Aluminum vs, Cast Iron Block

[Manowar]

Yes.

We build them on Long Island and have customers here in the Northeast Corridor. My comments above include those engines.

-But those guys can't share their experience which is what you seek. We're not getting any trouble reports, which is my point-don't fear aluminum engines. Imports and some domestics are loaded with 'em.

[WildBill3]

wow @461 cubes for the big small block .the price looks good to ManoWar nice to see the progression of cubes to keep up with the Bowties small block.

[quickjack]

"I've had one Dart block where the sleeves sunk .002" in a time period from new to the first freshen. There were no symptoms. The builder took .002 off the deck and they never moved again."

Scott,
The sleeves are installed .002" above the deck and will seat when the deck plate is used for honing. If the builder cuts the deck beforehand to achieve a flush condition the sleeves will ultimately seat, leaving them .002 below the deck. The subsequent .002 cut simply brought things back to where they would have been.

[scottj]

Originally Posted by quickjack

Scott,
The sleeves are installed .002" above the deck and will seat when the deck plate is used for honing. If the builder cuts the deck beforehand to achieve a flush condition the sleeves will ultimately seat, leaving them .002 below the deck. The subsequent .002 cut simply brought things back to where they would have been.

That would explain it. I just happened to notice that the deck had been restamped 9.323 from 9.325. My current builder inherited the motor at the first freshen. Probably because I didn't ask for one, he didn't offer an explanation other than the sleeves had sunk. Thanks.

[ffindling]

Originally Posted by Jamo

The obvious intent for referring to the Vega motor was that, like the RoverneeBuick motor...citing fairly wide spread issues from decades ago is hardly worthy as support that aluminum motors are problematic.

I agree. The aluminum Buick motor gained an undeserved reputation for
the brief period it was sold in GM products here. The Brits obtained the design
rights to it and produced it for over 30 years as a solid, reliable engine.

....Fred

[82ACAUTOCRAFT]

The Rover V8 is actually quite unreliable and it is similar to the FE in a smaller package. It's why I brought the subject in this thread. The early Buick blocks did not suffer from early failures as the Rover do because of the block casting process and bore size. GM dropped the aluminum version because of cost and started producing the engine in cast iron in Buick's and Oldsmobile's in the mid 60's. The Rover block is sand cast and the bores have grown bigger over the years making the walls too thin. The Rover engine suffered from main bearing failure and Sleeve failure. (Mainly in 4.0 and 4.6 liters Range Rovers where this engine works very hard and engine temperature has to be kept high for emission requirements). In the 90's, Rover introduced a cross bolted design much like the FE 427 and solved the main bearing problem. However, the sleeve failure remained and is due to the walls behind the sleeve being too thin and cracking and the sleeve moving down and letting coolant in the cylinder. When this happens, mechanics not familiar with the Rover V8 think the head gasket has blown when in fact it is much more serious and the block is in fact dead. Some aftermarket British companies now cast their own block with flanged sleeves to prevent this from happening again. One even makes a big bore Siamese design which works quite well. Having owned a couple of Range Rovers and a Morgan Plus Eight, I am all too familiar with this engine. Ironically, head gasket failures on Rover V8 are rare.

[StangerX]

An aluminum block is a horsepower sponge you lose atleast 10% horsepower
by useing one. Is the wieght worth that, maybe if you are really road racing it
,but then now days you would use a SBF iron block for that. What do they use in prostock iron only.

[Bunkie314]

Manowar,

Got any spec's on how tight you thread in the freeze plugs? Do you use an NPT cut block with a NPST plug? I've got some weap issues, as if you can't tell by the question. Don't want to overtighten or go to something soft and gall. Any help you could offer? Steel to aluminum torque spec maybe?

StangerX,

I have been rolling the aluminum heads over in my mind thinking of this very issue of better "Heat Sink". I questioned the block as well. Any data to confirm you remarks? Heat up with the aluminum block is quick, which to me states btu loss into the casting and not into the combustion gas expansion. I think that is the reason they run them hotter is the parasitic loss that is going on.

We should continue this topic further. I am quite interested on views and data available on this.

[undy]

Originally Posted by StangerX

An aluminum block is a horsepower sponge you lose atleast 10% horsepower
by useing one.

...couldn't be further from the truth.

[Ant]

StangerX,

10% loss of power by using an aluminium block, is that because the aluminium conducts the heat better than cast iron, or removes heat/energy generated, so in effect an alloy motor is a heater?
I find your claim very questionable, as the efficiency of the engine is to do with design, and heat is a by product of this.

