Aluminum small block pros/cons?

[mattpatt]

I'm considering many options in buying an SPF cobra. Amongst those are the choice between an iron or aluminum SB block. I'm guessing that the roughly 100 pound weight savings will translate into faster 0-60 AND also better cornering. Don't know anything about other things like heat, reliability, etc. Right now I'm looking at the World SB 427s (~500 hp) in iron or aluminum blocks. Anybody got any experience or thoughts on this?

thx

Matt

[vector1]

dart or fms would be my 1 2 picks, you gonna build or buy complete.

[Excaliber]

I'm guessing that the roughly 100 pound weight savings will translate into faster 0-60 AND also better cornering.

I'm guessing you'll never drive it hard enough to discern any difference. If so, you'll need a really accurate stop watch because thats the ONLY way you will be able to tell.

[madmaxx]

No brainer, iron. Until FMS proves themselves with their new 427 go for the Roush or Keith Craft with the DART Sportsman block.

Aluminium can obviosly be made to be as reliable, but it grows more, and in general can't take the abuse of iron such as temperature excursions, like a stuck thermostat etc.

If you are concerned about weight, loose 20lbs, take the washer bottle and other components under the SPF hood which are not used.

[patrickt]

Originally Posted by Excaliber

I'm guessing you'll never drive it hard enough to discern any difference. If so, you'll need a really accurate stop watch because thats the ONLY way you will be able to tell.

Absolutely correct. And, if you are building what looks to be a big block car on the outside, it really should have a big block engine under the hood... otherwise the other big block cars will make fun of it and won't let it play in any of the reindeer games.

[Michael C Henry]

A lot of cities are using induction loops just below the surface as sensors at street lights. I wouldn't be surprised if they wouldn't know you're their and you end up waiting untill another iron block car shows up.

[Wild Card 289]

So that´s why Corvettes always end up sitting at the lights so long.........

[bobcowan]

.... 351W block weights
Dart Iron - 160# $2,366 + machine work
Dart Alum - 83# $5,578 + machine work
Ford Iron - 100# 'ish $750 prepped and ready to go.


I debated that same question. You'll spend a lot of money to lose a little bit of weight. If you're racing for money and need every last edge, it's worth it. Otherwise it's strictly for bragging rights. I race for points only, and didn't feel it was worth it the extra money.

After I blew up the stock block 427, I bought the Dart iron Eagle Sportsman strictly for track durabiility. For street use, I'd use a stock block.

[vector1]

.........351w block weights
dart iron - 205#
dart alum - 105#
ford production 165#

[mattpatt]

Definitely sounds like a waste of $s (for me) for an aluminum block. So are there any "little" reindeer games? <{:>))

[patrickt]

Originally Posted by mattpatt

So are there any "little" reindeer games? <{:>))

The "little block versus big block" issue is probably the most discussed Cobra issue on this forum. You can get just as much "usable horsepower" from a small block as you can an FE, and there is even a little weight savings, along with a significant costs savings. However, IMO the small block falls down in two important areas: Looks and Sound. The first one's pretty obvious, so I won't dwell on it. The subject of sound, though, is much more complex. Newbs tend to think that, just because the displacement of the engines may be the same, the sound of the engines will be the same (that is, between a big block and a small block). Nothing could be further from the truth. Or, as Ernie (Excaliber) would write, "An FE is truly a non-campaniform idiophone." If you think of a 427 small block as a bell, then a stock FE would be the same bell, but cast using a larger "cope," (the cavity of the resulting bell will still be identical). The bell will make an entirely different sound, even if you used the exact same clapper (and I'll just skip over the iron v. aluminum comparison). Did you know that deaf people can "hear" my Cobra? And it's not even that loud because I had special sidepipes made to reduce the overall decibel level. But they can feel it. Some guys don't care about that and, truth be told, they don't want to spend the money on an FE (which is understandable). But, in the end, there's just no comparison for the overall effect of an FE. If you're putting together a 427 style car, please try and put in an FE.

[madmaxx]

How much is a complete RELIABLE FE built to 550 hp and 550 ft-lbs, Iron block?

[patrickt]

Originally Posted by madmaxx

How much is a complete RELIABLE FE built to 550 hp and 550 ft-lbs, Iron block?

It's going to be over $10k for a 390 and, depending on whether it's a 428 or 427, whether it's an original iron block, or a new block, and what you have in it, you're going to get closer to $15k, or even $20k for a top of the line build. No, I'm not kidding. And even for a "top o' the line" FE build there's a tremendous amount of luck involved on whether it runs the way you want, doesn't leak, and doesn't break all the time.

EDIT: A lot of builders will undercut Keith Craft and still do a fine job, but his prices will at least give you a feel for what you're dealing with: http://www.keithcraft.com/ourengines4.html

[madmaxx]

Heck a polished roush 427 is touching $15k, throw in the billet valve covers and you are easily over $15K.

