Not many are offer the bang/$$, admittedly, but there are.

 

Interesting about the 96-98 blocks. What about the 99,01 models?

Harlan....you mean Matt Harlan?

Regardless of the LS1 and cobra block capabilities, the OEM and racing industry I would say tends to favor iron blocks when extremely high cylinder pressures (ie from boost) are involved. Mostly because aluminum tends to exhibit poor fatigue properties when under high stress, and the fact that you need EXCELLENT cooling to counteract the rapid thermal cycles that aluminum naturally undergoes.

As pointed out by E. Haskell however, either material is capable of big numbers, and the weak link in the new evo X engine, following suit with most engines out there, will most likely not be the block.

 

one of teh main reasons that stis motors are weaker is teh fact that they have al blocks.. peeople that want to make evo power generally sleve the 2.5s

 

I prefer Iron block, weighs heavier than the Al block but can withstand serious power and boost. It was proven for a long time in the 4G63 engine.

 

The 99/01 blocks were Windsor blocks which are still pretty durable, but the 96-98 block was made by Teksid in Italy--they also make Ferrari blocks. I'm not sure if his first name is Matt

 

interesting choice of suppliers...

BTW, his name is matt, I just looked his tag name up. He graduated a few years ahead of me in college. Smart guy, he designed an engine controller for an FZR600 from scratch and had it running in about half a year.

 

Iron block is definately better, however the evo should be fine with the aluminum block with iron sleeves. It will withstand hp modification well im guessing, but i dont know if it can withstand super high gains such as 600whp. If youre a serious drag racer, it will be an issue for you, if not, youll most likely not mod your car passed 400whp anyway and this shouldnt be a problem im guessing for the new evo. Anyway, we see lots of sti's doing fine with aluminum block/iron sleaves so maybe its just a myth that they cannot handle high hp gains

The engine itself will receive some harsh criticism initially because its a brand new engine and the aftermarket will take some time to adjust to it, and mitsubishi will obviously tweak it over the years, which is actually a good reason not to get a first year evo X, because you know there will be a lot of issues with them. It would be nice if they stuck with the 4g63, but sometimes you just have to move on for better or worse.

In terms of aluminum blocks being cheaper to manufacture, im not sure of that, i heard its much harder to shape and mold aluminum compared to iron because its very easy to burn right through aluminum. Aluminum takes much more time and effort to mold properly, which is why cars with aluminum parts are more expensive. I know a couple of chopper gearheads and im somewhat a chopper gearhead myself and whenever they see an aluminum frame or aluminum gas tank on a chopper they always tell me how difficult it was to weld and shape, so im not sure if cost is an issue when converting from aluminum to iron block

 

You're right al is fiddly to fabricate, specially in sheet form. This is due to its flexibility and sensitivity to heat. However, this doesn't really have a lot to do with the engine block as it will be cast and machined with no fabrication or shaping required.

 

I think the AL block will provide 90% of us a better motor. How many of you guys are really looking for more than 600HP anyway?

Without a doubt a modern AL block can easily take 400HP. Thats all most of us ever aim for anyway. Besides....odds are you'll be able to swap in an old school iron block motor if you wish.

 

I'm moving this to Evo Engine...

 

Titanium block is the way to go. Cheap, easy to work with