[Manowar]

[quote=Bunkie314]Manowar,

Got any spec's on how tight you thread in the freeze plugs? Do you use an NPT cut block with a NPST plug? I've got some weap issues, as if you can't tell by the question. Don't want to overtighten or go to something soft and gall. Any help you could offer? Steel to aluminum torque spec maybe?

Our plugs are 1 5/16 x 12 with o-ring. Anti-seize threads lightly and snug them without damaging o-ring.

The concerns about power loss with aluminum blocks are greatly overstated here, based on our experience. We build over a hunderd a year. We ran a 540 on Tues with the aluminum block option which is rated at 630 and it made 701 on it's best pull. Iron versions have been steadily making in the 690 range.
Factor in a 100+ lb. weight loss plus the ability to increase compression with aluminum components (thus increasing power) and you easily exceed the possible 12 or so horsepower differential across a 500 HP rated engine, iron vs aluminum.

[quickjack]

In a high compression or forced induction race engine, the iron block will make more power due to better ring seal, and this can often negate the weight advantage - especially in a drag race car or a heavy car.
On a high performance street or mild race engine, the difference will be minimal.

[fostereast]

I suspect an aluminum block out of the box has better ring seal than an NOS 427 block. The sleeves in general are much stronger due to the way they are cast and the 427 iron block starts out with pretty thin cylinder walls

If your comparing the new Genesis and Pond iron blocks to aluminum, they all (both Iron and Aluminum) have siamese cylinder bores and I bet the aluminum still wins due to its cast sleeves.

IMHO

[quickjack]

The thing is, no one here is building these things to a really highly stressed state. So, I suspect the actual differences in power output due solely to the block type used are not an issue.

[Manowar]

I agree, that was my earlier point. Also, "living" with an aluminum block today is not a hardship.

[Bunkie314]

Manowar,

So a STOR configuration? Damn, I was hoping for another answer. Since it is together and in the car, re-machining is not an option for me. Guess I will go with the ceramic sealant first before I take them out, again. I'm getting somewhat tired of dealing with weeping. Its not creating a big deal, I'm just a bit over anal retentive on leaks. Well, and squeaks too. I've only used maybe a cup in 800 miles and I'm not sure if all of it has been from the plugs since I'm using a 7 lb cap and it does lift. Initially I was using a 15 lb cap and the plugs leak severely. System pressure seems to be running higher for the same temperature which brings in the next topic.

I've noted quite a difference in warm up time with the alloy block. It would be interesting to compare coolant system heat rejection differences between alloy and cast. Could possibly quantified by measuring thermal input, T-stat cycle time, coolant system pressure, and coolant flow rates at a given load just to get a comparison. This is way over simplified, so don't beat me up. Due to the increase in coolant system pressure there is power loss. Question is the significance to the overall cycle and as pointed out does it really make a difference for 500 HP. I suspect that alloy heads have a more significant role than a alloy block due to overall exposure time.

[82ACAUTOCRAFT]

I don't think HP loss in aluminum blocks is an issue, they use steel liners anyway. Aluminum heads however, make a tiny bit less power than iron ones because of greater heat dissipation but this is offset by a greater resistance to detonation still because of the heat dissipation. The only problems I can see with alloy blocks are those due to porosity, expansion and the softness of the metal and those of course can be solved with proper enginering and machining. Sand casting is not the best way to make strong parts in aluminum but I suspect it is the process used by Genesis, Pond and dove, is it?
One thing I have noticed after installing Edelbrock alloy heads and Intake M. on both my FEs' is how much cooler the engines ran! I have had no problem with either motor by the way. I just bought another original 427 block, this is the one I will use, it is drilled for hydraulic L and came off a Fairlane. It is going in an original car and after the car is painted, I want to forget about the motor and not worry about leaks or other mechanical issues.

[Commander]

A possible reason for lower HP levels in alloy blocks could be structural stiffness.

Instead of the force from the combustion event being transmitted through the rods to the crank cradled in a firm iron structure, it is transmitted down to a crank that is in a not so crystalline structure which will absorb some of the power into itself. The aluminum will have more of a damping effect on the power strokes.

The answer to whether that matters one wit in to anyone here, is most probably : no.

[82ACAUTOCRAFT]

Forget about power loss, I don't think it's a factor! Reliability is "THE FACTOR" and if it's not an issue then let's enjoy our new aluminum blocks and have fun!

[fostereast]

I think the biggest difference is in the robustness of a street solution.

For example: I know the old Cast iron v8's could overheat and be OK, many new aluminum headed engines warp when overheated. I don't know what happens with the reproduction aluminum heads and blocks used in Cobra replicas when the engine overheats; if things warp and seals are lost, some people may make a decision to use cast iron to reduce the potential problems.

There may be other considerations as well.