Just because I am a glutant for punishment my next one will have a big block be it a new block etc. The problem with mine is the enigne is like a timex watch it starts and runs everytime, doesnt leak a drop and I can smoke the tires going into third. Gas mileage suks at about 12 mpg, I need a bigger tank. I did drive a spf with a 460 in once, definetly had more torque on the low end but each one can easily burn the tires off the rim in 1st gear, With the 460 you could let out the clutch with no gas and the engine speed would not even dip but it had nothing at the upper end and was a dog. Not a big difference in sound although spf side pipes are on the quite side, which I like.

Originally Posted by patrickt

It's going to be over $10k for a 390 and, depending on whether it's a 428 or 427, whether it's an original iron block, or a new block, and what you have in it, you're going to get closer to $15k, or even $20k for a top of the line build. No, I'm not kidding. And even for a "top o' the line" FE build there's a tremendous amount of luck involved on whether it runs the way you want, doesn't leak, and doesn't break all the time.

EDIT: A lot of builders will undercut Keith Craft and still do a fine job, but his prices will at least give you a feel for what you're dealing with: http://www.keithcraft.com/ourengines4.html

[patrickt]

Originally Posted by madmaxx

Heck a polished roush 427 is touching $15k, throw in the billet valve covers and you are easily over $15K.

Some of the more expensive FE builds (that I know of, that is) come from Roush. Some of the readers here might enjoy perusing the cost of the different Roush engines. http://www.mustangdepot.com/OnLineCa...ne-pricing.htm

[PANAVIA]

The link that patrickt has put up is a HTML version of the XLS that ROUSH dealers get as a guideline for retail pricing of the motors. -- it dates from 2008.

(your mileage may vary)

[RICK LAKE]

mattpatt There are a couple of things left out besides weight.
#1 if you are going to build a motor, what are the heads made out of?? iron or Aluminum? Same for the intake. Cross matching runs into trouble over time. This is an iron and aluminum part. The expansion rates are not the same and cause leaks of coolant or oil. Either inside or out of the motor. IMO Stay with one metal.
#2 If you damage a block, window or spin a bearing. IMO alot easier to repair and reuse unless it's cracked down the main gallery of the block. Ford has had some problem withthis on the small blocks. These blocks are also thin wall motors like the 427. Aftermarket blocks have alot of room for stroker kits. 351 blocks are running 460 cubes and still getting bigger. Same for FE motors going to 527 and now almost 600 cubes.
#3 There are only a couple of Racers and builders making new parts for the FE motor which give the advantage to the 351 motor for better parts and cheaper. Nascar motors can be gotten used and need some work for street usage.
#4 Wieght wise my all aluminum shelby is 492 pounds with iron crank and steel rods. This is iron small block wieght with about 100-150 ft of extra torque. This is the last and main thing, build a motor with the broadest power band you can. For get about the HP numbers. Build TORQUE, this is what moves the car. Keep the rpm max around 6,000 rpms for and FE and 6,500 for a windsor and you will have many years for fun with low maintainance. Go for more power, higher rpms, and the life of the motor drops. Also have you ever driven a 2,500 pound car with a 500/500 hp torque car?? They are a handful. Rick L.

[patrickt]

Originally Posted by PANAVIA

The link that patrickt has put up is a HTML version of the XLS that ROUSH dealers get as a guideline for retail pricing of the motors. -- it dates from 2008.

(your mileage may vary)

I tried to find the prices that Shelby charges now to build FEs, but failed. I doubt it would be on the lower end of the scale, though.

[vector1]

Originally Posted by mattpatt

Definitely sounds like a waste of $s (for me) for an aluminum block. So are there any "little" reindeer games? <{:>))

the dart shp block is the new kid on the block and priced very competitively, i've seen them new $1600 shipped, would make a good basis for a 427 and be the one to use imo.

it's a pitty ol' shelby had to use a fe or these guys would be pushing something else.

[Cougar]

Rick, I have to disagree with your statement about torque... just a little. Of my 2 cars, I much prefer running my higher horsepower, higher rpm 347 motor over the mild but very torquey 392. The low rpm abundance of torque in the 392 just can't effectively be put to the ground in these light cars with street tires, but the high revs and strong upper end of my 347 is always amusing.
Matt, where is the battery in the SPF cars? If it is in the rear, like the FFRs, then there may be another pro to the aluminum. Go with an aluminum block, and move the battery to the front and you have shaved a significant amount of weight and better balanced the car. If you plan to do any autocrossing, I would think that it should definitely have a real and measurable effect.
Have you seen the 2010 FRPP catalog? They have a new aluminum 4 bolt small block crate motor announced on page 77, but there is no power or pricing set yet. On the next page they have the same spec motor in iron; 535 hp and 545 ft-lb for $8800 (a steal!). Once Ford announces the price for the aluminum crate, and the weight of both, you will have a direct comparison.
Peter