What's the appeal of an aluminum engine block?

[RodKnock]

Originally Posted by blykins

We're not driving Porsches.

And you're likely not driving Toyota's, Subaru's, Miatas, RX-7's, Corvette's, BMW's, etc. either, but the "hot rod" consumer desires lightweight parts.

Since the dawn of time, tennis rackets, baseball bats, wiffle balls, engine blocks, have become lighter. Why? To go faster, hit the ball farther, etc.

One word. Plastics.

[RodKnock]

Originally Posted by moore_rb

Well, yeah, but it's more important for the Porsche guys to obsess about weight (and more importantly, about weight distribution)...

It wouldn't be such a big deal to them, if the Germans hadn't deliberately designed their cars to run around backwards...

just teasin'

I'm having fun! I hope everyone else is too.

BTW, Happy Thanksgiving everyone.

[blykins]

My guess is that an aluminum body is exactly like an original.

"I" would drop a cast iron block into a CSX or Kirkham, because I like repop stuff.....not resto-mod stuff.

Let me ask you, Rod......why do you think all the engine builders want a cast iron block?

Undy,

Aluminum blocks expand. They squirm. They distort. You lose ring seal. Remember, you GAIN .014-.015" of valve lash (or lose that much preload on a hydraulic cam) on an all-aluminum engine between cold and hot. Think about how much things are moving around.

I think all that's worth saying has already been said and this isn't going to turn into a small block/big block thread on my account. So, I'll see you all on the other side.

[RodKnock]

Originally Posted by patrickt

Now, if you would just do exactly as I tell you, you will be healthier, wealthier and wiser than RodKnock will ever be.

I don't think so.

Why does everyone post in 3's? That's another complaint of mine. There was "power, reliability and quality" and now Patrick is posting "healthier, wealthier and wiser." What's up with that? Do all of you have OCD or something?

[RodKnock]

Originally Posted by blykins

Let me ask you, Rod......why do you think all the engine builders want a cast iron block?

"All." Another global statement. You're speaking for every engine builder in the US or the world? I don't recall Tom Lucas steering me away from aluminum and pitching me feverishly to buy a cast iron block.

Brent, it's OK. We understand your position after 12 pages. You're not building anymore engines with aluminum blocks (or until business slows down).

[RodKnock]

Originally Posted by undy

Brent, I'm assuming the only reason you're seeing increased HP is due to cast iron's increased thermal retention? Once aluminum heats up and comes up to "designed clearances" ring sealing should be the same as cast iron. Blow-by and effective static or dynamic compression ratios should also be the same as iron. My training leads me to think that the horsepower differences should be minimal. Thoughts?? Just curious...

^^^I like what Undy said. He knows what he's talking about.

[undy]

Originally Posted by RodKnock

^^^I like what Undy said. He knows what he's talking about.

In the case here it would seem that the position dictates the argument, not the argument dictates the position.

BTW... I wouldn't trade my alloy pond 482 for 2 cast iron 482s.

[patrickt]

Originally Posted by RodKnock

Why does everyone post in 3's?

Because it stems from the three ethical principles of Zoroastrianism. Simple, really.

[RodKnock]

Originally Posted by undy

Three words for porosity issues... Vacuum Casting Impregnation.

Undy does the "three word" thing too.

He also seems pretty smart to me. He wouldn't trade his Pond alloy for two cast iron BBM's.

Statements (and even solutions) by Barry R:

Originally Posted by Barry_R

Every single aluminum block I do will get impregnated from now on (Bill - your's was done too) after I had an issue a few years ago. The cost is added into the build, but I do not call it out because customer get nervous about a process the might not understand. This place does a bunch of military and OEM transmission stuff.

The weight savings is nice and I can fully understand the desire. The blocks themselves seem to be consistently inconsistent in quality. I have always been able to build them into good engines but they are always a challenge and I kind of agree with the sentiment - they should cost 20% more for labor because of the extra effort required.

The 427 stuff is definitely cool - given the choice I would prefer to build an iron block every time. We pretty much never have any issues with 390 based 445 builds, and we do them at a rate of two or three per month.

I noticed that Barry mentions building and not having many, if any, issues with original cast iron FE blocks, but doesn't mention aftermarket cast iron blocks. Hmmm.

[patrickt]

Originally Posted by RodKnock

Undy does the "three word" thing too.

That's because Undy is a strong proponent of Humata, Hukhta and Huveshta. Just ask him.

[undy]

Originally Posted by patrickt

That's because Undy is a strong proponent of Humata, Hukhta and Huveshta. Just ask him.

No, not all of them are good...

[patrickt]

Originally Posted by undy

No, not all of them are good...

Well then I'll throw in Havarti... it's my favorite cheese.

[blykins]

Forgot to add....aluminum blocked engines lose compression when they get hot. Stuff grows. A lot.

[undy]

So... I get that it's a costly and risky to build an alloy FE. I agree with that, but what I differ on is the increased HP. Yes, I hear that it "moves around a lot", concur there too. But... that's on warm-up. Once things warm up to design temperature, if it was built correctly, the bearing clearances, piston to cylinder clearances, ring gaps & lifter clearances/preloads etc get where they're supposed to be. Unless you run a cold engine the HP levels should be very close to being equal. I've heard no explanation thus for proving otherwise.

All alloy engines, OEM inclusive, would be subject to this. It just isn't so...

EDIT: just saw Brent's post. I guess we'll have to agree to disagree here. It's really a moot point considering the intent of the original post.

[blykins]

That's fine Dave, it's an accepted fact by engine builders that doesn't need to be argued here.

Under higher horsepower conditions, you will lose power with an aluminum block due to cylinder distortion, loss of ring seal, and a decrease of compression. This isn't an operating temperature issue but just a strength issue. I have torn down all-aluminum FE builds where the block was honed with torque plates, but the sleeves still had "shadows" from where the cylinders distorted. I suppose you could "hot hone" the blocks, but there again......why put the effort into it?

To be fair, yes, you can "design in" more compression ratio, but you still have to deal with the squirming around of the blocks. Bearing clearances are something that the engine builder has to set ahead of time, along with running the valves to make sure everything is kosher when it's hot.

I looked at my dyno sheets. I don't have any *exact* combinations where the only difference is the block material. Maybe Barry might have something like that. I think I've talked to Barry about this before (engine builders do talk to each other, BTW) and he said with his career at Federal Mogul, he rubbed elbows with a lot of the race teams....the general consensus was that iron blocks made more power.

Maybe he'll chime in....

[patrickt]

Brent, I think you should be paid for putting up with all this crap....

[blykins]

I have trouble discerning between the guys who ultimately want to know/learn and the guys who just like to stir the pot.

[patrickt]

Originally Posted by blykins

I have trouble discerning between the guys who ultimately want to know/learn and the guys who just like to stir the pot.

That's because we swap hats on the fly....

[blykins]

Ok, some data I found from the FE forum since I don't have any dyno sheets to prove my point.

From Dave Shoe (speaking to Robert Pond):

"The horsepower differences between iron nand aluminum blocks have been repeatedly characterized by Robert Pond, though I am necessarily distorting his claims because I lack sufficient experience to fully comprehend all his findings. He has been particularly interested in horsepower gains as small as a single horsepower, as his Stock Eliminator racing engines are constrained in the modifications which are allowed. I've spoken to Robert a little bit about "free horsepower", and he strongly contends that the block, all by itself, can provide dozens of free horsepower between the 600 to 1000 horsepower levels, just by its cylinder rigidity characteristics."

From Barry R, speaking of his Federal Mogul days:

"Well - - I can add a little fuel to the fire.
I supply rings and bearings to a large percentage of Pro Stock, Cup, and fastest street car competitors. In virtually 100% of situations where the weight is not critical (meaning that they would have to add ballast to offset any weight benefit from aluminum to meet a mandated minimum) these competitors ALL run an iron block of some sort.

Iron blocks simply make more power. Every time. The commonly bandied about number is somewhere between 15 and 30 - depending on the power level and the particular engine in question. Big beefy billet caps on aluminum blocks are kinda like a super strong steel lid on a cardboard box - when they're stronger than the parent material the value is limited. Ultimate power handling potential is not an issue - both materials have been proven at levels beyond anything feasable in an FE (I have seen numbers near 3000HP).

When properly prepped and designed, neither material will show bearing issues - but aluminum does require tighter cold clearances. Fuel motors don't count - - repairability is more important than the nominal power difference when you're at that level. The sole benefits to an aluminum block are identical to those of aluminum heads - weight ease of modification and repairability."

[blykins]

Happy Thanksgiving all....I'm taking a few days vacation.